1
|
Voigt C, Dubbert M, Launiainen S, Porada P, Oestmann J, Piayda A. Impact of vegetation composition and seasonality on sensitivity of modelled CO 2 exchange in temperate raised bogs. Sci Rep 2024; 14:11023. [PMID: 38744922 PMCID: PMC11094101 DOI: 10.1038/s41598-024-61229-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 05/02/2024] [Indexed: 05/16/2024] Open
Abstract
Encroachment of vascular plants (VP) in temperate raised bogs, as a consequence of altered hydrological conditions and nutrient input, is widely observed. Effects of such vegetation shift on water and carbon cycles are, however, largely unknown and identification of responsible plant physiological traits is challenging. Process-based modelling offers the opportunity of gaining insights into ecosystem functioning beyond observations, and to infer decisive trait shifts of plant functional groups. We adapted the Soil-Vegetation-Atmosphere Transfer model pyAPES to a temperate raised bog site by calibration against measured peat temperature, water table and surface CO2 fluxes. We identified the most important traits determining CO2 fluxes by conducting Morris sensitivity analysis (MSA) under changing conditions throughout the year and simulated VP encroachment. We further investigated transferability of results to other sites by extending MSA to parameter ranges derived from literature review. We found highly variable intra-annual plant traits importance determining ecosystem CO2 fluxes, but only a partial shift of importance of photosynthetic processes from moss to VP during encroachment. Ecosystem respiration was dominated by peat respiration. Overall, carboxylation rate, base respiration rate and temperature sensitivity (Q10) were most important for determining bog CO2 balance and parameter ranking was robust even under the extended MSA.
Collapse
Affiliation(s)
- Claas Voigt
- Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Straße 84, 15374, Müncheberg, Germany.
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 65A, 38116, Braunschweig, Germany.
| | - Maren Dubbert
- Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Straße 84, 15374, Müncheberg, Germany
| | - Samuli Launiainen
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, 00790, Helsinki, Finland
| | - Philipp Porada
- Institute of Plant Science and Microbiology, Universität Hamburg, Ohnhorststr. 18, 22609, Hamburg, Germany
| | - Jan Oestmann
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 65A, 38116, Braunschweig, Germany
| | - Arndt Piayda
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 65A, 38116, Braunschweig, Germany
| |
Collapse
|
2
|
Zheng Y, Zhao W, Chen A, Chen Y, Chen J, Zhu Z. Vegetation canopy structure mediates the response of gross primary production to environmental drivers across multiple temporal scales. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170439. [PMID: 38281630 DOI: 10.1016/j.scitotenv.2024.170439] [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: 10/29/2023] [Revised: 01/10/2024] [Accepted: 01/23/2024] [Indexed: 01/30/2024]
Abstract
Gross primary production (GPP) is a critical component of the global carbon cycle and plays a significant role in the terrestrial carbon budget. The impact of environmental factors on GPP can occur through both direct (by influencing photosynthetic efficiency) and indirect (through the modulation of vegetation structure) pathways, but the extent to which these mechanisms contribute has been seldom quantified. In this study, we used structural equation modeling and observations from the FLUXNET network to investigate the direct and indirect effects of environmental factors on terrestrial ecosystem GPP at multiple temporal scales. We found that canopy structure, represented by leaf area index (LAI), is a crucial intermediate factor in the GPP response to environmental drivers. Environmental factors affect GPP indirectly by altering canopy structure, and the relative proportion of indirect effects decreased with increasing LAI. The study also identified different effects of environmental factors on GPP across time scales. At the half-hourly time scale, radiation was the primary driver of GPP. In contrast, the influences of temperature and vapor pressure deficit took on greater prominence at longer time scales. About half of the total effect of temperature on GPP was indirect through the regulation of canopy structure, and the indirect effect increased with increasing time scale (GPPNT-based models: 0.135 (half-hourly) vs. 0.171 (daily) vs. 0.189 (weekly) vs. 0.217 (monthly); GPPDT-based models: 0.139 vs. 0.170 vs. 0.187 vs. 0.215; all values were reported in gC m-2 d-1 °C-1, P < 0.001); while the indirect effect of radiation on GPP was comparatively lower, accounting for less than a quarter of the total effect. Furthermore, we observed a direct, negative-to-positive impact of precipitation on GPP across timescales. These findings provide crucial information on the interplay between environmental factors and LAI on GPP and enable a deeper understanding of the driving mechanisms of GPP.
