Ocupação de microhábitats artificiais por invertebrados de solo em um fragmento florestal no sul do Brasil

The degradation of the soil system and loss of organic layer can cause a decrease in the biodiversity of soil fauna, directly affecting its functional characteristics. Strategies that aim at ecological restoration of degraded areas, must take into account the heterogeneous nature of original systems, especially in the soil surface. The general objective of this study was to investigate the importance of cryptic microhabitats for soil invertebrate communities, through the introduction of artificial structures (mud tiles) on the litter fall. The study area consisted of native forest fragment in Triunfo, RS, Brazil, in which 40 mud tiles were distributed. Every quarter, for a year, 10 tiles were surveyed and 10 litter samples (control group) were collect. A total of 1025 individuals were found distributed in 17 taxonomic groups of invertebrates under the tiles and 935 individuals in 13 groups in the litter fall (control). It was verified that ants and harvestman had been more abundant under tiles than in the control. The abundance of spiders and molluscs was not significantly different between treatments. There were larger amounts of beetle, woodlice and immature insects in the litter fall samples. The mean richness of taxa was larger below the tile and a trend of finding more herbivores and omnivores below these structures was observed. The mud tiles, in this experiment, had fulfilled its task to supply basic information on the importance of cryptic microhabitats for the invertebrate fauna. More research needs to be conducted to clarify and establish the influence of spatial heterogeneity on the dynamics on the soil-litter system for restoring degraded areas. Key words: invertebrates, microhabitat, litter fall, restoration.A degradação do sistema edáfico e a perda de seus horizontes orgânicos podem ocasionar um decréscimo da biodiversidade da fauna do solo, afetando diretamente suas características funcionais. Estratégias que visem à restauração ecológica de áreas degradadas devem levar em conta a heterogeneidade dos sistemas originais, em especial da superfície do solo. Este estudo teve como objetivo geral investigar a importância da presença de microhábitats crípticos para as comunidades de invertebrados do solo a partir da introdução de estruturas artificiais (telhas de barro) sobre a serapilheira. A área de estudo consistiu em um fragmento de mata nativa no município de Triunfo, RS, Brasil, no qual foram distribuídas 40 telhas em cima da serapilheira. Trimestralmente, até o término de um ano, foram amostradas 10 telhas e retiradas 10 amostras de serapilheira (controle) do local. Foram coletados 1.025 indivíduos, distribuídos em 17 grupos taxonômicos de invertebrados sob as telhas e 935 indivíduos e 13 grupos na serapilheira. Foram verificadas maior abundância de formigas e opiliões nas amostragens de telhas e maior abundância de coleópteros, isópodes e insetos imaturos nas amostragens controle de serapilheira. Aranhas e moluscos não apresentaram abundâncias diferentes entre os tratamentos. A riqueza média de táxons foi considerada maior abaixo da telha e foram observados mais herbívoros e onívoros abaixo destas estruturas. As telhas de barro, neste experimento, cumpriram a tarefa de fornecer informações básicas sobre a importância de microhábitats crípticos à fauna de invertebrados. Mais pesquisas deveriam ser realizadas, esclarecendo e ressaltando a importância da heterogeneidade espacial na dinâmica do sistema solo-serapilheira e nas estratégias de restauração de áreas degradadas.Palavras-chave: invertebrados, microhábitats, serapilheira, restauração

Ocupação de microhábitats artificiais por invertebrados de solo em um fragmento florestal no sul do Brasil

