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Mu Y, Jia X, Ye Z, Zha T, Guo X, Black TA, Zhang Y, Hao S, Han C, Gao S, Qin S, Liu P, Tian Y. Dry-season length affects the annual ecosystem carbon balance of a temperate semi-arid shrubland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170532. [PMID: 38296104 DOI: 10.1016/j.scitotenv.2024.170532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 12/25/2023] [Accepted: 01/26/2024] [Indexed: 02/03/2024]
Abstract
Semi-arid ecosystems have been shown to dominate over tropical forests in determining the trend and interannual variability of land carbon (C) sink. However, the magnitude and variability of ecosystem C balance remain largely uncertain for temperate semi-arid shrublands at the decadal scale. Using eddy-covariance and micro-meteorological measurements, we quantified the interannual variation in net ecosystem production (NEP) and its components, gross primary production (GPP) and ecosystem respiration (Reco, i.e., the sum of autotrophic and heterotrophic respiration), in a semi-arid shrubland of the Mu Us Desert, northern China during 2012-2022. This shrubland was an overall weak C sink over the 11 years (NEP = 12 ± 46 g C m-2 yr-1, mean ± SD). Annual NEP ranged from -66 to 77 g C m-2 yr-1, with the ecosystem frequently switching between being an annual C sink and a C source. GPP was twice as sensitive as Reco to prolonged dry seasons, leading to a close negative relationship between annual NEP and dry-season length (R2 = 0.80, P < 0.01). Annual GPP (R2 = 0.51, P = 0.01) and NEP (R2 = 0.58, P < 0.01) were positively correlated with annual rainfall. Negative annual NEP (the ecosystem being a C source) tended to occur when the dry season exceeded 50 d yr-1 or rainfall dropped below 280 mm yr-1. Increases in dry-season length strengthened the effects of low soil moisture relative to high vapor pressure deficit in constraining NEP. Both GPP and NEP were more closely correlated with C uptake amplitude (annual maximum daily values) than with C uptake period. These findings indicate that dry-season extension under climate change may reduce the long-term C sequestration in semi-arid shrublands. Plant species adapted to prolonged dry seasons should be used in ecosystem restoration in the studied area to enhance ecosystem functions.
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Affiliation(s)
- Yanmei Mu
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
| | - Xin Jia
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Key Laboratory for Soil and Water Conservation, National Forestry and Grassland Administration, Beijing Forestry University, Beijing 100083, China.
| | - Ziqi Ye
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada
| | - Tianshan Zha
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Key Laboratory for Soil and Water Conservation, National Forestry and Grassland Administration, Beijing Forestry University, Beijing 100083, China
| | - Xulin Guo
- Department of Geography and Planning, University of Saskatchewan, Saskatoon, SK S7N 5C8, Canada
| | - T Andrew Black
- Biometeorology and Soil Physics Group, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Yuqing Zhang
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Key Laboratory for Soil and Water Conservation, National Forestry and Grassland Administration, Beijing Forestry University, Beijing 100083, China
| | - Shaorong Hao
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
| | - Cong Han
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
| | - Shengjie Gao
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
| | - Shugao Qin
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; Key Laboratory for Soil and Water Conservation, National Forestry and Grassland Administration, Beijing Forestry University, Beijing 100083, China
| | - Peng Liu
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Key Laboratory for Soil and Water Conservation, National Forestry and Grassland Administration, Beijing Forestry University, Beijing 100083, China
| | - Yun Tian
- Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China
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Zheng Y, Du S, Sun W, Feng C, Su Q. Spatiotemporal patterns of net regional productivity and its causes throughout Ordos, China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:22038-22054. [PMID: 38400969 DOI: 10.1007/s11356-024-32368-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 02/03/2024] [Indexed: 02/26/2024]
Abstract
A comprehensive understanding of the terrestrial carbon sink is essential for proficient regional carbon management. However, previous studies predominantly relied on net ecosystem productivity (NEP) as an indicator of regional carbon sink, overlooking the impacts of carbon emissions from physical processes and carbon leakage associated with anthropogenic activities. In this study, net region productivity (NRP), a vital metric representing carbon sink dynamics in regional multi-landscape ecosystems, was employed to systematically analyze the patterns, trends, and causes of carbon sink in Ordos. The results revealed that spatially averaged NRP in Ordos was 70.334 g·m-2·a-1, indicating a carbon sink effect. The coefficient of variation of NRP was 68.035%, with a higher NRP in the southern region. Normalized difference vegetation index (NDVI) predominantly controlled the spatial heterogeneity of NRP in Ordos, while precipitation emerged as the primary climatic factor influencing spatial differences in NRP. Regional variations in the impact of environmental factors on NRP were evident. In most areas, NRP showed a notable increasing trend influenced by various factors. Specifically, the simultaneous rise in NDVI and improvements in hydrothermal conditions contributed to the gradual elevation of NRP, each with varying degrees of influence across Ordos and its sub-regions.
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Affiliation(s)
- Yurong Zheng
- College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China
| | - Shouhang Du
- College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China.
| | - Wenbin Sun
- College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China
| | - Cui Feng
- College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China
| | - Qing Su
- College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China
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3
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Zhang MY, Ma YJ, Chen P, Shi FZ, Wei JQ. Growing-season carbon budget of alpine meadow ecosystem in the Qinghai Lake Basin: a continued carbon sink through this century according to the Biome-BGC model. CARBON BALANCE AND MANAGEMENT 2023; 18:25. [PMID: 38112828 PMCID: PMC10729358 DOI: 10.1186/s13021-023-00244-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 12/09/2023] [Indexed: 12/21/2023]
Abstract
BACKGROUND The alpine meadow is one of the most important ecosystems in the Qinghai-Tibet Plateau (QTP), and critically sensitive to climate change and human activities. Thus, it is crucial to precisely reveal the current state and predict future trends in the carbon budget of the alpine meadow ecosystem. The objective of this study was to explore the applicability of the Biome-BGC model (BBGC) in the Qinghai Lake Basin (QLB), identify the key parameters affecting the variation of net ecosystem exchange (NEE), and further predict the future trends in carbon budget in the QLB. RESULTS The alpine meadow mainly acted as carbon sink during the growing season. For the eco-physiological factors, the YEL (Yearday to end litterfall), YSNG (Yearday to start new growth), CLEC (Canopy light extinction coefficient), FRC:LC (New fine root C: new leaf C), SLA (Canopy average specific leaf area), C:Nleaf (C:N of leaves), and FLNR (Fraction of leaf N in Rubisco) were confirmed to be the top seven parameters affecting carbon budget of the alpine meadow. For the meteorological factors, the sensitivity of NEE to precipitation was greater than that to vapor pressure deficit (VPD), and it was greater to radiation than to air temperature. Moreover, the combined effect of two different meteorological factors on NEE was higher than the individual effect of each one. In the future, warming and wetting would enhance the carbon sink capacity of the alpine meadow during the growing season, but extreme warming (over 3.84 ℃) would reduce NEE (about 2.9%) in the SSP5-8.5 scenario. CONCLUSION Overall, the alpine meadow ecosystem in the QLB generally performs as a carbon sink at present and in the future. It is of great significance for the achievement of the goal of carbon neutrality and the management of alpine ecosystems.
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Affiliation(s)
- Meng-Ya Zhang
- School of Geography and Planning, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Yu-Jun Ma
- School of Geography and Planning, Sun Yat-Sen University, Guangzhou, 510275, China.
| | - Peng Chen
- School of Geography and Planning, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Fang-Zhong Shi
- School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Jun-Qi Wei
- School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
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4
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Zhang Y, Fang J, Smith WK, Wang X, Gentine P, Scott RL, Migliavacca M, Jeong S, Litvak M, Zhou S. Satellite solar-induced chlorophyll fluorescence tracks physiological drought stress development during 2020 southwest US drought. GLOBAL CHANGE BIOLOGY 2023; 29:3395-3408. [PMID: 36929655 DOI: 10.1111/gcb.16683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 03/13/2023] [Indexed: 05/16/2023]
Abstract
Monitoring and estimating drought impact on plant physiological processes over large regions remains a major challenge for remote sensing and land surface modeling, with important implications for understanding plant mortality mechanisms and predicting the climate change impact on terrestrial carbon and water cycles. The Orbiting Carbon Observatory 3 (OCO-3), with its unique diurnal observing capability, offers a new opportunity to track drought stress on plant physiology. Using radiative transfer and machine learning modeling, we derive a metric of afternoon photosynthetic depression from OCO-3 solar-induced chlorophyll fluorescence (SIF) as an indicator of plant physiological drought stress. This unique diurnal signal enables a spatially explicit mapping of plants' physiological response to drought. Using OCO-3 observations, we detect a widespread increasing drought stress during the 2020 southwest US drought. Although the physiological drought stress is largely related to the vapor pressure deficit (VPD), our results suggest that plants' sensitivity to VPD increases as the drought intensifies and VPD sensitivity develops differently for shrublands and grasslands. Our findings highlight the potential of using diurnal satellite SIF observations to advance the mechanistic understanding of drought impact on terrestrial ecosystems and to improve land surface modeling.
