Análisis ecológico comparativo de los castañares de Extremadura y de la región Cántabro-Astur (España)

A partir de los datos ecológicos de los territorios ocupados por Castanea sativa Miller en las Comunidades Autónomas españolas de Extremadura, Cantabria y en el Principado de Asturias se efectúa un estudio conjunto de sus caracteres generales. Además, se buscan los parámetros que son significativamente distintos en las regiones extremeña y cántabro-astur. Mediante análisis de componentes principales y discriminantes se pone de manifiesto en qué radica, esencialmente, la diversidad de comportamiento de ambas poblaciones

Modelos predictivos de la estructura selvícola en castañares extremeños (España)

Se estudian una serie de datos físiográficos. climáticos y edáficos del [crricoria ocupado por Castanea saliva Miller en la Comunidad Autónoma de Ex[cemadura y se evalúan los caracteres selvícolas de estas masas. En primer lugar, se selecciona un reducido número de parámetros representativos de la estruceura selvícola de ellas. Asimismo, se establecen unos modelos predictivos de dicha estructura en función de los parámetros ecológicos escogidos por el análisis de regresión

Together we stand, divided we fall: Effects of livestock grazing on vegetation patches in a desert community

Questions Vegetation patches formed by interacting xeric species are the main drivers of dryland structure and function. Plant aggregation enhances microclimatic conditions and triggers abiotic and biotic processes, such as nutrient cycling and accumulation, and species interactions. However, vegetation patches may be modified by disturbances in unpredictable ways. We tested whether livestock grazing affects vegetation structure and plant spatial associations in a desert community, by considering the role of plant species in ecological succession. Location Patagonian Monte Desert, Argentina. Methods We used high-quality standardized photographs along transects to characterize plant community structure (i.e., cover, abundance, richness), spatial patterns (i.e. plant-plant associations), and classified species based on their successional role (i.e. early, intermediate and late species). We used regression models and network analysis to evaluate the effect of grazing on vegetation. Results In general, grazing modified community structure, reducing total cover, abundance and richness. Grazing modulated community spatial patterns, simplifying and removing vegetation patches. The impact of grazing depended on the species successional role. The abundance and cover of early species were less affected by grazing than intermediate and late species, the latter being the most affected. However, species richness significantly decreased with increasing stocking rates, regardless of their successional role. Late species were present in most plant spatial associations, indicating a major contribution to multi-specific vegetation patches formation. Conclusions The reduction in species richness and low abundance of late species highlights the need to prevent irreversible degradation caused by overgrazing. Late species emerge as key structures of vegetation in desert rangelands facilitating the establishment and protecting other plant species. Due to the critical role of vegetation patches in maintaining desert ecosystem functioning, conservation and management practices should focus on late species, while early species, responsible for vegetation patch formation in overgrazed situations, should be preferred for restoration practices