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Liu Y, Nadezhdina N, Hu W, Clothier B, Duan J, Li X, Xi B. Evaporation-driven internal hydraulic redistribution alleviates root drought stress: Mechanisms and modeling. PLANT PHYSIOLOGY 2023; 193:1058-1072. [PMID: 37350505 DOI: 10.1093/plphys/kiad364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 06/02/2023] [Accepted: 06/05/2023] [Indexed: 06/24/2023]
Abstract
Many tree species have developed extensive root systems that allow them to survive in arid environments by obtaining water from a large soil volume. These root systems can transport and redistribute soil water during drought by hydraulic redistribution (HR). A recent study revealed the phenomenon of evaporation-driven hydraulic redistribution (EDHR), which is driven by evaporative demand (transpiration). In this study, we confirmed the occurrence of EDHR in Chinese white poplar (Populus tomentosa) through root sap flow measurements. We utilized microcomputed tomography technology to reconstruct the xylem network of woody lateral roots and proposed conceptual models to verify EDHR from a physical perspective. Our results indicated that EDHR is driven by the internal water potential gradient within the plant xylem network, which requires 3 conditions: high evaporative demand, soil water potential gradient, and special xylem structure of the root junction. The simulations demonstrated that during periods of extreme drought, EDHR could replenish water to dry roots and improve root water potential up to 38.9% to 41.6%. This highlights the crucial eco-physiological importance of EDHR in drought tolerance. Our proposed models provide insights into the complex structure of root junctions and their impact on water movement, thus enhancing our understanding of the relationship between xylem structure and plant hydraulics.
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Affiliation(s)
- Yang Liu
- Laboratory for Silviculture and Forest Ecosystem in Arid- and Semi-Arid Region of State Forestry and Grassland Administration, Beijing Forestry University, Beijing 10083, China
- Ministry of Education Key Laboratory of Silviculture and Conservation, Beijing Forestry University, Beijing 100083, China
| | - Nadezhda Nadezhdina
- Institute of Forest Botany, Dendrology and Geobiocenology, Mendel University in Brno, Zemedelska 3, Brno 61300, Czech Republic
| | - Wei Hu
- New Zealand Institute for Plant & Food Research Ltd., Private Bag 4707, Christchurch 8140, New Zealand
| | - Brent Clothier
- New Zealand Institute for Plant & Food Research Ltd., Fitzherbert Science Centre, Palmerston North 4442, New Zealand
| | - Jie Duan
- Laboratory for Silviculture and Forest Ecosystem in Arid- and Semi-Arid Region of State Forestry and Grassland Administration, Beijing Forestry University, Beijing 10083, China
- Ministry of Education Key Laboratory of Silviculture and Conservation, Beijing Forestry University, Beijing 100083, China
| | - Ximeng Li
- College of Life and Environmental Science, Minzu University of China, Beijing 100081, China
| | - Benye Xi
- Laboratory for Silviculture and Forest Ecosystem in Arid- and Semi-Arid Region of State Forestry and Grassland Administration, Beijing Forestry University, Beijing 10083, China
- Ministry of Education Key Laboratory of Silviculture and Conservation, Beijing Forestry University, Beijing 100083, China
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Wei L, Qiu Z, Zhou G, Zuecco G, Liu Y, Wen Y. Soil water hydraulic redistribution in a subtropical monsoon evergreen forest. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 835:155437. [PMID: 35476947 DOI: 10.1016/j.scitotenv.2022.155437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/07/2022] [Accepted: 04/18/2022] [Indexed: 06/14/2023]
Abstract
Hydraulic redistribution (HR), which is the passive movement of water through plant roots from wet to dry soil due to the water gradient, is important for plant physiology and ecohydrological processes. However, our poor knowledge on HR in the humid monsoon climate zone hampers the understanding of the interactions between vegetation and soil water during frequent droughts in evergreen forests. Thus, 5 years (2011-2015) of data, including meteorological parameters and soil moisture content at depths of 10, 30, 50, and 100 cm in soil profiles, were compared at one evergreen broad-leaved forest and at one clear-cutting forest site in south China. Analyses of soil moisture dynamics show that HR was frequently triggered within the depth of 30 cm at the evergreen broad-leaved forest, while (if any) was less visible at the clear-cutting forest site. The daily averaged magnitude of redistributed soil water reached the maximum of 0.81 mm/d. The HR mainly occurred during the monsoon dry season (i.e., from October to March of the following year), possibly indicating a different cause, i.e., asynchronous variations in rainfall and plant water use shape the seasonal patterns of soil water HR, compared to other humid zones. During the study period when HR occurred, the average daily HR in the soil profiles replenished approximately 34-50% of the water consumption in the 0-30 cm soil layer. The simulation results of a distributed hydrology-soil-vegetation model incorporating a HR scheme indicate that evapotranspiration enhanced during drought periods when HR occurred. In the future climate change context, comprehensive investigations on the water fluxes in the atmosphere-vegetation-soil continuum are needed to fully understand the effects of HR on the physiological responses of plants and on the water cycle.
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Affiliation(s)
- Lezhang Wei
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China; Linköping University - Guangzhou University Research Center on Urban Sustainable Development, Guangzhou University, Guangzhou 510006, China
| | - Zhijun Qiu
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, China.
| | - Guangyi Zhou
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, China
| | - Giulia Zuecco
- Department of Land, Environment, Agriculture and Forestry, University of Padova, via dell'Università 16, 35020 Legnaro, PD, Italy
| | - Yu Liu
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China; Linköping University - Guangzhou University Research Center on Urban Sustainable Development, Guangzhou University, Guangzhou 510006, China
| | - Ya Wen
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
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Yang G, Huang L, Shi Y. Magnitude and determinants of plant root hydraulic redistribution: A global synthesis analysis. FRONTIERS IN PLANT SCIENCE 2022; 13:918585. [PMID: 35937319 PMCID: PMC9355616 DOI: 10.3389/fpls.2022.918585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Plant root hydraulic redistribution (HR) has been widely recognized as a phenomenon that helps alleviate vegetation drought stress. However, a systematic assessment of the magnitude of HR and its drivers at the global scale are lacking. We collected 37 peer-reviewed papers (comprising 47 research sites) published in 1900-2018 and comprehensively analyzed the magnitude of HR and its underlying factors. We used a weighting method to analyze HR magnitude and its effect on plant transpiration. Machine learning algorithms (boosted regression trees) and structural equation modeling were used to determine the influence of each factor on HR magnitude. We found that the magnitude of HR was 0.249 mm H2O d-1 (95% CI, 0.113-0.384) and its contribution to plant transpiration was 27.4% (3-79%). HR varied significantly among different terrestrial biomes and mainly occurred in forests with drier conditions, such as temperate forest ecosystems (HR = 0.502 mm H2O d-1), where HR was significantly higher than in other ecosystems (p < 0.01). The magnitude of HR in angiosperms was significantly higher than that in gymnosperms (p < 0.05). The mean magnitude of HR first increased and then decreased with an increase in humidity index; conversely, the mean magnitude of HR decreased with an increase in water table depth. HR was significantly positively correlated with root length and transpiration. Plant characteristics and environmental factors jointly accounted for 61.0% of the variation in HR, and plant transpiration was the major factor that directly influenced HR (43.1% relative importance; p < 0.001), and soil texture was an important indirect driver of HR. Our synthesis offers a comprehensive perspective of how plant characteristics and environmental factors influence HR magnitude.
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Affiliation(s)
- Guisen Yang
- Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environmental Resources, Chinese Academy of Sciences, Lanzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Lei Huang
- Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environmental Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Yafei Shi
- Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environmental Resources, Chinese Academy of Sciences, Lanzhou, China
- University of Chinese Academy of Sciences, Beijing, China
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El-Sappah AH, Rather SA, Wani SH, Elrys AS, Bilal M, Huang Q, Dar ZA, Elashtokhy MMA, Soaud N, Koul M, Mir RR, Yan K, Li J, El-Tarabily KA, Abbas M. Heat Stress-Mediated Constraints in Maize ( Zea mays) Production: Challenges and Solutions. FRONTIERS IN PLANT SCIENCE 2022; 13:879366. [PMID: 35615131 PMCID: PMC9125997 DOI: 10.3389/fpls.2022.879366] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 03/30/2022] [Indexed: 05/05/2023]
Abstract
An increase in temperature and extreme heat stress is responsible for the global reduction in maize yield. Heat stress affects the integrity of the plasma membrane functioning of mitochondria and chloroplast, which further results in the over-accumulation of reactive oxygen species. The activation of a signal cascade subsequently induces the transcription of heat shock proteins. The denaturation and accumulation of misfolded or unfolded proteins generate cell toxicity, leading to death. Therefore, developing maize cultivars with significant heat tolerance is urgently required. Despite the explored molecular mechanism underlying heat stress response in some plant species, the precise genetic engineering of maize is required to develop high heat-tolerant varieties. Several agronomic management practices, such as soil and nutrient management, plantation rate, timing, crop rotation, and irrigation, are beneficial along with the advanced molecular strategies to counter the elevated heat stress experienced by maize. This review summarizes heat stress sensing, induction of signaling cascade, symptoms, heat stress-related genes, the molecular feature of maize response, and approaches used in developing heat-tolerant maize varieties.