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Affiliation(s)
- Yao Zhang
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing, China
- Institute of Carbon Neutrality, Peking University, Beijing, China
| | - Jianing Fang
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing, China
- Department of Earth and Environmental Engineering, Columbia University, New York, New York, USA
| | - William Kolby Smith
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - Xian Wang
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, New York, USA
| | - Russell L Scott
- Southwest Watershed Research Center, USDA Agricultural Research Service, Tucson, Arizona, USA
| | | | - Sujong Jeong
- Department of Environmental Planning, Graduate School of Environmental Studies, Seoul National University, Seoul, South Korea
| | - Marcy Litvak
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Sha Zhou
- State Key Laboratory of Earth Surface Processes and Resources Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, China
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5
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Müller LM, Bahn M. Drought legacies and ecosystem responses to subsequent drought. GLOBAL CHANGE BIOLOGY 2022; 28:5086-5103. [PMID: 35607942 PMCID: PMC9542112 DOI: 10.1111/gcb.16270] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 04/29/2022] [Accepted: 05/03/2022] [Indexed: 05/19/2023]
Abstract
Climate change is expected to increase the frequency and severity of droughts. These events, which can cause significant perturbations of terrestrial ecosystems and potentially long-term impacts on ecosystem structure and functioning after the drought has subsided are often called 'drought legacies'. While the immediate effects of drought on ecosystems have been comparatively well characterized, our broader understanding of drought legacies is just emerging. Drought legacies can relate to all aspects of ecosystem structure and functioning, involving changes at the species and the community scale as well as alterations of soil properties. This has consequences for ecosystem responses to subsequent drought. Here, we synthesize current knowledge on drought legacies and the underlying mechanisms. We highlight the relevance of legacy duration to different ecosystem processes using examples of carbon cycling and community composition. We present hypotheses characterizing how intrinsic (i.e. biotic and abiotic properties and processes) and extrinsic (i.e. drought timing, severity, and frequency) factors could alter resilience trajectories under scenarios of recurrent drought events. We propose ways for improving our understanding of drought legacies and their implications for subsequent drought events, needed to assess the longer-term consequences of droughts on ecosystem structure and functioning.
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Affiliation(s)
- Lena M. Müller
- Department of EcologyUniversity of InnsbruckInnsbruckAustria
| | - Michael Bahn
- Department of EcologyUniversity of InnsbruckInnsbruckAustria
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WUE and CO2 Estimations by Eddy Covariance and Remote Sensing in Different Tropical Biomes. REMOTE SENSING 2022. [DOI: 10.3390/rs14143241] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The analysis of gross primary production (GPP) is crucial to better understand CO2 exchanges between terrestrial ecosystems and the atmosphere, while the quantification of water-use efficiency (WUE) allows for the estimation of the compensation between carbon gained and water lost by the ecosystem. Understanding these dynamics is essential to better comprehend the responses of environments to ongoing climatic changes. The objective of the present study was to analyze, through AMERIFLUX and LBA network measurements, the variability of GPP and WUE in four distinct tropical biomes in Brazil: Pantanal, Amazonia, Caatinga and Cerrado (savanna). Furthermore, data measured by eddy covariance systems were used to assess remotely sensed GPP products (MOD17). We found a distinct seasonality of meteorological variables and energy fluxes with different latent heat controls regarding available energy in each site. Remotely sensed GPP was satisfactorily related with observed data, despite weak correlations in interannual estimates and consistent overestimations and underestimations during certain months. WUE was strongly dependent on water availability, with values of 0.95 gC kg−1 H2O (5.79 gC kg−1 H2O) in the wetter (drier) sites. These values reveal new thresholds that had not been previously reported in the literature. Our findings have crucial implications for ecosystem management and the design of climate policies regarding the conservation of tropical biomes, since WUE is expected to change in the ongoing climate change scenario that indicates an increase in frequency and severity of dry periods.
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7
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Hossain ML, Kabir MH, Nila MUS, Rubaiyat A. Response of grassland net primary productivity to dry and wet climatic events in four grassland types in Inner Mongolia. PLANT-ENVIRONMENT INTERACTIONS (HOBOKEN, N.J.) 2021; 2:250-262. [PMID: 37284512 PMCID: PMC10168099 DOI: 10.1002/pei3.10064] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/11/2021] [Accepted: 09/27/2021] [Indexed: 06/08/2023]
Abstract
Increasing frequency and intensity of climate extremes have profound impacts on grassland biodiversity functioning and stability. Using Moderate Resolution Imaging Spectroradiometer (MODIS) net primary productivity (NPP) data and standardized precipitation evapotranspiration index, we assessed the response of NPP to growing-season and annual climate extremes and time-lag of climatic conditions across four grassland types (meadow steppe, typical steppe, steppe desert, and desert steppe) in Inner Mongolia, China from the period 2000 to 2019. Results showed that annual NPP varied significantly across four grassland types, with the highest NPP in meadow steppe and the lowest in desert steppe. Annual NPP of all grassland types increased over the past 20 years, but NPP in meadow steppe and typical steppe decreased for the period 2012-2019. Irrespective of grassland type, the 1- and 2-month time-lag of climatic conditions showed significant effects on annual NPP. Growing-season climate was found the better predictor of annual NPP in all grassland types than the annual climate. Compared with growing-season normal climates, annual NPP was lowest in extreme dry events in all grasslands, while highest in extreme wet events in meadow steppe and typical steppe, and in moderate wet events in steppe desert and desert steppe. Typical steppe and steppe desert are highly vulnerable to the increasing intensity of climate extremes, as we found that the losses of NPP in these grasslands in extreme dry were almost double than that of moderate dry events. Surprisingly, for meadow steppe and desert steppe, the losses of NPP for both moderate and extreme dry events were almost the same, which highlights that a low-intensity drought may have profound impacts on the annual NPP of these grasslands. The study provides the key insight in scientific basis to improve our understanding of the effects of climate extremes on grassland NPP, which is critical to sustainable management of grassland and maintain ecosystem stability.
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Affiliation(s)
- Md Lokman Hossain
- Department of Environment Protection TechnologyGerman University BangladeshGazipurBangladesh
- Department of GeographyHong Kong Baptist UniversityHong Kong
| | - Md Humayain Kabir
- Institute of Forestry and Environmental SciencesUniversity of ChittagongChittagongBangladesh
- Wegener Center for Climate and Global ChangeUniversity of GrazGrazAustria
| | - Mst Umme Salma Nila
- CEN Centre for Earth System Research and SustainabilityInstitute of GeographyUniversity of HamburgHamburgGermany
| | - Ashik Rubaiyat
- Burckhardt Institute, Tropical Silviculture and Forest Ecology, Faculty of Forest Sciences and Forest EcologyUniversity of GöttingenGöttingenGermany
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8
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Haberstroh S, Caldeira MC, Lobo-do-Vale R, Martins JI, Moemken J, Pinto JG, Werner C. Nonlinear plant-plant interactions modulate impact of extreme drought and recovery on a Mediterranean ecosystem. THE NEW PHYTOLOGIST 2021; 231:1784-1797. [PMID: 34076289 DOI: 10.1111/nph.17522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/20/2021] [Indexed: 06/12/2023]
Abstract
Interaction effects of different stressors, such as extreme drought and plant invasion, can have detrimental effects on ecosystem functioning and recovery after drought. With ongoing climate change and increasing plant invasion, there is an urgent need to predict the short- and long-term interaction impacts of these stressors on ecosystems. We established a combined precipitation exclusion and shrub invasion (Cistus ladanifer) experiment in a Mediterranean cork oak (Quercus suber) ecosystem with four treatments: (1) Q. suber control; (2) Q. suber with rain exclusion; (3) Q. suber invaded by shrubs; and (4) Q. suber with rain exclusion and shrub invasion. As key parameter, we continuously measured ecosystem water fluxes. In an average precipitation year, the interaction effects of both stressors were neutral. However, the combination of imposed drought and shrub invasion led to amplifying interaction effects during an extreme drought by strongly reducing tree transpiration. Contrarily, the imposed drought reduced the competitiveness of the shrubs in the following recovery period, which buffered the negative effects of shrub invasion on Q. suber. Our results demonstrate the highly dynamic and nonlinear effects of interacting stressors on ecosystems and urges for further investigations on biotic interactions in a context of climate change pressures.
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Affiliation(s)
- Simon Haberstroh
- Ecosystem Physiology, Faculty of Environment and Natural Resources, University Freiburg, Freiburg, 79110, Germany
- Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Maria C Caldeira
- Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Raquel Lobo-do-Vale
- Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Joana I Martins
- Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Julia Moemken
- Institute for Meteorology and Climate Research (IMK-TRO), Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Joaquim G Pinto
- Institute for Meteorology and Climate Research (IMK-TRO), Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Christiane Werner
- Ecosystem Physiology, Faculty of Environment and Natural Resources, University Freiburg, Freiburg, 79110, Germany
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9
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Assessment of Drought Impact on Net Primary Productivity in the Terrestrial Ecosystems of Mongolia from 2003 to 2018. REMOTE SENSING 2021. [DOI: 10.3390/rs13132522] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Drought has devastating impacts on agriculture and other ecosystems, and its occurrence is expected to increase in the future. However, its spatiotemporal impacts on net primary productivity (NPP) in Mongolia have remained uncertain. Hence, this paper focuses on the impact of drought on NPP in Mongolia. The drought events in Mongolia during 2003–2018 were identified using the Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI). The Boreal Ecosystem Productivity Simulator (BEPS)-derived NPP was computed to assess changes in NPP during the 16 years, and the impacts of drought on the NPP of Mongolian terrestrial ecosystems was quantitatively analyzed. The results showed a slightly increasing trend of the growing season NPP during 2003–2018. However, a decreasing trend of NPP was observed during the six major drought events. A total of 60.55–87.75% of land in the entire country experienced drought, leading to a 75% drop in NPP. More specifically, NPP decline was prominent in severe drought areas than in mild and moderate drought areas. Moreover, this study revealed that drought had mostly affected the sparse vegetation NPP. In contrast, forest and shrubland were the least affected vegetation types.
