Communities of ground-living spiders in deciduous forests: Does tree species diversity matter?

Abstract

The relationships between species diversity and ecosystem functions are in the focus of recent ecological research. However, until now the influence of species diversity on ecosystem processes such as decomposition or mineral cycling is not well understood. In deciduous forests, spiders are an integral part of the forest floor food web. In the present study, patterns of spider diversity and community structure are related to diversity of deciduous forest stands in the Hainich National Park (Thuringia). In 2005, pitfall trapping and quantitative forest floor sampling were conducted in nine plots of forest stands with one (Diversity Level 1), three (DL 2) and five (DL 3) major deciduous tree species. Species richness, measured with both methods, as well as spider abundance in forest floor samples were highest in stands with medium diversity (DL 2) and lowest in pure beech stands (DL 1). The Shannon-Wiener index and spider numbers in pitfall traps decreased from DL 1 to DL 3, while the Shannon-Wiener index in forest floor samples increased in the opposite direction. Spider community composition differed more strongly between single plots than between diversity levels. Altogether, no general relationship between increasing tree species diversity and patterns of diversity and abundance in spider communities was found. It appears that there is a strong influence of single tree species dominating a forest stand and modifying structural habitat characteristics such as litter depth and herb cover which are important for ground-living spiders.

Predator Assemblage Structure and Temporal Variability of Species Richness and Abundance in Forests of High Tree Diversity

“…), but instead point rather to a structuring role of tree and shrub species identity in the assembly of epigeic spider communities (Schuldt et al . , Zhang & Adams ).…”

Sapling herbivory, invertebrate herbivores and predators across a natural tree diversity gradient in Germany’s largest connected deciduous forest

“…However, recent evaluations question the relevance of the enemies hypothesis in forest ecosystems, and relate predator abundance to the presence of certain tree species rather than to tree diversity as such (Schuldt et al 2008; Vehviläinen et al 2008). Here, predator abundance on beech saplings was high and increased in the species rich forest stands in June when the leaves where young.…”

Do birds see the forest for the trees? Scale-dependent effects of tree diversity on avian predation of artificial larvae

“…The enemies hypothesis has received much experimental scrutiny and support from studies in agricultural ecosystems and grasslands (Tonhasca 1993;Siemann et al 1998;Sobek et al 2009;Letourneau et al 2011;Straub et al 2014); however, fewer tests of this hypothesis have been conducted in forest ecosystems. These studies have produced mixed results with some reporting negative effects of tree diversity on predator effectiveness (Schuldt et al 2011;Zou et al 2013) and others showing stronger effects of tree species composition (Riihimäki et al 2005;Kaitaniemi et al 2007;Vehviläinen et al 2008), density (Sperber et al 2004;Schuldt et al 2008) or tree species identity (Sobek et al 2009), rather than tree species richness per se (Zhang and Adams 2011). Thus, more studies are required to better understand relationships between diversity and top-down control of insect pests in forest ecosystems.…”