Abstract
The composition of the spider fauna of riparian forests is insufficiently known. These forests, adjacent to both aquatic and terrestrial environments, are recognised as having important ecosystem functions. We compare the composition of spider assemblages of four riparian forests in different drainage basins, along with their microhabitats (edges and forest interior), in the state of Rio Grande do Sul, southern Brazil. Sampling was carried out in the riparian forests of the following rivers: Piratini, municipality of Arroio Grande; Camaqua, municipality of Cristal; Sinos, municipality of Parobe, and Maquine, municipality of Maquine. Two samples per season were collected in two years, by sampling the tree-shrub strata with a beating tray, following fixed transects. There were six transects per drainage basin, two per microhabitat: grassland edge, forest interior and river edge. Overall, 42,057 spiders were sampled (juveniles: 79%; adults: 21%). Among the adults (8,851 individuals), we identified 440 species. Similarity analyses (ANOSIM) indicated that the araneofauna composition of the four drainage basins differ in their quantitative (Morisita) and qualitative (Simpson) similarity indexes. There were no differences in composition among microhabitats. The composition of the Maquine River basin was the most distinct, possibly due to a greater influence of the Atlantic forest on it and a greater dominance of the Linyphiidae Sphecozone personata (Simon, 1894) (SIMPER analysis, contribution to dissimilarity: 12.15%). Differences in spider composition on large spatial scales most likely reflect regional variations in a number of environmental factors, and result in each area having in increased importance in terms of conservation.
Highlights
The fact that spiders are widely distributed in terrestrial ecosystems makes them efficient organisms to help elucidate biodiversity patterns (Uetz 1991, Foelix 1996, Platnick 1999, Cardoso 2009)
Riparian forests are peculiar: they occupy a small proportion of the hydrographic basin they belong to, are considered ecologically stable and are well defined, have high plant biomass production and support high biodiversity levels compared to other forest environments (Davide & Botelho 1999)
Brazilian native riparian forests were partly substituted for large plantations of exotic trees and, very close to rivers, by agricultural endeavors, a process that has resulted in numerous forest remnants and semi-natural areas (Dennis 1997, Malavasi et al 2004)
Summary
The fact that spiders are widely distributed in terrestrial ecosystems makes them efficient organisms to help elucidate biodiversity patterns (Uetz 1991, Foelix 1996, Platnick 1999, Cardoso 2009). In order to know and to catalogue the biodiversity elements of a given place, it is necessary to conduct biodiversity surveys (Dennis & Ruggiero 1996) Such inventories should not be restricted to a list of species, but need to include information on systematics, ecology, and biogeography (Halffter et al 2001). Riparian forests are peculiar: they occupy a small proportion of the hydrographic basin they belong to, are considered ecologically stable and are well defined, have high plant biomass production and support high biodiversity levels compared to other forest environments (Davide & Botelho 1999) They are considered extremely important for plant dispersal, and as “corridors” for animal movement (Naiman et al 1993, Malavasi et al 2004), including spiders (Raizer et al 2005, Rodrigues et al 2014). We give a list of the spider species found in these riparian forests
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
