Plant traits affecting herbivory on tree recruits in highly diverse subtropical forests

Abstract

Differences in herbivory among woody species can greatly affect the functioning of forest ecosystems, particularly in species-rich (sub)tropical regions. However, the relative importance of the different plant traits which determine herbivore damage remains unclear. Defence traits can have strong effects on herbivory, but rarely studied geographical range characteristics could complement these effects through evolutionary associations with herbivores. Herein, we use a large number of morphological, chemical, phylogenetic and biogeographical characteristics to analyse interspecific differences in herbivory on tree saplings in subtropical China. Unexpectedly, we found no significant effects of chemical defence traits. Rather, herbivory was related to the plants' leaf morphology, local abundance and climatic niche characteristics, which together explained 70% of the interspecific variation in herbivory in phylogenetic regression. Our study indicates that besides defence traits and apparency to herbivores, previously neglected measures of large-scale geographical host distribution are important factors influencing local herbivory patterns among plant species.

Influence of plant resistance traits in selectiveness and species strength in a tropical plant‐herbivore network

“…Our fi ndings show the relevance of considering more than one foliar attribute to predict the interaction patterns in a plant-herbivore network, as has been documented when predicting herbivore damage ( Agrawal and Fishbein, 2006 ;Carmona et al, 2011 ;Loranger et al, 2012 ;Schuldt et al, 2012 ). Our results suggest that leaf mechanical traits (toughness and trichome density) were better predictors of plant species strength and herbivore selectiveness than the percentage of oxidized phenolics.…”

Herbivore and pathogen effects on tree growth are additive, but mediated by tree diversity and plant traits

“…Effects of herbivores on pathogens, and vice versa, were most pronounced for tree species with a narrow niche breadth. Climatic niche breadth might be a proxy for long‐term, evolutionary associations between plant species, and their consumer assemblages (Schuldt et al., 2012; Scriber, 2010). Plant species with a wider niche breadth probably have accumulated a more diverse set of consumer species over time (Lewinsohn et al., 2005; Miller, 2012), which could lead to higher consumer pressure and higher damage at local scales (Schuldt et al., 2012).…”

“…Tree species richness reduced pathogen damage particularly on tree species with such wide climatic niches. We speculate that an evolutionarily more stable host–pathogen relationship in these tree species (e.g., because wider climatic niches allowed the persistence of these relationships during past climatic changes, or because they allow for larger and less extinction‐prone pathogen populations; Schuldt et al., 2012) might have promoted host specialization of pathogen species (Brändle & Brandl, 2001). Highly specialized pathogens can be expected to respond particularly strongly to host dilution in species‐rich plant communities (Hantsch et al., 2014).…”

“…We, therefore, included in our analyses important plant traits that have frequently been shown to influence leaf damage (Coley & Barone, 1996; Perez‐Harguindeguy et al., 2003; Poorter, de Plassche, Willems, & Boot, 2004; Schuldt et al., 2012). Morphological leaf traits comprised leaf area, specific leaf area (SLA), leaf dry matter content (LDMC), and leaf toughness.…”

“…Niche marginality was quantified as the distance between the overall mean of the range‐standardized bioclim values of a species' niche (niche centroid) and the mean value of these 19 variables at the experimental site. Subsequently, this distance was weighted by the proportion of climate niche space occupied by a species in the total climate space of all 40 study species (see Schuldt et al., 2012 for details).…”