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Fragmentation creates heterogeneous landscapes with different interactions and trajectories. In this scenario, the understanding in how forest fragment sizes influence forest species patterns can lead the way for biodiversity management and conservation in agricultural landscapes. The aim of this study was to compare the density and the diameter distribution of Bertholletia excelsa, Carapa guianensis and Cedrelinga cateniformis among fragments of different sizes, located at the Agro-Extractivist Settlement Project Praialta Piranheira, Pará State, Brazil. Data were collected from adult and sapling trees in six forest fragments. Adult and sapling density was compared among fragment sizes by the Mann–Whitney test, while diameter distributions were compared by a summary statistic calculated using the scores of a PCA produced with the results of the binomial logit model between tree DBH and the cumulative DBH proportions. The density of adult trees of three species is similar among different-sized fragments. Only the saplings of C. cateniformis showed a significant difference in density among fragment sizes. The DBH distribution of adults, for all three species, seems to also not respond to fragmentation, since the differences in the DBH distribution curves among fragments were large. The results of this study suggest that in areas established for agroextractivism, all fragments (large and small) no longer have sustainable populations (except only one C. guianensis population), probably due to anthropic pressure exerted by agroextractivism. So, it is important to ensure the structural and environmental quality of the forest fragments for the conservation of the species. [ABSTRACT FROM AUTHOR]

Scattered trees are an important feature of the matrix of agricultural landscapes, but their role in biodiversity conservation is still controversial and largely unexplored. We aim to investigate the value of scattered trees to maintain the functional and phylogenetic diversity within the matrix of an agricultural landscape dominated by commercial Eucalyptus plantation in southeastern Brazil. For this, we established a grid of 100 × 100 m cells covering the full extent of a farm, conducted an inventory and georeferenced all scattered trees present within each cell in the grid. Further, we modeled the spatial distribution of the taxonomic, functional and phylogenetic diversity of trees in the farm. Scattered trees presented lower taxonomic, phylogenetic and functional diversity than the native vegetation nearby, and these diversity indices were strongly related to local species richness. However, the scattered trees held 64% and 85% of the total functional and phylogenetic diversity in agricultural land use, respectively. Further, the scattered trees maintained higher functional and phylogenetic diversity levels in agricultural land use than expected for random assemblages of species. Scattered trees in the landscape are unprotected by Brazilian environmental laws since they are not included in any network of protected areas. Here we demonstrated the importance of conservation of scattered trees to reduce the loss of phylogenetic and functional diversity in agricultural landscapes, counteracting the loss of species that occurs in highly productive agroecosystems. [ABSTRACT FROM AUTHOR]