Collapse
Affiliation(s)
- Yaoyao Zheng
- School of Urban Planning and Design, Shenzhen Graduate School, Peking University, Shenzhen 518055, China; Key Laboratory of Earth Surface System and Human-Earth Relations, Ministry of Natural Resources of China, Shenzhen Graduate School, Peking University, Shenzhen 518055, China
| | - Weiqing Zhao
- School of Urban Planning and Design, Shenzhen Graduate School, Peking University, Shenzhen 518055, China; Key Laboratory of Earth Surface System and Human-Earth Relations, Ministry of Natural Resources of China, Shenzhen Graduate School, Peking University, Shenzhen 518055, China
| | - Anping Chen
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO, USA
| | - Yue Chen
- School of Urban Planning and Design, Shenzhen Graduate School, Peking University, Shenzhen 518055, China; Key Laboratory of Earth Surface System and Human-Earth Relations, Ministry of Natural Resources of China, Shenzhen Graduate School, Peking University, Shenzhen 518055, China
| | - Jiana Chen
- School of Urban Planning and Design, Shenzhen Graduate School, Peking University, Shenzhen 518055, China; Key Laboratory of Earth Surface System and Human-Earth Relations, Ministry of Natural Resources of China, Shenzhen Graduate School, Peking University, Shenzhen 518055, China
| | - Zaichun Zhu
- School of Urban Planning and Design, Shenzhen Graduate School, Peking University, Shenzhen 518055, China; Key Laboratory of Earth Surface System and Human-Earth Relations, Ministry of Natural Resources of China, Shenzhen Graduate School, Peking University, Shenzhen 518055, China.
| |
Collapse
|
3
|
Tikkasalo OP, Leppä K, Launiainen S, Peltoniemi M, Mäkipää R, Rinne-Garmston KT, Sahlstedt E, Young GHF, Bokareva A, Lohila A, Korkiakoski M, Schiestl-Aalto P, Lehtonen A. Modeling the response of Norway spruce tree-ring carbon and oxygen isotopes to selection harvest on a drained peatland forest. TREE PHYSIOLOGY 2024; 44:tpad119. [PMID: 37756632 PMCID: PMC10993295 DOI: 10.1093/treephys/tpad119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 08/22/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023]
Abstract
Continuous cover forestry (CCF) has gained interest as an alternative to even-aged management particularly on drained peatland forests. However, relatively little is known about the physiological response of suppressed trees when larger trees are removed as a part of CCF practices. Consequently, studies concentrating on process-level modeling of the response of trees to selection harvesting are also rare. Here, we compared, modeled and measured harvest response of previously suppressed Norway spruce (Picea abies) trees to a selection harvest. We quantified the harvest response by collecting Norway spruce tree-ring samples in a drained peatland forest site and measuring the change in stable carbon and oxygen isotopic ratios of wood formed during 2010-20, including five post-harvest years. The measured isotopic ratios were compared with ecosystem-level process model predictions for ${\kern0em }^{13}$C discrimination and ${\kern0em }^{18}$O leaf water enrichment. We found that the model predicted similar but lower harvest response than the measurements. Furthermore, accounting for mesophyll conductance was important for capturing the variation in ${\kern0em }^{13}$C discrimination. In addition, we performed sensitivity analysis on the model, which suggests that the modeled ${\kern0em }^{13}$C discrimination is sensitive to parameters related to CO2 transport through stomata to the mesophyll.