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10
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Niu B, Zhang X, Piao S, Janssens IA, Fu G, He Y, Zhang Y, Shi P, Dai E, Yu C, Zhang J, Yu G, Xu M, Wu J, Zhu L, Desai AR, Chen J, Bohrer G, Gough CM, Mammarella I, Varlagin A, Fares S, Zhao X, Li Y, Wang H, Ouyang Z. Warming homogenizes apparent temperature sensitivity of ecosystem respiration. SCIENCE ADVANCES 2021; 7:7/15/eabc7358. [PMID: 33837072 PMCID: PMC8034862 DOI: 10.1126/sciadv.abc7358] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 02/24/2021] [Indexed: 06/02/2023]
Abstract
Warming-induced carbon loss through terrestrial ecosystem respiration (Re) is likely getting stronger in high latitudes and cold regions because of the more rapid warming and higher temperature sensitivity of Re (Q 10). However, it is not known whether the spatial relationship between Q 10 and temperature also holds temporally under a future warmer climate. Here, we analyzed apparent Q 10 values derived from multiyear observations at 74 FLUXNET sites spanning diverse climates and biomes. We found warming-induced decline in Q 10 is stronger at colder regions than other locations, which is consistent with a meta-analysis of 54 field warming experiments across the globe. We predict future warming will shrink the global variability of Q 10 values to an average of 1.44 across the globe under a high emission trajectory (RCP 8.5) by the end of the century. Therefore, warming-induced carbon loss may be less than previously assumed because of Q 10 homogenization in a warming world.
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Affiliation(s)
- Ben Niu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xianzhou Zhang
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Shilong Piao
- College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
- Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China
| | - Ivan A Janssens
- Department of Biology, University of Antwerpen, Universiteitsplein 1, Wilrijk B-2610, Belgium
| | - Gang Fu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Yongtao He
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yangjian Zhang
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Peili Shi
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Erfu Dai
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Chengqun Yu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Jing Zhang
- College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China
| | - Guirui Yu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Ming Xu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Jianshuang Wu
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, 100081 Beijing, China
| | - Liping Zhu
- Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China
| | - Ankur R Desai
- Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jiquan Chen
- Department of Geography, Michigan State University, East Lansing, MI 48823, USA
| | - Gil Bohrer
- Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Christopher M Gough
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284-2012, USA
| | - Ivan Mammarella
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, P.O. Box 68, Helsinki FI-00014, Finland
| | - Andrej Varlagin
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow 119071, Russia
| | - Silvano Fares
- National Research Council of Italy, Institute of BioEconomy, Via dei Taurini 19, 00100 Rome, Italy
| | - Xinquan Zhao
- Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
| | - Yingnian Li
- Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
| | - Huiming Wang
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhu Ouyang
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
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11
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Actual Evapotranspiration Estimates in Arid Cold Regions Using Machine Learning Algorithms with In Situ and Remote Sensing Data. WATER 2021. [DOI: 10.3390/w13060870] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Actual evapotranspiration (ETa) estimations in arid regions are challenging because this process is highly dynamic over time and space. Nevertheless, several studies have shown good results when implementing empirical regression formulae that, despite their simplicity, are comparable in accuracy to more complex models. Although many types of regression formulae to estimate ETa exist, there is no consensus on what variables must be included in the analysis. In this research, we used machine learning algorithms—through implementation of empirical linear regression formulae—to find the main variables that control daily and monthly ETa in arid cold regions, where there is a lack of available ETa data. Meteorological data alone and then combined with remote sensing vegetation indices (VIs) were used as input in ETa estimations. In situ ETa and meteorological data were obtained from ten sites in Chile, Australia, and the United States. Our results indicate that the available energy is the main meteorological variable that controls ETa in the assessed sites, despite the fact that these regions are typically described as water-limited environments. The VI that better represents the in situ ETa is the Normalized Difference Water Index, which represents water availability in plants and soils. The best performance of the regression equations in the validation sites was obtained for monthly estimates with the incorporation of VIs (R2 = 0.82), whereas the worst performance of these equations was obtained for monthly ETa estimates when only meteorological data were considered. Incorporation of remote-sensing information results in better ETa estimates compared to when only meteorological data are considered.
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12
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Tramontana G, Migliavacca M, Jung M, Reichstein M, Keenan TF, Camps‐Valls G, Ogee J, Verrelst J, Papale D. Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks. GLOBAL CHANGE BIOLOGY 2020; 26:5235-5253. [PMID: 32497360 PMCID: PMC7496462 DOI: 10.1111/gcb.15203] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 04/28/2020] [Indexed: 06/11/2023]
Abstract
The eddy covariance (EC) technique is used to measure the net ecosystem exchange (NEE) of CO2 between ecosystems and the atmosphere, offering a unique opportunity to study ecosystem responses to climate change. NEE is the difference between the total CO2 release due to all respiration processes (RECO), and the gross carbon uptake by photosynthesis (GPP). These two gross CO2 fluxes are derived from EC measurements by applying partitioning methods that rely on physiologically based functional relationships with a limited number of environmental drivers. However, the partitioning methods applied in the global FLUXNET network of EC observations do not account for the multiple co-acting factors that modulate GPP and RECO flux dynamics. To overcome this limitation, we developed a hybrid data-driven approach based on combined neural networks (NNC-part ). NNC-part incorporates process knowledge by introducing a photosynthetic response based on the light-use efficiency (LUE) concept, and uses a comprehensive dataset of soil and micrometeorological variables as fluxes drivers. We applied the method to 36 sites from the FLUXNET2015 dataset and found a high consistency in the results with those derived from other standard partitioning methods for both GPP (R2 > .94) and RECO (R2 > .8). High consistency was also found for (a) the diurnal and seasonal patterns of fluxes and (b) the ecosystem functional responses. NNC-part performed more realistic than the traditional methods for predicting additional patterns of gross CO2 fluxes, such as: (a) the GPP response to VPD, (b) direct effects of air temperature on GPP dynamics, (c) hysteresis in the diel cycle of gross CO2 fluxes, (d) the sensitivity of LUE to the diffuse to direct radiation ratio, and (e) the post rain respiration pulse after a long dry period. In conclusion, NNC-part is a valid data-driven approach to provide GPP and RECO estimates and complementary to the existing partitioning methods.
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Affiliation(s)
- Gianluca Tramontana
- DIBAFDepartment for Innovation in BiologicalAgro‐food and Forestry SystemsUniversity of TusciaViterboItaly
- Image Processing Laboratory (IPL)Parc Científic Universitat de ValènciaUniversitat de ValènciaPaternaSpain
| | | | - Martin Jung
- Max Planck Institute for BiogeochemistryJenaGermany
| | | | - Trevor F. Keenan
- Department of Environmental Science, Policy and ManagementUC BerkeleyBerkeleyCAUSA
- Earth and Environmental Sciences AreaLawrence Berkeley National LabBerkeleyCAUSA
| | - Gustau Camps‐Valls
- Image Processing Laboratory (IPL)Parc Científic Universitat de ValènciaUniversitat de ValènciaPaternaSpain
| | | | - Jochem Verrelst
- Image Processing Laboratory (IPL)Parc Científic Universitat de ValènciaUniversitat de ValènciaPaternaSpain
| | - Dario Papale
- DIBAFDepartment for Innovation in BiologicalAgro‐food and Forestry SystemsUniversity of TusciaViterboItaly
- Euro‐Mediterranean Center on Climate Change (CMCC)ViterboItaly
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13
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Performance of the Remotely-Derived Products in Monitoring Gross Primary Production across Arid and Semi-Arid Ecosystems in Northwest China. LAND 2020. [DOI: 10.3390/land9090288] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
As an important component to quantify the carbon budget, accurate evaluation of terrestrial gross primary production (GPP) is crucial for large-scale applications, especially in dryland ecosystems. Based on the in situ data from six flux sites in northwestern China from 2014 to 2016, this study compares seasonal and interannual dynamics of carbon fluxes between these arid and semi-arid ecosystems and the atmosphere. Meanwhile, the reliability of multiple remotely-derived GPP products in representative drylands was examined, including the Breathing Earth System Simulator (BESS), the Moderate Resolution Imaging Spectroradiometer (MODIS) and data derived from the OCO-2 solar-induced chlorophyll fluorescence (GOSIF). The results indicated that the carbon fluxes had clear seasonal patterns, with all ecosystems functioning as carbon sinks. The maize cropland had the highest GPP with 1183 g C m−2 y−1. Although the net ecosystem carbon exchange (NEE) in the Tamarix spp. ecosystem was the smallest among these flux sites, it reached 208 g C m−2 y−1. Furthermore, distinct advantages of GOSIF GPP (with R2 = 0.85–0.98, and RMSE = 0.87–2.66 g C m−2 d−1) were found with good performance. However, large underestimations in three GPP products existed during the growing seasons, except in grassland ecosystems. The main reasons can be ascribed to the uncertainties in the key model parameters, including the underestimated light use efficiency of the MODIS GPP, the same coarse land cover product for the BESS and MODIS GPP, the coarse gridded meteorological data, and distribution of C3 and C4 plants. Therefore, it still requires more work to accurately quantify the GPP across these dryland ecosystems.