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Affiliation(s)
- Ahmed H. El-Sappah
- School of Agriculture, Forestry and Food Engineering, Yibin University, Yibin, China
- Department of Genetics, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
- Key Laboratory of Sichuan Province for Refining Sichuan Tea, Yibin, China
| | - Shabir A. Rather
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, China
| | - Shabir Hussain Wani
- Mountain Research Centre for Field Crops Khudwani Anantnag, SKUAST–Kashmir, Srinagar, India
| | - Ahmed S. Elrys
- Department of Soil Science, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Muhammad Bilal
- School of Life Sciences and Food Engineering, Huaiyin Institute of Technology, Huaian, China
| | - Qiulan Huang
- Key Laboratory of Sichuan Province for Refining Sichuan Tea, Yibin, China
- College of Tea Science, Yibin University, Yibin, China
| | - Zahoor Ahmad Dar
- Dryland Agriculture Research Station, SKUAST–Kashmir, Srinagar, India
| | | | - Nourhan Soaud
- Department of Crop Science, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Monika Koul
- Department of Botany, Hansraj College, University of Delhi, New Delhi, India
| | - Reyazul Rouf Mir
- Division of Genetics and Plant Breeding, Faculty of Agriculture (FoA), SKUAST–Kashmir, Sopore, India
| | - Kuan Yan
- School of Agriculture, Forestry and Food Engineering, Yibin University, Yibin, China
- Key Laboratory of Sichuan Province for Refining Sichuan Tea, Yibin, China
| | - Jia Li
- School of Agriculture, Forestry and Food Engineering, Yibin University, Yibin, China
- Key Laboratory of Sichuan Province for Refining Sichuan Tea, Yibin, China
| | - Khaled A. El-Tarabily
- Department of Biology, College of Science, United Arab Emirates University, Al Ain, United Arab Emirates
- Harry Butler Institute, Murdoch University, Murdoch, WA, Australia
| | - Manzar Abbas
- School of Agriculture, Forestry and Food Engineering, Yibin University, Yibin, China
- Key Laboratory of Sichuan Province for Refining Sichuan Tea, Yibin, China
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5
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Hou E, Litvak ME, Rudgers JA, Jiang L, Collins SL, Pockman WT, Hui D, Niu S, Luo Y. Divergent responses of primary production to increasing precipitation variability in global drylands. GLOBAL CHANGE BIOLOGY 2021; 27:5225-5237. [PMID: 34260799 DOI: 10.1111/gcb.15801] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
Interannual variability in precipitation has increased globally as climate warming intensifies. The increased variability impacts both terrestrial plant production and carbon (C) sequestration. However, mechanisms driving these changes are largely unknown. Here, we examined mechanisms underlying the response of aboveground net primary production (ANPP) to interannual precipitation variability in global drylands with mean annual precipitation (MAP) <500 mm year-1 , using a combined approach of data synthesis and process-based modeling. We found a hump-shaped response of ANPP to precipitation variability along the MAP gradient. The response was positive when MAP < ~300 mm year-1 and negative when MAP was higher than this threshold, with a positive peak at 140 mm year-1 . Transpiration and subsoil water content mirrored the response of ANPP to precipitation variability; evaporation responded negatively and water loss through runoff and drainage responded positively to precipitation variability. Mean annual temperature, soil type, and plant physiological traits all altered the magnitude but not the pattern of the response of ANPP to precipitation variability along the MAP gradient. By extrapolating to global drylands (<500 mm year-1 MAP), we estimated that ANPP would increase by 15.2 ± 6.0 Tg C year-1 in arid and hyper-arid lands and decrease by 2.1 ± 0.5 Tg C year-1 in dry sub-humid lands under future changes in interannual precipitation variability. Thus, increases in precipitation variability will enhance primary production in many drylands in the future.
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Affiliation(s)
- Enqing Hou
- Center for Ecosystem Science and Society, Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Marcy E Litvak
- Department of Biology, MSC03-2020, University of New Mexico, Albuquerque, New Mexico, USA
| | - Jennifer A Rudgers
- Department of Biology, MSC03-2020, University of New Mexico, Albuquerque, New Mexico, USA
| | - Lifen Jiang
- Center for Ecosystem Science and Society, Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Scott L Collins
- Department of Biology, MSC03-2020, University of New Mexico, Albuquerque, New Mexico, USA
| | - William T Pockman
- Department of Biology, MSC03-2020, University of New Mexico, Albuquerque, New Mexico, USA
| | - Dafeng Hui
- Department of Biological Sciences, Tennessee State University, Nashville, Tennessee, USA
| | - Shuli Niu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
| | - Yiqi Luo
- Center for Ecosystem Science and Society, Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
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6
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Querejeta JI, Ren W, Prieto I. Vertical decoupling of soil nutrients and water under climate warming reduces plant cumulative nutrient uptake, water-use efficiency and productivity. THE NEW PHYTOLOGIST 2021; 230:1378-1393. [PMID: 33550582 DOI: 10.1111/nph.17258] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 02/01/2021] [Indexed: 05/21/2023]
Abstract
Warming-induced desiccation of the fertile topsoil layer could lead to decreased nutrient diffusion, mobility, mineralization and uptake by roots. Increased vertical decoupling between nutrients in topsoil and water availability in subsoil/bedrock layers under warming could thereby reduce cumulative nutrient uptake over the growing season. We used a Mediterranean semiarid shrubland as model system to assess the impacts of warming-induced topsoil desiccation on plant water- and nutrient-use patterns. A 6 yr manipulative field experiment examined the effects of warming (2.5°C), rainfall reduction (30%) and their combination on soil resource utilization by Helianthemum squamatum shrubs. A drier fertile topsoil ('growth pool') under warming led to greater proportional utilization of water from deeper, wetter, but less fertile subsoil/bedrock layers ('maintenance pool') by plants. This was linked to decreased cumulative nutrient uptake, increased nonstomatal (nutritional) limitation of photosynthesis and reduced water-use efficiency, above-ground biomass growth and drought survival. Whereas a shift to greater utilization of water stored in deep subsoil/bedrock may buffer the negative impact of warming-induced topsoil desiccation on transpiration, this plastic response cannot compensate for the associated reduction in cumulative nutrient uptake and carbon assimilation, which may compromise the capacity of plants to adjust to a warmer and drier climate.
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Affiliation(s)
- José Ignacio Querejeta
- Departamento de Conservación de Suelos y Agua, Centro de Edafología y Biología Aplicada del Segura - Consejo Superior de Investigaciones Científicas (CEBAS-CSIC), Murcia, 30100, Spain
| | - Wei Ren
- Departamento de Conservación de Suelos y Agua, Centro de Edafología y Biología Aplicada del Segura - Consejo Superior de Investigaciones Científicas (CEBAS-CSIC), Murcia, 30100, Spain
- Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing, 400715, China
| | - Iván Prieto
- Departamento de Conservación de Suelos y Agua, Centro de Edafología y Biología Aplicada del Segura - Consejo Superior de Investigaciones Científicas (CEBAS-CSIC), Murcia, 30100, Spain
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7
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Studying Unimodal, Bimodal, PDI and Bimodal-PDI Variants of Multiple Soil Water Retention Models: I. Direct Model Fit Using the Extended Evaporation and Dewpoint Methods. WATER 2020. [DOI: 10.3390/w12030900] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study focuses on the reliable parametrization of the full Soil Water Retention Curve (SWRC) from saturation to oven-dryness using high resolution but limited range measured water retention data by the Hydraulic Property Analyzer (HYPROP) system. We studied the performance of five unimodal water retention models including the Brooks and Corey model (BC model), the Fredlund and Xing model (FX model), the Kosugi model (K model), the van Genuchten constrained model with four free parameters (VG model), and the van Genuchten unconstrained model with five free parameters (VGm model). In addition, eleven alternative expressions including Peters–Durner–Iden (PDI), bimodal, and bimodal-PDI variants of the original models were evaluated. We used a data set consisting of 94 soil samples from Turkey and the United States with high-resolution measured data (a total of 9264 measured water retention data pairs) mainly via the HYPROP system and supplemented for some samples with measured dry-end data using the WP4C instrument. Among unimodal expressions, the FX and the K models with the Mean Absolute Error (MAE) values equal to 0.005 cm3 cm−3 and 0.015 cm3 cm−3 have the highest and the lowest accuracy, respectively. Overall, the alternative variants provided a better fit than the unimodal expressions. The unimodal models, except for the FX model, fail to provide reliable dry-end estimations using HYPROP data (average MAE: 0.041 cm3 cm−3, average r: 0.52). Our results suggested that only models that account for the zero water content at the oven dryness and properly shift from the middle range to dry-end (i.e., the FX model and PDI variants) can adequately represent the full SWRC using typical data obtained via the HYPROP system.
