Predator density outweighs experimental warming effects on short-term carbon and nitrogen loss from arctic shrub litter

Rapid climate change in the Arctic is altering biological communities and their subsequent effects on ecosystem functioning. For example, warming-induced shrub expansion accelerates biogeochemical cycles in part by increasing high-quality litter inputs. Likewise, warming may enable higher densities of wolf spiders, which are dominant invertebrate predators whose activities indirectly alter plant litter decomposition rates. Although shrubs and wolf spiders are responding to climate change simultaneously, it is unclear how more shrub litter and more spiders together will influence elemental cycling in Arctic ecosystems. To test how warming could influence these processes, we used a fully factorial mesocosm experiment to quantify effects of wolf spiders on litter decomposition of an expanding species of dwarf deciduous shrub (Betula nana) under ambient and warmed conditions. We found higher densities of wolf spiders were consistently associated with more litter mass loss and more C and N r..., , # Data from: Predator density outweighs experimental warming effects on short-term carbon and nitrogen loss from arctic shrub litter

Dataset DOI: [10.5061/dryad.9p8cz8www](https://doi.org/10.5061/dryad.9p8cz8www)

This dataset was produced from a field mesocosm experiment near Toolik Field Station (68°38′N and 149°43′W, elevation 760 m) on the North Slope of Alaska during June-July 2012. We investigated the effects of wolf spider densities and experimental warming (using open-topped chambers) on mass, C and N loss from litter of Betula nana, which is an expansive shrub in the Arctic.

Five blocks were distributed in a homogenous area of moist acidic tundra, with each block containing a plot for each of the six experimental treatments, which were all possible combinations of the temperature treatment (ambient/high) and the spider density treatment (low/control/high).

We deployed three replicate litter bags at evenly spaced locations within each plot.

Each row in the dataset represents...,