Grantee Research Project Results
Effects of Avian Predation on Canopy and Understory Leaf-Chewing Arthropods on Mature White Oak (Quercus Alba)
EPA Grant Number: F5F21891Title: Effects of Avian Predation on Canopy and Understory Leaf-Chewing Arthropods on Mature White Oak (Quercus Alba)
Investigators: Barber, Nicholas A.
Institution: University of Missouri - St Louis
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2005 through August 31, 2008
Project Amount: $100,421
RFA: STAR Graduate Fellowships (2005) RFA Text | Recipients Lists
Research Category: Academic Fellowships
Objective:
The objective of this study is to determine the role of insectivorous birds in structuring herbivorous arthropod community structure and the importance of predation on white oak (Quercus alba) growth and reproduction.
Approach:
In March, before budburst, bird exclosures will be assembled on individual branches in the canopy and understory of 18 mature white oaks (Quercus alba) on three separate slopes; each branch will be paired with an exclosure-free control branch. Herbivore censuses will be conducted in early May, late June/early July, and early September; canopy branches will be accessed using a bucket truck. Herbivores will be identified to species, when possible. Leaves will be collected to determine quality using chemical assays. Herbivory will be estimated by measuring area eaten on leaves. Effects on tree growth will be determined by measuring annual twig expansion; fecundity will be estimated by counting per-branch acorn formation. The bird community on each slope will be estimated using fixed-radius point counts. Herbivore communities will be analyzed using non-metric multidimensional scaling;repeated-measures ANOVA will be used to analyze differences between canopy versus understory and exclosure versus control branches in herbivore density, herbivore species richness, community composition, leaf damage, and tree growth.
Expected Results:
If birds account for differences in insect abundance between the understory and canopy, then enclosed branches in understory and canopy will have equivalent abundance and composition of insects despite differences in leaf quality. If instead, leaf quality drives the differences, bird exclusion will have no effect. Furthermore, insect abundance will correlate with plant-to-plant differences in leaf quality within a vegetation layer.