Earthworms in natural grasslands and agropastoral systems in the Brazilian Pampa.

In this study, we sampled grazed natural grassland and agropastoral systems in two regions (Alegrete and Aceguá) in the highly diverse Brazilian Pampa region which is undergoing significant change in land use cover. By hand sorting the soil, a total of five species were found, belonging to the families Glossoscolecidae (Glossoscolex sp.50 and Glossoscolex sp.51), Ocnerodrilidae (Kerriona sp.6 and Eukerria sp.3), and Lumbricidae (Aporrectodea trapezoides). The former four were identified as native-new to science-and the latter as exotic. Differences were observed in both earthworm species richness and abundance between regions and land-use systems, likely due to environmental conditions and agricultural practices, respectively. Agropastoral systems had higher abundance and species richness than natural grasslands, though these differences varied by location. This suggests that conversion from natural grassland to agropastoral systems can maintain native earthworms and, possibly, enhance ecosystem services. However, an exotic species was found in high abundance at one agropastoral site. These results highlight the need for additional biodiversity studies on earthworms in the Brazilian Pampa and for research on the impacts of land use changes in this region.

The Program for Biodiversity Research in Brazil: The role of regional networks for biodiversity knowledge, dissemination, and conservation.

The Program for Biodiversity Research (PPBio) is an innovative program designed to integrate all biodiversity research stakeholders. Operating since 2004, it has installed long-term ecological research sites throughout Brazil and its logic has been applied in some other southern-hemisphere countries. The program supports all aspects of research necessary to understand biodiversity and the processes that affect it. There are presently 161 sampling sites (see some of them at Supplementary Appendix), most of which use a standardized methodology that allows comparisons across biomes and through time. To date, there are about 1200 publications associated with PPBio that cover topics ranging from natural history to genetics and species distributions. Most of the field data and metadata are available through PPBio web sites or DataONE. Metadata is available for researchers that intend to explore the different faces of Brazilian biodiversity spatio-temporal variation, as well as for managers intending to improve conservation strategies. The Program also fostered, directly and indirectly, local technical capacity building, and supported the training of hundreds of undergraduate and graduate students. The main challenge is maintaining the long-term funding necessary to understand biodiversity patterns and processes under pressure from global environmental changes.

Long-term ecological research in southern Brazil grasslands: Effects of grazing exclusion and deferred grazing on plant and arthropod communities.

Grazing exclusion may lead to biodiversity loss and homogenization of naturally heterogeneous and species-rich grassland ecosystems, and these effects may cascade to higher trophic levels and ecosystem properties. Although grazing exclusion has been studied elsewhere, the consequences of alleviating the disturbance regime in grassland ecosystems remain unclear. In this paper, we present results of the first five years of an experiment in native grasslands of southern Brazil. Using a randomized block experimental design, we examined the effects of three grazing treatments on plant and arthropod communities: (i) deferred grazing (i.e., intermittent grazing), (ii) grazing exclusion and (iii) a control under traditional continuous grazing, which were applied to 70 x 70 m experimental plots, in six regionally distributed blocks. We evaluated plant community responses regarding taxonomic and functional diversity (life-forms) in separate spatial components: alpha (1 x 1 m subplots), beta, and gamma (70 x 70 m plots), as well as the cascading effects on arthropod high-taxa. By estimating effect sizes (treatments vs. control) by bootstrap resampling, both deferred grazing and grazing exclusion mostly increased vegetation height, plant biomass and standing dead biomass. The effect of grazing exclusion on plant taxonomic diversity was negative. Conversely, deferred grazing increased plant taxonomic diversity, but both treatments reduced plant functional diversity. Reduced grazing pressure in both treatments promoted the break of dominance by prostrate species, followed by fast homogenization of vegetation structure towards dominance of ligneous and erect species. These changes in the plant community led to increases in high-taxa richness and abundance of vegetation-dwelling arthropod groups under both treatments, but had no detectable effects on epigeic arthropods. Our results indicate that decision-making regarding the conservation of southern Brazil grasslands should include both intensive and alleviated levels of grazing management, but not complete grazing exclusion, to maximize conservation results when considering plant and arthropod communities.

