Effects of within‐patch characteristics on the vulnerability of a plant to herbivory

Abstract

Consumption of a focal plant by herbivores depends, not only on the physical and chemical characteristics of that plant, but also on the characteristics of the neighbouring vegetation. Consumption of focal plants has been related to their own characteristics and to the quality of the neighbouring vegetation, but the two have not been combined to examine the relative importance of focal plant and neighbouring vegetation characteristics. We conducted a series of feeding trials to examine the relative importance of focal plant and various characteristics of neighbouring vegetation to browsing of a focal plant within vegetation patches. We planted Eucalyptus nitens seedlings of high and low nutrient status amongst vegetation patches differing in palatability, abundance and height. Generalist mammalian herbivores, red‐bellied pademelons (Thylogale billardierii), were allowed to feed in each of these patches one at a time, and seedling consumption was recorded. Results were considered in light of the attractant‐decoy and apparency hypotheses, which focus on the outcome to plants, and in terms of foraging theory, which is process‐focussed. Seedling and vegetation characteristics were both important. Seedlings of high nutrient status were preferred over those of low nutrient status. The relative quality, abundance and height of neighbouring vegetation all influenced browsing of a focal plant. Seedlings were more vulnerable amongst vegetation that was of low palatability, of low abundance, or was short. Seedling and vegetation effects were additive in two of three trials. Results were consistent with both the attractant‐decoy and apparency hypotheses, and could be explained in terms of maximising foraging efficiency. They demonstrate the need to consider characteristics of both the focal plant and its neighbouring vegetation when predicting the vulnerability of the former to browsing by generalist herbivores.

Restoration of woodpasture on former agricultural land: The importance of safe sites and time gaps before grazing for tree seedlings

“…High densities of rabbits are able to completely prevent regeneration of woody species in abandoned fields (Oosterveld, 1983). Small herbivores like red-bellied pademelons (Thylogale billardierii) even select seedlings to consume in an unpalatable neighbourhood (Miller et al, 2007). At our study sites, rabbits were present in low densities, but burrows were concentrated in bramble thickets.…”

Interactive effects of large herbivores and plant diversity on insect abundance in a meadow steppe in China

“…The difference in plant species diversity is a typically important characteristic of heterogeneity, and diverse plant communities can markedly affect foraging strategies of large herbivores and their concomitant impacts on the dynamics of vegetation itself (Bergvall et al, 2006;Miller et al, 2007;Wang et al, 2011). Our previous work found that complex spatial neighborhood of several plant species makes the palatable species for herbivores to less selected, contributing to the maintenance of plant diversity (Wang et al, 2010).…”

Spatially complex neighboring relationships among grassland plant species as an effective mechanism of defense against herbivory

“…However, how the patterns of spatial association between plants defend against herbivory has not been empirically explored. Recently, an increasing number of empirical studies have focused on how the spatial neighboring relationship between preferred and non-preferred species affects herbivory risk (Miller et al 2007;Bergvall et al 2008;Bee et al 2009). Almost all research has been conducted on the basis of two hypotheses.…”