Impact of a reduced winter snowpack on litter arthropod abundance and diversity in a northern hardwood forest ecosystem

Projected changes in climate for the northeastern USA over the next 100 years include a reduction in the depth and duration of the winter snowpack, which could affect soil temperatures and frost regimes. We conducted a snow-removal experiment in a northern hardwood forest at the Hubbard Brook Experimental Forest in central New Hampshire over 2 years to induce soil freezing and evaluate its effect on the abundance, richness, and diversity of soil arthropods during the growing season. Snow removal at the beginning of winter increased the depth and duration of soil frost, decreased soil temperatures, and led to a reduced abundance of some arthropod taxa, including Araneae (reduced by 57%; P = 0.0001), Pseudoscorpionida (75%; P < 0.0001), Hymenoptera (57%; P = 0.0033), Collembola (24%; P = 0.0019), adult Coleoptera (23%; P = 0.0057), and larval Diptera (33%; P < 0.0001) and an increase in other taxa, including Hemiptera (increased by 7%; P = 0.032). Taxa that did not respond significantly to snow removal included Chilopoda (P = 0.55), Acari (P = 0.66), Diplopoda (P = 0.66), adult Diptera (P = 0.54), and larval Coleoptera (P = 0.39). A delayed snowpack over two winters also resulted in decreased arthropod richness by 30% (P < 0.0001) and Simpson's index of diversity by 22% (P = 0.0002) during the two subsequent growing seasons. Results of this study demonstrate that predicted changes in the winter snowpack and depth and duration of soil frost may reduce the abundance and alter the community composition of arthropods living in the forest floor of northern hardwood forests, which could have implications for the structure and function of northern forest ecosystems.