Earthworm communities in relation to tree diversity in a deciduous forest

Migge-Kleian S, Cesarz S, Fahrenholz N, Platner C, Schaefer M. Earthworm communities in relation to tree diversity in a deciduous forest. EUROPEAN JOURNAL OF SOIL BIOLOGY. 2007;43:S61-S67.The understanding of belowground biodiversity is still rather incomplete and interactions between above- and belowground systems have rarely been looked at when explaining belowground biodiversity patterns. The present study presents results of the influence of tree species diversity on the earthworm community in a central European deciduous mixed forest. Within the Hainich National Park three replicate sites were chosen within three levels of tree diversity ranging from one species (beech, DL1) to three species (beech, lime, ash, DL2) to five species stands (beech, lime, ash, hornbeam, maple, DL3). Earthworms were extracted by heat from soil and litter samples at four sampling dates at each site. In addition, in spring four samples per site were sorted by hand and identified to species level. Generally, earthworm densities were positively correlated with tree diversity in May and November but negatively in February. Sites with low tree species diversity had earthworm populations which were more stable due to a more permanent and deeper litter layer. Increasing proportions of high quality litter in DL2 und DL3 were correlated with higher densities of both epigeic and endogeic earthworm species, while litter in DL1 sites was mainly inhabited by epigeic species. Generally, there was a positive correlation between earthworm and tree species diversity indicating the importance of diverse food qualities for the decomposer fauna at the local scale especially in springtime. (C) 2007 Elsevier Masson SAS. All rights reserved

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

Schuldt A, Fahrenholz N, Brauns M, Migge-Kleian S, Platner C, Schaefer M. Communities of ground-living spiders in deciduous forests: Does tree species diversity matter? BIODIVERSITY AND CONSERVATION. 2008;17(5):1267-1284.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