Collapse
Affiliation(s)
- Olli-Pekka Tikkasalo
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Kersti Leppä
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Samuli Launiainen
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Mikko Peltoniemi
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Raisa Mäkipää
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Katja T Rinne-Garmston
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Elina Sahlstedt
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Giles H F Young
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Aleksandra Bokareva
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Annalea Lohila
- Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland
- Institute for Atmospheric and Earth System Research (INAR)/Physics, Faculty of Sciences, University of Helsinki, P.O. Box 68, FI-00014 Helsinki, Finland
| | - Mika Korkiakoski
- Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland
| | - Pauliina Schiestl-Aalto
- Institute for Atmospheric and Earth System Research (INAR)/Physics, Faculty of Sciences, University of Helsinki, P.O. Box 68, FI-00014 Helsinki, Finland
| | - Aleksi Lehtonen
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| |
Collapse
|
4
|
Anttila J, Tikkasalo OP, Hölttä T, Lintunen A, Vainio E, Leppä K, Haikarainen IP, Koivula H, Ghasemi Falk H, Kohl L, Launiainen S, Pihlatie M. Model of methane transport in tree stems: Case study of sap flow and radial diffusion. PLANT, CELL & ENVIRONMENT 2024; 47:140-155. [PMID: 37712449 DOI: 10.1111/pce.14718] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 08/10/2023] [Accepted: 09/04/2023] [Indexed: 09/16/2023]
Abstract
The transport processes of methane (CH4 ) in tree stems remain largely unknown, although they are critical in assessing the whole-forest CH4 dynamics. We used a physically based dynamic model to study the spatial and diurnal dynamics of stem CH4 transport and fluxes. We parameterised the model using data from laboratory experiments with Pinus sylvestris and Betula pendula and compared the model to experimental data from a field study. Stem CH4 flux in laboratory and field conditions were explained by the axial advective CH4 transport from soil with xylem sap flow and the radial CH4 diffusion through the stem conditions. Diffusion resistance caused by the bark permeability did not significantly affect gas transport or stem CH4 flux in the laboratory experiments. The role of axial diffusion of CH4 in trees was unresolved and requires further studies. Due to the transit time of CH4 in the stem, the diurnal dynamics of stem CH4 fluxes can deviate markedly from the diurnal dynamics of sap flow.
Collapse
Affiliation(s)
- Jani Anttila
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
- Natural Resources Institute Finland (Luke), Helsinki, Finland
- Department of Forest Sciences, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - Olli-Pekka Tikkasalo
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
- Natural Resources Institute Finland (Luke), Helsinki, Finland
- Department of Forest Sciences, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - Teemu Hölttä
- Department of Forest Sciences, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - Anna Lintunen
- Department of Forest Sciences, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
- Department of Physics, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - Elisa Vainio
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
- Department of Forest Sciences, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - Kersti Leppä
- Natural Resources Institute Finland (Luke), Helsinki, Finland
| | - Iikka P Haikarainen
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
- Department of Forest Sciences, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - Hanna Koivula
- Department of Food and Nutrition, Helsinki Institute of Sustainability Science, HELSUS, University of Helsinki, Helsinki, Finland
| | - Homa Ghasemi Falk
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
| | - Lukas Kohl
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
- Department of Forest Sciences, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | | | - Mari Pihlatie
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
- Department of Forest Sciences, Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
- Department of Agricultural Sciences, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland
| |
Collapse
|
5
|
Euskirchen ES, Edgar CW, Kane ES, Waldrop MP, Neumann RB, Manies KL, Douglas TA, Dieleman C, Jones MC, Turetsky MR. Persistent net release of carbon dioxide and methane from an Alaskan lowland boreal peatland complex. GLOBAL CHANGE BIOLOGY 2024; 30:e17139. [PMID: 38273498 DOI: 10.1111/gcb.17139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 11/20/2023] [Accepted: 12/18/2023] [Indexed: 01/27/2024]
Abstract
Permafrost degradation in peatlands is altering vegetation and soil properties and impacting net carbon storage. We studied four adjacent sites in Alaska with varied permafrost regimes, including a black spruce forest on a peat plateau with permafrost, two collapse scar bogs of different ages formed following thermokarst, and a rich fen without permafrost. Measurements included year-round eddy covariance estimates of net carbon dioxide (CO2 ), mid-April to October methane (CH4 ) emissions, and environmental variables. From 2011 to 2022, annual rainfall was above the historical average, snow water equivalent increased, and snow-season duration shortened due to later snow return. Seasonally thawed active layer depths also increased. During this period, all ecosystems acted as slight annual sources of CO2 (13-59 g C m-2 year-1 ) and stronger sources of CH4 (11-14 g CH4 m-2 from ~April to October). The interannual variability of net ecosystem exchange was high, approximately ±100 g C m-2 year-1 , or twice what has been previously reported across other boreal sites. Net CO2 release was positively related to increased summer rainfall and winter snow water equivalent and later snow return. Controls over CH4 emissions were related to increased soil moisture and inundation status. The dominant emitter of carbon was the rich fen, which, in addition to being a source of CO2 , was also the largest CH4 emitter. These results suggest that the future carbon-source strength of boreal lowlands in Interior Alaska may be determined by the area occupied by minerotrophic fens, which are expected to become more abundant as permafrost thaw increases hydrologic connectivity. Since our measurements occur within close proximity of each other (≤1 km2 ), this study also has implications for the spatial scale and data used in benchmarking carbon cycle models and emphasizes the necessity of long-term measurements to identify carbon cycle process changes in a warming climate.