The degradation of the soil system and loss of organic layer can cause a decrease in the biodiversity of soil fauna, directly affecting its functional characteristics. Strategies that aim at ecological restoration of degraded areas, must take into account the heterogeneous nature of original systems, especially in the soil surface. The general objective of this study was to investigate the importance of cryptic microhabitats for soil invertebrate communities, through the introduction of artificial structures (mud tiles) on the litter fall. The study area consisted of native forest fragment in Triunfo, RS, Brazil, in which 40 mud tiles were distributed. Every quarter, for a year, 10 tiles were surveyed and 10 litter samples (control group) were collect. A total of 1025 individuals were found distributed in 17 taxonomic groups of invertebrates under the tiles and 935 individuals in 13 groups in the litter fall (control). It was verified that ants and harvestman had been more abundant under tiles than in the control. The abundance of spiders and molluscs was not significantly different between treatments. There were larger amounts of beetle, woodlice and immature insects in the litter fall samples. The mean richness of taxa was larger below the tile and a trend of finding more herbivores and omnivores below these structures was observed. The mud tiles, in this experiment, had fulfilled its task to supply basic information on the importance of cryptic microhabitats for the invertebrate fauna. More research needs to be conducted to clarify and establish the influence of spatial heterogeneity on the dynamics on the soil-litter system for restoring degraded areas. Key words: invertebrates, microhabitat, litter fall, restoration.A degradação do sistema edáfico e a perda de seus horizontes orgânicos podem ocasionar um decréscimo da biodiversidade da fauna do solo, afetando diretamente suas características funcionais. Estratégias que visem à restauração ecológica de áreas degradadas devem levar em conta a heterogeneidade dos sistemas originais, em especial da superfície do solo. Este estudo teve como objetivo geral investigar a importância da presença de microhábitats crípticos para as comunidades de invertebrados do solo a partir da introdução de estruturas artificiais (telhas de barro) sobre a serapilheira. A área de estudo consistiu em um fragmento de mata nativa no município de Triunfo, RS, Brasil, no qual foram distribuídas 40 telhas em cima da serapilheira. Trimestralmente, até o término de um ano, foram amostradas 10 telhas e retiradas 10 amostras de serapilheira (controle) do local. Foram coletados 1.025 indivíduos, distribuídos em 17 grupos taxonômicos de invertebrados sob as telhas e 935 indivíduos e 13 grupos na serapilheira. Foram verificadas maior abundância de formigas e opiliões nas amostragens de telhas e maior abundância de coleópteros, isópodes e insetos imaturos nas amostragens controle de serapilheira. Aranhas e moluscos não apresentaram abundâncias diferentes entre os tratamentos. A riqueza média de táxons foi considerada maior abaixo da telha e foram observados mais herbívoros e onívoros abaixo destas estruturas. As telhas de barro, neste experimento, cumpriram a tarefa de fornecer informações básicas sobre a importância de microhábitats crípticos à fauna de invertebrados. Mais pesquisas deveriam ser realizadas, esclarecendo e ressaltando a importância da heterogeneidade espacial na dinâmica do sistema solo-serapilheira e nas estratégias de restauração de áreas degradadas.Palavras-chave: invertebrados, microhábitats, serapilheira, restauração

First Record of the Dolichoderine Ant Genus Gracilidris Wild & Cuezzo (Hymenoptera: Formicidae) from Southern Brazil

ABSTRACT - The dolichoderine ant species Gracilidris pombero, sole representative of the genus, is recorded for the first time in southern Brazil. Until now, the species was known only for the open fields of the South American dry diagonal and for a single locality in the Colombian Amazon. The specimens reported here were collected with pitfall traps in grasslands of the Pampa biome, Rio Grande do Sul state, Brazil. This record represents the southernmost occurrence for the genus, extending its distribution in approximately 450 km to the south in the Neotropics and in almost 1,150 km to the south in Brazil

Ground-Dwelling and Vegetation Ant Fauna in Southern Brazilian Grasslands

Non-forest ecosystems, as natural grasslands from Southern Brazil, are still neglected in conservation policies. Measuring their biodiversity is one of the main steps to generate management strategies for these habitats. This study aims to (i) describe grassland ant richness and composition in Rio Grande do Sul state, and (ii) compare ant communities sampled on the ground and in grassland vegetation, adding to our knowledge of habitat use patterns and vegetation associated species. Six sites were sampled, three belonging to the Pampa biome and three in highland region from the Atlantic Forest biome. Ant fauna was collected once per year in summer during four years in each site with pitfalls traps and sweeping nets. Overall, 29,812 ant individuals were sampled belonging to eight subfamilies, 30 genera e 106 species. The grasslands of Pampa accumulated 91 species and 45 exclusive species, while highland grasslands summed up 61 species and only 15 exclusive species. Species composition differs between biomes as well as between sampling methods. Ant communities sampled from vegetation represented a clear subset of the fauna sampled with pitfall traps, and indication analysis showed only two species associated with this stratum: Myrmelachista gallicola and Pseudomyrmex nr. flavidulus. This study highlights the importance of Southern Brazilian grasslands and the need for specific conservation strategies for the natural grasslands from each biome

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

Decomposição foliar de espécies pioneiras e macrofauna de solo em ecossistemas degradados pela deposição de cinzas e extração do carvão

