Interactions between terrestrial and aquatic systems influence the structure of river habitats and, consequently, affect their benthic macroinvertebrate composition. The aim of this study was to evaluate the effects of spatial and environmental variables (local physical and chemical variables of water and regional landscape characteristics) on the benthic macroinvertebrate community of the Pandeiros River Basin. Biotic and abiotic variables were evaluated at 20 sampling sites distributed across the primary sub-basins of the Pandeiros River Basin. We found that the macroinvertebrates were primarily affected by environmental variables. The most important environmental variables were pebble proportion and water conductivity at the local scale (7.2% of explained variation) and elevation and nonforest areas at the regional scale (6.9% of explained variation). The spatial variables were representative only in shared explained variation with the environmental matrices (local-spatial = 0.2% and regional-spatial = 2%; all matrices combined = 4.4%). Sampling sites with higher non-forest areas, lower elevations, and steeper slopes presented low pebble fractions and higher electrical conductivities. Habitat diversity was lower when the percentage of pebbles decreased, resulting in decreased taxonomic richness and diversity in macroinvertebrate communities. High electrical conductivities and non-forest areas also had negative effects on macroinvertebrate density due to the loss of habitat diversity. We conclude that higher proportions of pebbles in the substrate and higher altitudes were likely the primary variables for positive effects on the taxonomic richness and density of macroinvertebrate communities.
This study aimed to analyze relationships among the structure of the tree component, edaphic variables and canopy discontinuity along a toposequence in a seasonal upland (hillside) forest in southern Brazil. Soil and vegetation were sampled in 25 plots of 20 × 20 m each. We described the vegetation in terms of structure, richness and diversity, as well as by species distribution patterns. We evaluated canopy continuity, determined sloping and calculated spatial coordinates. We applied partial canonical correspondence analysis (pCCA) to determine whether species distribution correlated with environmental and spatial variables. We identified 1201 individuals belonging to 76 species within 30 families. The species with highest density and frequency were Gymnanthes concolor Spreng., Calyptranthes tricona D.Legrand, Eugenia moraviana O.Berg and Trichilia claussenii DC. The pCCAs indicated significant correlations with environmental and spatial variables. Sand content, boron content and soil density collectively explained 36.17% of the species matrix variation (total inertia), whereas the spatial variables x, y and xy 2 collectively explained 14.27%. The interaction between environmental and spatial variables explained nearly 4.5%. However, 45.05% remained unexplained, attributed to stochastic variation or unmeasured variables. Terrain morphology and canopy discontinuity had no apparent influence on richness, and changes in species distribution were correlated with sloping, which affects soil features and determines the directional distribution of some species. factors associated with topography, such as riparian forests along flood gradients Giehl & Jarenkow 2008) and hillside forests (Sühs & Budke 2011, Loregian et al. 2012. In general, studies have shown that most species have clustered spatial distribution, and that many generate dense clusters, decreasing the richness and abundance of other species in nearby areas. Sühs & Budke (2011) evaluated the distribution and association among tree species in a hillside forest, having observed greater association among species at more advanced successional stages and greater dissociation among species at distinct stages (for example, pioneer and shade-tolerant). These results highlight the role of biotic relationships, whereas relationships of facilitation and competition may often result in spatial patterns that are less dependent upon physical environment.Although these factors are extremely important on the community scale, on a regional scale, climatic factors have been identified as determinants of the distribution of plant species (Giehl & Jarenkow 2012). From this perspective, deciduous forests have been described as being strongly associated with the seasonality of precipitation and temperature This study aims to investigate the relationship between the distribution of tree species and spatial-environmental variables in a hillside forest situated on a moderate slope gradient (average slope of 25%) and that, therefore, could offer different establishment cond...
