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Safaei M, Kleinebecker T, Weis M, Große-Stoltenberg A. Tracking effects of extreme drought on coniferous forests from space using dynamic habitat indices. Heliyon 2024; 10:e27864. [PMID: 38560251 PMCID: PMC10981029 DOI: 10.1016/j.heliyon.2024.e27864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 02/27/2024] [Accepted: 03/07/2024] [Indexed: 04/04/2024] Open
Abstract
Terrestrial ecosystems such as coniferous forests in Central Europe are experiencing changes in health status following extreme droughts compounding with severe heat waves. The increasing temporal resolution and spatial coverage of earth observation data offer new opportunities to assess these dynamics. Dense time-series of optical satellite data allow for computing Dynamic Habitat Indices (DHIs), which have been predominantly used in biodiversity studies. However, DHIs cover three aspects of vegetation changes that could be affected by drought: annual productivity, minimum cover, and seasonality. Here, we evaluate the health status of coniferous forests in the federal state of Hesse in Germany over the period 2017-2020 including the severe drought year of 2018 using DHIs based on the Normalized Difference Vegetation Index (NDVI) for drought assessment. To identify the most important variables affecting coniferous forest die-off, a series of environmental variables together with the three DHIs components were used in a logistic regression (LR) model. Each DHI component changed significantly across non-damaged and damaged sites in all years (p-value 0.05). When comparing 2017 to 2019, DHI-based annual productivity decreased and seasonality increased. Most importantly, none of the DHI components had reached pre-drought conditions, which likely indicates a change in ecosystem functioning. We also identified spatially explicit areas highly affected by drought. The LR model revealed that in addition to common environmental parameters related to temperature, precipitation, and elevation, DHI components were the most important factors explaining the health status. Our analysis demonstrates the potential of DHIs to capture the effect of drought events on Central European coniferous forest ecosystems. Since the spaceborne data are available at the global level, this approach can be applied to track the dynamics of ecosystem conditions in other regions, at larger spatial scales, and for other Land Use/Land Cover types.
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Affiliation(s)
- Mojdeh Safaei
- Division of Landscape Ecology and Landscape Planning, Institute of Landscape Ecology and Resource Management, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University Giessen, Heinrich-Buff Ring 26-32, 35392, Giessen, Germany
| | - Till Kleinebecker
- Division of Landscape Ecology and Landscape Planning, Institute of Landscape Ecology and Resource Management, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University Giessen, Heinrich-Buff Ring 26-32, 35392, Giessen, Germany
- Center for International Development and Environmental Research (ZEU), Senckenbergstrasse 3, 35390, Giessen, Germany
| | - Manuel Weis
- Hessian Agency for Nature Conservation, Environment and Geology (HLNUG), Rheingaustraße 186, 65203, Wiesbaden, Germany
| | - André Große-Stoltenberg
- Division of Landscape Ecology and Landscape Planning, Institute of Landscape Ecology and Resource Management, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University Giessen, Heinrich-Buff Ring 26-32, 35392, Giessen, Germany
- Center for International Development and Environmental Research (ZEU), Senckenbergstrasse 3, 35390, Giessen, Germany
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Wei J, von Arx G, Fan Z, Ibrom A, Mund M, Knohl A, Peters RL, Babst F. Drought alters aboveground biomass production efficiency: Insights from two European beech forests. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 919:170726. [PMID: 38331275 DOI: 10.1016/j.scitotenv.2024.170726] [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: 09/05/2023] [Revised: 02/03/2024] [Accepted: 02/03/2024] [Indexed: 02/10/2024]
Abstract
The fraction of photosynthetically assimilated carbon that trees allocate to long-lasting woody biomass pools (biomass production efficiency - BPE), is a key metric of the forest carbon balance. Its apparent simplicity belies the complex interplay between underlying processes of photosynthesis, respiration, litter and fruit production, and tree growth that respond differently to climate variability. Whereas the magnitude of BPE has been routinely quantified in ecological studies, its temporal dynamics and responses to extreme events such as drought remain less well understood. Here, we combine long-term records of aboveground carbon increment (ACI) obtained from tree rings with stand-level gross primary productivity (GPP) from eddy covariance (EC) records to empirically quantify aboveground BPE (= ACI/GPP) and its interannual variability in two European beech forests (Hainich, DE-Hai, Germany; Sorø, DK-Sor, Denmark). We found significant negative correlations between BPE and a daily-resolved drought index at both sites, indicating that woody growth is de-prioritized under water limitation. During identified extreme years, early-season drought reduced same-year BPE by 29 % (Hainich, 2011), 31 % (Sorø, 2006), and 14 % (Sorø, 2013). By contrast, the 2003 late-summer drought resulted in a 17 % reduction of post-drought year BPE at Hainich. Across the entire EC period, the daily-to-seasonal drought response of BPE resembled that of ACI, rather than that of GPP. This indicates that BPE follows sink dynamics more closely than source dynamics, which appear to be decoupled given the distinctive climate response patterns of GPP and ACI. Based on our observations, we caution against estimating the magnitude and variability of the carbon sink in European beech (and likely other temperate forests) based on carbon fluxes alone. We also encourage comparable studies at other long-term EC measurement sites from different ecosystems to further constrain the BPE response to rare climatic events.