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8
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Fu C, Wang G, Bible K, Goulden ML, Saleska SR, Scott RL, Cardon ZG. Hydraulic redistribution affects modeled carbon cycling via soil microbial activity and suppressed fire. GLOBAL CHANGE BIOLOGY 2018; 24:3472-3485. [PMID: 29654607 DOI: 10.1111/gcb.14164] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/19/2018] [Indexed: 06/08/2023]
Abstract
Hydraulic redistribution (HR) of water from moist to drier soils, through plant roots, occurs world-wide in seasonally dry ecosystems. Although the influence of HR on landscape hydrology and plant water use has been amply demonstrated, HR's effects on microbe-controlled processes sensitive to soil moisture, including carbon and nutrient cycling at ecosystem scales, remain difficult to observe in the field and have not been integrated into a predictive framework. We incorporated a representation of HR into the Community Land Model (CLM4.5) and found the new model improved predictions of water, energy, and system-scale carbon fluxes observed by eddy covariance at four seasonally dry yet ecologically diverse temperate and tropical AmeriFlux sites. Modeled plant productivity and microbial activities were differentially stimulated by upward HR, resulting at times in increased plant demand outstripping increased nutrient supply. Modeled plant productivity and microbial activities were diminished by downward HR. Overall, inclusion of HR tended to increase modeled annual ecosystem uptake of CO2 (or reduce annual CO2 release to the atmosphere). Moreover, engagement of CLM4.5's ground-truthed fire module indicated that though HR increased modeled fuel load at all four sites, upward HR also moistened surface soil and hydrated vegetation sufficiently to limit the modeled spread of dry season fire and concomitant very large CO2 emissions to the atmosphere. Historically, fire has been a dominant ecological force in many seasonally dry ecosystems, and intensification of soil drought and altered precipitation regimes are expected for seasonally dry ecosystems in the future. HR may play an increasingly important role mitigating development of extreme soil water potential gradients and associated limitations on plant and soil microbial activities, and may inhibit the spread of fire in seasonally dry ecosystems.
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Affiliation(s)
- Congsheng Fu
- Department of Civil & Environmental Engineering, Center for Environmental Science and Engineering, University of Connecticut, Storrs, Connecticut
| | - Guiling Wang
- Department of Civil & Environmental Engineering, Center for Environmental Science and Engineering, University of Connecticut, Storrs, Connecticut
| | - Kenneth Bible
- Forest Service, Pacific Northwest Research Station, Portland, Oregon
| | - Michael L Goulden
- Department of Earth System Science, University of California, Irvine, California
| | - Scott R Saleska
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona
| | - Russell L Scott
- Southwest Watershed Research Center, USDA-Agricultural Research Service, Tucson, Arizona
| | - Zoe G Cardon
- The Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts
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9
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The Effects of Dynamic Root Distribution on Land–Atmosphere Carbon and Water Fluxes in the Community Earth System Model (CESM1.2.0). FORESTS 2018. [DOI: 10.3390/f9040172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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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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11
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The dominant role of climate change in determining changes in evapotranspiration in Xinjiang, China from 2001 to 2012. PLoS One 2017; 12:e0183071. [PMID: 28841645 PMCID: PMC5571968 DOI: 10.1371/journal.pone.0183071] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 07/28/2017] [Indexed: 11/22/2022] Open
Abstract
The Xinjiang Uyghur Autonomous Region of China has experienced significant land cover and climate change since the beginning of the 21st century. However, a reasonable simulation of evapotranspiration (ET) and its response to environmental factors are still unclear. For this study, to simulate ET and its response to climate and land cover change in Xinjiang, China from 2001 to 2012, we used the Common Land Model (CoLM) by adding irrigation effects for cropland and modifying root distributions and the root water uptake process for shrubland. Our results indicate that mean annual ET from 2001 to 2012 was 131.22 (±21.78) mm/year and demonstrated no significant trend (p = 0.12). The model simulation also indicates that climate change was capable of explaining 99% of inter-annual ET variability; land cover change only explained 1%. Land cover change caused by the expansion of croplands increased annual ET by 1.11 mm while climate change, mainly resulting from both decreased temperature and precipitation, reduced ET by 21.90 mm. Our results imply that climate change plays a dominant role in determining changes in ET, and also highlight the need for appropriate land-use strategies for managing water sources in dryland ecosystems within Xinjiang.
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12
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Yu K, Foster A. Modeled hydraulic redistribution in tree-grass, CAM-grass, and tree-CAM associations: the implications of crassulacean acid metabolism (CAM). Oecologia 2015; 180:1113-25. [PMID: 26712135 DOI: 10.1007/s00442-015-3518-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 11/24/2015] [Indexed: 11/26/2022]
Abstract
Past studies have largely focused on hydraulic redistribution (HR) in trees, shrubs, and grasses, and recognized its role in interspecies interactions. HR in plants that conduct crassulacean acid metabolism (CAM), however, remains poorly investigated, as does the effect of HR on transpiration in different vegetation associations (i.e., tree-grass, CAM-grass, and tree-CAM associations). We have developed a mechanistic model to investigate the net direction and magnitude of HR at the patch scale for tree-grass, CAM-grass, and tree-CAM associations at the growing season to yearly timescale. The modeling results show that deep-rooted CAM plants in CAM-grass associations could perform hydraulic lift at a higher rate than trees in tree-grass associations in a relatively wet environment, as explained by a significant increase in grass transpiration rate in the shallow soil layer, balancing a lower transpiration rate by CAM plants. By comparison, trees in tree-CAM associations may perform hydraulic descent at a higher rate than those in tree-grass associations in a dry environment. Model simulations also show that hydraulic lift increases the transpiration of shallow-rooted plants, while hydraulic descent increases that of deep-rooted plants. CAM plants transpire during the night and thus perform HR during the day. Based on these model simulations, we suggest that the ability of CAM plants to perform HR at a higher rate may have different effects on the surrounding plant community than those of plants with C3 or C4 photosynthetic pathways (i.e., diurnal transpiration).
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Affiliation(s)
- Kailiang Yu
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, 22904, USA.
| | - Adrianna Foster
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, 22904, USA
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Yu K, D'Odorico P. Hydraulic lift as a determinant of tree-grass coexistence on savannas. THE NEW PHYTOLOGIST 2015; 207:1038-1051. [PMID: 25925655 DOI: 10.1111/nph.13431] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/23/2015] [Indexed: 06/04/2023]
Abstract
The coexistence of woody plants and grasses in savannas is determined by a complex set of interacting factors that determine access to resources and demographic dynamics, under the control of external drivers and vegetation feedbacks with the physical environment. Existing theories explain coexistence mainly as an effect of competitive relations and/or disturbances. However, theoretical studies on the way facilitative interactions resulting from hydraulic lift affect tree-grass coexistence and the range of environmental conditions in which savannas are stable are still lacking. We investigated the role of hydraulic lift in the stability of tree-grass coexistence in savannas. To that end, we developed a new mechanistic model that accounts for both competition for soil water in the shallow soil and fire-induced disturbance. We found that hydraulic lift favors grasses, which scavenge the water lifted by woody plants. Thus, hydraulic lift expands (at the expenses of woodlands) the range of environmental conditions in which savannas are stable. These results indicate that hydraulic lift can be an important mechanism responsible for the coexistence of woody plants and grasses in savannas. Grass facilitation by trees through the process of hydraulic lift could allow savannas to persist stably in mesic regions that would otherwise exhibit a forest cover.
