Recent years have witnessed a proliferation of quantitative methods for biogeographic inference. In particular, novel parametric approaches represent exciting new opportunities for the study of range evolution. Here, ...Recent years have witnessed a proliferation of quantitative methods for biogeographic inference. In particular, novel parametric approaches represent exciting new opportunities for the study of range evolution. Here, we review a selection of current methods for biogeographic analysis and discuss their respective properties. These methods include generalized parsimony approaches, weighted ancestral area analysis, dispersal-vicariance analysis, the dispersal--extinction--cladogenesis model and other maximum likelihood approaches, and Bayesian stochastic mapping of ancestral ranges, including a novel approach to inferring range evolution in the context of island biogeography. Some of these methods were developed specifically for problems of ancestral range reconstruction, whereas others were designed for more general problems of character state reconstruction and subsequently applied to the study of ancestral ranges. Methods for reconstructing ancestral history on a phylogenetic tree differ not only in the types of ancestral range states that are allowed, but also in the various historical events that may change the ancestral ranges. We explore how the form of allowed ancestral ranges and allowed transitions can both affect the outcome of ancestral range estimation. Finally, we mention some promising avenues for future work in the development of model-based approaches to biogeographic analysis.展开更多
Background:Historical forests(circa 1799 to 1846)of Indiana were predominantly composed of American beech(25%of all trees)and upland oaks(27%of all trees).I compared historical forest composition,using studies of smal...Background:Historical forests(circa 1799 to 1846)of Indiana were predominantly composed of American beech(25%of all trees)and upland oaks(27%of all trees).I compared historical forest composition,using studies of smaller areas to approximate composition for uncommon species or genera(<4.5%of all trees)and forest types,to current forest composition and forest types in Indiana.I also compiled published historical density estimates from small studies and estimated current density for the state.Results:Current forests are diverse with an even composition of many eastern broadleaf species.In addition to upland oaks,which decreased to 13%of all trees,only sugar maple currently comprises greater than 10%of all trees.Other increasing species were yellow-poplar,red maple,black cherry,and eastern redcedar.Eastern redcedar increased from no presence to one of the most abundant ten species(≥3.5%of composition),similarly to the pine genus,becoming more common currently than American beech.Beech or oak or beech-oak forest types(≥24%of all trees)became eastern broadleaf forests,with no dominant species,and black cherry,red maple,and eastern redcedar forest types now occurred.Estimates of historical oak or beech forests ranged from 28 trees per hectare to 175 trees per hectare,which probably represent savannas and woodlands.Current mean density of Indiana forests is 385 trees per hectare,ranging from 180 trees per hectare to 450 trees per hectare.These forests likely contain dense layers of woody vegetation,filling the midstory and replacing herbaceous vegetation in the ground layer.Conclusion:Historically dominant beech and oak forests in the eastern United States have transitioned to an alternative state of closed eastern broadleaf forests due to uncontrolled establishment of many tree species.展开更多
Free and open access to the Landsat archive has enabled the detection and delineation of an unprecedented number of fire events across the globe.Despite the availability and potential of these data,few studies have an...Free and open access to the Landsat archive has enabled the detection and delineation of an unprecedented number of fire events across the globe.Despite the availability and potential of these data,few studies have analysed residual vegetation patterns and/or partial mortality of fire across the Canadian boreal forest,and those available,are either incomplete or inaccurate.Further,they all differ in the methods and spatial language,which makes it difficult for managers to interpret fire patterns over large areas.There is an urgent need for methods to help unify fire pattern observations across the Canadian boreal forest.This study explores the capacity of the Landsat data archive when coupled with a recently developed fire mapping approach and a robust spatial language to characterize and compare tree mortality patterns across the boreal plains ecozone,Canada.With 507 fires 2.5 Mha mapped,this study represents the most comprehensive analysis of mortality patterns for study area.Summaries from this demonstration generated an accurate characterization of the fire patterns the various ecoregions based on seven key fire metrics.The comparison between ecoregions revealed differences in the amount of residual vegetation,which in turn suggested various climate,topography and/or vegetation ecosystem drivers.展开更多
Considering from point of view of the dynamics,it is convenient to regard the field to be predicted as a small disturbance superposed on the historical analogous field,and thus the statistical technique can be used in...Considering from point of view of the dynamics,it is convenient to regard the field to be predicted as a small disturbance superposed on the historical analogous field,and thus the statistical technique can be used in combining with the dynamics.Along this line,a coupled atmosphere-earth surface analogy-dynamical model is formulated and applied to making monthly prediction. This approach facilitated the utility of the useful information contained in both the historical data set and the initial field to improve the dynamic model based solo on the latter and show better skill in prediction.展开更多
基金support from the National Institute of Environmental Health Sciences (USA) training grant to the NCSU Bioinformatics Research Centersupported by National Institutes of Health (USA) grant no.GM070806
文摘Recent years have witnessed a proliferation of quantitative methods for biogeographic inference. In particular, novel parametric approaches represent exciting new opportunities for the study of range evolution. Here, we review a selection of current methods for biogeographic analysis and discuss their respective properties. These methods include generalized parsimony approaches, weighted ancestral area analysis, dispersal-vicariance analysis, the dispersal--extinction--cladogenesis model and other maximum likelihood approaches, and Bayesian stochastic mapping of ancestral ranges, including a novel approach to inferring range evolution in the context of island biogeography. Some of these methods were developed specifically for problems of ancestral range reconstruction, whereas others were designed for more general problems of character state reconstruction and subsequently applied to the study of ancestral ranges. Methods for reconstructing ancestral history on a phylogenetic tree differ not only in the types of ancestral range states that are allowed, but also in the various historical events that may change the ancestral ranges. We explore how the form of allowed ancestral ranges and allowed transitions can both affect the outcome of ancestral range estimation. Finally, we mention some promising avenues for future work in the development of model-based approaches to biogeographic analysis.
