The influence of hydrologic gradients on processing rates and macroinvertebrate colonization patterns on tulip poplar leaves in headwater stream channels in a Cumberland Plateau watershed, u.s.a

Hydrologic gradients along the longitudinal course of stream channels can have multiple effects on biotic communities and ecosystem-level processes.  This project assessed the differences in processing rates and macroinvertebrate colonization patterns of tulip poplar (Liriodendron tulipifera) leaves between ephemeral and perennial reaches of headwater stream channels in a Cumberland Plateau watershed in eastern Kentucky, U.S.A. Tulip poplar leaves were collected during autumnal abscission and air dried for 2 weeks. Leaf packs were assembled 5 ± 0.1 g packs, wetted, and placed in mesh bags. Leaf pack samples were collected monthly from each study channel. Packs were prepared as ash free dry mass to calculate breakdown rates (-k). Macroinvertebrates were identified to the lowest practical level (i.e. genus) and placed into functional feeding groups. There was no statistical significance in breakdown rates between reaches (ephemeral vs. perennial; ANOVA, F = 4.87, p = 0.52). In addition, there was no statistical significance in shredder biomass per leaf pack between reaches (ANOVA, F = 4.21, p = 0.065).  Both results imply the hydrologic gradient was too shallow to induce between-reach distinct processing rates and macroinvertebrate colonization patterns.