Vegetation‐Climate Feedbacks Enhance Spatial Heterogeneity of Pan‐Amazonian Ecosystem States Under Climate Change. Issue 8 (28th April 2021)

• Record Type: Journal Article
• Authors: Wu, Minchao; Smith, Benjamin; Schurgers, Guy; Ahlström, Anders; Rummukainen, Markku
• Is Part Of: Geophysical research letters. Volume 48:Issue 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-04-28
• Subjects: above‐ground biomass -- Amazonian ecosystems -- spatial heterogeneity -- vegetation feedback; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL092001
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Amazonian ecosystems range from rainforest to open dryland vegetation, with a following decrease in biomass along the moisture gradient. Biomass can vary greatly at the ecological transition zone between grass dominated savannahs and the forest. It is not well understood if the transition zone could expand under climate change, and thereby reduce ecosystem stability and carbon storage in biomass. Here, we quantify such changes by using a high‐resolution regional Earth system model under RCP 8.5 climate scenario. We disentangle the effects of climate, CO2, and land use by considering vegetation‐climate feedbacks. Our results suggest that future climate change combined with elevated atmospheric CO2 concentration tends to induce a larger spatial gradient of ecosystem states, increasing the transition area by ∼110% at the end of the century. Vegetation feedbacks generally amplify the climate effect by intensifying the climate‐induced warming and drought, further enhancing spatial heterogeneity. Plain Language Summary: Deforestation and the changing climate are threatening the Amazonian ecosystems, making the fate of this vast biological carbon stock remain largely uncertain under future climate change. Previous studies suggest that the Amazon rainforest may lose a certain degree of capacity to recover under continuous warming and increasing drought. However, changes in rainforest could affect climate at local to regional scale, and in turn affect rainforest. Assessments of Amazonian ecosystem changes considering such vegetation feedbacks could therefore be more promising. Here, we assess the future changes in Pan‐Amazonian ecosystem states by employing a fully coupled biosphere‐atmosphere numerical model that can capture local and regional climate phenomena. By considering vegetation feedbacks, effects of the main drivers, including climate, elevated CO2, and land use, can be more realistically quantified. Our results suggest that the Amazonian region will be at a higher risk of abrupt change in ecosystem composition and will have a larger area with unstable vegetation state under future climate change compared with the present‐day climate. We point out that vegetation feedbacks, with a substantial contribution to the simulated changes in ecosystem transition, could be important to understand the capacity of ecosystems to recover and should gain necessary attention in regional climate change studies. Key Points: Main drivers for changes in spatial heterogeneity of the Pan‐Amazonian ecosystem states under climate change are decomposed Spatial heterogeneity of ecosystem state is suggested to increase over an extended ecosystem transition region Vegetation feedbacks amplify climate effects on such changes