Tree plantations have become one of the fastest-growing land uses and their impact on biodiversity was evaluated mainly at the taxonomic level. The aim of this study was to analyze environmental changes after the Eucalyptus plantation in an area originally covered by natural grasslands, taking into account the alpha and beta (taxonomic and functional) diversity of plant communities. We selected nine plantation ages, along a 12 years chronosequence, with three replicates per age and three protected grasslands as the original situation. At each replicate, we established three plots to measure plant species cover, diversity and environmental variables. Results showed that species richness, and all diversity indices, significantly declined with increasing plantation age. Canopy cover, soil pH, and leaf litter were the environmental drivers that drove the decrease in taxonomic and functional diversity of plants through the forest chronosequence. Based on the path analyses results, canopy cover had an indirect effect on plant functional diversity, mediated by leaf litter depth, soil pH, and plant species richness. The high dispersal potential, annual, barochorous, and zoochorous plant species were the functional traits more affected by the eucalypt plantations. We recommend two management practices: reducing forest densities to allow higher light input to the understory and, due to the fact that leaf litter was negatively associated with all diversity facets, we recommend reducing their accumulation or generate heterogeneity in its distribution to enhance biodiversity.

Land-use change is one of the major drivers of biodiversity loss by introducing environmental modifications, which excludes native species unable to adapt to the novel conditions. Grasslands are among the most threatened biomes; understanding the influence of different land-use types on native species is crucial to achieving sustainable management policies. We hypothesized that land-use types that partially conserve the original vegetation cover would show higher taxonomic and functional diversity and similarity with native assemblages than land-use types that replace the original vegetation cover. We compared the taxonomic and functional alpha and beta diversity of spider assemblages between soybean crops, eucalypt plantations, and cattle fields with seminatural grasslands. Through null models, we assessed the standardized effect sizes to test differences in the strength of environmental filtering among land-use types. Environmental changes introduced by different land-use types resulted in assemblages differentiated in species and trait composition, taxonomically and functionally impoverished with respect to seminatural grasslands. All land-use types drove species replacement and trait loss and replacement of grassland spiders. Each land-use showed a characteristic species and trait composition. Most of the grassland traits were not lost but were under or over-represented according to the land-use type. Only in soybean crops the formation of spider communities would be mainly driven by environmental filtering. Changes in land-use decreased species diversity and modified the composition of spider species and functional traits leading to differentiated spider assemblages. As spider species and traits varied among land-uses, a mitigation measure against grasslands biodiversity loss could be the development of productive landscapes with a mosaic of land-use types, as each of them would provide microhabitats for species with different requirements. Because land-use types mainly led to the rearrangement of grassland functional trait values, most of spider functions might be conserved in mosaics of land-use types.

R������. La lechuza vizcachera es una rapaz típica de la Región Pampeana, que construye su nido en madrigueras en el suelo. Dado el impacto negativo de la expansión del cultivo de soja sobre la diversidad de aves, resulta clave estudiar su efecto sobre la selección y las características del hábitat en múltiples escalas. Se investigó el uso del hábitat de nidificación antes y después del brote de la soja de primera y la selección del hábitat de nidificación después del brote de la soja, en tres escalas espaciales: nido (hábitat donde la lechuza vizcachera construye su nido), sitio de nidificación (círculo de radio 50 m) y área de acción (círculo de radio 600 m). Se recorrieron caminos secundarios localizando nidos de lechuzas y se establecieron 23 puntos al azar para analizar la selección de hábitat. El uso del hábitat varió según la escala y la etapa del cultivo. Antes del brote de la soja, 63% de los nidos se ubicaron en el interior de campos ganaderos, mientras que después, 55% de los nidos se encontraron en los bordes. En la escala de sitio de nidificación, la cobertura de los tipos de hábitat y la distancia al alambrado fueron similares antes y después del brote de la soja. En la escala de área de acción, antes del brote de la soja, la lechuza vizcachera nidificó rodeada de áreas con rastrojo; después, en áreas con cultivo de soja. La lechuza vizcachera seleccionó los bordes de campos de cultivo para ubicar sus nidos, evitó la cercanía de caminos y arboledas en la escala de sitio, y en la escala de área de acción nidificó cerca de alambrados y evitó las arboledas. Recomendamos mantener los bordes de cultivo con vegetación no manejada para proveer hábitat de nidificación para la lechuza vizcachera.[Palabras clave: sistemas agrícolas, soja, nidificación] A�������. Nesting site selection by the Burrowing Owl (Athene cunicularia) in Rolling Pampa agroecosystems.The Burrowing owl is a common raptor species in Pampean agrosystems of Argentina, that builds nests in burrows under the ground. Given the negative effect of expanding soybean crops on avian diversity, it is key to study that effect on habitat selection at multiples scales. We investigated the use of nesting habitat before and after the growing of soybean shoots and nesting site selection after the growing of soybean shoots, at three spatial scales: nest scale (habitat type where the nest was located), nesting site scale (a circle of 50 m radius centered on the nest) and home range (a circle of 600 m radius). Surveys were conducted on secondary roads, searching for nests, and 23 random points were established on the same roads to evaluate nest site selection. Habitat use changed with the spatial scale and stage of crop development. Before the soybean shooting, 63% of nests were located into livestock fields, whereas after the soybean shooting, 55% of nests were located in field edges. At the nesting site scale, the cover of habitat types and distance to fences were similar before and after soybean shooting. At the home range scale, Burrowing Owl nested in...

Understanding how human land-uses impact on local communities is required to implement management and conservational policies and practices. Tree plantations have become one of the fastest-growing land uses in recent decades and their impact on biodiversity was evaluated mainly at the taxonomic level. Our aim was to analyze the effects of changes in environmental drivers along the 12 years eucalypt plantations chronosequence on alfa, beta, taxonomic and functional diversity of understory plant communities. We selected nine plantation ages with three replicates per age and three protected grasslands as reference habitat. At each replicate, we established three plots to measure plant species cover and environmental variables, which are expected to change with plantation age. Results showed that species richness and all diversity indices significantly declined with increasing plantation age. Canopy cover, soil pH, and leaf litter were the most important drivers that explained the decline in taxonomic and functional diversity of plants through the forest plantation. Based on the Path analyses results, canopy cover had an indirect relationship with plant functional diversity mediated by leaf litter, soil pH and plant species richness. The results of the association between functional traits and environmental variables have revealed that high dispersal potential, annual, barochorous, and zoochorous plant species were the functional traits more affected by the eucalypt plantations. Given that leaf litter was negatively associated with all diversity facets, we recommend reducing their accumulation within eucalypt plantation to enhance biodiversity conservation and the provision of pampean grassland ecosystem functions.