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14
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Modelling High-Resolution Actual Evapotranspiration through Sentinel-2 and Sentinel-3 Data Fusion. REMOTE SENSING 2020. [DOI: 10.3390/rs12091433] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Sentinel-2 and Sentinel-3 satellite constellation contains most of the spatial, temporal and spectral characteristics required for accurate, field-scale actual evapotranspiration (ET) estimation. The one remaining major challenge is the spatial scale mismatch between the thermal-infrared observations acquired by the Sentinel-3 satellites at around 1 km resolution and the multispectral shortwave observations acquired by the Sentinel-2 satellite at around 20 m resolution. In this study we evaluate a number of approaches for bridging this gap by improving the spatial resolution of the thermal images. The resulting data is then used as input into three ET models, working under different assumptions: TSEB, METRIC and ESVEP. Latent, sensible and ground heat fluxes as well as net radiation produced by the models at 20 m resolution are validated against observations coming from 11 flux towers located in various land covers and climatological conditions. The results show that using the sharpened high-resolution thermal data as input for the TSEB model is a sound approach with relative root mean square error of instantaneous latent heat flux of around 30% in agricultural areas. The proposed methodology is a promising solution to the lack of thermal data with high spatio-temporal resolution required for field-scale ET modelling and can fill this data gap until next generation of thermal satellites are launched.
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15
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Pei Y, Dong J, Zhang Y, Yang J, Zhang Y, Jiang C, Xiao X. Performance of four state-of-the-art GPP products (VPM, MOD17, BESS and PML) for grasslands in drought years. ECOL INFORM 2020. [DOI: 10.1016/j.ecoinf.2020.101052] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Maurer GE, Hallmark AJ, Brown RF, Sala OE, Collins SL. Sensitivity of primary production to precipitation across the United States. Ecol Lett 2020; 23:527-536. [DOI: 10.1111/ele.13455] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/03/2019] [Accepted: 12/17/2019] [Indexed: 12/01/2022]
Affiliation(s)
- Gregory E. Maurer
- Department of Environmental Science, Policy, and Management University of California, Berkeley Berkeley CA 94720 USA
| | | | - Renée F. Brown
- Department of Biology University of New Mexico Albuquerque NM 87131 USA
| | - Osvaldo E. Sala
- School of Life Sciences Arizona State University Tempe AZ 85287 USA
- School of Sustainability Arizona State University Tempe AZ 85287 USA
- Global Drylands Center Arizona State University Tempe AZ 85287 USA
| | - Scott L. Collins
- Department of Biology University of New Mexico Albuquerque NM 87131 USA
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17
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Massmann A, Gentine P, Lin C. When Does Vapor Pressure Deficit Drive or Reduce Evapotranspiration? JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS 2019; 11:3305-3320. [PMID: 31894191 PMCID: PMC6919419 DOI: 10.1029/2019ms001790] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 09/06/2019] [Accepted: 09/12/2019] [Indexed: 05/30/2023]
Abstract
Increasing vapor pressure deficit (VPD) increases atmospheric demand for water. While increased evapotranspiration (ET) in response to increased atmospheric demand seems intuitive, plants are capable of reducing ET in response to increased VPD by closing their stomata. We examine which effect dominates the response to increasing VPD: atmospheric demand and increases in ET or plant response (stomata closure) and decreases in ET. We use Penman-Monteith, combined with semiempirical optimal stomatal regulation theory and underlying water use efficiency, to develop a theoretical framework for assessing ET response to VPD. The theory suggests that depending on the environment and plant characteristics, ET response to increasing VPD can vary from strongly decreasing to increasing, highlighting the diversity of plant water regulation strategies. The ET response varies due to (1) climate, with tropical and temperate climates more likely to exhibit a positive ET response to increasing VPD than boreal and arctic climates; (2) photosynthesis strategy, with C3 plants more likely to exhibit a positive ET response than C4 plants; and (3) plant type, with crops more likely to exhibit a positive ET response, and shrubs and gymniosperm trees more likely to exhibit a negative ET response. These results, derived from previous literature connecting plant parameters to plant and climate characteristics, highlight the utility of our simplified framework for understanding complex land-atmosphere systems in terms of idealized scenarios in which ET responds to VPD only. This response is otherwise challenging to assess in an environment where many processes coevolve together.
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Affiliation(s)
- Adam Massmann
- Department of Earth and Environmental EngineeringColumbia UniversityNew YorkNYUSA
| | - Pierre Gentine
- Department of Earth and Environmental EngineeringColumbia UniversityNew YorkNYUSA
| | - Changjie Lin
- Department of Earth and Environmental EngineeringColumbia UniversityNew YorkNYUSA
- State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic EngineeringTsinghua UniversityBeijingChina
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18
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Winkler DE, Belnap J, Hoover D, Reed SC, Duniway MC. Shrub persistence and increased grass mortality in response to drought in dryland systems. GLOBAL CHANGE BIOLOGY 2019; 25:3121-3135. [PMID: 31025434 DOI: 10.1111/gcb.14667] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 04/15/2019] [Indexed: 05/13/2023]
Abstract
Droughts in the southwest United States have led to major forest and grassland die-off events in recent decades, suggesting plant community and ecosystem shifts are imminent as native perennial grass populations are replaced by shrub- and invasive plant-dominated systems. These patterns are similar to those observed in arid and semiarid systems around the globe, but our ability to predict which species will experience increased drought-induced mortality in response to climate change remains limited. We investigated meteorological drought-induced mortality of nine dominant plant species in the Colorado Plateau Desert by experimentally imposing a year-round 35% precipitation reduction for eight continuous years. We distributed experimental plots across numerous plant, soil, and parent material types, resulting in 40 distinct sites across a 4,500 km2 region of the Colorado Plateau Desert. For all 8 years, we tracked c. 400 individual plants and evaluated mortality responses to treatments within and across species, and through time. We also examined the influence of abiotic and biotic site factors in driving mortality responses. Overall, high mortality trends were driven by dominant grass species, including Achnatherum hymenoides, Pleuraphis jamesii, and Sporobolus cryptandrus. Responses varied widely from year to year and dominant shrub species were generally resistant to meteorological drought, likely due to their ability to access deeper soil water. Importantly, mortality increased in the presence of invasive species regardless of treatment, and native plant die-off occurred even under ambient conditions, suggesting that recent climate changes are already negatively impacting dominant species in these systems. Results from this long-term drought experiment suggest major shifts in community composition and, as a result, ecosystem function. Patterns also show that, across multiple soil and plant community types, native perennial grass species may be replaced by shrubs and invasive annuals in the Colorado Plateau Desert.
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Affiliation(s)
- Daniel E Winkler
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah
| | - Jayne Belnap
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah
| | - David Hoover
- Rangeland Resources & Systems Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Fort Collins, Colorado
| | - Sasha C Reed
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah
| | - Michael C Duniway
- U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah
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19
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Li L, Zheng Z, Biederman JA, Xu C, Xu Z, Che R, Wang Y, Cui X, Hao Y. Ecological responses to heavy rainfall depend on seasonal timing and multi-year recurrence. THE NEW PHYTOLOGIST 2019; 223:647-660. [PMID: 30934122 DOI: 10.1111/nph.15832] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Accepted: 03/25/2019] [Indexed: 06/09/2023]
Abstract
Heavy rainfall events are expected to increase in frequency and severity in the future. However, their effects on natural ecosystems are largely unknown, in particular with different seasonal timing of the events and recurrence over multiple years. We conducted a 4 yr manipulative experiment to explore grassland response to heavy rainfall imposed in either the middle of, or late in, the growing season in Inner Mongolia, China. We measured hierarchical responses at individual, community and ecosystem levels. Surprisingly, above-ground biomass remained stable in the face of heavy rainfall, regardless of seasonal timing, whereas heavy rainfall late in the growing season had consistent negative impacts on below-ground and total biomass. However, such negative biomass effects were not significant for heavy rainfall in the middle of the growing season. By contrast, heavy rainfall in the middle of the growing season had greater positive effects on ecosystem CO2 exchanges, mainly reflected in the latter 2 yr of the 4 yr experiment. This two-stage response of CO2 fluxes was regulated by increased community-level leaf area and leaf-level photosynthesis and interannual variability of natural precipitation. Overall, our study demonstrates that ecosystem impacts of heavy rainfall events crucially depend on the seasonal timing and multiannual recurrence. Plant physiological and morphological adjustment appeared to improve the capacity of the ecosystem to respond positively to heavy rainfall.