Spider community responds to litter complexity: insights from a small-scale experiment in an exotic pine stand / Comunidade de aranhas responde a complexidade da serapilheira: percepções de um experimento de pequena escala em um talhão de pinus exótico

Conservation of biodiversity in agroecosystems is an urgent need, and a suitable approach to maximize animal biodiversity and their services is the restoration of habitat heterogeneity. Here we investigated the value of increasing litter complexity in tree plantations of exotic pine for ground spiders. We hypothesized that increasing the litter complexity of these systems, as it would be the case in ecologically designed plantations, would increase spider aggregations. We performed a small-scale litter manipulation experiment within an exotic pine stand in the municipality of Minas do Leão, Rio Grande do Sul, Brazil, and compared spider diversity in simple (only pine needles) and complex substrates (with the addition of diverse native broadleaves). We found 1,110 spiders, 19 families and 32 morphospecies. The most abundant families were Linyphiidae, Theridiidae and Salticidade, and the dominant morphospecies were Thymoites sp. 2 and Lygarina sp. Web-building spiders represented 61% of total spider abundance, and 17 species, while hunting spiders, 49% and 15 species. As expected, densities of spider individuals and species from both web-building and hunting spiders were higher in complex litter substrate. Potential preys (Collembola) also responded positively to the treatment, and had influence of spider community patterns. Our results suggest that ensuring some degree of plant and litter diversity within pine stands (e.g. understory establishment) might foster spider aggregations and possibly help to conserve their diversity at local-scales.

A conservação da biodiversidade em agroecossistemas é uma necessidade urgente, e uma abordagem adequada a maximizar a biodiversidade animal e seus serviços é a restauração da heterogeneidade de habitats. Aqui nós investigamos o valor do aumento da complexidade da serapilheira em plantações exóticas de pinus para aranhas de solo. Nossa hipótese é que aumentando a complexidade da serapilheira nestes sistemas, como seria o caso em plantações com design ecológico, as agregações de aranhas aumentariam. Nós realizamos uma manipulação experimental de pequena escala em uma plantação exótica de pinus no município de Minas do Leão, Rio Grande do Sul, e comparamos a diversidade de aranhas em substrato simples (somente acículas de pinus) e complexo (com adição de folhas nativas diversas). Nós encontramos 1.110 aranhas, 19 famílias e 32 morfoespécies. As famílias mais abundantes foram Linyphiidae, Theridiidae e Salticidade, e as morfoespécies dominantes foram Thymoites sp. 2 e Lygarina sp. Aranhas de teia representaram 61% da abundância total de aranhas e 17 espécies, enquanto aranhas caçadoras, 49% e 15 espécies. Como esperado, densidades de indivíduos e de espécies de ambas construtoras de teia e caçadoras foram maiores em substrato complexo. Potenciais presas (Collembola) também responderam positivamente ao tratamento, e influenciaram os padrões das comunidades de aranhas. Nossos resultados sugerem que garantir algum grau de diversidade de plantas e serapilheira dentro de talhões de pinus (e.g. estabelecimento de sub-bosque) poderia promover agregações de aranhas e possivelmente ajudar a conservar sua diversidade em escalas locais.

Spider community responds to litter complexity: insights from a small-scale experiment in an exotic pine stand

ABSTRACT Conservation of biodiversity in agroecosystems is an urgent need, and a suitable approach to maximize animal biodiversity and their services is the restoration of habitat heterogeneity. Here we investigated the value of increasing litter complexity in tree plantations of exotic pine for ground spiders. We hypothesized that increasing the litter complexity of these systems, as it would be the case in ecologically designed plantations, would increase spider aggregations. We performed a small-scale litter manipulation experiment within an exotic pine stand in the municipality of Minas do Leão, Rio Grande do Sul, Brazil, and compared spider diversity in simple (only pine needles) and complex substrates (with the addition of diverse native broadleaves). We found 1,110 spiders, 19 families and 32 morphospecies. The most abundant families were Linyphiidae, Theridiidae and Salticidade, and the dominant morphospecies were Thymoites sp. 2 and Lygarina sp. Web-building spiders represented 61% of total spider abundance, and 17 species, while hunting spiders, 49% and 15 species. As expected, densities of spider individuals and species from both web-building and hunting spiders were higher in complex litter substrate. Potential preys (Collembola) also responded positively to the treatment, and had influence of spider community patterns. Our results suggest that ensuring some degree of plant and litter diversity within pine stands (e.g. understory establishment) might foster spider aggregations and possibly help to conserve their diversity at local-scales.

