Turning over a new leaf: the temporal variation of Carabidae (Coleoptera) and Gnaphosidae (Araneae) in leaf litter

Temperate deciduous forests produce a layer of leaf litter on the forest floor annually.  This layer is dynamic and both the composition and depth change throughout the year.  The leaf litter layer is an important habitat to many arthropods since they utilize it for food, shelter from adverse environmental conditions, and protection from predators.

Two commonly encountered and diverse taxa found within the litter layer are the ground beetles (Coleoptera: Carabidae) and the ground spiders (Araneae: Gnaphosidae).  Carabidae and Gnaphosidae were collected from the Ozark Mountains of Arkansas from April 2014 to March 2015 and were identified on a monthly basis to measure temporal fluctuations between species diversity and abundance.  A total of 480 Berlese samples and 208 pitfall trap samples were collected and processed from four sites across Northwest Arkansas including: Lake Wedington, Lake Wilson, and Withrow Springs 1 & 2.  From those samples, 645 carabid individuals of 47 species were collected and 421 gnaphosid individuals of 15 species were collected.

Statistical analyses detected no significant differences in number of individuals and species diversity of carabids and gnaphosids among sites, whereas species richness did differ among sites for carabids.  Similarly, leaf litter depth had no significant effect on the number of individuals collected, species richness (with exception to carabids at Withrow 1), or species diversity of carabids and gnaphosids.  Both the carabids and gnaphosids were the most abundant and diverse during the spring.