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Affiliation(s)
- Linfeng Li
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Environmental Futures Research Institute, School of Environment and Science, Griffith University, Brisbane, Qld, 4111, Australia
| | - Zhenzhen Zheng
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Joel A Biederman
- Southwest Watershed Research Center, Agricultural Research Service, Tucson, AZ, 85719, USA
| | - Cong Xu
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhihong Xu
- Environmental Futures Research Institute, School of Environment and Science, Griffith University, Brisbane, Qld, 4111, Australia
| | - Rongxiao Che
- Institude of International Rivers and Eco-security, Yunnan University, Kunming, Yunnan, 650091, China
| | - Yanfen Wang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences (CAS), Beijing, 100101, China
| | - Xiaoyong Cui
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences (CAS), Beijing, 100101, China
| | - Yanbin Hao
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences (CAS), Beijing, 100101, China
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20
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Zhao H, Jia G, Wang H, Zhang A, Xu X. Seasonal and interannual variations in carbon fluxes in East Asia semi-arid grasslands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 668:1128-1138. [PMID: 31018453 DOI: 10.1016/j.scitotenv.2019.02.378] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/23/2019] [Accepted: 02/24/2019] [Indexed: 06/09/2023]
Abstract
Semiarid regions have substantial interannual variation in carbon exchange between terrestrial ecosystem and atmosphere but the diverse responses of carbon fluxes to climate variability are poorly known. We compared carbon exchange processes and the responses to environmental factors in a meadow steppe at Tongyu (TY) and a typical steppe at Maodeng (MD) using long-term continuous eddy covariance measurements. TY precipitation was 25% greater than MD. Both grasslands had interannual fluctuations of carbon sink and source and acted as weak carbon sinks averagely (-22.9 ± 41.0 gCm-2 yr-1 for TY and - 11.8 ± 45.0 gCm-2 yr-1 for MD). The seasonal dynamics of carbon fluxes were significantly related to water availability at MD but more strongly related to air temperature at TY. During dry years, the controlling effect of water availability on carbon fluxes increased. Summer precipitation and soil moisture played key roles in the interannual variations in carbon fluxes in both grasslands. At MD, net carbon uptake was negatively related to summer air temperature likely because warming induced water deficit decreased photosynthesis. Greenness index derived from PhenoCam images captured key phenological phases and diverse magnitude of canopy dynamics. The index was correlated with seasonal and annual variations in carbon fluxes at both grasslands, suggesting the potential of PhenoCam for monitoring the spatial and temporal variations in canopy dynamics in different semiarid grasslands.
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Affiliation(s)
- Huichen Zhao
- Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; University of Chinese Academy of Sciences, Beijing 101408, China
| | - Gensuo Jia
- Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
| | - Hesong Wang
- College of Forestry, Beijing Forestry University, Beijing 100083, China
| | - Anzhi Zhang
- Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
| | - Xiyan Xu
- Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
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21
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Bai J, Shi H, Yu Q, Xie Z, Li L, Luo G, Jin N, Li J. Satellite-observed vegetation stability in response to changes in climate and total water storage in Central Asia. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 659:862-871. [PMID: 31096416 DOI: 10.1016/j.scitotenv.2018.12.418] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/27/2018] [Accepted: 12/27/2018] [Indexed: 06/09/2023]
Abstract
Ecosystems in arid and semi-arid regions are vulnerable to climatic and anthropogenic disturbances. However, our understanding of vegetation stability (including resistance and resilience, which are the abilities of ecosystems to resist perturbations and return to pre-disturbance structure or function, respectively) in response to environmental changes in dryland ecosystems remains insufficient, particularly in the absence of large-scale observations of water availability. Here we introduced GRACE monthly total water storage anomaly (TWSA) data into an autoregressive model with remote sensed EVI, air temperature and precipitation to investigate the short-term vegetation stability and its influencing factors in Central Asia (CA) during 2003-2015. The results showed that the grid-level vegetation resilience in CA increased logarithmically as mean annual precipitation (R2 = 0.33, P < 0.05) but decreased linearly with increasing mean annual temperature (R2 = 0.41, P < 0.05). Vegetation resilience was not correlated with TWSA, due to the decoupling of TWSA with precipitation both spatially and temporally in the majority of CA. At the biome level, vegetation resilience also increased as a logarithmical function of aridity index (R2 = 0.80, P < 0.05). Vegetation resistance to TWSA showed minor difference across biomes, while vegetation resistance to precipitation functioned as a parabolic curve along the aridity gradient (R2 = 0.59, P < 0.05). Our results suggest that accounting for the effects of total water column instead of precipitation only is critical in understanding vegetation-water relationships in drylands. The steep decrease in vegetation resilience in areas with high temperature and low water availability implies a high risk of collapse for these water-limited ecosystems if there are severe droughts. Furthermore, reduction in total water storage, induced by, e.g., large-scale extraction of surface runoff or shallow-layer groundwater for irrigation, can result in negative influences to natural biomes in dryland regions.
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Affiliation(s)
- Jie Bai
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China
| | - Hao Shi
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A & F University, Yangling 712100, China.
| | - Qiang Yu
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A & F University, Yangling 712100, China; School of Life Sciences, University of Technology Sydney, Sydney 2000, Australia; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Zunyi Xie
- Centre for Biodiversity and Conservation Science, School of Earth and Environmental Sciences, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Longhui Li
- Key Laboratory of Virtual Geographic Environment of Ministry of Education, Nanjing Normal University, Nanjing 210023, China
| | - Geping Luo
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China
| | - Ning Jin
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A & F University, Yangling 712100, China
| | - Jun Li
- Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
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22
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Environmental and Vegetative Controls on Soil CO2 Efflux in Three Semiarid Ecosystems. SOIL SYSTEMS 2019. [DOI: 10.3390/soilsystems3010006] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Soil CO2 efflux (Fsoil) is a major component of the ecosystem carbon balance. Globally expansive semiarid ecosystems have been shown to influence the trend and interannual variability of the terrestrial carbon sink. Modeling Fsoil in water-limited ecosystems remains relatively difficult due to high spatial and temporal variability associated with dynamics in moisture availability and biological activity. Measurements of the processes underlying variability in Fsoil can help evaluate Fsoil models for water-limited ecosystems. Here we combine automated soil chamber and flux tower data with models to investigate how soil temperature (Ts), soil moisture (θ), and gross ecosystem photosynthesis (GEP) control Fsoil in semiarid ecosystems with similar climates and different vegetation types. Across grassland, shrubland, and savanna sites, θ regulated the relationship between Fsoil and Ts, and GEP influenced Fsoil magnitude. Thus, the combination of Ts, θ, and GEP controlled rates and patterns of Fsoil. In a root exclusion experiment at the grassland, we found that growing season autotrophic respiration accounted for 45% of Fsoil. Our modeling results indicate that a combination of Ts, θ, and GEP terms is required to model spatial and temporal dynamics in Fsoil, particularly in deeper-rooted shrublands and savannas where coupling between GEP and shallow θ is weaker than in grasslands. Together, these results highlight that including θ and GEP in Fsoil models can help reduce uncertainty in semiarid ecosystem carbon dynamics.
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Tang Y, Jiang J, Chen C, Chen Y, Wu X. Rainfall pulse response of carbon fluxes in a temperate grass ecosystem in the semiarid Loess Plateau. Ecol Evol 2018; 8:11179-11189. [PMID: 30519435 PMCID: PMC6262730 DOI: 10.1002/ece3.4587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 09/05/2018] [Accepted: 09/11/2018] [Indexed: 11/08/2022] Open
Abstract
Rainfall pulses can significantly influence carbon cycling in water-limited ecosystems. The magnitude of carbon flux component responses to precipitation may vary depending on precipitation amount and antecedent soil moisture, associated with nonlinear responses of plants and soil microbes. The present study was carried out in a temperate grass ecosystem during 2013-2015 in the semiarid Loess Plateau of China, to examine the response of carbon fluxes to precipitation using the "threshold-delay" model. The unique contribution of environmental variables such as precipitation amount and antecedent soil moisture before rainfall (SWC_antecedent) to carbon fluxes in response to rainfall was also investigated. The lower threshold of effective rainfall was 6.6 mm for gross ecosystem production (GEP), 8.5 mm for net ecosystem production (NEP), and 4.5 mm for ecosystem respiration (RE); and the upper threshold of effective rainfall was 21.4 mm for GEP and NEP, and 16.8 mm for RE. Rainfall amount was positively affected the relative rainfall responses of GEP, NEP, and RE. However, SWC_antecedent at 20 cm soil depth offset the response of GEP to rainfall pulses, and SWC_antecedent at 5 cm soil depth offset the response of NEP and RE to rainfall pulses, with corresponding partial slopes of linear regressions of -0.50, -0.40, and -0.52. These results indicated that NEP was more sensitive to rainfall pulses and RE was more sensitive to SWC_antecedent. These results demonstrate the importance of rainfall events of <10 mm and that the negative effect of SWC_antecedent should also be considered when estimating ecosystem carbon fluxes in this semiarid region.