RESUMO A conservação da biodiversidade em agroecossistemas é uma necessidade urgente, e uma abordagem adequada a maximizar a biodiversidade animal e seus serviços é a restauração da heterogeneidade de habitats. Aqui nós investigamos o valor do aumento da complexidade da serapilheira em plantações exóticas de pinus para aranhas de solo. Nossa hipótese é que aumentando a complexidade da serapilheira nestes sistemas, como seria o caso em plantações com design ecológico, as agregações de aranhas aumentariam. Nós realizamos uma manipulação experimental de pequena escala em uma plantação exótica de pinus no município de Minas do Leão, Rio Grande do Sul, e comparamos a diversidade de aranhas em substrato simples (somente acículas de pinus) e complexo (com adição de folhas nativas diversas). Nós encontramos 1.110 aranhas, 19 famílias e 32 morfoespécies. As famílias mais abundantes foram Linyphiidae, Theridiidae e Salticidade, e as morfoespécies dominantes foram Thymoites sp. 2 e Lygarina sp. Aranhas de teia representaram 61% da abundância total de aranhas e 17 espécies, enquanto aranhas caçadoras, 49% e 15 espécies. Como esperado, densidades de indivíduos e de espécies de ambas construtoras de teia e caçadoras foram maiores em substrato complexo. Potenciais presas (Collembola) também responderam positivamente ao tratamento, e influenciaram os padrões das comunidades de aranhas. Nossos resultados sugerem que garantir algum grau de diversidade de plantas e serapilheira dentro de talhões de pinus (e.g. estabelecimento de sub-bosque) poderia promover agregações de aranhas e possivelmente ajudar a conservar sua diversidade em escalas locais.

Spider community responds to litter complexity: insights from a small-scale experiment in an exotic pine stand / Comunidade de aranhas responde a complexidade da serapilheira: percepções de um experimento de pequena escala em um talhão de pinus exótico

Conservation of biodiversity in agroecosystems is an urgent need, and a suitable approach to maximize animal biodiversity and their services is the restoration of habitat heterogeneity. Here we investigated the value of increasing litter complexity in tree plantations of exotic pine for ground spiders. We hypothesized that increasing the litter complexity of these systems, as it would be the case in ecologically designed plantations, would increase spider aggregations. We performed a small-scale litter manipulation experiment within an exotic pine stand in the municipality of Minas do Leão, Rio Grande do Sul, Brazil, and compared spider diversity in simple (only pine needles) and complex substrates (with the addition of diverse native broadleaves). We found 1,110 spiders, 19 families and 32 morphospecies. The most abundant families were Linyphiidae, Theridiidae and Salticidade, and the dominant morphospecies were Thymoites sp. 2 and Lygarina sp. Web-building spiders represented 61% of total spider abundance, and 17 species, while hunting spiders, 49% and 15 species. As expected, densities of spider individuals and species from both web-building and hunting spiders were higher in complex litter substrate. Potential preys (Collembola) also responded positively to the treatment, and had influence of spider community patterns. Our results suggest that ensuring some degree of plant and litter diversity within pine stands (e.g. understory establishment) might foster spider aggregations and possibly help to conserve their diversity at local-scales.(AU)

A conservação da biodiversidade em agroecossistemas é uma necessidade urgente, e uma abordagem adequada a maximizar a biodiversidade animal e seus serviços é a restauração da heterogeneidade de habitats. Aqui nós investigamos o valor do aumento da complexidade da serapilheira em plantações exóticas de pinus para aranhas de solo. Nossa hipótese é que aumentando a complexidade da serapilheira nestes sistemas, como seria o caso em plantações com design ecológico, as agregações de aranhas aumentariam. Nós realizamos uma manipulação experimental de pequena escala em uma plantação exótica de pinus no município de Minas do Leão, Rio Grande do Sul, e comparamos a diversidade de aranhas em substrato simples (somente acículas de pinus) e complexo (com adição de folhas nativas diversas). Nós encontramos 1.110 aranhas, 19 famílias e 32 morfoespécies. As famílias mais abundantes foram Linyphiidae, Theridiidae e Salticidade, e as morfoespécies dominantes foram Thymoites sp. 2 e Lygarina sp. Aranhas de teia representaram 61% da abundância total de aranhas e 17 espécies, enquanto aranhas caçadoras, 49% e 15 espécies. Como esperado, densidades de indivíduos e de espécies de ambas construtoras de teia e caçadoras foram maiores em substrato complexo. Potenciais presas (Collembola) também responderam positivamente ao tratamento, e influenciaram os padrões das comunidades de aranhas. Nossos resultados sugerem que garantir algum grau de diversidade de plantas e serapilheira dentro de talhões de pinus (e.g. estabelecimento de sub-bosque) poderia promover agregações de aranhas e possivelmente ajudar a conservar sua diversidade em escalas locais.(AU)

Spider trait assembly patterns and resilience under fire-induced vegetation change in South Brazilian grasslands.

Disturbances induce changes on habitat proprieties that may filter organism's 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.