Luciana Regina Podgaiski

Spider Trait Assembly Patterns and Resilience under Fire-Induced Vegetation Change in South Brazilian Grasslands

Disturbances induce changes on habitat proprieties that may filter organisms functional traits thereby shaping the structure and interactions of many trophic levels. We tested if communities of predators with foraging traits dependent on habitat structure respond to environmental change through cascades affecting the functional traits of plants. We monitored the response of spider and plant communities to fire in South Brazilian Grasslands using pairs of burned and unburned plots. Spiders were determined to the family level and described in feeding behavioral and morphological traits measured on each individual. Life form and morphological traits were recorded for plant species. One month after fire the abundance of vegetation hunters and the mean size of the chelicera increased due to the presence of suitable feeding sites in the regrowing vegetation, but irregular web builders decreased due to the absence of microhabitats and dense foliage into which they build their webs. Six months after fire rosette-form plants with broader leaves increased, creating a favourable habitat for orb web builders which became more abundant, while graminoids and tall plants were reduced, resulting in a decrease of proper shelters and microclimate in soil surface to ground hunters which became less abundant. Hence, fire triggered changes in vegetation structure that lead both to trait-convergence and trait-divergence assembly patterns of spiders along gradients of plant biomass and functional diversity. Spider individuals occurring in more functionally diverse plant communities were more diverse in their traits probably because increased possibility of resource exploitation, following the habitat heterogeneity hypothesis. Finally, as an indication of resilience, after twelve months spider communities did not differ from those of unburned plots. Our findings show that functional traits provide a mechanistic understanding of the response of communities to environmental change, especially when more than one trophic level is considered.

Neotropical woodlice (isopoda) colonizing leaf-litter of pioneer plants in a coal residue disposal environment

The irregular disposal of coal combustion residues has adverse impacts on terrestrial ecosystems. Pioneer plants and soil invertebrates play an important role in the recovery of these areas. The goal of this study was to investigate the colonization patterns of terrestrial isopods (Oniscidea) in leaf litter of three spontaneous pioneer plants (grass - Poaceae, shrub – Euphorbiaceae, tree Anarcadiaceae) at sites used for fly ash or boiler slag disposal. The experiment consisted of eight blocks (four per disposal site) of 12 litter bags each (four per plant species) that were randomly removed after 6, 35, 70 or 140 days of field exposure. Three isopod species were found in the litter bags: Atlantoscia floridana (van Name, 1940) (Philosciidae; n = 116), Benthana taeniata Araujo & Buckup, 1994 (Philosciidae; n = 817) and Balloniscus sellowii (Brandt, 1833) (Balloniscidae; n = 48). The isopods colonized the three leaf-litter species equally during the exposure period. However, the pattern of leaf-litter colonization by these species suggests a conflict of objectives between high quality food and shelter availability. The occurrence of A. floridana and the abundance and fecundity of B. taeniata were influenced by the residue type, indicating that the isopods have different degrees of tolerance to the characteristics of the studied sites. Considering that terrestrial isopods are abundant detritivores and stimulate the humus-forming processes, it is suggested that they could have an indirect influence on the soil restoration of this area.

Prescribed patch burnings increase thrips species richness and body size in grassland communities

Prescribed patch burning is a well‐known tool for grassland and savanna management that has been recognised as a suitable strategy to enhance biodiversity at landscape‐level scales. Nevertheless, effective monitoring of the biota responses to fire is an essential step towards biodiversity conservation. We investigated fire effects on thrips communities (Thysanoptera) – a group of minute and diverse insect in grasslands. We performed a replicated small‐scale fire experiment in South Brazilian Campos, and tested for fire effects on total abundance, species richness of different feeding guilds (e.g. leaf, flower and fungal feeders) and thrips species body size in the short (1 month) and long‐term (1 year). We found positive fire effects on leaf herbivore richness in recently burned patches where the resprouted vegetation had enhanced nutritional quality, and also later on following the diversification of plant communities. The richness of fungivorous thrips was also benefited by resource heterogeneity in burned patches 1 year after fire. A positive fire effect on thrips community body size was also found at this time, possibly indicating that larger species had an advantage in dispersal to the spatially distributed burned patches across the unburned grassland matrix. Effects on total abundances were not detected. Our study emphasises the role of prescribed patch burnings in producing high quality resource‐rich habitat spots for Thysanoptera communities at local scales.

Baeotingis Drake & Poor, 1939 and Coleopterodes Philippi, 1864 (Hemiptera: Heteroptera: Tingidae): first genera records for Brazil from Pampa

Individuals of two genera, Baeotingis Drake & Poor, 1939, and Coleopterodes Philippi, 1814, were collected from natural grassland areas in Eldorado do Sul and Lavras do Sul municipalities, in Rio Grande do Sul state. This constitutes the first records of these taxa for Brazil. The distribution of these genera including all species was reviewed and a map with these geographical data is provided. We have discussed both geographical distribution patterns in the light of Morrones biogeographical areas.