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Affiliation(s)
- Kailiang Yu
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA
| | - Paolo D'Odorico
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA
- National Socio-Environmental Synthesis Center, University of Maryland, Annapolis, MD 21401, USA
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Eller CB, Burgess SSO, Oliveira RS. Environmental controls in the water use patterns of a tropical cloud forest tree species, Drimys brasiliensis (Winteraceae). TREE PHYSIOLOGY 2015; 35:387-399. [PMID: 25716877 DOI: 10.1093/treephys/tpv001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 01/04/2015] [Indexed: 06/04/2023]
Abstract
Trees from tropical montane cloud forest (TMCF) display very dynamic patterns of water use. They are capable of downwards water transport towards the soil during leaf-wetting events, likely a consequence of foliar water uptake (FWU), as well as high rates of night-time transpiration (Enight) during drier nights. These two processes might represent important sources of water losses and gains to the plant, but little is known about the environmental factors controlling these water fluxes. We evaluated how contrasting atmospheric and soil water conditions control diurnal, nocturnal and seasonal dynamics of sap flow in Drimys brasiliensis (Miers), a common Neotropical cloud forest species. We monitored the seasonal variation of soil water content, micrometeorological conditions and sap flow of D. brasiliensis trees in the field during wet and dry seasons. We also conducted a greenhouse experiment exposing D. brasiliensis saplings under contrasting soil water conditions to deuterium-labelled fog water. We found that during the night D. brasiliensis possesses heightened stomatal sensitivity to soil drought and vapour pressure deficit, which reduces night-time water loss. Leaf-wetting events had a strong suppressive effect on tree transpiration (E). Foliar water uptake increased in magnitude with drier soil and during longer leaf-wetting events. The difference between diurnal and nocturnal stomatal behaviour in D. brasiliensis could be attributed to an optimization of carbon gain when leaves are dry, as well as minimization of nocturnal water loss. The leaf-wetting events on the other hand seem important to D. brasiliensis water balance, especially during soil droughts, both by suppressing tree transpiration (E) and as a small additional water supply through FWU. Our results suggest that decreases in leaf-wetting events in TMCF might increase D. brasiliensis water loss and decrease its water gains, which could compromise its ecophysiological performance and survival during dry periods.
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Affiliation(s)
- Cleiton B Eller
- Department of Plant Biology, Institute of Biology, University of Campinas - UNICAMP, CP6109, Campinas, SP, Brazil
| | - Stephen S O Burgess
- School of Plant Biology, The University of Western Australia - UWA, Perth, WA 6009, Australia
| | - Rafael S Oliveira
- Department of Plant Biology, Institute of Biology, University of Campinas - UNICAMP, CP6109, Campinas, SP, Brazil School of Plant Biology, The University of Western Australia - UWA, Perth, WA 6009, Australia
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Linking Populus euphratica hydraulic redistribution to diversity assembly in the arid desert zone of Xinjiang, China. PLoS One 2014; 9:e109071. [PMID: 25275494 PMCID: PMC4183514 DOI: 10.1371/journal.pone.0109071] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 09/07/2014] [Indexed: 11/19/2022] Open
Abstract
The hydraulic redistribution (HR) of deep-rooted plants significantly improves the survival of shallow-rooted shrubs and herbs in arid deserts, which subsequently maintain species diversity. This study was conducted in the Ebinur desert located in the western margin of the Gurbantonggut Desert. Isotope tracing, community investigation and comparison analysis were employed to validate the HR of Populus euphratica and to explore its effects on species richness and abundance. The results showed that, P. euphratica has HR. Shrubs and herbs that grew under the P. euphratica canopy (under community: UC) showed better growth than the ones growing outside (Outside community: OC), exhibiting significantly higher species richness and abundance in UC than OC (p<0.05) along the plant growing season. Species richness and abundance were significantly logarithmically correlated with the P. euphratica crown area in UC (R2 = 0.51 and 0.84, p<0.001). In conclusion, P. euphratica HR significantly ameliorates the water conditions of the shallow soil, which then influences the diversity assembly in arid desert communities.
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Prieto IN, Pugnaire FI, Ryel RJ. Water uptake and redistribution during drought in a semiarid shrub species. FUNCTIONAL PLANT BIOLOGY : FPB 2014; 41:812-819. [PMID: 32481035 DOI: 10.1071/fp13300] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 02/11/2014] [Indexed: 06/11/2023]
Abstract
In arid systems, most plant mortality occurs during long drought periods when water is not available for plant uptake. In these systems, plants often benefit from scarce rain events occurring during drought but some of the mechanisms underlying this water use remain unknown. In this context, plant water use and redistribution after a large rain event could be a mechanism that allows deep-rooted shrubs to conservatively use water during drought. We tested this hypothesis by comparing soil and plant water dynamics in Artemisia tridentata ssp. vaseyana (Rydb.) Beetle shrubs that either received a rain event (20mm) or received no water. Soil water content (SWC) increased in shallow layers after the event and increased in deep soil layers through hydraulic redistribution (HR). Our results show that Artemisia shrubs effectively redistributed the water pulse downward recharging deep soil water pools that allowed greater plant water use throughout the subsequent drought period, which ameliorated plant water potentials. Shrubs used shallow water pools when available and then gradually shifted to deep-water pools when shallow water was being used up. Both HR recharge and the shift to shallow soil water use helped conserve deep soil water pools. Summer water uptake in Artemisia not only improved plant water relations but also increased deep soil water availability during drought.
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Affiliation(s)
- Iv N Prieto
- Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, Carretera de Sacramento s/n, E-04120 La Cañada de San Urbano, Almería, Spain
| | - Francisco I Pugnaire
- Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, Carretera de Sacramento s/n, E-04120 La Cañada de San Urbano, Almería, Spain
| | - Ronald J Ryel
- Utah State University, Department of Wildland Resources, 5230 Old Main Hill, Logan, UT 84322, USA
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Matimati I, Verboom GA, Cramer MD. Do hydraulic redistribution and nocturnal transpiration facilitate nutrient acquisition in Aspalathus linearis? Oecologia 2014; 175:1129-42. [PMID: 24972698 DOI: 10.1007/s00442-014-2987-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 05/29/2014] [Indexed: 11/28/2022]
Abstract
The significance of soil water redistribution by roots and nocturnal transpiration for nutrient acquisition were assessed for deep-rooted 3-year-old leguminous Aspalathus linearis shrubs of the Cape Floristic Region (South Africa). We hypothesised that hydraulic redistribution and nocturnal transpiration facilitate nutrient acquisition by releasing moisture in shallow soil to enable acquisition of shallow-soil nutrients during the summer drought periods and by driving water fluxes from deep to shallow soil powering mass-flow nutrient acquisition, respectively. A. linearis was supplied with sub-surface (1-m-deep) irrigation rates of 0, 2 or 4 L day(-1 )plant(-1). Some plants were unfertilized, whilst others were surface- or deep-fertilized (1 m depth) with Na(15)NO3 and CaP/FePO4. We also supplied deuterium oxide ((2)H2O) at 1 m depth at dusk and measured its predawn redistribution to shallow soil and plant stems. Hydraulic redistribution of deep water was substantial across all treatments, accounting for 34-72 % of surface-soil predawn moisture. Fourteen days after fertilization, the surface-fertilized plants exhibited increased hydraulic redistribution and increased (15)N and P acquisition with higher rates of deep-irrigation. Deep-fertilization also increased hydraulic redistribution to surface soils, although these plants additionally accumulated (2)H2O in their stem tissue overnight, probably due to nocturnal transpiration. Plants engaged in nocturnal transpiration also increased (15)N and P acquisition from deep fertilizer sources. Thus, both nocturnal transpiration and hydraulic redistribution increased acquisition of shallow soil N and P, possibly through a combination of increased nutrient availability and mobility.
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Affiliation(s)
- Ignatious Matimati
- Department of Biological Sciences, University of Cape Town, Private Bag X1, Rondebosch, 7701, South Africa
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Neumann RB, Cardon ZG, Teshera-Levye J, Rockwell FE, Zwieniecki MA, Holbrook NM. Modelled hydraulic redistribution by sunflower (Helianthus annuus L.) matches observed data only after including night-time transpiration. PLANT, CELL & ENVIRONMENT 2014; 37:899-910. [PMID: 24118010 DOI: 10.1111/pce.12206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/05/2013] [Accepted: 09/09/2013] [Indexed: 06/02/2023]
Abstract
The movement of water from moist to dry soil layers through the root systems of plants, referred to as hydraulic redistribution (HR), occurs throughout the world and is thought to influence carbon and water budgets and ecosystem functioning. The realized hydrologic, biogeochemical and ecological consequences of HR depend on the amount of redistributed water, whereas the ability to assess these impacts requires models that correctly capture HR magnitude and timing. Using several soil types and two ecotypes of sunflower (Helianthus annuus L.) in split-pot experiments, we examined how well the widely used HR modelling formulation developed by Ryel et al. matched experimental determination of HR across a range of water potential driving gradients. H. annuus carries out extensive night-time transpiration, and although over the last decade it has become more widely recognized that night-time transpiration occurs in multiple species and many ecosystems, the original Ryel et al. formulation does not include the effect of night-time transpiration on HR. We developed and added a representation of night-time transpiration into the formulation, and only then was the model able to capture the dynamics and magnitude of HR we observed as soils dried and night-time stomatal behaviour changed, both influencing HR.