Regeneração de espécies arbóreas e relações com componente adulto em uma fl oresta estacional no vale do rio Uruguai, Brasil RESUMO (Regeneração de espécies arbóreas e relações com componente adulto em uma fl oresta estacional no vale do rio Uruguai, Brasil). O estudo de fenômenos relacionados às variações na estrutura das comunidades vegetais tem cada vez mais envolvido a avaliação do potencial de regeneração das espécies arbóreas, uma vez que a regeneração torna as fl orestas capazes de se restaurarem após distúrbios naturais ou antrópicos. Neste sentido, objetivou-se avaliar o componente arbóreo regenerante, identifi cando composição e abundância, grupos funcionais de dispersão, estratificação vertical e necessidades de luz para germinação, além de estimativas de riqueza e diversidade e comparar estes valores com o respectivo componente adulto. O levantamento foi realizado em 20 unidades amostrais de 10 x 10 m, sendo amostrados todos os indivíduos com altura ≥ 0,30 m e diâmetro a altura do solo ≤ 4,7 cm. O levantamento do componente adulto, avaliado em estudo anterior, foi estabelecido em unidades amostrais de 20 x 20 metros, sendo amostrados todos os indivíduos com diâmetro à altura do peito ≥ 4,7 cm. Foram amostrados 1.649 indivíduos em regeneração, pertencentes a 64 espécies, com densidade total estimada em 8.245 ind.ha -1. As espécies com maior densidade absoluta foram Gymnanthes concolor Spreng., Trichilia elegans A.Juss. e Calyptranthes tricona D.Legrand. Uma análise de coordenadas principais indicou nítida separação das unidades amostrais amostradas e um teste de Mantel revelou haver independência entre as matrizes de composição e abundância dos componentes adulto e regenerante (r = 0,19; p = 0,1). Dentre os grupos funcionais, verifi cou-se que o componente regenerante está mantendo as mesmas proporções observadas para o componente adulto, com maior proporção de espécies zoocóricas, dependentes de luz para germinação e formadoras do dossel fl orestal. Ao contrário do esperado, houve diminuição da riqueza no componente regenerante (p < 0,001) e manutenção da equabilidade ao longo da área. Palavras ABSTRACT(Tree regeneration and relationships with adult trees in a seasonal forest in the Uruguai river valley, Brazil). Studies related to variation in plant communities have been involved the analysis of regenerative potential of tree species, because saplings may enable forests to restore themselves aft er natural or human disturbances. Th e goal of this study was to analyze tree regeneration by identifying composition and abundance, the ecological groups of dispersion, vertical stratifi cation and light requirements for germination and to look for changes in expected richness, diversity and relationships with structure of adult trees. A sapling survey was conducted in 20 sample units of 10 x 10 m where all individual living trees were sampled that had a height ≥ 0.30 m and diameter at soil height ≤ 4.7 cm. Adult trees with a diameter at breast height ≥ 4.7 cm were surveyed in 20 x 20 m sampling units, acc...
A qualitative and quantitative analysis of the environmental damages occurrences was conducted through the lawful documents established for charging at the State Prosecution Service of São Carlos city, State of São Paulo, during 1991Paulo, during -2000
RESUMO(Padrões espaciais e ecológicos de espécies arbóreas refletem a estrutura em mosaicos de uma floresta subtropical). A abundância e distribuição espacial das espécies podem ser reflexos das necessidades do seu nicho ecológico, além de reflexos das variações ambientais no tempo e espaço. Os objetivos do presente trabalho foram analisar a distribuição espacial e grupos ecológicos das espécies arbóreas em um remanescente de floresta subtropical e avaliar a interferência destes padrões sobre métricas de riqueza e diversidade. Os padrões espaciais foram avaliados considerando uma área amostral de 1 ha dividida em unidades amostrais contíguas de 10 x 10 m, onde todos os indivíduos com perímetro à altura do peito ≥ 15 cm foram amostrados. A descrição dos padrões foi obtida por meio de correlogramas (índice I de Moran), considerando diversas classes de distância, índices de agregação e diagramas de superfície. A co-ocorrência entre espécies foi analisada por meio de índices de associação espacial. A maioria das espécies apresentou distribuição agrupada e com autocorrelação espacial positiva, sobretudo para as menores classes de distância, indicando a formação de pequenos grupos de indivíduos. Da mesma forma, 17 espécies apresentaram associações espaciais (co--ocorrências), formando densos agrupamentos e, embora não tenham interferido sobre a riqueza específica, Casearia sylvestris e Ocotea diospyrifolia diminuíram a equabilidade em alguns setores da área. Espécies tolerantes à sombra apresentaram-se associadas, bem como, espécies dependentes de luz, indicando que a dinâmica de mosaicos pode interferir diretamente sobre a distribuição das espécies, sobretudo pela limitação de dispersão.Palavras-chave: autocorrelação espacial, correlogramas, índices de distância, limitação de dispersão, riqueza de espécies ABSTRACT (Spatial and ecological patterns of tree species reflect patch dynamics of a subtropical forest). The abundance and spatial distribution of species may reflect on niche requirements, interactions among individuals and across as time and space. In this way, the aims of this work were to analyze tree species distribution and ecological groups in a remnant of subtropical forest to evaluate the interference of such patterns over richness and diversity metrics. We evaluated the spatial patterns of a 1 ha area divided into 10 x 10 m sampling units where we surveyed all living trees with perimeter at breast height ≥ 15 cm. Pattern descriptions were obtained by using correlograms (Moran's I) over several distance classes, aggregation indices and surface diagrams. The co-occurrence among species was obtained by using spatial association indices. Furthermore, 17 species showed aggregated distribution and positive spatial autocorrelation, mainly in the shorter distance classes, which indicated the occurrence of several small groups of individuals. In addition, many species were spatially associated with dense groups and although such groups do not influence species richness, Casearia sylvestris and Ocotea diospyrifol...
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