Distribution and community structure of araneocoenoses (Araneae) along an altitudinal gradient on Kozuf Mountain (North Macedonia).

The aim of this paper is to perform a biocoenological analysis of spiders and to follow their distribution along an altitudinal gradient on Kozuf Mountain. The research area extends from the foothill to the highest parts of the mountain (89–2080 m a.s.l.), covering 17 localities, characterized by a broad spectrum of habitats. The material was collected monthly, in the period of June–November 2016, with the use of pitfall traps. A bimodal increase in species richness was recorded as a consequence of more favourable conditions at an intermediate altitude in mountain ecosystems. The lowest abundance (0.77 ind. trap−1) was noted in the arid locality at the lowest altitude (89 m a.s.l.), while the highest values were registered in open habitats above 1500 m a.s.l. This is a result of the higher abundance of epigeic invertebrates in open areas in comparison to forests. The araneofauna can be divided into six araneocoenoses: an araneocoenosis inhabiting arid localities, a mygalomorph/Mediterranean araneocoenosis, a montane beech forest araneocoenosis, an araneocoenosis inhabiting damp localities, an araneocoenosis inhabiting open high-altitude localities and an araneocoenosis inhabiting high altitude forest habitats. A low degree of similarity between the araneocoenoses was detected due to the heterogeneity of habitats and altitudes. Both altitude and habitat type had strong effects on community structure and distribution with the latter having a stronger impact. [ABSTRACT FROM AUTHOR]