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Affiliation(s)
- Rebecca B Neumann
- Department of Civil and Environmental Engineering, University of Washington, 201 More Hall, Seattle, WA, 98195, USA; Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave, Cambridge, MA, 02138, USA
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21
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Bradford JB, Schlaepfer DR, Lauenroth WK. Ecohydrology of Adjacent Sagebrush and Lodgepole Pine Ecosystems: The Consequences of Climate Change and Disturbance. Ecosystems 2014. [DOI: 10.1007/s10021-013-9745-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Prieto I, Ryel RJ. Internal hydraulic redistribution prevents the loss of root conductivity during drought. TREE PHYSIOLOGY 2014; 34:39-48. [PMID: 24436338 DOI: 10.1093/treephys/tpt115] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Shrubs of the Great Basin desert in Utah are subjected to a prolonged summer drought with the potential consequence of reduced water transport capability of the xylem due to drought-induced cavitation. Hydraulic redistribution (HR) is the passive movement of water from deep to shallow soil through plant roots. Hydraulic redistribution can increase water availability in shallow soil and ameliorate drought stress, providing better soil and root water status, which could affect shallow root conductivity (Ks) and native root embolism. We tested this hypothesis in an Artemisia tridentata Nutt. mono-specific stand grown in a common garden in Utah. We enhanced HR artificially by applying a once a week deep-irrigation treatment increasing the water potential gradient between deep and shallow soil layers. Plants that were deep-watered had less negative water potentials and greater stomatal conductance and transpiration rates than non-watered control plants. After irrigation with labeled water (δD), xylem water in stems and shallow roots of watered shrubs was enriched with respect to control shrubs, a clear indication of deep water uptake and HR. Shallow root conductivity was threefold greater and shrubs experienced lower native embolism when deep-watered. We found clear evidence of water transfer between deep and shallow roots through internal HR that delayed depletion of shallow soil water content, maintained Ks and prevented root embolism. Overall, our results show a positive effect of HR on root water transport capacity in otherwise dry soil, with important implications for plant water status.
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Affiliation(s)
- Iván Prieto
- Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, Carretera de Sacramento s/n, E-04120 La Cañada de San Urbano, Almería, Spain
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23
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Hao XM, Li Y, Deng HJ. Assessment of hydraulic redistribution on desert riparian forests in an extremely arid area. ENVIRONMENTAL MONITORING AND ASSESSMENT 2013; 185:10027-10038. [PMID: 23793541 DOI: 10.1007/s10661-013-3310-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 06/11/2013] [Indexed: 06/02/2023]
Abstract
The roots of Populus euphratica, a plant that grows in the lower reaches of the Tarim River, Northwest China, exhibit a significant level of hydraulic redistribution; however, quantitative assessments of the water-sharing process and its ecological effects are limited. This study was designed to obtain such data using an assessment model based on field observation parameters, including soil water content (soil water potential), root distribution, and stable isotope δ(18)O values of soil and plant samples during the entire growing season. The results showed that hydraulic redistribution in P. euphratica can be detected in 0-120 cm soil layers, with the amount of hydraulically redistributed water (HRW) in the soil found at different depths as follows: 60-80 > 40-60 > 20-40 > 0-20 > 80-100 > 100-120 cm. The variations in HRW in soil layers can be partly attributed to the vertical distribution of roots. The denser roots found at greater depths positively influenced the amount of redistributed water in lower soil layers. During the growing season, the amount of HRW reached a daily average of 0.27 mm, which allowed increased transpiration and provided an adequate water supply to herbs. Based on the stable isotope (δ(18)O) data, the amount of HRW provided by the roots of P. euphratica could meet 22-41% of its water demand.
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Affiliation(s)
- Xing-Ming Hao
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi, Xinjiang, 830011, People's Republic of China,
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24
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Berry ZC, Hughes NM, Smith WK. Cloud immersion: an important water source for spruce and fir saplings in the southern Appalachian Mountains. Oecologia 2013; 174:319-26. [DOI: 10.1007/s00442-013-2770-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/31/2013] [Indexed: 11/28/2022]
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25
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Cardon ZG, Stark JM, Herron PM, Rasmussen JA. Sagebrush carrying out hydraulic lift enhances surface soil nitrogen cycling and nitrogen uptake into inflorescences. Proc Natl Acad Sci U S A 2013; 110:18988-93. [PMID: 24191007 PMCID: PMC3839719 DOI: 10.1073/pnas.1311314110] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plant roots serve as conduits for water flow not only from soil to leaves but also from wetter to drier soil. This hydraulic redistribution through root systems occurs in soils worldwide and can enhance stomatal opening, transpiration, and plant carbon gain. For decades, upward hydraulic lift (HL) of deep water through roots into dry, litter-rich, surface soil also has been hypothesized to enhance nutrient availability to plants by stimulating microbially controlled nutrient cycling. This link has not been demonstrated in the field. Working in sagebrush-steppe, where water and nitrogen limit plant growth and reproduction and where HL occurs naturally during summer drought, we slightly augmented deep soil water availability to 14 HL+ treatment plants throughout the summer growing season. The HL+ sagebrush lifted greater amounts of water than control plants and had slightly less negative predawn and midday leaf water potentials. Soil respiration was also augmented under HL+ plants. At summer's end, application of a gas-based (15)N isotopic labeling technique revealed increased rates of nitrogen cycling in surface soil layers around HL+ plants and increased uptake of nitrogen into HL+ plants' inflorescences as sagebrush set seed. These treatment effects persisted even though unexpected monsoon rainstorms arrived during assays and increased surface soil moisture around all plants. Simulation models from ecosystem to global scales have just begun to include effects of hydraulic redistribution on water and surface energy fluxes. Results from this field study indicate that plants carrying out HL can also substantially enhance decomposition and nitrogen cycling in surface soils.
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Affiliation(s)
- Zoe G. Cardon
- The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269-3043; and
| | - John M. Stark
- Biology Department and the Ecology Center, Utah State University, Logan, UT 84322-5305
| | - Patrick M. Herron
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269-3043; and
| | - Jed A. Rasmussen
- Biology Department and the Ecology Center, Utah State University, Logan, UT 84322-5305
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26
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Kumar R, Jat M, Shankar V. Evaluation of modeling of water ecohydrologic dynamics in soil–root system. Ecol Modell 2013. [DOI: 10.1016/j.ecolmodel.2013.08.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Eller CB, Lima AL, Oliveira RS. Foliar uptake of fog water and transport belowground alleviates drought effects in the cloud forest tree species, Drimys brasiliensis (Winteraceae). THE NEW PHYTOLOGIST 2013; 199:151-162. [PMID: 23534879 DOI: 10.1111/nph.12248] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 02/24/2013] [Indexed: 05/13/2023]
Abstract
Foliar water uptake (FWU) is a common water acquisition mechanism for plants inhabiting temperate fog-affected ecosystems, but the prevalence and consequences of this process for the water and carbon balance of tropical cloud forest species are unknown. We performed a series of experiments under field and glasshouse conditions using a combination of methods (sap flow, fluorescent apoplastic tracers and stable isotopes) to trace fog water movement from foliage to belowground components of Drimys brasiliensis. In addition, we measured leaf water potential, leaf gas exchange, leaf water repellency and growth of plants under contrasting soil water availabilities and fog exposure in glasshouse experiments to evaluate FWU effects on the water and carbon balance of D. brasiliensis saplings. Fog water diffused directly through leaf cuticles and contributed up to 42% of total foliar water content. FWU caused reversals in sap flow in stems and roots of up to 26% of daily maximum transpiration. Fog water transported through the xylem reached belowground pools and enhanced leaf water potential, photosynthesis, stomatal conductance and growth relative to plants sheltered from fog. Foliar uptake of fog water is an important water acquisition mechanism that can mitigate the deleterious effects of soil water deficits for D. brasiliensis.
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Affiliation(s)
- Cleiton B Eller
- Department of Plant Biology, Institute of Biology, University of Campinas - UNICAMP, CP6109, Campinas, São Paulo, Brazil
| | - Aline L Lima
- Department of Plant Biology, Institute of Biology, University of Campinas - UNICAMP, CP6109, Campinas, São Paulo, Brazil
| | - Rafael S Oliveira
- Department of Plant Biology, Institute of Biology, University of Campinas - UNICAMP, CP6109, Campinas, São Paulo, Brazil
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28
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Simulation of the effect of root distribution on hydraulic redistribution in a desert riparian forest. Ecol Res 2013. [DOI: 10.1007/s11284-013-1058-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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29
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Li L, Wang YP, Yu Q, Pak B, Eamus D, Yan J, van Gorsel E, Baker IT. Improving the responses of the Australian community land surface model (CABLE) to seasonal drought. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012jg002038] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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30
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Neumann RB, Cardon ZG. The magnitude of hydraulic redistribution by plant roots: a review and synthesis of empirical and modeling studies. THE NEW PHYTOLOGIST 2012; 194:337-352. [PMID: 22417121 DOI: 10.1111/j.1469-8137.2012.04088.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Hydraulic redistribution (HR) - the movement of water from moist to dry soil through plant roots - occurs worldwide within a range of different ecosystems and plant species. The proposed ecological and hydrologic impacts of HR include increasing dry-season transpiration and photosynthetic rates, prolonging the life span of fine roots and maintaining root-soil contact in dry soils, and moving rainwater down into deeper soil layers where it does not evaporate. In this review, we compile estimates of the magnitude of HR from ecosystems around the world, using representative empirical and modeling studies from which we could extract amounts of water redistributed by plant root systems. The reported average magnitude of HR varies by nearly two orders of magnitude across ecosystems, from 0.04 to 1.3 mm H(2)O d(-1) in the empirical literature, and from 0.1 to 3.23 mm H(2)O d(-1) in the modeling literature. Using these synthesized data, along with other published studies, we examine this variation in the magnitude of upward and downward HR, considering effects of plant, soil and ecosystem characteristics, as well as effects of methodological details (in both empirical and modeling studies) on estimates of HR. We take both ecological and hydrologic perspectives.
