Responses of litter-dwelling arthropods to varying levels and patterns of green-tree retention

Tim D. Schowalter

Department of Entomology
404 Life Sciences Bldg.
Louisiana State University
Baton Rouge, LA 70803
(225) 578-1634
tschowalter@agcenter.lsu.edu

Juraj Halaj

Cascadien, Inc.
1903 NW Lantana Drive
Corvallis, OR 97330-1016
Jhalaj@cascadien.com
http://www.cascadien.com

A 3-year study is currently underway to address potential effects of the level and pattern of green-tree retention on population densities of litter-dwelling arthropods.  The sensitivity of epigeal arthropods to changes in canopy cover suggests that manipulated patterns of green-tree retention in the DEMO study should significantly impact the abundance and distribution of these organisms.  We hypothesize that (1) 1-ha aggregates of intact forest may not be sufficient to maintain viable populations of forest-interior species and (2) the abundance of sensitive species should reflect the extent of partial canopy cover (15% vs. 40% retention). In addition, the design of this study will allow us to assess the effect of forest edge on the composition and population dynamics of litter-dwelling arthropods.

This study involves extensive seasonal sampling of litter arthropods using a series of pitfall traps located near grid points in five treatments (control, 15%A, 15%D, 40%A and 40%D) across five of the DEMO blocks.  Within the aggregated retention treatments, traps in forest interior, edge and exterior positions will allow us to evaluate arthropod responses across a broad gradient of environmental conditions.  Processing of samples from the first field season (2002) is currently underway.