European larch(Larix decidua) forests of the western Alps form extensivecultural landscapes whose resilience to global changes is currently unknown. Resilience describes the capacity of ecological systems to maintain ...European larch(Larix decidua) forests of the western Alps form extensivecultural landscapes whose resilience to global changes is currently unknown. Resilience describes the capacity of ecological systems to maintain the same state, i.e., the same function, processes, structure, and composition despite disturbances, environmental changes and internal fluctuations. Our aim is to explore the resilience of larch forests to changes in climate and land use in the western Italian Alps.To do so, we examined whether larch forests can be described as an alternative stable state in mountain forest ecosystems. We used tree basal area data obtained from field forest inventories in combination with topography, forest structure, land use, and climate information. We applied three different probabilistic methods: frequency distributions, logistic regressions, and potential analyses to infer the resilience of larch forests relative to that of other forest types.We found patters indicative of alternative stable states: bimodality in the frequency distribution of the percent of larch basal area, and the presence of an unstable state, i.e., mixed larch forests, in the potential analyses. We also found:(1) high frequency ofpurelarchforestsathighelevation,(2)the probability of pure larch forests increased mostly with elevation, and(3) pure larch forests were a stable state in the upper montane and subalpine belts.Our study shows that the resilience of larch forests may increase with elevation, most likely due to the altitudinal effect on climate. Under the same climate conditions, land use seems to be the main factor governing the dominance of larch forests. In fact, subalpine larch forests may be more resilient, and natural succession after land abandonment, e.g., towards Pinuscembra forests, seems slower than in montane larch forests. In contrast, in the upper montane belt only intense land use regimes characterized by open canopies and forest grazing may maintain larch forests.We conclude that similar approaches could be applied in other forest ecosystems to infer the resilience of tree species.展开更多
Background:Pyrogeography is a major field of investigation in wildfire science because of its capacity to describe the spatial and temporal variations of fire disturbance.We propose a systematic pyrogeographic analyti...Background:Pyrogeography is a major field of investigation in wildfire science because of its capacity to describe the spatial and temporal variations of fire disturbance.We propose a systematic pyrogeographic analytical approach to cluster regions on the basis of their pyrosimilarities.We employed the Affinity Propagation algorithm to cluster pyroregions using Italian landscape as a test bed and its current wildfire metrics in terms of density,seasonality and stand replacing fire ratio.A discussion follows on how pyrogeography varies according to differences in the human,biophysical,socioeconomic,and climatic spheres.Results:The algorithm identified seven different pyroregion clusters.Two main gradients were identified that partly explain the variability of wildfire metrics observed in the current pyroregions.First,a gradient characterized by increasing temperatures and exposure to droughts,which coincides with a decreasing latitude,and second,a human pressure gradient displaying increasing population density in areas at lower elevation.These drivers exerted a major influence on wildfire density,burnt area over available fuels and stand replacing,which were associated to warmdry climate and high human pressure.The study statistically highlighted the importance of a North–South gradient,which represents one of the most important drivers of wildfire regimes resulting from the variations in climatic conditions but showing collinearity with socioeconomic aspects as well.Conclusion:Our fully replicable analytical approach can be applied at multiple scales and used for the entire European continent to uncover new and larger pyroregions.This could create a basis for the European Commission to promote innovative and collaborative funding programs between regions that demonstrate pyrosimilarities.展开更多
文摘European larch(Larix decidua) forests of the western Alps form extensivecultural landscapes whose resilience to global changes is currently unknown. Resilience describes the capacity of ecological systems to maintain the same state, i.e., the same function, processes, structure, and composition despite disturbances, environmental changes and internal fluctuations. Our aim is to explore the resilience of larch forests to changes in climate and land use in the western Italian Alps.To do so, we examined whether larch forests can be described as an alternative stable state in mountain forest ecosystems. We used tree basal area data obtained from field forest inventories in combination with topography, forest structure, land use, and climate information. We applied three different probabilistic methods: frequency distributions, logistic regressions, and potential analyses to infer the resilience of larch forests relative to that of other forest types.We found patters indicative of alternative stable states: bimodality in the frequency distribution of the percent of larch basal area, and the presence of an unstable state, i.e., mixed larch forests, in the potential analyses. We also found:(1) high frequency ofpurelarchforestsathighelevation,(2)the probability of pure larch forests increased mostly with elevation, and(3) pure larch forests were a stable state in the upper montane and subalpine belts.Our study shows that the resilience of larch forests may increase with elevation, most likely due to the altitudinal effect on climate. Under the same climate conditions, land use seems to be the main factor governing the dominance of larch forests. In fact, subalpine larch forests may be more resilient, and natural succession after land abandonment, e.g., towards Pinuscembra forests, seems slower than in montane larch forests. In contrast, in the upper montane belt only intense land use regimes characterized by open canopies and forest grazing may maintain larch forests.We conclude that similar approaches could be applied in other forest ecosystems to infer the resilience of tree species.
文摘Background:Pyrogeography is a major field of investigation in wildfire science because of its capacity to describe the spatial and temporal variations of fire disturbance.We propose a systematic pyrogeographic analytical approach to cluster regions on the basis of their pyrosimilarities.We employed the Affinity Propagation algorithm to cluster pyroregions using Italian landscape as a test bed and its current wildfire metrics in terms of density,seasonality and stand replacing fire ratio.A discussion follows on how pyrogeography varies according to differences in the human,biophysical,socioeconomic,and climatic spheres.Results:The algorithm identified seven different pyroregion clusters.Two main gradients were identified that partly explain the variability of wildfire metrics observed in the current pyroregions.First,a gradient characterized by increasing temperatures and exposure to droughts,which coincides with a decreasing latitude,and second,a human pressure gradient displaying increasing population density in areas at lower elevation.These drivers exerted a major influence on wildfire density,burnt area over available fuels and stand replacing,which were associated to warmdry climate and high human pressure.The study statistically highlighted the importance of a North–South gradient,which represents one of the most important drivers of wildfire regimes resulting from the variations in climatic conditions but showing collinearity with socioeconomic aspects as well.Conclusion:Our fully replicable analytical approach can be applied at multiple scales and used for the entire European continent to uncover new and larger pyroregions.This could create a basis for the European Commission to promote innovative and collaborative funding programs between regions that demonstrate pyrosimilarities.