Dois estudos envolvendo o processo de decomposição foliar de espécies pioneiras e os organismos da macrofauna de solo foram realizados em ecossistemas degradados pela deposição de cinzas e extração do carvão no Rio Grande do Sul, Brasil. Os estudos resultaram em três artigos científicos. O primeiro estudo (1° artigo) acessou a decomposição foliar e a colonização da macrofauna nos folhiços do capim-bermuda (Cynodon dactylon- Poaceae), da mamona (Ricinus communis- Euphorbiaceae), e da aroeira-vermelha (Schinus terebinthifolius- Anacardiaceae), plantas participantes da sucessão natural inicial, em áreas de deposição de cinzas leves e cinzas grossas/escória na mata ciliar do Rio Jacuí, em São Jerônimo. O segundo artigo - originário deste primeiro estudo-tratou exclusivamente sobre os padões de colonização de espécies de tatuzinhos de solo (Isopoda), grupo de animais detritívoros com alta abundância no local, no folhiço das mesmas três plantas. Ainda, compararam-se as suas abundâncias e algumas características reprodutivas entre os dois depósitos de cinzas. O segundo estudo (terceiro artigo) testou uma técnica de manejo para acelerar o processo da decomposição foliar de Pinus elliottii (Pinaceae) e enriquecer a fauna de macroartrópodes de solo em uma floresta monodominate de pinus sobre solo minerado e reconstruído topograficamente no município de Minas do Leão. Todos os estudos foram realizados empregando-se a técnica de bolsas-de-folhiço, que consistiu em bolsa de nylon de 30 X 20 cm e malha de 0.2 X 1.0 cm. A decomposição foi medida calculando-se a perda de massa foliar seca nas datas amostrais (6, 35, 70 e 140 dias após a exposição das folhas - 1° e 2° artigo ; 3 e 6 meses - 3° artigo ). Foram realizadas análises de macronutrientes do material foliar remanescente. A macrofauna (indivíduos > 2 mm) foi retirada manualmente das bolsas-de-folhiço em laboratório, ou com extrator de Berlese-Tüllgren modificado (3° artigo), separada em ordens e morfoespeciada. Foi constatado que a mamona apresentou decomposição foliar mais rápida (k= 20.7) e maior densidade de indivíduos da macrofauna no seu folhiço, mas, no entanto, apresentou menor riqueza de espécies do que as outras plantas pioneiras. Os folhiços do capim-bermuda e da aroeira-vermelha foram similares com relação à decomposição e a diversidade da macrofauna. As espécies de tatuzinhos colonizaram igualmente as três espécies de plantas ao longo do tempo. Apesar da decomposição foliar não ter sido influenciada, a ocorrência de Atlantoscia floridana (Isopoda), a abundância e fecundidade de fêmeas de Benthana taeniata (Isopoda), e a composição total de espécies da macrofauna foram afetadas pelos diferentes depósitos de cinzas de carvão. Como esperado, a adição de folhas de plantas nativas sobre o solo homogêneo da floresta monodominante de pinus em solo minerado modificou a composição química do folhiço de pinus e aumentou a diversidade dos macroartrópodes de solo, demonstrado ser uma estratégia potencial ao manejo e à restauração ecológica. Estes estudos têm como metas contribur ao entendimento sobre a ecologia (processos ecológicos e interação organismos - folhiço) de áreas degradadas pela deposição de cinzas e áreas de extração e processamento do carvão no sul do Brasil.Two studies concerning the leaf decomposition of pioneer plant species and the soil macrofauna organisms were performed in ecosystems degraded by the deposition of ashes and coal extraction in Rio Grande do Sul, Brazil. These studies resulted in three scientific articles. The first study (primary article) accessed the decomposition and the macrofauna colonization among leaves of bermuda-grass (Cynodon dactylon - Poaceae), the castor oil plant (Ricinus communis - Euphorbiaceae), and the Brazilian peppertree (Schinus terebinthifolius - Anacardiaceae); all are plants that participate in the initial natural succession in areas of deposition of fly ashes and boiler slag in Rio Jacuí's ciliar forest, located in São Jerônimo. The second article (derived from the primary study) exclusively analyzes the colonization patterns of woodlice species (Isopoda), a detritivorous group with high abundance at the site, among the leaf-litter of the same three plants. Their abundances and some reproductive characteristics were compared between the two deposits of ashes. The second study (tertiary article) tested a technique of management to motivate the leaf decomposition of Pinus elliottii (Pinaceae), and to enrich the soil macroarthropod fauna in a pinus monospecific forest with spontaneous establishment on a mined and rebuilt soil located in Minas do Leão. All of these studies were accomplished using the litter bags technique, which consists of a 30 X 20 cm nylon bag and a 0.2 X 1.0 cm mesh. The decomposition was measured by calculating the leaf-litter mass loss through multiple sampling dates (6, 35, 70 and 140 days after leaf expositions - primary and secondary articles; or 3 and 6 months after leaf expositions - tertiary article). The nutrient contents in the remaining leaf-litter were analyzed. The macrofauna (individuals > 2 mm) were removed manually from the litter bags in the laboratory, or with a modified Berlese-Tüllgren extractor (tertiary study), and the microfauna were separated by orders and morphospecies. We verified that the castor oil plant presented a faster decomposition rate (k = 20.7) and a larger density of macrofauna individuals, but presented a smaller species richness compared to the other pioneer plants. The leaf-litter of the bermuda-grass and the Brazilian peppertree were similar in terms of decomposition and macrofauna diversity. The woodlice species colonized the three species of plants equally along the time scale. Despite no effects on decomposition, the occurrence of Atlantoscia floridana (Isopoda), the abundance and fecundity of Benthana taeniata females (Isopoda), and the total macrofauna species composition was strongly affected by the different deposits of coal ashes. As expected, the input of leaves from native plants on the homogeneous soil of the pinus forest modified the chemical composition of the pinus leaf-litter and increased the soil arthropod diversity, showing that it could be a potential strategy for management and ecological restoration of damaged areas. These studies aimed to contribute to the understanding about ecological processes and the interaction between organisms and litter in areas with extraction and processing of coal in southern Brazil