Journal ArticleDOI
Spatial heterogeneity in the relative impacts of foliar quality and predation pressure on red oak, Quercus rubra, arthropod communities.
TLDR
There was no evidence of a trophic cascade either in terms of leaf damage or tree growth, and more variation in arthropod density among trees within sites than variation inArthropoddensity among sites, indicating the importance of micro-site variation in structuring Arthropod communities.Abstract:
Predation pressure and resource availability often interact in structuring herbivore communities, with their relative influence varying in space and time. The operation of multiple ecological pressures and guild-specific herbivore responses may combine to override simple predictions of how the roles of plant quality and predation pressure vary in space. For 2 years at the Coweeta LTER in the Southern Appalachian Mountains, we conducted a bird exclosure experiment on red oak (Quercus rubra) saplings to investigate the effects of bird predation on red oak arthropod communities. We established bird exclosures at six sites along an elevational gradient and estimated variation in foliar nitrogen and bird predation pressure along this gradient. Foliar nitrogen concentrations increased with elevation while our index of bird predation pressure was variable across sites. Greater arthropod densities were detected inside exclosures; however, this result was mainly driven by the response of phloem feeders which were much more prevalent inside exclosures than on control trees. There was little evidence for an effect of bird predation on the other arthropod guilds. Consequently, there was no evidence of a trophic cascade either in terms of leaf damage or tree growth. Finally, we found more variation in arthropod density among trees within sites than variation in arthropod density among sites, indicating the importance of micro-site variation in structuring arthropod communities.read more
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Elevational gradients in plant defences and insect herbivory: recent advances in the field and prospects for future research
TL;DR: A recent review as mentioned in this paper synthesizes current knowledge on elevational gradients in plant-insect herbivore interactions, critically analyses research gaps and highlights recent advances that contribute to filling these gaps.
Journal ArticleDOI
The equal effectiveness of different defensive strategies.
TL;DR: It is found that in general, ant-associated species had levels of herbivory equal to those of species that are unattractive to ants; the pattern was unaffected by plant life form, climate and phylogenetic relationships between species.
Journal ArticleDOI
Plant neighbours mediate bird predation effects on arthropod abundance and herbivory
TL;DR: The removal of plant neighbours increased prey accessibility for foraging insectivorous birds and decreased chewer damage on seedlings, and the density of concealed‐feeder insects (leaf miners) increased with plant neighbour removal and when seedlings were less damaged by chewer guild, suggesting intraguild competition.
Journal ArticleDOI
Linking conservation implications of modified disturbance regimes, plant communities, plant associations, and arthropod communities.
TL;DR: These results are the first to demonstrate that modified disturbance regimes can influence multiple trophic levels both directly due to species-specific variation in susceptibility of plants to herbivory and indirectly through effects of plant associations.
References
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Book
Model Selection and Multimodel Inference: A Practical Information-Theoretic Approach
TL;DR: The second edition of this book is unique in that it focuses on methods for making formal statistical inference from all the models in an a priori set (Multi-Model Inference).
Journal ArticleDOI
Using SAS PROC MIXED to Fit Multilevel Models, Hierarchical Models, and Individual Growth Models
TL;DR: This paper is written as a step-by-step tutorial that shows how to fit the two most common multilevel models: (a) school effects models, designed for data on individuals nested within naturally occurring hierarchies (e.g., students within classes); and (b) individual growth models,designed for exploring longitudinal data (on individuals) over time.
Journal ArticleDOI
Food Web Complexity and Community Dynamics
Gary A. Polis,Donald R. Strong +1 more
TL;DR: It is concluded that trophic cascades and top-down community regulation as envisioned by trophIC-level theories are relatively uncommon in nature.
Journal ArticleDOI
Exploitation Ecosystems in Gradients of Primary Productivity
TL;DR: A reasonable fit between predictions and observations is found, although the sparsity of data and methodological uncertainties weaken the corroboration in several cases.