El Bosque Atlántico es uno de los principales focos de biodiversidad en el mundo. Su sotobosque puede estar dominado por especies como el bambú nativo Chusquea ramosissima (tacuarembó), que puede ser un agresivo colonizador de claros o lagunas (gaps) y cambiar las condiciones bióticas y abióticas en comparación al bosque maduro. Se ha observado una fuerte asociación entre las arañas Salticidae y el tipo de microhábitats, con frecuencia vinculada a la estructura de la vegetación. Dado que se conoce poco acerca de la diversidad de arañas en los claros por caída de árboles del Bosque Atlántico, se exploraron las diferencias en los ensambles de Salticidae en tres hábitats: el Sotobosque de bosque típico, Claros de Bambú (tacuarembó) y en áreas de restauración (remoción del tacuarembó). La región de estudio se encuentra en el extremo sur del Bosque Atlántico, ecorregión Bosque Atlántico Alto Paraná en la provincia de Misiones, Argentina. En total se colectaron 515 arañas (32 especies; 106 adultos). Se detectaron diferencias en la composición de especies entre hábitats, donde el Sotobosque y los Claros de Bambú difirieron en cerca del 50% de las especies. Los Claros de Bambú tuvieron el mayor número de especies exclusivas, no obstante, los tres hábitats no difirieron en sus índices de diversidad taxonómica media. Además, la riqueza fue mayor en los Claros de Bambú comparados con el Sotobosque, lo que podría reflejar una mayor diversidad de nichos en el primer hábitat.

Urbanization has a great impact on the diversity of living organisms. Spiders, for example, have been shown to respond negatively (some orb weaving species) and positively (ground dwelling species) to urbanization. The effects of urbanization on crab spiders (Thomisidae) (sit-and-wait predators that generally ambush their prey on flowers and leaves) are not sufficiently known. This paper describes the Thomisidae community that inhabits green patches in a temperate Neotropical city, Cordoba, Argentina, and its surroundings, and ascertains whether there are differences in species richness, abundance and composition between urban and exurban sites. Samples were collected from 30 sites during the summer and spring of 2013 and 2014, using the garden-vacuum method. We compared the abundance, richness and composition of Thomisidae among three habitat categories (urban, suburban and external). Seven species in three genera, Misumenops, Wechselia and Tmarus, were detected. Misumenops was the most abundant genus in Córdoba, and Tmarus elongates Mello-Leitão, 1929 was collected in Argentina for the first time. The abundance, richness and composition of thomisid spiders did not differ between habitat categories, indicating that urbanization does not have a negative effect on the communities of these spiders in open green spaces. Site variability, on the other hand, does, suggesting that local factors may be more relevant than broad-scale factors to explain community patterns in this family.

Deforestation and land-cover changes have transformed the Argentinian Dry Chaco into a mosaic dominated by crops and ranch fields. Although land-use activities are seen as one of the major driving forces of biodiversity loss, the specific impacts in this ecoregion are poorly understood. In this study, we analyse the effects of land uses and management on ground-dwelling spiders in agroecosystems of the Dry Chaco, in the North of Argentina. We identified four land-use classes: secondary forests, pastures, orchards, and crops. Additionally, 15 environmental variables were recorded within these land-use classes. Management, tree cover and species richness of trees, shrubs and herbs were the most important variables determining spider community composition. Three families, lycosids (Lycosidae), thomisids (Thomisidae), and zodariids (Zodariidae), were associated as taxonomic indicators as well as functional indicators of the different groups of land uses; thus suggesting that functional traits of ground-dwelling spiders reflect habitat changes within the agricultural landscape they inhabit.

Spiders, natural enemies of several insects of economical and sanitary relevance, are sensitive to anthropogenic disturbances. Urban habitats, home to nearly half of the world’s human population, are growing in number and size. Consequently, natural habitats are lost and impervious surfaces increase. We compared the overall spider species and guilds assemblage characteristics associated with vegetation, between sites located within different urbanisation levels (urban and suburban) and in relation to local and landscape traits. The most abundant guilds were sheet web weavers and ambush hunters. The overall richness of spiders and richness and abundance of two guilds (space web weavers and stalker hunters) were higher in suburban than urban sites. The overall spider abundance, Shannon-Weaver diversity and the Shannon evenness index did not change between urban and suburban sites. While the species composition differed between urban and suburban sites, comprising the urban spider species a subset of those found in the suburban pool. Species abundances were negatively related with the percentage of bare ground, canopy cover, and urban level. Richness was positively related to low vegetation. Guilds’ responses differed concerning their life histories. At a landscape level, high consolidation (impervious surface) degree surrounding the green patches had negative effects while medium values had positive effects. Higher diversity was associated with intermediate mixtures of vegetation and impervious cover. In conclusion, the spider’s community and guild characteristics were associated with environmental, landscape and local factors through the urbanised landscape.