Winter climate change influences on soil faunal distribution and abundance: Implications for decomposition in the Northern Forest

Winter is typically considered a dormant period in northern forests, but important ecological processes continue during this season in these ecosystems. At the Hubbard Brook Experimental Forest, located in the White Mountains of New Hampshire, we used an elevational climate gradient to investigate how changes in winter climate affect the litter and soil invertebrate community and related decomposition rates of Acer saccharum (Sugar Maple) litter over a 2-year period. The overall abundance and richness of litter invertebrates declined with increasing elevation, while the diversity and abundance of soil invertebrates was similar across the gradient. Snow depth and soil temperature were correlated to the abundance and distribution of the litter invertebrate community, whereas soil organic matter, soil moisture, and soil frost were correlated with the distribution and abundance of the soil invertebrate community. Decomposition rates were initially faster at lower-elevation sites following 1 year of decomposition, then stabilized at the end of 2 years with no difference between higher- and lower-elevation sites. This pattern may be explained by the distribution and abundance of the litter and soil invertebrates. Higher abundances of litter invertebrates, especially Collembola, at lower-elevation sites contribute to faster initial breakdown of litter, while greater abundances of Acari in soils at higher elevation contribute to the later stages of decay. The interaction between decomposition and the associated invertebrate community responded to changes in climatic conditions, with both soil temperature and soil moisture being important determinants.