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Affiliation(s)
- Yakun Tang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess PlateauInstitute of Soil and Water ConservationNorthwest A&F UniversityYanglingChina
| | - Jun Jiang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess PlateauInstitute of Soil and Water ConservationNorthwest A&F UniversityYanglingChina
| | - Chen Chen
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess PlateauInstitute of Soil and Water ConservationNorthwest A&F UniversityYanglingChina
| | - Yunming Chen
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess PlateauInstitute of Soil and Water ConservationNorthwest A&F UniversityYanglingChina
| | - Xu Wu
- State Key Laboratory of Soil Erosion and Dry‐land Farming on the Loess PlateauInstitute of Soil and Water ConservationChinese Academy of Sciences and the Ministry of Water ResourcesYanglingChina
- University of Chinese Academy of ScienceBeijingChina
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24
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Mojzes A, Ónodi G, Lhotsky B, Kalapos T, Csontos P, Kröel-Dulay G. Within-generation and transgenerational plasticity in growth and regeneration of a subordinate annual grass in a rainfall experiment. Oecologia 2018; 188:1059-1068. [PMID: 30276461 DOI: 10.1007/s00442-018-4264-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 09/25/2018] [Indexed: 11/25/2022]
Abstract
Precipitation changes may induce shifts in plant species or life form dominance in ecosystems, making some previously subordinate species abundant. The plasticity of certain plant functional traits of these expanding subordinate species may be one possible mechanism behind their success. In this study, we tested if the subordinate winter annual grass Secale sylvestre shows plasticity in growth and reproduction in response to altered environment associated with field-scale rainfall manipulations (severe drought, moderate drought, and watering) in a semiarid grassland, and whether the maternal environment influences offspring germination or growth in a subsequent pot experiment. Compared to control plots, S. sylvestre plants grew 38% taller, and produced 32% more seeds in severe drought plots, while plants in watered plots were 17% shorter, and had 22% less seeds. Seed mass was greatest in severe drought plots. Plants growing in drought plots had offspring with enhanced juvenile shoot growth compared to the progeny whose mother plants grew in watered plots. These responses are most likely explained by the decreased cover of previously dominant perennial grasses in severe drought plots, which resulted in wetter soil compared to control and watered plots during the peak growth of S. sylvestre. We conclude that the plasticity of this subordinate annual species in response to changing environment may help to gain dominance with recurring droughts that suppress perennial grasses. Our results highlight that exploring both within-generation and transgenerational plasticity of subordinate species may lead to a better prediction of changes in plant species dominance under climate change.
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Affiliation(s)
- Andrea Mojzes
- MTA Centre for Ecological Research, Institute of Ecology and Botany, Alkotmány u. 2-4, Vácrátót, 2163, Hungary.
| | - Gábor Ónodi
- MTA Centre for Ecological Research, Institute of Ecology and Botany, Alkotmány u. 2-4, Vácrátót, 2163, Hungary.,MTA Centre for Ecological Research, GINOP Sustainable Ecosystems Group, Klebelsberg Kuno u. 3, Tihany, 8237, Hungary
| | - Barbara Lhotsky
- MTA Centre for Ecological Research, Institute of Ecology and Botany, Alkotmány u. 2-4, Vácrátót, 2163, Hungary
| | - Tibor Kalapos
- Department of Plant Systematics, Ecology and Theoretical Biology, Institute of Biology, Eötvös Loránd University, Pázmány P. stny 1/C, Budapest, 1117, Hungary
| | - Péter Csontos
- MTA Centre for Agricultural Research, Institute for Soil Sciences and Agricultural Chemistry, Herman O. út 15, Budapest, 1022, Hungary
| | - György Kröel-Dulay
- MTA Centre for Ecological Research, Institute of Ecology and Botany, Alkotmány u. 2-4, Vácrátót, 2163, Hungary.,MTA Centre for Ecological Research, GINOP Sustainable Ecosystems Group, Klebelsberg Kuno u. 3, Tihany, 8237, Hungary
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25
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Ganjurjav H, Hu G, Wan Y, Li Y, Danjiu L, Gao Q. Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai-Tibetan Plateau. Ecol Evol 2018; 8:1507-1520. [PMID: 29435228 PMCID: PMC5792621 DOI: 10.1002/ece3.3741] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 11/07/2017] [Accepted: 11/26/2017] [Indexed: 11/26/2022] Open
Abstract
Climate is a driver of terrestrial ecosystem carbon exchange, which is an important product of ecosystem function. The Qinghai-Tibetan Plateau has recently been subjected to a marked increase in temperature as a consequence of global warming. To explore the effects of warming on carbon exchange in grassland ecosystems, we conducted a whole-year warming experiment between 2012 and 2014 using open-top chambers placed in an alpine meadow, an alpine steppe, and a cultivated grassland on the central Qinghai-Tibetan Plateau. We measured the gross primary productivity, net ecosystem CO 2 exchange (NEE), ecosystem respiration, and soil respiration using a chamber-based method during the growing season. The results show that after 3 years of warming, there was significant stimulation of carbon assimilation and emission in the alpine meadow, but both these processes declined in the alpine steppe and the cultivated grassland. Under warming conditions, the soil water content was more important in stimulating ecosystem carbon exchange in the meadow and cultivated grassland than was soil temperature. In the steppe, the soil temperature was negatively correlated with ecosystem carbon exchange. We found that the ambient soil water content was significantly correlated with the magnitude of warming-induced change in NEE. Under high soil moisture condition, warming has a significant positive effect on NEE, while it has a negative effect under low soil moisture condition. Our results highlight that the NEE in steppe and cultivated grassland have negative responses to warming; after reclamation, the natural meadow would subject to loose more C in warmer condition. Therefore, under future warmer condition, the overextension of cultivated grassland should be avoided and scientific planning of cultivated grassland should be achieved.
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Affiliation(s)
- Hasbagan Ganjurjav
- Institute of Environment and Sustainable Development in AgricultureChinese Academy of Agricultural SciencesBeijingChina
- Key Laboratory for Agro‐EnvironmentMinistry of AgricultureBeijingChina
| | - Guozheng Hu
- Institute of Environment and Sustainable Development in AgricultureChinese Academy of Agricultural SciencesBeijingChina
- Key Laboratory for Agro‐EnvironmentMinistry of AgricultureBeijingChina
| | - Yunfan Wan
- Institute of Environment and Sustainable Development in AgricultureChinese Academy of Agricultural SciencesBeijingChina
- Key Laboratory for Agro‐EnvironmentMinistry of AgricultureBeijingChina
| | - Yue Li
- Institute of Environment and Sustainable Development in AgricultureChinese Academy of Agricultural SciencesBeijingChina
- Key Laboratory for Agro‐EnvironmentMinistry of AgricultureBeijingChina
| | - Luobu Danjiu
- Nagqu Grassland StationTibet Autonomous RegionNagquChina
| | - Qingzhu Gao
- Institute of Environment and Sustainable Development in AgricultureChinese Academy of Agricultural SciencesBeijingChina
- Key Laboratory for Agro‐EnvironmentMinistry of AgricultureBeijingChina
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26
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Biederman JA, Scott RL, Bell TW, Bowling DR, Dore S, Garatuza-Payan J, Kolb TE, Krishnan P, Krofcheck DJ, Litvak ME, Maurer GE, Meyers TP, Oechel WC, Papuga SA, Ponce-Campos GE, Rodriguez JC, Smith WK, Vargas R, Watts CJ, Yepez EA, Goulden ML. CO 2 exchange and evapotranspiration across dryland ecosystems of southwestern North America. GLOBAL CHANGE BIOLOGY 2017; 23:4204-4221. [PMID: 28295911 DOI: 10.1111/gcb.13686] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 02/09/2017] [Accepted: 03/07/2017] [Indexed: 06/06/2023]
Abstract
Global-scale studies suggest that dryland ecosystems dominate an increasing trend in the magnitude and interannual variability of the land CO2 sink. However, such analyses are poorly constrained by measured CO2 exchange in drylands. Here we address this observation gap with eddy covariance data from 25 sites in the water-limited Southwest region of North America with observed ranges in annual precipitation of 100-1000 mm, annual temperatures of 2-25°C, and records of 3-10 years (150 site-years in total). Annual fluxes were integrated using site-specific ecohydrologic years to group precipitation with resulting ecosystem exchanges. We found a wide range of carbon sink/source function, with mean annual net ecosystem production (NEP) varying from -350 to +330 gCm-2 across sites with diverse vegetation types, contrasting with the more constant sink typically measured in mesic ecosystems. In this region, only forest-dominated sites were consistent carbon sinks. Interannual variability of NEP, gross ecosystem production (GEP), and ecosystem respiration (Reco ) was larger than for mesic regions, and half the sites switched between functioning as C sinks/C sources in wet/dry years. The sites demonstrated coherent responses of GEP and NEP to anomalies in annual evapotranspiration (ET), used here as a proxy for annually available water after hydrologic losses. Notably, GEP and Reco were negatively related to temperature, both interannually within site and spatially across sites, in contrast to positive temperature effects commonly reported for mesic ecosystems. Models based on MODIS satellite observations matched the cross-site spatial pattern in mean annual GEP but consistently underestimated mean annual ET by ~50%. Importantly, the MODIS-based models captured only 20-30% of interannual variation magnitude. These results suggest the contribution of this dryland region to variability of regional to global CO2 exchange may be up to 3-5 times larger than current estimates.