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Affiliation(s)
- Jingshu Wei
- School of Natural Resources and the Environment, University of Arizona, 1064 E Lowell Street, Tucson, AZ 85721, USA; Swiss Federal Institute for Forest Snow and Landscape Research WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland; CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun Town, Mengla County, Yunnan Province 666303, China.
| | - Georg von Arx
- Swiss Federal Institute for Forest Snow and Landscape Research WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland; Oeschger Centre for Climate Change Research, University of Bern, Hochschulstrasse 4, CH-3012 Bern, Switzerland
| | - Zexin Fan
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun Town, Mengla County, Yunnan Province 666303, China
| | - Andreas Ibrom
- Biosystems Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, Denmark
| | - Martina Mund
- Forestry Research and Competence Centre Gotha, Jägerstraße1, D-99867 Gotha, Germany
| | - Alexander Knohl
- Bioclimatology, University of Göttingen, Büsgenweg 2, D-37077 Göttingen, Germany
| | - Richard L Peters
- Environmental Sciences - Botany, University of Basel, Schönbeinstrasse 6, Basel CH-4056, Switzerland
| | - Flurin Babst
- School of Natural Resources and the Environment, University of Arizona, 1064 E Lowell Street, Tucson, AZ 85721, USA; Laboratory of Tree-Ring Research, University of Arizona, 1215 E Lowell Street, Tucson, AZ 85721, USA
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Tumajer J, Altman J, Lehejček J. Linkage between growth phenology and climate-growth responses along landscape gradients in boreal forests. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167153. [PMID: 37730045 DOI: 10.1016/j.scitotenv.2023.167153] [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: 07/24/2023] [Revised: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 09/22/2023]
Abstract
Boreal forests represent an important carbon sink and, therefore, significantly contribute to climate change mitigation. Tree-ring width series of boreal species reflect climate variation at the moment of tree-ring formation but also lagged climatic effects from dormancy preceding tree-ring formation and antecedent growing seasons. However, little is known about how the growth sensitivity to climate in specific intra-annual periods varies across the landscape. Here, we assessed growth responses to climate variation during the 45 months preceding the tree-ring formation for nine boreal stands of Picea glauca and Picea mariana distributed along the gradients of elevation and slope aspect. We combined process-based modeling of wood formation and remote sensing data to determine growth phenology at each site. Next, we classified intra-annual seasons with significant climate-growth correlations based on the timing of dormancy and growth periods. Both the phenology and the climate-growth relationships systematically shifted with elevation and, to a lower extent, also with slope orientation at the treeline. The mean duration of the growing season varied between 100 days at treelines above 900 m and 160 days at lowlands below 500 m. The growth at treelines was stimulated by temperature in the summer of the tree-ring formation year and two years before tree-ring formation. The period of significant climate-growth correlations during the current summer did not exceed three months in agreement with the local duration of the growing season. The growth of trees in lower elevations was instead stimulated by high temperature during the dormancy periods but restricted by high temperature in antecedent summer seasons. In conclusion, our study highlights the linkage between the timing of climate-growth sensitivity and growth phenology, primarily determined by proximity to the treeline. Consequently, accounting for landscape gradients in growth phenology is crucial for upscaling the climatic limits of boreal stands' growth as climate change progresses.
