FOREST FRAGMENT GROUPING ANALYSIS UNDER SELECTIVE LOGGING IN AMAZONIAN BIOME

ABSTRACT: The aim of this study was to analyse the existence of floristic groups in Seasonal Semi-deciduous Forest fragments under the effects of selective logging located in Tapurah-MT. The given clusters were allocated and measured, and each one had five subunits of 500 m². For each sampling unit, all of the arboreal and shrub species with a diameter at breast height (DBH) equal to or greater than 10 cm were considered. In the sampling subunits studied, the vegetation matrix was composed of the density of the 20 species in the fragment with the greatest importance. The presence of floristic groups was verified by a grouping analysis through the species association method. Euclidean distance with Hellinger’s transformation was used as a similarity measure between the groupings, and Ward’s linking method was used for the dendrogram elaboration. The number of groups was established by Kendall’s coefficient, and correlations between the groups and the species were assessed. Once the concordance was determined, the number of groups in which the species were correlated was chosen. The species’ auto-ecological characteristics, mainly the propagating material dispersion type and average DBH, were the main factors responsible for the species association and similarity inside each floristic group. Keywords: similarity between species groups; species association; floristic group; environmental disturbance.   Análise de agrupamento de fragmento florestal sob efeitos da extração seletiva no bioma amazônico   RESUMO: O objetivo deste estudo foi analisar a existência de grupos florísticos em fragmentos de Floresta Estacional Semidecidual sob os efeitos da exploração madeireira seletiva localizada em Tapurah-MT. Os transectos foram subdivididos em cinco subunidades de 500 m². Para cada unidade amostral, foram consideradas todas as árvores com DAP maior ou igual a 10 cm. Nas subunidades amostrais estudadas, a matriz de vegetação foi composta pela densidade das 20 espécies de maior importância no fragmento. A presença de grupos florísticos foi verificada por meio de uma análise de agrupamento pelo método de associação de espécies. A distância euclidiana com a transformação de Hellinger foi usada como uma medida de similaridade entre os agrupamentos, e o método de ligação de Ward foi usado para a elaboração do dendrograma. O número de grupos foi estabelecido pelo coeficiente de Kendall e as correlações entre os grupos e as espécies foram avaliadas. Uma vez determinada a concordância, optou-se pelo número de grupos em que as espécies estavam correlacionadas. Foi verificado que as características auto-ecológicas das espécies, principalmente o tipo de dispersão do material propagado e o DAP médio, foram os principais responsáveis pela associação e similaridade das espécies dentro de cada grupo florístico. Palavras-chave: similaridade entre grupos florísticos; associação de espécies; agrupamentos florísticos; perturbação ambiental.ABSTRACT: The aim of this study was to analyse the existence of floristic groups in Seasonal Semi-deciduous Forest fragments under the effects of selective logging located in Tapurah-MT. The given clusters were allocated and measured, and each one had five subunits of 500 m². For each sampling unit, all of the arboreal and shrub species with a diameter at breast height (DBH) equal to or greater than 10 cm were considered. In the sampling subunits studied, the vegetation matrix was composed of the density of the 20 species in the fragment with the greatest importance. The presence of floristic groups was verified by a grouping analysis through the species association method. Euclidean distance with Hellinger’s transformation was used as a similarity measure between the groupings, and Ward’s linking method was used for the dendrogram elaboration. The number of groups was established by Kendall’s coefficient, and correlations between the groups and the species were assessed. Once the concordance was determined, the number of groups in which the species were correlated was chosen. The species’ auto-ecological characteristics, mainly the propagating material dispersion type and average DBH, were the main factors responsible for the species association and similarity inside each floristic group. Keywords: similarity between species groups; species association; floristic group; environmental disturbance.   Análise de agrupamento de fragmento florestal sob efeitos da extração seletiva no bioma amazônico   RESUMO: O objetivo deste estudo foi analisar a existência de grupos florísticos em fragmentos de Floresta Estacional Semidecidual sob os efeitos da exploração madeireira seletiva localizada em Tapurah-MT. Os transectos foram subdivididos em cinco subunidades de 500 m². Para cada unidade amostral, foram consideradas todas as árvores com DAP maior ou igual a 10 cm. Nas subunidades amostrais estudadas, a matriz de vegetação foi composta pela densidade das 20 espécies de maior importância no fragmento. A presença de grupos florísticos foi verificada por meio de uma análise de agrupamento pelo método de associação de espécies. A distância euclidiana com a transformação de Hellinger foi usada como uma medida de similaridade entre os agrupamentos, e o método de ligação de Ward foi usado para a elaboração do dendrograma. O número de grupos foi estabelecido pelo coeficiente de Kendall e as correlações entre os grupos e as espécies foram avaliadas. Uma vez determinada a concordância, optou-se pelo número de grupos em que as espécies estavam correlacionadas. Foi verificado que as características auto-ecológicas das espécies, principalmente o tipo de dispersão do material propagado e o DAP médio, foram os principais responsáveis pela associação e similaridade das espécies dentro de cada grupo florístico. Palavras-chave: similaridade entre grupos florísticos; associação de espécies; agrupamentos florísticos; perturbação ambiental

Tree diversity and above-ground biomass in the South America Cerrado biome and their conservation implications

Less than half of the original two million square kilometers of the Cerrado vegetation remains standing, and there are still many uncertainties as to how to conserve and prioritize remaining areas effectively. A key limitation is the continuing lack of geographically-extensive evaluation of ecosystem-level properties across the biome. Here we sought to address this gap by comparing the woody vegetation of the typical cerrado of the Cerrado–Amazonia Transition with that of the core area of the Cerrado in terms of both tree diversity and vegetation biomass. We used 21 one-hectare plots in the transition and 18 in the core to compare key structural parameters (tree height, basal area, and above-ground biomass), and diversity metrics between the regions. We also evaluated the effects of temperature and precipitation on biomass, as well as explored the species diversity versus biomass relationship. We found, for the first time, both that the typical cerrado at the transition holds substantially more biomass than at the core, and that higher temperature and greater precipitation can explain this difference. By contrast, plot-level alpha diversity was almost identical in the two regions. Finally, contrary to some theoretical expectations, we found no positive relationship between species diversity and biomass for the Cerrado woody vegetation. This has implications for the development of effective conservation measures, given that areas with high biomass and importance for the compensation of greenhouse gas emissions are often not those with the greatest diversity