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Affiliation(s)
- Joel A Biederman
- Southwest Watershed Research Center, Agricultural Research Service, Tucson, AZ, USA
| | - Russell L Scott
- Southwest Watershed Research Center, Agricultural Research Service, Tucson, AZ, USA
| | - Tom W Bell
- Earth Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA
| | - David R Bowling
- Department of Biology, University of Utah, Salt Lake City, UT, USA
| | - Sabina Dore
- School of Forestry, Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, USA
| | - Jaime Garatuza-Payan
- Departamento de Ciencias del Agua y Medio Ambiente, Instituto Tecnológico de Sonora, Ciudad Obregón, Sonora, Mexico
| | - Thomas E Kolb
- School of Forestry, Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ, USA
| | - Praveena Krishnan
- Atmospheric Turbulence and Diffusion Division, Air Resources Laboratory, National Oceanographic and Atmospheric Administration, Oak Ridge, TN, USA
| | - Dan J Krofcheck
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Marcy E Litvak
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Gregory E Maurer
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Tilden P Meyers
- Atmospheric Turbulence and Diffusion Division, Air Resources Laboratory, National Oceanographic and Atmospheric Administration, Oak Ridge, TN, USA
| | - Walter C Oechel
- Global Change Research Group, Department of Biology, San Diego State University, San Diego, CA, USA
- Department of Geography, College of Life and Environmental Sciences, Exeter, UK
| | - Shirley A Papuga
- School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, USA
| | | | - Julio C Rodriguez
- Departamento de Agricultura y Ganaderia, Universidad de Sonora, Hermosillo, Sonora, Mexico
| | - William K Smith
- School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, USA
| | - Rodrigo Vargas
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA
| | | | - Enrico A Yepez
- Departamento de Ciencias del Agua y Medio Ambiente, Instituto Tecnológico de Sonora, Ciudad Obregón, Sonora, Mexico
| | - Michael L Goulden
- Department of Earth System Science, University of California Irvine, Irvine, CA, USA
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27
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Barron-Gafford GA, Sanchez-Cañete EP, Minor RL, Hendryx SM, Lee E, Sutter LF, Tran N, Parra E, Colella T, Murphy PC, Hamerlynck EP, Kumar P, Scott RL. Impacts of hydraulic redistribution on grass-tree competition vs facilitation in a semi-arid savanna. THE NEW PHYTOLOGIST 2017; 215:1451-1461. [PMID: 28737219 DOI: 10.1111/nph.14693] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 05/28/2017] [Indexed: 06/07/2023]
Abstract
A long-standing ambition in ecosystem science has been to understand the relationship between ecosystem community composition, structure and function. Differential water use and hydraulic redistribution have been proposed as one mechanism that might allow for the coexistence of overstory woody plants and understory grasses. Here, we investigated how patterns of hydraulic redistribution influence overstory and understory ecophysiological function and how patterns vary across timescales of an individual precipitation event to an entire growing season. To this end, we linked measures of sap flux within lateral and tap roots, leaf-level photosynthesis, ecosystem-level carbon exchange and soil carbon dioxide efflux with local meteorology data. The hydraulic redistribution regime was characterized predominantly by hydraulic descent relative to hydraulic lift. We found only a competitive interaction between the overstory and understory, regardless of temporal time scale. Overstory trees used nearly all water lifted by the taproot to meet their own transpirational needs. Our work suggests that alleviating water stress is not the reason we find grasses growing in the understory of woody plants; rather, other stresses, such as excessive light and temperature, are being ameliorated. As such, both the two-layer model and stress gradient hypothesis need to be refined to account for this coexistence in drylands.
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Affiliation(s)
- Greg A Barron-Gafford
- School of Geography & Development, University of Arizona, Tucson, AZ, 85721, USA
- College of Science, Biosphere 2, University of Arizona, Tucson, AZ, 85721, USA
- School of Natural Resources & the Environment, University of Arizona, Tucson, AZ, 85721, USA
| | - Enrique P Sanchez-Cañete
- School of Geography & Development, University of Arizona, Tucson, AZ, 85721, USA
- College of Science, Biosphere 2, University of Arizona, Tucson, AZ, 85721, USA
- Centro Andaluz de Medio Ambiente (IISTA-CEAMA), Granada, 18006, Spain
| | - Rebecca L Minor
- School of Geography & Development, University of Arizona, Tucson, AZ, 85721, USA
- College of Science, Biosphere 2, University of Arizona, Tucson, AZ, 85721, USA
| | - Sean M Hendryx
- School of Natural Resources & the Environment, University of Arizona, Tucson, AZ, 85721, USA
| | - Esther Lee
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Leland F Sutter
- School of Geography & Development, University of Arizona, Tucson, AZ, 85721, USA
- School of Natural Resources & the Environment, University of Arizona, Tucson, AZ, 85721, USA
- Southwest Watershed Research Center, USDA-ARS, Tucson, AZ, 85719, USA
| | - Newton Tran
- School of Environmental Science, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Elizabeth Parra
- College of Science, Biosphere 2, University of Arizona, Tucson, AZ, 85721, USA
| | - Tony Colella
- School of Geography & Development, University of Arizona, Tucson, AZ, 85721, USA
| | - Patrick C Murphy
- School of Geography & Development, University of Arizona, Tucson, AZ, 85721, USA
| | - Erik P Hamerlynck
- Eastern Oregon Agricultural Research Center, USDA-ARS, Burns, OR, 97720, USA
| | - Praveen Kumar
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Russell L Scott
- Southwest Watershed Research Center, USDA-ARS, Tucson, AZ, 85719, USA
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28
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Xu X, Polley HW, Hofmockel K, Wilsey BJ. Species composition but not diversity explains recovery from the 2011 drought in Texas grasslands. Ecosphere 2017. [DOI: 10.1002/ecs2.1704] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Xia Xu
- Department of Ecology, Evolution and Organismal Biology Iowa State University Ames Iowa 50011 USA
| | - H. Wayne Polley
- Grassland, Soil and Water Research Laboratory USDA‐ARS Temple Texas 76502 USA
| | - Kirsten Hofmockel
- Department of Ecology, Evolution and Organismal Biology Iowa State University Ames Iowa 50011 USA
| | - Brian J. Wilsey
- Department of Ecology, Evolution and Organismal Biology Iowa State University Ames Iowa 50011 USA
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29
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Hamerlynck EP, Sheley RL, Davies KW, Svejcar TJ. Postdefoliation ecosystem carbon and water flux and canopy growth dynamics in sagebrush steppe bunchgrasses. Ecosphere 2016. [DOI: 10.1002/ecs2.1376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Erik P. Hamerlynck
- United States Department of Agriculture—Agricultural Research ServiceEastern Oregon Agricultural Research Center 67826‐A Highway 205 Burns Oregon 97720 USA
| | - Roger L. Sheley
- United States Department of Agriculture—Agricultural Research ServiceEastern Oregon Agricultural Research Center 67826‐A Highway 205 Burns Oregon 97720 USA
| | - Kirk W. Davies
- United States Department of Agriculture—Agricultural Research ServiceEastern Oregon Agricultural Research Center 67826‐A Highway 205 Burns Oregon 97720 USA
| | - Tony J. Svejcar
- United States Department of Agriculture—Agricultural Research ServiceEastern Oregon Agricultural Research Center 67826‐A Highway 205 Burns Oregon 97720 USA
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30
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Barnes ML, Moran MS, Scott RL, Kolb TE, Ponce‐Campos GE, Moore DJP, Ross MA, Mitra B, Dore S. Vegetation productivity responds to sub‐annual climate conditions across semiarid biomes. Ecosphere 2016. [DOI: 10.1002/ecs2.1339] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Mallory L. Barnes
- School of Natural Resources and the Environment University of Arizona TucsonArizona 85719 USA
| | - M. Susan Moran
- United States Department of Agriculture, Agricultural Research Service Southwest Watershed Research Center TucsonArizona 85719 USA
| | - Russell L. Scott
- United States Department of Agriculture, Agricultural Research Service Southwest Watershed Research Center TucsonArizona 85719 USA
| | - Thomas E. Kolb
- School of Forestry Northern Arizona University FlagstaffArizona 86001 USA
| | - Guillermo E. Ponce‐Campos
- United States Department of Agriculture, Agricultural Research Service Southwest Watershed Research Center TucsonArizona 85719 USA
| | - David J. P. Moore
- School of Natural Resources and the Environment University of Arizona TucsonArizona 85719 USA
| | - Morgan A. Ross
- School of Natural Resources and the Environment University of Arizona TucsonArizona 85719 USA
| | - Bhaskar Mitra
- School of Natural Resources and the Environment University of Arizona TucsonArizona 85719 USA
| | - Sabina Dore
- School of Forestry Northern Arizona University FlagstaffArizona 86001 USA
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31
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Biederman JA, Scott RL, Goulden ML, Vargas R, Litvak ME, Kolb TE, Yepez EA, Oechel WC, Blanken PD, Bell TW, Garatuza-Payan J, Maurer GE, Dore S, Burns SP. Terrestrial carbon balance in a drier world: the effects of water availability in southwestern North America. GLOBAL CHANGE BIOLOGY 2016; 22:1867-1879. [PMID: 26780862 DOI: 10.1111/gcb.13222] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 01/03/2016] [Indexed: 06/05/2023]
Abstract
Global modeling efforts indicate semiarid regions dominate the increasing trend and interannual variation of net CO2 exchange with the atmosphere, mainly driven by water availability. Many semiarid regions are expected to undergo climatic drying, but the impacts on net CO2 exchange are poorly understood due to limited semiarid flux observations. Here we evaluated 121 site-years of annual eddy covariance measurements of net and gross CO2 exchange (photosynthesis and respiration), precipitation, and evapotranspiration (ET) in 21 semiarid North American ecosystems with an observed range of 100 - 1000 mm in annual precipitation and records of 4-9 years each. In addition to evaluating spatial relationships among CO2 and water fluxes across sites, we separately quantified site-level temporal relationships, representing sensitivity to interannual variation. Across the climatic and ecological gradient, photosynthesis showed a saturating spatial relationship to precipitation, whereas the photosynthesis-ET relationship was linear, suggesting ET was a better proxy for water available to drive CO2 exchanges after hydrologic losses. Both photosynthesis and respiration showed similar site-level sensitivity to interannual changes in ET among the 21 ecosystems. Furthermore, these temporal relationships were not different from the spatial relationships of long-term mean CO2 exchanges with climatic ET. Consequently, a hypothetical 100-mm change in ET, whether short term or long term, was predicted to alter net ecosystem production (NEP) by 64 gCm(-2) yr(-1). Most of the unexplained NEP variability was related to persistent, site-specific function, suggesting prioritization of research on slow-changing controls. Common temporal and spatial sensitivity to water availability increases our confidence that site-level responses to interannual weather can be extrapolated for prediction of CO2 exchanges over decadal and longer timescales relevant to societal response to climate change.