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Affiliation(s)
- Rebecca B Neumann
- Department of Civil and Environmental Engineering, 201 More Hall, University of Washington, Seattle, WA 98195, USA
| | - Zoe G Cardon
- The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA
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31
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Prieto I, Armas C, Pugnaire FI. Water release through plant roots: new insights into its consequences at the plant and ecosystem level. THE NEW PHYTOLOGIST 2012; 193:830-841. [PMID: 22250761 DOI: 10.1111/j.1469-8137.2011.04039.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Hydraulic redistribution (HR) is the passive movement of water between different soil parts via plant root systems, driven by water potential gradients in the soil-plant interface. New data suggest that HR is a heterogeneous and patchy process. In this review we examine the main biophysical and environmental factors controlling HR and its main implications at the plant, community and ecosystem levels. Experimental evidence and the use of novel modelling approaches suggest that HR may have important implications at the community scale, affecting net primary productivity as well as water and vegetation dynamics. Globally, HR may influence hydrological and biogeochemical cycles and, ultimately, climate.
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Affiliation(s)
- Iván Prieto
- Estación Experimental de Zonas Áridas - Consejo Superior de Investigaciones Científicas (EEZA-CSIC), Carretera de Sacramento s/n, E-04120 La Cañada de San Urbano, Almería, Spain
| | - Cristina Armas
- Estación Experimental de Zonas Áridas - Consejo Superior de Investigaciones Científicas (EEZA-CSIC), Carretera de Sacramento s/n, E-04120 La Cañada de San Urbano, Almería, Spain
| | - Francisco I Pugnaire
- Estación Experimental de Zonas Áridas - Consejo Superior de Investigaciones Científicas (EEZA-CSIC), Carretera de Sacramento s/n, E-04120 La Cañada de San Urbano, Almería, Spain
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32
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Brooksbank K, Veneklaas EJ, White DA, Carter JL. The fate of hydraulically redistributed water in a semi-arid zone eucalyptus species. TREE PHYSIOLOGY 2011; 31:649-658. [PMID: 21743058 DOI: 10.1093/treephys/tpr052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Although hydraulic redistribution has been observed for a range of tree species, including Eucalyptus kochii subsp. borealis (C. Gardner) D. Nicolle, there is limited direct evidence that water taken up by deep roots in moist soil is in fact exuded by shallow roots in dry soil. This paper reports an experiment designed to test this hypothesis. Water enriched with deuterium was added to the groundwater via a slotted tube at 4.5 m depth below 5-year-old E. kochii subsp. borealis trees. Nocturnal sap flow increased markedly immediately after deep irrigation, indicating that the trees were using water from this depth. Two weeks later, samples of surface soil and xylem water were found to contain levels of deuterium up to 30% higher than soils and xylem water from a control plot upslope of the main treatment plot. This is strong evidence that trees used groundwater and that efflux of important amounts of hydraulically redistributed water occurred via the roots of E. kochii subsp. borealis.
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Affiliation(s)
- Kim Brooksbank
- School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
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Bleby TM, McElrone AJ, Jackson RB. Water uptake and hydraulic redistribution across large woody root systems to 20 m depth. PLANT, CELL & ENVIRONMENT 2010; 33:2132-48. [PMID: 20716068 DOI: 10.1111/j.1365-3040.2010.02212.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Deep water uptake and hydraulic redistribution (HR) are important processes in many forests, savannas and shrublands. We investigated HR in a semi-arid woodland above a unique cave system in central Texas to understand how deep root systems facilitate HR. Sap flow was measured in 9 trunks, 47 shallow roots and 12 deep roots of Quercus, Bumelia and Prosopis trees over 12 months. HR was extensive and continuous, involving every tree and 83% of roots, with the total daily volume of HR over a 1 month period estimated to be approximately 22% of daily transpiration. During drought, deep roots at 20 m depth redistributed water to shallow roots (hydraulic lift), while after rain, shallow roots at 0-0.5 m depth redistributed water among other shallow roots (lateral HR). The main driver of HR appeared to be patchy, dry soil near the surface, although water may also have been redistributed to mid-level depths via deeper lateral roots. Deep roots contributed up to five times more water to transpiration and HR than shallow roots during drought but dramatically reduced their contribution after rain. Our results suggest that deep-rooted plants are important drivers of water cycling in dry ecosystems and that HR can significantly influence landscape hydrology.
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Affiliation(s)
- Timothy M Bleby
- School of Plant Biology, The University of Western Australia, Crawley, WA, Australia.
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Markewitz D, Devine S, Davidson EA, Brando P, Nepstad DC. Soil moisture depletion under simulated drought in the Amazon: impacts on deep root uptake. THE NEW PHYTOLOGIST 2010; 187:592-607. [PMID: 20659251 DOI: 10.1111/j.1469-8137.2010.03391.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
*Deep root water uptake in tropical Amazonian forests has been a major discovery during the last 15 yr. However, the effects of extended droughts, which may increase with climate change, on deep soil moisture utilization remain uncertain. *The current study utilized a 1999-2005 record of volumetric water content (VWC) under a throughfall exclusion experiment to calibrate a one-dimensional model of the hydrologic system to estimate VWC, and to quantify the rate of root uptake through 11.5 m of soil. *Simulations with root uptake compensation had a relative root mean square error (RRMSE) of 11% at 0-40 cm and < 5% at 350-1150 cm. The simulated contribution of deep root uptake under the control was c. 20% of water demand from 250 to 550 cm and c. 10% from 550 to 1150 cm. Furthermore, in years 2 (2001) and 3 (2002) of throughfall exclusion, deep root uptake increased as soil moisture was available but then declined to near zero in deep layers in 2003 and 2004. *Deep root uptake was limited despite high VWC (i.e. > 0.30 cm(3) cm(-3)). This limitation may partly be attributable to high residual water contents (theta(r)) in these high-clay (70-90%) soils or due to high soil-to-root resistance. The ability of deep roots and soils to contribute increasing amounts of water with extended drought will be limited.
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Affiliation(s)
- Daniel Markewitz
- Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, GA 30602, USA.
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Hydraulic lift through transpiration suppression in shrubs from two arid ecosystems: patterns and control mechanisms. Oecologia 2010; 163:855-65. [DOI: 10.1007/s00442-010-1615-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Accepted: 03/13/2010] [Indexed: 10/19/2022]
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36
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Hodge A. Roots: The Acquisition of Water and Nutrients from the Heterogeneous Soil Environment. PROGRESS IN BOTANY 2010. [DOI: 10.1007/978-3-642-02167-1_12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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37
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Hao GY, Jones TJ, Luton C, Zhang YJ, Manzane E, Scholz FG, Bucci SJ, Cao KF, Goldstein G. Hydraulic redistribution in dwarf Rhizophora mangle trees driven by interstitial soil water salinity gradients: impacts on hydraulic architecture and gas exchange. TREE PHYSIOLOGY 2009; 29:697-705. [PMID: 19324702 DOI: 10.1093/treephys/tpp005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Rhizophora mangle L. trees of Biscayne National Park (Florida, USA) have two distinct growth forms: tall trees (5-10 m) growing along the coast and dwarf trees (1 m or less) growing in the adjacent inland zone. Sharp decreases in salinity and thus increases in soil water potential from surface soil to about a depth of 1 m were found at the dwarf mangrove site but not at the tall mangrove site. Consistent with our prediction, hydraulic redistribution detected by reverse sap flow in shallow prop roots was observed during nighttime, early morning and late afternoon in dwarf trees, but not in tall trees. In addition, hydraulic redistribution was observed throughout the 24-h period during a low temperature spell. Dwarf trees had significantly lower sapwood-specific hydraulic conductivity, smaller stem vessel diameter, lower leaf area to sapwood area ratio (LA/SA), smaller leaf size and higher leaf mass per area. Leaves of dwarf trees had lower CO(2) assimilation rate and lower stomatal conductance compared to tall trees. Leaf water potentials at midday were more negative in tall trees that are consistent with their substantially higher stomatal conductance and LA/SA. The substantially lower water transport efficiency and the more conservative water use of dwarf trees may be due to a combination of factors such as high salinity in the surface soil, particularly during dry periods, and substantial reverse sap flow in shallow roots that make upper soil layers with high salinity a competing sink of water to the transpiring leaves. There may also be a benefit for the dwarf trees in having hydraulic redistribution because the reverse flow and the release of water to upper soil layers should lead to dilution of the high salinity in the rhizosphere and thus relieve its potential harm to dwarf R. mangle trees.