Collapse
Affiliation(s)
- Eugénie S Euskirchen
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, USA
- Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska, USA
| | - Colin W Edgar
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, USA
| | - Evan S Kane
- College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan, USA
- Northern Research Station, USDA Forest Service, Houghton, Michigan, USA
| | - Mark P Waldrop
- U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Moffett Fields, Mountain View, California, USA
| | - Rebecca B Neumann
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
| | - Kristen L Manies
- U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Moffett Fields, Mountain View, California, USA
| | - Thomas A Douglas
- U.S. Army Cold Regions Research & Engineering Laboratory, Fort Wainwright, Fairbanks, Alaska, USA
| | - Catherine Dieleman
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Miriam C Jones
- U.S. Geological Survey, Florence Bascom Geoscience Center, Reston, Virginia, USA
| | - Merritt R Turetsky
- Institute of Arctic and Alpine Research, Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, USA
| |
Collapse
|
6
|
Tang Y, Sahlstedt E, Young G, Schiestl‐Aalto P, Saurer M, Kolari P, Jyske T, Bäck J, Rinne‐Garmston KT. Estimating intraseasonal intrinsic water-use efficiency from high-resolution tree-ring δ 13 C data in boreal Scots pine forests. THE NEW PHYTOLOGIST 2023; 237:1606-1619. [PMID: 36451527 PMCID: PMC10108005 DOI: 10.1111/nph.18649] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 11/16/2022] [Indexed: 05/26/2023]
Abstract
Intrinsic water-use efficiency (iWUE), a key index for carbon and water balance, has been widely estimated from tree-ring δ13 C at annual resolution, but rarely at high-resolution intraseasonal scale. We estimated high-resolution iWUE from laser-ablation δ13 C analysis of tree-rings (iWUEiso ) and compared it with iWUE derived from gas exchange (iWUEgas ) and eddy covariance (iWUEEC ) data for two Pinus sylvestris forests from 2002 to 2019. By carefully timing iWUEiso via modeled tree-ring growth, iWUEiso aligned well with iWUEgas and iWUEEC at intraseasonal scale. However, year-to-year patterns of iWUEgas , iWUEiso , and iWUEEC were different, possibly due to distinct environmental drivers on iWUE across leaf, tree, and ecosystem scales. We quantified the modification of iWUEiso by postphotosynthetic δ13 C enrichment from leaf sucrose to tree rings and by nonexplicit inclusion of mesophyll and photorespiration terms in photosynthetic discrimination model, which resulted in overestimation of iWUEiso by up to 11% and 14%, respectively. We thus extended the application of tree-ring δ13 C for iWUE estimates to high-resolution intraseasonal scale. The comparison of iWUEgas , iWUEiso , and iWUEEC provides important insights into physiological acclimation of trees across leaf, tree, and ecosystem scales under climate change and improves the upscaling of ecological models.
