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Publication Date
10 June 2024

Changes in Above- Versus Belowground Biomass Distribution in Permafrost Regions in Response to Climate Warming

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Smoothed changes of above- to belowground biomass ratio (η) at the alpine wetlands (blue; n = 680), alpine meadows (orange; n = 1,214), and alpine steppes (red; n = 1,119)

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Science

Permafrost regions store approximately half of the carbon in land ecosystems and are warming at a rate at least twice as fast as other biomes. This high warming rate significantly impacts vegetation growth and causes changes in plant composition, physiology, and the allocation of biomass between above- and belowground components. The above- to belowground biomass ratio (η) is a critical metric for understanding these changes and their implications for carbon storage and climate feedback mechanisms. This study analyzed data from 3,013 plots and 26,337 species-specific measurements across the Tibetan Plateau from 1995 to 2021, focusing on three vegetation types: alpine wetlands, meadows, and steppes.

Impact

Climate warming has led to a 17% increase in the above- to belowground biomass ratio (η) in alpine wetlands, while η decreased by 26% in alpine meadows and 48% in alpine steppes. These shifts are driven by temperature-induced changes in plant growth preferences rather than species composition changes. Soil temperature emerged as the primary climatic driver influencing η, with different effects across vegetation types. Soil moisture was shown to modulate the sensitivity of η to soil temperature in alpine meadows and steppes. These findings also highlight the need for improvements in biogeochemical models to accurately predict carbon cycling and storage in response to climate change.

Summary

This work reveals significant changes in the distribution of plant biomass in permafrost regions of the Tibetan Plateau due to climate warming. The increase in aboveground biomass in alpine wetlands and the greater allocation of biomass to belowground parts in alpine meadows and steppes reflect adaptive responses to temperature changes. These adaptations have important implications for carbon storage and emissions, emphasizing the need for refined ecosystem models to better predict future climate scenarios. The research underscores the critical role of soil temperature and moisture in driving these changes and calls for incorporating detailed plant biomass distribution responses into climate models for more accurate projections.

Point of Contact
Qing Zhu
Institution(s)
Lawrence Berkeley National Laboratory
Funding Program Area(s)
Publication