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Affiliation(s)
- Joel A Biederman
- Southwest Watershed Research Center, Agricultural Research Service, Tucson, AZ, 85719, USA
| | - Russell L Scott
- Southwest Watershed Research Center, Agricultural Research Service, Tucson, AZ, 85719, USA
| | - Michael L Goulden
- Department of Earth System Science, University of California Irvine, Irvine, CA, 92697, USA
| | - Rodrigo Vargas
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Marcy E Litvak
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Thomas E Kolb
- School of Forestry, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Enrico A Yepez
- Departamento de Ciencias del Agua y Medio Ambiente, Instituto Tecnológico de Sonora, Cd. Obregón, Sonora, 85000, México
| | - Walter C Oechel
- Global Change Research Group and Department of Biology, San Diego State University, San Diego, CA, 92182, USA
- Department of Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
| | - Peter D Blanken
- Department of Geography, University of Colorado, Boulder, CO, 80309, USA
| | - Tom W Bell
- Earth Research Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Jaime Garatuza-Payan
- Departamento de Ciencias del Agua y Medio Ambiente, Instituto Tecnológico de Sonora, Cd. Obregón, Sonora, 85000, México
| | - Gregory E Maurer
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Sabina Dore
- School of Forestry, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Sean P Burns
- Department of Geography, University of Colorado, Boulder, CO, 80309, USA
- National Center for Atmospheric Research, Boulder, CO, 80301, USA
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32
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On the Downscaling of Actual Evapotranspiration Maps Based on Combination of MODIS and Landsat-Based Actual Evapotranspiration Estimates. REMOTE SENSING 2014. [DOI: 10.3390/rs61110483] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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33
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Moran MS, Ponce-Campos GE, Huete A, McClaran MP, Zhang Y, Hamerlynck EP, Augustine DJ, Gunter SA, Kitchen SG, Peters DPC, Starks PJ, Hernandez M. Functional response of U.S. grasslands to the early 21st-century drought. Ecology 2014; 95:2121-33. [PMID: 25230464 DOI: 10.1890/13-1687.1] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Grasslands across the United States play a key role in regional livelihood and national food security. Yet, it is still unclear how this important resource will respond to the prolonged warm droughts and more intense rainfall events predicted with climate change. The early 21st-century drought in the southwestern United States resulted in hydroclimatic conditions that are similar to those expected with future climate change. We investigated the impact of the early 21st-century drought on aboveground net primary production (ANPP) of six desert and plains grasslands dominated by C4 (warm season) grasses in terms of significant deviations between observed and expected ANPP. In desert grasslands, drought-induced grass mortality led to shifts in the functional response to annual total precipitation (P(T)), and in some cases, new species assemblages occurred that included invasive species. In contrast, the ANPP in plains grasslands exhibited a strong linear function of the current-year P(T) and the previous-year ANPP, despite prolonged warm drought. We used these results to disentangle the impacts of interannual total precipitation, intra-annual precipitation patterns, and grassland abundance on ANPP, and thus generalize the functional response of C4 grasslands to predicted climate change. This will allow managers to plan for predictable shifts in resources associated with climate change related to fire risk, loss of forage, and ecosystem services.
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34
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Scott RL, Huxman TE, Barron-Gafford GA, Darrel Jenerette G, Young JM, Hamerlynck EP. When vegetation change alters ecosystem water availability. GLOBAL CHANGE BIOLOGY 2014; 20:2198-210. [PMID: 24777485 DOI: 10.1111/gcb.12511] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 11/27/2013] [Indexed: 05/20/2023]
Abstract
The combined effects of vegetation and climate change on biosphere-atmosphere water vapor (H2 O) and carbon dioxide (CO2 ) exchanges are expected to vary depending, in part, on how biotic activity is controlled by and alters water availability. This is particularly important when a change in ecosystem composition alters the fractional covers of bare soil, grass, and woody plants so as to influence the accessibility of shallower vs. deeper soil water pools. To study this, we compared 5 years of eddy covariance measurements of H2 O and CO2 fluxes over a riparian grassland, shrubland, and woodland. In comparison with the surrounding upland region, groundwater access at the riparian sites increased net carbon uptake (NEP) and evapotranspiration (ET), which were sustained over more of the year. Among the sites, the grassland used less of the stable groundwater resource, and increasing woody plant density decoupled NEP and ET from incident precipitation (P), resulting in greater exchange rates that were less variable year to year. Despite similar gross patterns, how groundwater accessibility affected NEP was more complex than ET. The grassland had higher respiration (Reco ) costs. Thus, while it had similar ET and gross carbon uptake (GEP) to the shrubland, grassland NEP was substantially less. Also, grassland carbon fluxes were more variable due to occasional flooding at the site, which both stimulated and inhibited NEP depending upon phenology. Woodland NEP was large, but surprisingly similar to the less mature, sparse shrubland, even while having much greater GEP. Woodland Reco was greater than the shrubland and responded strongly and positively to P, which resulted in a surprising negative NEP response to P. This is likely due to the large accumulation of carbon aboveground and in the surface soil. These long-term observations support the strong role that water accessibility can play when determining the consequences of ecosystem vegetation change.
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Affiliation(s)
- Russell L Scott
- Southwest Watershed Research Center, USDA-ARS, Tucson, 85716, AZ, USA
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35
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Actual Evapotranspiration (Water Use) Assessment of the Colorado River Basin at the Landsat Resolution Using the Operational Simplified Surface Energy Balance Model. REMOTE SENSING 2013. [DOI: 10.3390/rs6010233] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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36
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Zhang C, Li C, Luo G, Chen X. Modeling plant structure and its impacts on carbon and water cycles of the Central Asian arid ecosystem in the context of climate change. Ecol Modell 2013. [DOI: 10.1016/j.ecolmodel.2013.06.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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37
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Yang F, Zhou G. Sensitivity of temperate desert steppe carbon exchange to seasonal droughts and precipitation variations in Inner Mongolia, China. PLoS One 2013; 8:e55418. [PMID: 23393576 PMCID: PMC3564909 DOI: 10.1371/journal.pone.0055418] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 12/22/2012] [Indexed: 11/18/2022] Open
Abstract
Arid grassland ecosystems have significant interannual variation in carbon exchange; however, it is unclear how environmental factors influence carbon exchange in different hydrological years. In this study, the eddy covariance technique was used to investigate the seasonal and interannual variability of CO₂ flux over a temperate desert steppe in Inner Mongolia, China from 2008 to 2010. The amounts and times of precipitation varied significantly throughout the study period. The precipitation in 2009 (186.4 mm) was close to the long-term average (183.9±47.6 mm), while the precipitation in 2008 (136.3 mm) and 2010 (141.3 mm) was approximately a quarter below the long-term average. The temperate desert steppe showed carbon neutrality for atmospheric CO₂ throughout the study period, with a net ecosystem carbon dioxide exchange (NEE) of -7.2, -22.9, and 26.0 g C m⁻² yr⁻¹ in 2008, 2009, and 2010, not significantly different from zero. The ecosystem gained more carbon in 2009 compared to other two relatively dry years, while there was significant difference in carbon uptake between 2008 and 2010, although both years recorded similar annual precipitation. The results suggest that summer precipitation is a key factor determining annual NEE. The apparent quantum yield and saturation value of NEE (NEE(sat)) and the temperature sensitivity coefficient of ecosystem respiration (R(eco)) exhibited significant variations. The values of NEE(sat) were -2.6, -2.9, and -1.4 µmol CO₂ m⁻² s⁻¹ in 2008, 2009, and 2010, respectively. Drought suppressed both the gross primary production (GPP) and R(eco), and the drought sensitivity of GPP was greater than that of R(eco). The soil water content sensitivity of GPP was high during the dry year of 2008 with limited soil moisture availability. Our results suggest the carbon balance of this temperate desert steppe was not only sensitive to total annual precipitation, but also to its seasonal distribution.
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Affiliation(s)
- Fulin Yang
- Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province, Key Open Laboratory of Arid Climatic Change and Disaster Reduction of China Meteorological Administration (CMA), Institute of Arid Meteorology, CMA, Lanzhou, China
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Haidian District, Beijing, China
| | - Guangsheng Zhou
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Haidian District, Beijing, China
- Chinese Academy of Meteorological Sciences, Haidian District, Beijing, China
- * E-mail:
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Blonquist JM, Montzka SA, Munger JW, Yakir D, Desai AR, Dragoni D, Griffis TJ, Monson RK, Scott RL, Bowling DR. The potential of carbonyl sulfide as a proxy for gross primary production at flux tower sites. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jg001723] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Felzer BS, Cronin TW, Melillo JM, Kicklighter DW, Schlosser CA, Dangal SRS. Nitrogen effect on carbon-water coupling in forests, grasslands, and shrublands in the arid western United States. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jg001621] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Responses of Ecosystem Carbon Cycling to Climate Change Treatments Along an Elevation Gradient. Ecosystems 2011. [DOI: 10.1007/s10021-011-9464-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Tang R, Li ZL, Chen KS. Validating MODIS-derived land surface evapotranspiration with in situ measurements at two AmeriFlux sites in a semiarid region. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jd014543] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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