Weak links between microclimate, plant traits, and decomposition
at the landscape scale could be explained by absence of other known
controls not accounted for in our analysis
Despite considerable variation in both environmental conditions (Figure
2c) and decomposition (Figure 3) across our study plots, the observed
relationships between environmental conditions and decomposition were
weak (Figure 4). This suggests that the topographical, vegetation, soil,
and microclimate predictors we measured did not capture all ecologically
relevant conditions and processes that control decomposition dynamics
within this tundra landscape. For instance, we did not explicitly
measure differences in decomposer communities and/or temporal activity.
Comparable SEM studies from both tundra (Robinson et al. 2022) and other
environments (e.g., Tresch et al. 2019, Xiao et al. 2019) identified
decomposer community composition and activity as a key control on
decomposition (but see Joly et al. 2023), and vegetation patterns along
elevational gradients might not always reflect differences in microbial
communities (Bryant et al. 2008, Fierer et al. 2011). Furthermore, soil
organic matter content has been shown to drive abundances of soil
microbial groups as well as decomposition rates in subarctic Iceland
(Robinson et al. 2022). Also, longer-term soil moisture measurements
might more accurately capture the variability in soil moisture
conditions experienced by decomposers than our short (one growing
season) time-series and hence could hold more power for predicting
decomposition rates (Blok et al. 2010, Christiansen et al. 2017).
Similarly, as environmental conditions in the Arctic tundra vary
considerably between growing season and winter, complementing burial
periods (e.g., growing season vs. winter vs. year-round) would help to
disentangle potential seasonal differences in the controlling factors of
Arctic decomposition dynamics, as well as differences in early vs.
late-stage decomposition (Keuskamp et al. 2013, GarcĂa-Palacios et al.
2016, Canessa et al. 2021). We suggest that future studies account for
these additional factors to model tundra plant litter decomposition more
accurately.