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Affiliation(s)
- Guang-You Hao
- Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan Province 666303, China
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Espino S, Schenk HJ. Hydraulically integrated or modular? Comparing whole-plant-level hydraulic systems between two desert shrub species with different growth forms. THE NEW PHYTOLOGIST 2009; 183:142-152. [PMID: 19368668 DOI: 10.1111/j.1469-8137.2009.02828.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
* Hydraulic systems of shrubs vary between hydraulically integrated and modular architectures; the latter divide the shrub into independent hydraulic units. Hydraulic systems of two common North American desert shrub species, the multi-branched Ambrosia dumosa and the single-stemmed Encelia farinosa (both Asteraceae), were compared to test for division into independent hydraulic units and the implications of such a division for water loss through leaves and roots. * Hydraulic systems of mature shrubs in the field were characterized using dye tracers and by documenting the degree of stem segmentation. Young pot-grown shrubs were subjected to heterogeneous and homogeneous watering. Spatial within-canopy variation of leaf water potentials and stomatal conductances, as well as soil water contents, were measured in response to manipulated soil water heterogeneity. * Results show that young Ambrosia shrubs are divided into independent hydraulic units long before they physically split into separate ramets as mature shrubs, and that young and mature Encelia shrubs possess integrated hydraulic systems. No hydraulic redistribution was detected for eitherspecies. * Our study shows that functional segmentation into independent hydraulic units precedes physical axis splitting, rather than being the consequence of split axes, and suggests that mature shrubs with round basal stems are likely to be hydraulically integrated.
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Affiliation(s)
- Susana Espino
- Department of Biological Science, California State University Fullerton, PO Box 6850, Fullerton, CA 92834-6850, USA
| | - H Jochen Schenk
- Department of Biological Science, California State University Fullerton, PO Box 6850, Fullerton, CA 92834-6850, USA
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Baker IT, Prihodko L, Denning AS, Goulden M, Miller S, da Rocha HR. Seasonal drought stress in the Amazon: Reconciling models and observations. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jg000644] [Citation(s) in RCA: 232] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- I. T. Baker
- Atmospheric Science; Colorado State University; Fort Collins Colorado USA
| | - L. Prihodko
- Natural Resources Ecology Laboratory; Colorado State University; Fort Collins Colorado USA
| | - A. S. Denning
- Atmospheric Science; Colorado State University; Fort Collins Colorado USA
| | - M. Goulden
- Department of Earth System Science, Ecology, and Evolutionary Biology; University of California; Irvine California USA
| | - S. Miller
- Atmospheric Sciences Research Center; State University of New York; Albany New York USA
| | - H. R. da Rocha
- Instituto de Astronomica, Geofisica e Ciencias Atmosfericas; Universidade de São Paulo; São Paulo Brazil
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Ryel RJ, Ivans CY, Peek MS, Leffler AJ. Functional Differences in Soil Water Pools: a New Perspective on Plant Water Use in Water-Limited Ecosystems. PROGRESS IN BOTANY 2008. [DOI: 10.1007/978-3-540-72954-9_16] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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41
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Zheng Z, Wang G. Modeling the dynamic root water uptake and its hydrological impact at the Reserva Jaru site in Amazonia. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2007jg000413] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Zhe Zheng
- Department of Civil and Environmental Engineering; University of Connecticut; Storrs Connecticut USA
- Center for Environmental Sciences and Engineering; University of Connecticut; Storrs Connecticut USA
| | - Guiling Wang
- Department of Civil and Environmental Engineering; University of Connecticut; Storrs Connecticut USA
- Center for Environmental Sciences and Engineering; University of Connecticut; Storrs Connecticut USA
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Allen MF, Vargas R, Graham EA, Swenson W, Hamilton M, Taggart M, Harmon TC, Rat'Ko A, Rundel P, Fulkerson B, Estrin D. Soil Sensor Technology: Life within a Pixel. Bioscience 2007. [DOI: 10.1641/b571008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Warren JM, Meinzer FC, Brooks JR, Domec JC, Coulombe R. Hydraulic redistribution of soil water in two old-growth coniferous forests: quantifying patterns and controls. THE NEW PHYTOLOGIST 2007; 173:753-765. [PMID: 17286824 DOI: 10.1111/j.1469-8137.2006.01963.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Although hydraulic redistribution of soil water (HR) by roots is a widespread phenomenon, the processes governing spatial and temporal patterns of HR are not well understood. We incorporated soil/plant biophysical properties into a simple model based on Darcy's law to predict seasonal trajectories of HR. We investigated the spatial and temporal variability of HR across multiple years in two old-growth coniferous forest ecosystems with contrasting species and moisture regimes by measurement of soil water content (theta) and water potential (Psi) throughout the upper soil profile, root distribution and conductivity, and relevant climate variables. Large HR variability within sites (0-0.5 mm d(-1)) was attributed to spatial patterns of roots, soil moisture and depletion. HR accounted for 3-9% of estimated total site water depletion seasonally, peaking at 0.16 mm d(-1) (ponderosa pine; Pinus ponderosa) or 0.30 mm d(-1) (Douglas-fir; Pseudotsuga menziesii), then declining as modeled pathway conductance dropped with increasing root cavitation. While HR can vary tremendously within a site, among years and among ecosystems, this variability can be explained by natural variability in Psi gradients and seasonal courses of root conductivity.
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Affiliation(s)
| | | | - J Renée Brooks
- Western Ecology Division, US EPA/NHEERL, Corvallis, OR 97333
| | - Jean-Christophe Domec
- Department of Wood Science and Engineering, Oregon State University, Corvallis, OR 97331
| | - Rob Coulombe
- Dynamac Corporation, 200 SW 35th St, Corvallis, OR 97333, USA
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Brooks JR, Meinzer FC, Warren JM, Domec JC, Coulombe R. Hydraulic redistribution in a Douglas-fir forest: lessons from system manipulations. PLANT, CELL & ENVIRONMENT 2006; 29:138-50. [PMID: 17086760 DOI: 10.1111/j.1365-3040.2005.01409.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Hydraulic redistribution (HR) occurs in many ecosystems; however, key questions remain about its consequences at the ecosystem level. The objectives of the present study were to quantify seasonal variation in HR and its driving force, and to manipulate the soil-root system to elucidate physiological components controlling HR and utilization of redistributed water. In the upper soil layer of a young Douglas-fir forest, HR was negligible in early summer, but increased to 0.17 mm day(-1) (20-60 cm layer) by late August when soil water potential was approximately -1 MPa. When maximum HR rates were observed, redistributed water replenished approximately 40% of the water depleted from the upper soil on a daily basis. Manipulations to the soil or to the soil/plant water potential driving force altered the rate of observed HR indicating that the rate of HR is controlled by a complex interplay between competing soil and plant water potential gradients and pathway resistances. Separating roots from the transpiring tree resulted in increased HR, and sap flow measurements on connected and disconnected roots showed reversal of water flow, a prerequisite for HR. Irrigating a small plot with deuterated water demonstrated that redistributed water was taken up by small understorey plants as far as 5 m from the watering source, and potentially further, but the utilization pattern was patchy. HR in the upper soil layers near the watering plot was twice that of the control HR. This increase in HR also increased the amount of water utilized by plants from the upper soil. These results indicate that the seasonal timing and magnitude of HR was strongly governed by the development of water potential differences within the soil, and the competing demand for water by the above ground portion of the tree.
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Affiliation(s)
- J Renée Brooks
- Western Ecology Division, US EPA/NHEERL, 200 SW 35th St, Corvallis OR 97333, USA.
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45
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Abstract
Roots are important conduits for the redistribution of water within the rooting zone. Root systems are often highly branched, and water flow between regions undoubtedly involves passage through junctions between individual roots. This study considered junctions in the roots of Douglas-fir with regard to the resistances encountered by water flow through the xylem. Flow into the root branch distally along the main root encountered much greater resistance than flow into the branch and proximally along the main root (toward the plant stem). When the main root proximal to the junction was gradually shortened, the resistance to flow in the branch root and distally along the main root increased dramatically. Thus, flow in this manner appears to depend on lateral flow within the root over many centimetres proximal to the junction and not just within the direct connection at the junction. These results suggest that the hydraulic nature of junctions is an important aspect of hydraulic redistribution of water within the soil utilizing flow through roots.
