Discussion

Our structural equation modelling of the variation in decomposition rates across the tundra landscape in Western Greenland indicated that: (1) micro-environmental factors play a minor role in explaining variation in decomposition at the landscape scale; (2) environmental predictors differ little in their importance for mass loss of Green Tea (soil temperature and moisture) and Rooibos Tea (no significant predictors); and (3) only some indirect effects of vegetation on decomposition through microclimate were significant, while there was no evidence for direct (trait) related effects. However, the overall explanatory power of our SEM was low and the overall fit was non-significant. This suggests that other factors than the topographical, vegetation, soil and microclimate variables included here control the mechanisms behind decomposition across our studied tundra landscape, such as decomposer communities or annual and seasonal variation in micro-environmental conditions (see detailed discussion below). Overall, our results highlight the need for further research to advance our understanding of decomposition processes and carbon cycling in the changing Arctic. Below, we discuss the findings in relation to our research questions and derive some general recommendations for future decomposition studies in the tundra.