文摘Background:Historical forests(circa 1799 to 1846)of Indiana were predominantly composed of American beech(25%of all trees)and upland oaks(27%of all trees).I compared historical forest composition,using studies of smaller areas to approximate composition for uncommon species or genera(<4.5%of all trees)and forest types,to current forest composition and forest types in Indiana.I also compiled published historical density estimates from small studies and estimated current density for the state.Results:Current forests are diverse with an even composition of many eastern broadleaf species.In addition to upland oaks,which decreased to 13%of all trees,only sugar maple currently comprises greater than 10%of all trees.Other increasing species were yellow-poplar,red maple,black cherry,and eastern redcedar.Eastern redcedar increased from no presence to one of the most abundant ten species(≥3.5%of composition),similarly to the pine genus,becoming more common currently than American beech.Beech or oak or beech-oak forest types(≥24%of all trees)became eastern broadleaf forests,with no dominant species,and black cherry,red maple,and eastern redcedar forest types now occurred.Estimates of historical oak or beech forests ranged from 28 trees per hectare to 175 trees per hectare,which probably represent savannas and woodlands.Current mean density of Indiana forests is 385 trees per hectare,ranging from 180 trees per hectare to 450 trees per hectare.These forests likely contain dense layers of woody vegetation,filling the midstory and replacing herbaceous vegetation in the ground layer.Conclusion:Historically dominant beech and oak forests in the eastern United States have transitioned to an alternative state of closed eastern broadleaf forests due to uncontrolled establishment of many tree species.
基金Saskatchewan Environment,fRI Research Healthy Landscapes Program,the government of the Northwest Territories,Bandaloop Landscape-Ecosystem Services,and an NSERC Discovery and Engage grant to Coops(RGPIN 311926-13 and EGP 503226-16).
文摘Free and open access to the Landsat archive has enabled the detection and delineation of an unprecedented number of fire events across the globe.Despite the availability and potential of these data,few studies have analysed residual vegetation patterns and/or partial mortality of fire across the Canadian boreal forest,and those available,are either incomplete or inaccurate.Further,they all differ in the methods and spatial language,which makes it difficult for managers to interpret fire patterns over large areas.There is an urgent need for methods to help unify fire pattern observations across the Canadian boreal forest.This study explores the capacity of the Landsat data archive when coupled with a recently developed fire mapping approach and a robust spatial language to characterize and compare tree mortality patterns across the boreal plains ecozone,Canada.With 507 fires 2.5 Mha mapped,this study represents the most comprehensive analysis of mortality patterns for study area.Summaries from this demonstration generated an accurate characterization of the fire patterns the various ecoregions based on seven key fire metrics.The comparison between ecoregions revealed differences in the amount of residual vegetation,which in turn suggested various climate,topography and/or vegetation ecosystem drivers.
文摘Considering from point of view of the dynamics,it is convenient to regard the field to be predicted as a small disturbance superposed on the historical analogous field,and thus the statistical technique can be used in combining with the dynamics.Along this line,a coupled atmosphere-earth surface analogy-dynamical model is formulated and applied to making monthly prediction. This approach facilitated the utility of the useful information contained in both the historical data set and the initial field to improve the dynamic model based solo on the latter and show better skill in prediction.