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Affiliation(s)
- Jan Tumajer
- Department of Physical Geography and Geoecology, Faculty of Science, Charles University, Albertov 6, 12843 Prague, Czech Republic.
| | - Jan Altman
- Institute of Botany, The Czech Academy of Sciences, Dukelská 135, 37901 Třeboň, Czech Republic; Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Suchdol, Czech Republic
| | - Jiří Lehejček
- Department of Environment, Faculty of Environment, Jan Evangelista Purkyně University, Pasteurova 15, 400 96 Ústí nad Labem, Czech Republic; Department of Environmental Security, Faculty of Logistics and Crisis Management, Tomas Bata University in Zlin, Studentské nám. 1532, 686 01 Uherské Hradiště, Czech Republic
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Liu Q, Peng C, Schneider R, Cyr D, Liu Z, Zhou X, Du M, Li P, Jiang Z, McDowell NG, Kneeshaw D. Vegetation browning: global drivers, impacts, and feedbacks. TRENDS IN PLANT SCIENCE 2023; 28:1014-1032. [PMID: 37087358 DOI: 10.1016/j.tplants.2023.03.024] [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: 05/22/2022] [Revised: 03/22/2023] [Accepted: 03/30/2023] [Indexed: 05/03/2023]
Abstract
As global climate conditions continue to change, disturbance regimes and environmental drivers will continue to shift, impacting global vegetation dynamics. Following a period of vegetation greening, there has been a progressive increase in remotely sensed vegetation browning globally. Given the many societal benefits that forests provide, it is critical that we understand vegetation dynamic alterations. Here, we review associative drivers, impacts, and feedbacks, revealing the complexity of browning. Concomitant increases in browning include the weakening of ecosystem services and functions and alterations to vegetation structure and species composition, as well as the development of potential positive climate change feedbacks. Also discussed are the current challenges in browning detection and understanding associated impacts and feedbacks. Finally, we outline recommended strategies.
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Affiliation(s)
- Qiuyu Liu
- Institute of Environment Sciences, Department of Biology Sciences, University of Quebec at Montreal, Case Postale 8888, Succ. Centre-Ville, Montreal, H3C 3P8, Canada; School of Public Policy and Administration, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Changhui Peng
- Institute of Environment Sciences, Department of Biology Sciences, University of Quebec at Montreal, Case Postale 8888, Succ. Centre-Ville, Montreal, H3C 3P8, Canada; College of Geographic Science, Hunan Normal University, Changsha, 410081, China.
| | - Robert Schneider
- University of Quebec at Rimouski (UQAR), Rimouski, Quebec, G5L 3A1, Canada
| | - Dominic Cyr
- Science and Technology Branch, Environment and Climate Change Canada, 351 St-Joseph Blvd, Gatineau, Quebec, Canada
| | - Zelin Liu
- College of Geographic Science, Hunan Normal University, Changsha, 410081, China
| | - Xiaolu Zhou
- College of Geographic Science, Hunan Normal University, Changsha, 410081, China
| | - Mingxi Du
- School of Public Policy and Administration, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Peng Li
- College of Geographic Science, Hunan Normal University, Changsha, 410081, China
| | - Zihan Jiang
- Institute of Environment Sciences, Department of Biology Sciences, University of Quebec at Montreal, Case Postale 8888, Succ. Centre-Ville, Montreal, H3C 3P8, Canada; CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Nate G McDowell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Lab, PO Box 999, Richland, WA 99352, USA; School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA
| | - Daniel Kneeshaw
- Institute of Environment Sciences, Department of Biology Sciences, University of Quebec at Montreal, Case Postale 8888, Succ. Centre-Ville, Montreal, H3C 3P8, Canada; Centre for Forest Research, University of Quebec at Montreal, Case Postale 8888, Succ. Centre-Ville, Montreal, H3C 3P8, Canada
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