Combining Satellite Remote Sensing and Climate Data in Species Distribution Models to Improve the Conservation of Iberian White Oaks (Quercus L.) (original) (raw)
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Forest Ecology and Management, 2013
Different statistical techniques have been used to model species potential distribution related to environmental variables. This paper provides a comprehensive assessments of GARP and MaxEnt methods, and investigates for the first time the probability of occurrence of cork oak (Quercus suber L.) in Italy based on ecological niche modelling approaches. A detailed distribution of the species was achieved during a 3-year National Project (SuberItalia) and 17 environmental layers were employed to obtain the potential distribution of cork oak. The performance of the models were measured using the receiver operating characteristic (ROC) approach and Cohen's Kappa statistic. Results achieved by GARP and MaxEnt showed as the drought and the cold stresses are the main factors affecting cork oak occurrence in Italy. Moreover, the accuracy of the obtained prediction maps were compared to a specifically calibrated geo-statistical method at regional scale, pointing out a preliminary geographical assessment of the suitable surfaces to set apart for cork oak forest expansion in Italy, thereby useful to address reforestation and conservation concerns to face the ongoing area reduction of these forests.
Spatial heterogeneity of abiotic factors influences the structure and function of forests and must be taken into account for their conservation and sustainable management. In this study, we evaluate the heterogeneity of abiotic environmental variables in managed cork oak (Quercus suber L.) forests in southern Spain at patch, site and regional scales. The extent of spatial heterogeneity depended on the environmental variable examined and the scale considered. For example, soil Mn and P and light availability in the understorey were very heterogeneous at the regional scale, while soil N had low regional heterogeneity, but high spatial variability, at patch scale, attributed to open overstorey and grazing disturbance. There was a general trend of increasing heterogeneity with spatial scale. We also study the effects of a silvicultural practice—shrub clearing on the forest environment and its consequence for spatial heterogeneity. Shrub clearing increased understorey light and decreased its spatial heterogeneity with idiosyncratic effects on soil properties and their spatial heterogeneity at each site. Finally, we compare the heterogeneity (estimated by the coefficient of variation) obtained in these cork oak forests with a database compiled from published studies on other forest environments. The comparison revealed a remarkable extent of abiotic heterogeneity in the cork oak forests studied, suggesting that a sustainable management of these forests should combine intrinsic and human induced abiotic heterogeneity to preserve crucial ecological processes and to maintain high levels of biodiversity.