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Affiliation(s)
- Paul J Schulte
- Department of Biological Sciences, University of Nevada, Las Vegas, NV 89154-4004, USA.
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46
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Abstract
Hydraulic redistribution (HR), the nocturnal vertical transfer of soil water from moister to drier regions in the soil profile by roots, has now been observed in Amazonian trees. We have incorporated HR into an atmospheric general circulation model (the National Center for Atmospheric Research Community Atmospheric Model Version 2) to estimate its impact on climate over the Amazon and other parts of the globe where plants displaying HR occur. Model results show that photosynthesis and evapotranspiration increase significantly in the Amazon during the dry season when plants are allowed to redistribute soil water. Plants draw water up and deposit it into the surface layers, and this water subsidy sustains transpiration at rates that deep roots alone cannot accomplish. The water used for dry season transpiration is from the deep storage layers in the soil, recharged during the previous wet season. We estimate that HR increases dry season (July to November) transpiration by approximately 40% over the Amazon. Our model also indicates that such an increase in transpiration over the Amazon and other drought-stressed regions affects the seasonal cycles of temperature through changes in latent heat, thereby establishing a direct link between plant root functioning and climate.
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Affiliation(s)
- Jung-Eun Lee
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA.
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47
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Oliveira RS, Dawson TE, Burgess SSO, Nepstad DC. Hydraulic redistribution in three Amazonian trees. Oecologia 2005; 145:354-63. [PMID: 16091971 DOI: 10.1007/s00442-005-0108-2] [Citation(s) in RCA: 254] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Accepted: 03/24/2005] [Indexed: 11/28/2022]
Abstract
About half of the Amazon rainforest is subject to seasonal droughts of 3 months or more. Despite this drought, several studies have shown that these forests, under a strongly seasonal climate, do not exhibit significant water stress during the dry season. In addition to deep soil water uptake, another contributing explanation for the absence of plant water stress during drought is the process of hydraulic redistribution; the nocturnal transfer of water by roots from moist to dry regions of the soil profile. Here, we present data on patterns of soil moisture and sap flow in roots of three dimorphic-rooted species in the Tapajós Forest, Amazônia, which demonstrate both upward (hydraulic lift) and downward hydraulic redistribution. We measured sap flow in lateral and tap roots of our three study species over a 2-year period using the heat ratio method, a sap-flow technique that allows bi-directional measurement of water flow. On certain nights during the dry season, reverse or acropetal flow (i.e.,in the direction of the soil) in the lateral roots and positive or basipetal sap flow (toward the plant) in the tap roots of Coussarea racemosa (caferana), Manilkara huberi (maçaranduba) and Protium robustum (breu) were observed, a pattern consistent with upward hydraulic redistribution (hydraulic lift). With the onset of heavy rains, this pattern reversed, with continuous night-time acropetal sap flow in the tap root and basipetal sap flow in lateral roots, indicating water movement from wet top soil to dry deeper soils (downward hydraulic redistribution). Both patterns were present in trees within a rainfall exclusion plot (Seca Floresta) and to a more limited extent in the control plot. Although hydraulic redistribution has traditionally been associated with arid or strongly seasonal environments, our findings now suggest that it is important in ameliorating water stress and improving rain infiltration in Amazonian rainforests. This has broad implications for understanding and modeling ecosystem process and forest function in this important biome.
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Affiliation(s)
- Rafael S Oliveira
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
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Gao Q, Yu M, Zhang X, Xu H, Huang Y. Modelling seasonal and diurnal dynamics of stomatal conductance of plants in a semiarid environment. FUNCTIONAL PLANT BIOLOGY : FPB 2005; 32:583-598. [PMID: 32689158 DOI: 10.1071/fp04092] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Accepted: 04/19/2005] [Indexed: 06/11/2023]
Abstract
Seasonal and diurnal stomatal conductance, leaf transpiration, and soil water contents of two shrubs of Hippophae rhamnoides L. subsp. Sinensis Rousi and Caragana korshinskii Kom., two trees of Malus pomila Mill. and Robinia pseudoacacia L., and a forb, Artemisia gmelinii, were measured in field of the semiarid Loess Plateau, north China, during the growing season of 2002. We developed a dynamic, nonlinear semi-mechanistic model to relate stomatal conductance of these plants to soil water potential, incident photon flux density, vapour pressure deficit, and partial CO2 pressure, on leaf surface. The model can be easily adapted to ecosystem simulation because of its mathematical simplicity. Guard-cell osmotic pressure at zero light intensity, apparent elastic modulus of guard cells per leaf area, half-saturation light intensity, maximum light-inducible osmotic pressure, soil-to-leaf resistance at zero plant water potential, sensitivity of soil-to-leaf resistance to xylem water potential, and plant body water capacitance, are independent parameters of the model. The model was fitted to the field data of the five species with a non-linear least-square algorithm to obtain the parameters. The result indicates that the model explained, on average, 88% of seasonal and diurnal variation of stomatal conductance for the five species, in comparison with 67% of variation explained by an early model without plant body water capacitance. Comparisons of the physiological parameters among the species show that the woody species exhibited more tolerance for water stresses than the forb because of their higher dark osmotic pressure, greater capability of seasonal and diurnal osmotic regulation, and stiffer guard cell structure (or smaller stomatal density or both). A decreasing trend of soil-to-leaf resistance from the trees to the shrubs to the forb was found in this study. Midday depression of transpiration and stomatal conductance may or may not occur, depending on the magnitude of body water capacitance.
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Affiliation(s)
- Qiong Gao
- MOE Key Laboratory of Environmental Change and Natural Disasters, College of Resources Science and Technology, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Mei Yu
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
| | - Xinshi Zhang
- MOE Key Laboratory of Environmental Change and Natural Disasters, College of Resources Science and Technology, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Hongmei Xu
- MOE Key Laboratory of Environmental Change and Natural Disasters, College of Resources Science and Technology, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Yongmei Huang
- MOE Key Laboratory of Environmental Change and Natural Disasters, College of Resources Science and Technology, Beijing Normal University, Beijing 100875, People's Republic of China
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49
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Zou CB, Barnes PW, Archer S, McMurtry CR. Soil moisture redistribution as a mechanism of facilitation in savanna tree-shrub clusters. Oecologia 2005; 145:32-40. [PMID: 15942764 DOI: 10.1007/s00442-005-0110-8] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Accepted: 03/24/2005] [Indexed: 10/25/2022]
Abstract
Plant-soil water relations were examined in the context of a selective removal study conducted in tree-shrub communities occupying different but contiguous soil types (small discrete clusters on shallow, duplex soils versus larger, extensive groves on deep, sandy soils) in a subtropical savanna parkland. We (1) tested for the occurrence of soil moisture redistribution by hydraulic lift (HL), (2) determined the influence of edaphic factors on HL, and (3) evaluated the significance of HL for overstory tree-understory shrub interactions. Diel cycling and nocturnal increases in soil water potential (Psisoil), characteristic signatures of HL, occurred intermittently throughout an annual growth cycle in both communities over a range of moisture levels (Psisoil=-0.5 to -6.0 MPa) but only when soils were distinctly stratified with depth (dry surface/wet deep soil layers). The magnitude of mean (+/-SE) diel fluctuations in Psisoil (0.19+/-0.01 MPa) did not differ on the two community types, though HL occurred more frequently in groves (deep soils) than clusters (shallow soils). Selective removal of either Prosopis glandulosa overstory or mixed-species shrub understory reduced the frequency of HL, indicating that Prosopis and at least one other woody species was conducting HL. For Zanthoxylum fagara, a shallow-rooted understory shrub, Prosopis removal from clusters decreased leaf water potential (Psileaf) and net CO2 exchange (A) during periods of HL. In contrast, overstory removal had neutral to positive effects on more deeply-rooted shrub species (Berberis trifoliolata and Condalia hookeri). Removal of the shrub understory in groves increased A in the overstory Prosopis. Results indicate the following: (a) HL is common but temporally dynamic in these savanna tree-shrub communities; (b) edaphic factors influencing the degree of overstory/understory development, rooting patterns and soil moisture distribution influence HL; (c) net interactions between overstory and understory elements in these woody patches can be positive, negative and neutral over an annual cycle, and (d) Prosopis-mediated HL is an important mechanism of faciliation for some, but not all, understory shrubs.
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Affiliation(s)
- C B Zou
- Department of Rangeland Ecology and Management, Texas A&M University, College Station, TX, 77843-2126, USA
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50
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Leffler AJ, Peek MS, Ryel RJ, Ivans CY, Caldwell MM. HYDRAULIC REDISTRIBUTION THROUGH THE ROOT SYSTEMS OF SENESCED PLANTS. Ecology 2005. [DOI: 10.1890/04-0854] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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