Microclimate explains little variation in year-round decomposition across an Arctic tundra landscape

Litter decomposition represents a major path for atmospheric carbon influx into Arctic soils, thereby controlling below-ground carbon accumulation. Yet, little is known about how tundra litter decomposition varies with microenvironmental conditions, hindering accurate projections of tundra soil carb...

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Bibliographic Details
Published in:Nordic Journal of Botany
Main Authors: von Oppen, Jonathan, Assmann, Jakob J., Bjorkman, Anne D., Treier, Urs A., Elberling, Bo, Normand, Signe
Format: Article in Journal/Newspaper
Language:English
Published: 2024
Subjects:
Arctic tundra
carbon cycling
litter decomposition
microclimate
soil moisture
soil temperature
stratified random sampling
structural equation modelling (SEM)
tea bag index (TBI)
Arctic
Greenland
Climate change
Tundra
Online Access:https://pure.au.dk/portal/en/publications/aa3a8a1a-ad82-43b3-b2fc-2ac6a6b018d5
https://doi.org/10.1111/njb.04062
Description
Summary:Litter decomposition represents a major path for atmospheric carbon influx into Arctic soils, thereby controlling below-ground carbon accumulation. Yet, little is known about how tundra litter decomposition varies with microenvironmental conditions, hindering accurate projections of tundra soil carbon dynamics with future climate change. Over 14 months, we measured landscape-scale decomposition of two contrasting standard litter types (Green tea and Rooibos tea) in 90 plots covering gradients of micro-climate and -topography, vegetation cover and traits, and soil characteristics in Western Greenland. We used the tea bag index (TBI) protocol to estimate relative variation in litter mass loss, decomposition rate (k) and stabilisation factor (S) across space, and structural equation modelling (SEM) to identify relationships among environmental factors and decomposition. Contrasting our expectations, microenvironmental factors explained little of the observed variation in both litter mass loss, as well as k and S, suggesting that the variables included in our study were not the major controls of decomposer activity in the soil across the studied tundra landscape. We use these unexpected findings of our study combined with findings from the current literature to discuss future avenues for improving our understanding of the drivers of tundra decomposition and, ultimately, carbon cycling across the warming Arctic.

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