Collapse
Affiliation(s)
- Yu Tang
- Bioeconomy and Environment UnitNatural Resources Institute Finland (Luke)Latokartanonkaari 900790HelsinkiFinland
- Faculty of Agriculture and Forestry, Institute for Atmospheric and Earth System Research (INAR) / Forest SciencesUniversity of HelsinkiPO Box 2700014HelsinkiFinland
| | - Elina Sahlstedt
- Bioeconomy and Environment UnitNatural Resources Institute Finland (Luke)Latokartanonkaari 900790HelsinkiFinland
| | - Giles Young
- Bioeconomy and Environment UnitNatural Resources Institute Finland (Luke)Latokartanonkaari 900790HelsinkiFinland
| | - Pauliina Schiestl‐Aalto
- Faculty of Science, Institute for Atmospheric and Earth System Research (INAR) / PhysicsUniversity of HelsinkiPO Box 6800014HelsinkiFinland
| | - Matthias Saurer
- Forest DynamicsSwiss Federal Institute for Forest, Snow and Landscape Research (WSL)Zürcherstrasse 1118903BirmensdorfSwitzerland
| | - Pasi Kolari
- Faculty of Science, Institute for Atmospheric and Earth System Research (INAR) / PhysicsUniversity of HelsinkiPO Box 6800014HelsinkiFinland
| | - Tuula Jyske
- Production Systems UnitNatural Resources Institute FinlandTietotie 202150EspooFinland
| | - Jaana Bäck
- Faculty of Agriculture and Forestry, Institute for Atmospheric and Earth System Research (INAR) / Forest SciencesUniversity of HelsinkiPO Box 2700014HelsinkiFinland
| | - Katja T. Rinne‐Garmston
- Bioeconomy and Environment UnitNatural Resources Institute Finland (Luke)Latokartanonkaari 900790HelsinkiFinland
| |
Collapse
|
7
|
Leppä K, Tang Y, Ogée J, Launiainen S, Kahmen A, Kolari P, Sahlstedt E, Saurer M, Schiestl‐Aalto P, Rinne‐Garmston KT. Explicitly accounting for needle sugar pool size crucial for predicting intra-seasonal dynamics of needle carbohydrates δ 18 O and δ 13 C. THE NEW PHYTOLOGIST 2022; 236:2044-2060. [PMID: 35575976 PMCID: PMC9795997 DOI: 10.1111/nph.18227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/07/2022] [Indexed: 05/14/2023]
Abstract
We explore needle sugar isotopic compositions (δ18 O and δ13 C) in boreal Scots pine (Pinus sylvestris) over two growing seasons. A leaf-level dynamic model driven by environmental conditions and based on current understanding of isotope fractionation processes was built to predict δ18 O and δ13 C of two hierarchical needle carbohydrate pools, accounting for the needle sugar pool size and the presence of an invariant pinitol pool. Model results agreed well with observed needle water δ18 O, δ18 O and δ13 C of needle water-soluble carbohydrates (sugars + pinitol), and needle sugar δ13 C (R2 = 0.95, 0.84, 0.60, 0.73, respectively). Relative humidity (RH) and intercellular to ambient CO2 concentration ratio (Ci /Ca ) were the dominant drivers of δ18 O and δ13 C variability, respectively. However, the variability of needle sugar δ18 O and δ13 C was reduced on diel and intra-seasonal timescales, compared to predictions based on instantaneous RH and Ci /Ca , due to the large needle sugar pool, which caused the signal formation period to vary seasonally from 2 d to more than 5 d. Furthermore, accounting for a temperature-sensitive biochemical 18 O-fractionation factor and mesophyll resistance in 13 C-discrimination were critical. Interpreting leaf-level isotopic signals requires understanding on time integration caused by mixing in the needle sugar pool.
