Aspekte der Vertikalverteilung von Spinnen (Araneae) an Kiefernstämmen
Aspects of vertical distribution of spiders (Araneae) on pine trunks
From May to October 1991, spiders on pine trunks in a moorish pine forest in the Federsee nature reserve in Upper Swabia were caught with arboreal photoeblectors. To register vertical differences of intensity of activity, the eclectors were attached at different heights above the ground, one eclector on each trunk. Abiotic parameters (temperature, evaporation), the structure of the bark and its epiphytes were recorded. 108 species from 19 families were found. Most frequent were the families Linyphiidae, Theriidae and Anyphaenidae. The most abundant species was Entelecara penicillata. Intensity of activity, ecotype, dominance structure, dominance identity, diversity and eveness were used as parameters to investigate vertical changes in fauna structure. The investigations showed that the lowest trunk-region is frequently used by spiders normally living the field layer or the litter. These species, however, hardly ever climb up to higher regions. On the other hand, the eclector faunas of the middle and especially of the highest parts of the trunks near the canopies are heavily influenced by the canopy fauna. Several epitruncal species also show preferences for these different trunk-regions. Ecological and abiotic parameters show that the upper trunk-region is a much more extreme habitat than the lower one and the fauna structures are in accordance with this.
Araneae; pine trunks; arboreal photoelectors; vertical distribution