Consequences of land-use change and the wildfire disaster of 2017 for the central Chilean biodiversity hotspot

Central Chile is an important biodiversity hotspot in Latin America. Biodiversity hotspots are characterised by a high number of endemic species cooccurring with a high level of anthropogenic pressure. In central Chile, the pressure is caused by land-use change, in which near-natural primary and secondary forests are replaced and fragmented by commercial pine and eucalyptus plantations. Large forest fires are another factor that can potentially endanger biodiversity. Usually, environmental hazards, such as wildfires, are part of the regular environmental dynamic and not considered a threat to biodiversity. Nonetheless, this situation may change if land-use change and altered wildfire regimes coerce. Land-use change pressure may destroy landscape integrity in terms of habitat loss and fragmentation, while wildfires may destroy the last remnants of native forests. This study aims to understand the joint effects of land-use change and a catastrophic wildfire on habitat loss and habitat fragmentation of local plant species richness hotspots in central Chile. To achieve this, we apply a combination of ecological fieldwork, remote sensing, and geoprocessing to estimate the spread and spatial patterns of biodiverse habitats under current and past land-use conditions and how these habitats were altered by land-use change and by a single large wildfire event. We show that land-use change has exceeded the wildfire’s impacts on diverse habitats. Despite the fact that the impact of the wildfire was comparably small here, wildfire may coerce with land-use change regarding pressure on biodiversity hotspots. Our findings can be used to develop restoration concepts, targeting on an increase of habitat diversity within currently fire-cleared areas and evaluate their benefits for plant species richness conservation

Carbon and oxygen dual-isotopes indicate alternative physiological mechanisms opted by European beech trees to survive drought stress

Poor drought tolerance of European beech trees raised concerns in Europe. We hypothesized that beech could show an opposite physiological response to the same level of climatic drought with change in edaphic drought. We performed a combined analysis of δ$^{13}$C and δ$^{18}$O in tree rings to reveal retrospective temporal physiological responses of trees to drought. The edaphic drought was assessed by quantifying the capacity of soil to store water in plots (classified as “dry” and “less-dry”) near the drought limit of the species in three near-natural oak-beech ecotones in Germany and Switzerland. Neighbourhood competition was quantified. A climatic drought index was calculated from meteorological records and related to the δ$^{13}$C and δ$^{18}$O values of the trees. Trees from dry plots showed a higher response to drought and climatic dependency than less-dry plots. Neighbourhood competetion increased δ$^{18}$O values significantly. Dual isotope analysis shows a tendency of greater stomatal resistance in dry plots and higher stomatal conductance in less-dry plots. We conclude that beech trees belonging to the same population under changing soil water availability can show different physiological responses under climatic drought stress. Our finding indicates the high plasticity of the beech trees to survive drought stress with changing site conditions

Consequences of land-use change and the wildfire disaster of 2017 for the central Chilean biodiversity hotspot

Central Chile is an important biodiversity hotspot in Latin America. Biodiversity hotspots are characterised by a high number of endemic species cooccurring with a high level of anthropogenic pressure. In central Chile, the pressure is caused by land-use change, in which near-natural primary and secondary forests are replaced and fragmented by commercial pine and eucalyptus plantations. Large forest fires are another factor that can potentially endanger biodiversity. Usually, environmental hazards, such as wildfires, are part of the regular environmental dynamic and not considered a threat to biodiversity. Nonetheless, this situation may change if land-use change and altered wildfire regimes coerce. Land-use change pressure may destroy landscape integrity in terms of habitat loss and fragmentation, while wildfires may destroy the last remnants of native forests. This study aims to understand the joint effects of land-use change and a catastrophic wildfire on habitat loss and habitat fragmentation of local plant species richness hotspots in central Chile. To achieve this, we apply a combination of ecological fieldwork, remote sensing, and geoprocessing to estimate the spread and spatial patterns of biodiverse habitats under current and past land-use conditions and how these habitats were altered by land-use change and by a single large wildfire event. We show that land-use change has exceeded the wildfire’s impacts on diverse habitats. Despite the fact that the impact of the wildfire was comparably small here, wildfire may coerce with land-use change regarding pressure on biodiversity hotspots. Our findings can be used to develop restoration concepts, targeting on an increase of habitat diversity within currently fire-cleared areas and evaluate their benefits for plant species richness conservation.Karlsruher Institut für Technologie (KIT) (4220

Carbon and oxygen dual-isotopes in tree rings indicate alternative physiological responses opted by European beech trees to survive drought stress

Poor drought tolerance of European beech trees raised concerns in Europe. We hypothesized that beech could show an opposite physiological response to the same level of climatic drought with change in edaphic drought. We performed a combined analysis of δ13C and δ18O in tree rings to reveal retrospective temporal physiological responses of trees to drought. The edaphic drought was assessed by quantifying the capacity of soil to store water in plots (classified as “dry” and “less-dry”) near the drought limit of the species in three near-natural oak-beech ecotones in Germany and Switzerland. Neighbourhood competition was quantified. A climatic drought index was calculated from meteorological records and related to the δ13C and δ18O values of the trees. Trees from dry plots showed a higher response to drought and climatic dependency than less-dry plots. Neighbourhood competetion increased δ18O values significantly. Dual isotope analysis shows a tendency of greater stomatal resistance in dry plots and higher stomatal conductance in less-dry plots. We conclude that beech trees belonging to the same population under changing soil water availability can show different physiological responses under climatic drought stress. Our finding indicates the high plasticity of the beech trees to survive drought stress with changing site conditions.</p