Collapse
Affiliation(s)
- Kersti Leppä
- Natural Resources Institute Finland00790HelsinkiFinland
| | - Yu Tang
- Natural Resources Institute Finland00790HelsinkiFinland
- Faculty of Agriculture and Forestry, Institute for Atmospheric and Earth System Research (INAR)/Forest SciencesUniversity of Helsinki00014HelsinkiFinland
| | | | | | - Ansgar Kahmen
- Department of Environmental Sciences – BotanyUniversity of Basel4056BaselSwitzerland
| | - Pasi Kolari
- Faculty of Science, Institute for Atmospheric and Earth System Research (INAR)/PhysicsUniversity of Helsinki00014HelsinkiFinland
| | | | - Matthias Saurer
- Forest Dynamics, Swiss Federal Institute for ForestSnow and Landscape Research (WSL)8903BirmensdorfSwitzerland
| | - Pauliina Schiestl‐Aalto
- Faculty of Science, Institute for Atmospheric and Earth System Research (INAR)/PhysicsUniversity of Helsinki00014HelsinkiFinland
| | | |
Collapse
|
8
|
Desai AR, Murphy BA, Wiesner S, Thom J, Butterworth BJ, Koupaei‐Abyazani N, Muttaqin A, Paleri S, Talib A, Turner J, Mineau J, Merrelli A, Stoy P, Davis K. Drivers of Decadal Carbon Fluxes Across Temperate Ecosystems. JOURNAL OF GEOPHYSICAL RESEARCH. BIOGEOSCIENCES 2022; 127:e2022JG007014. [PMID: 37502709 PMCID: PMC10369927 DOI: 10.1029/2022jg007014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 07/29/2023]
Abstract
Long-running eddy covariance flux towers provide insights into how the terrestrial carbon cycle operates over multiple timescales. Here, we evaluated variation in net ecosystem exchange (NEE) of carbon dioxide (CO2) across the Chequamegon Ecosystem-Atmosphere Study AmeriFlux core site cluster in the upper Great Lakes region of the USA from 1997 to 2020. The tower network included two mature hardwood forests with differing management regimes (US-WCr and US-Syv), two fen wetlands with varying levels of canopy sheltering and vegetation (US-Los and US-ALQ), and a very tall (400 m) landscape-level tower (US-PFa). Together, they provided over 70 site-years of observations. The 19-tower Chequamegon Heterogenous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors 2019 campaign centered around US-PFa provided additional information on the spatial variation of NEE. Decadal variability was present in all long-term sites, but cross-site coherence in interannual NEE in the earlier part of the record became weaker with time as non-climatic factors such as local disturbances likely dominated flux time series. Average decadal NEE at the tall tower transitioned from carbon source to sink to near neutral over 24 years. Respiration had a greater effect than photosynthesis on driving variations in NEE at all sites. Declining snowfall offset potential increases in assimilation from warmer springs, as less-insulated soils delayed start of spring green-up. Higher CO2 increased maximum net assimilation parameters but not total gross primary productivity. Stand-scale sites were larger net sinks than the landscape tower. Clustered, long-term carbon flux observations provide value for understanding the diverse links between carbon and climate and the challenges of upscaling these responses across space.
Collapse
Affiliation(s)
- Ankur R. Desai
- Department of Atmospheric and Oceanic SciencesUniversity of Wisconsin–MadisonMadisonWIUSA
| | - Bailey A. Murphy
- Department of Atmospheric and Oceanic SciencesUniversity of Wisconsin–MadisonMadisonWIUSA
| | - Susanne Wiesner
- Department of Plant and Earth ScienceUniversity of Wisconsin–River FallsRiver FallsWIUSA
| | - Jonathan Thom
- Space Science and Engineering CenterUniversity of Wisconsin–MadisonMadisonWIUSA
| | - Brian J. Butterworth
- Cooperative Institute for Research in Environmental SciencesCU BoulderBoulderCOUSA
- NOAA Physical Sciences LaboratoryBoulderCOUSA
| | | | - Andi Muttaqin
- Department of Atmospheric and Oceanic SciencesUniversity of Wisconsin–MadisonMadisonWIUSA
| | - Sreenath Paleri
- Department of Atmospheric and Oceanic SciencesUniversity of Wisconsin–MadisonMadisonWIUSA
| | - Ammara Talib
- Department of Civil and Environmental EngineeringUniversity of Wisconsin–MadisonMadisonWIUSA
| | - Jess Turner
- Freshwater & Marine SciencesUniversity of Wisconsin–MadisonMadisonWIUSA
| | - James Mineau
- Department of Atmospheric and Oceanic SciencesUniversity of Wisconsin–MadisonMadisonWIUSA
| | - Aronne Merrelli
- Department of Climate and Space Sciences and EngineeringUniversity of MichiganAnn ArborMIUSA
| | - Paul Stoy
- Department of Plant and Earth ScienceUniversity of Wisconsin–River FallsRiver FallsWIUSA
| | - Ken Davis
- Department of MeteorologyPennsylvania State UniversityUniversity ParkPAUSA
| |
Collapse
|