Harvard Forest Research

Stratification of the forest-floor invertebrate foodweb: isotope dynamics, layer by layer

Principal Investigator: Clarisse Hart
Harvard Forest: Oct 12 2008 - Jan 30 2009:

Abstract:
From O-horizon to humus, each layer of a forest's soil and leaf litter differs isotopically, both in 13C and 15N. Persistent presence/absence stratification has also been shown among spider families along the same layer divisions. I propose that the stratification between these layers will show resilience in each layer's food web, with layer-specific differences in the isotopic signatures of the resident microarthropods and their spider predators.

Previous research has been limited to deciduous forests in Kentucky. The first phase of my study will be conducted in both hemlock and hardwood stands at the Simes Tract (outside the main plots). The second phase of the experiment will be conducted in the Luquillo Experimental Forest of Puerto Rico. At each of the three experimental sites, 30 stratified pitfall traps (filled with soapy water) and 10 stratified litter grab-nets (for Berlese funneling) will be installed to collect spiders and associated microarthropods from the leaf litter/O horizon/top A horizon. Massachusetts collection will occur over a two-week period in October, 2008. Puerto Rico collection will occur over a two-to-four-day period in November, 2008. Samples of the most prevalent spiders and microarthropods from each layer will be identified and sent to UNH for isoptopic analysis in the winter of 2008. :