Stable isotope analysis was used to determine the relative dietary importance of kelp-derived detritus to plankton and benthic organisms along a gradient of kelp abundance driven by recovering sea otter populations al...Stable isotope analysis was used to determine the relative dietary importance of kelp-derived detritus to plankton and benthic organisms along a gradient of kelp abundance driven by recovering sea otter populations along the west coast of Vancouver Island (WCVI), Canada. The study used region-specific kelp isotope values (<i>δ</i><sup>13</sup>C and <i>δ</i><sup>15</sup>N) and season-specific phytoplankton isotope values to model dietary contributions of kelp-derived detritus (KDD). In general, KDD contributions were moderate to high in most plankton size fractions during the summer and decreased during the winter, particularly in the kelp sparse region. Hypothesized regional and spatial (distance from the coast) differences in kelp detritus contributions to zooplankton w<span style="white-space:normal;"><span style="font-family:;" "="">ere</span></span><span style="white-space:normal;"><span style="font-family:;" "=""> not evident. Modeled estimates of the KDD contribution to benthic invertebrates w</span></span><span style="white-space:normal;"><span style="font-family:;" "="">ere</span></span><span style="white-space:normal;"><span style="font-family:;" "=""> high (>40%) and independent of the organism size, among regions and between seasons, with the exception of <i>Astraea gibberosa</i> in the kelp abundant region. Local oceanography, natural kelp isotope signature variation, and significant overlap between kelps’ and blooming phytoplankton isotope values led to a large uncertainty in the assessed KDD contributions in benthic organisms. These results highlighted the importance of the KDD as a widespread and stable year-round food source in coastal kelp populated regions.</span></span>展开更多
The HoekeBrown criterion was introduced in 1980 to provide input for the design of underground excavations in rock.The criterion now incorporates both intact rock and discontinuities,such as joints,characterized by th...The HoekeBrown criterion was introduced in 1980 to provide input for the design of underground excavations in rock.The criterion now incorporates both intact rock and discontinuities,such as joints,characterized by the geological strength index(GSI),into a system designed to estimate the mechanical behaviour of typical rock masses encountered in tunnels,slopes and foundations.The strength and deformation properties of intact rock,derived from laboratory tests,are reduced based on the properties of discontinuities in the rock mass.The nonlinear HoekeBrown criterion for rock masses is widely accepted and has been applied in many projects around the world.While,in general,it has been found to provide satisfactory estimates,there are several questions on the limits of its applicability and on the inaccuracies related to the quality of the input data.This paper introduces relatively few fundamental changes,but it does discuss many of the issues of utilization and presents case histories to demonstrate practical applications of the criterion and the GSI system.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
文摘Stable isotope analysis was used to determine the relative dietary importance of kelp-derived detritus to plankton and benthic organisms along a gradient of kelp abundance driven by recovering sea otter populations along the west coast of Vancouver Island (WCVI), Canada. The study used region-specific kelp isotope values (<i>δ</i><sup>13</sup>C and <i>δ</i><sup>15</sup>N) and season-specific phytoplankton isotope values to model dietary contributions of kelp-derived detritus (KDD). In general, KDD contributions were moderate to high in most plankton size fractions during the summer and decreased during the winter, particularly in the kelp sparse region. Hypothesized regional and spatial (distance from the coast) differences in kelp detritus contributions to zooplankton w<span style="white-space:normal;"><span style="font-family:;" "="">ere</span></span><span style="white-space:normal;"><span style="font-family:;" "=""> not evident. Modeled estimates of the KDD contribution to benthic invertebrates w</span></span><span style="white-space:normal;"><span style="font-family:;" "="">ere</span></span><span style="white-space:normal;"><span style="font-family:;" "=""> high (>40%) and independent of the organism size, among regions and between seasons, with the exception of <i>Astraea gibberosa</i> in the kelp abundant region. Local oceanography, natural kelp isotope signature variation, and significant overlap between kelps’ and blooming phytoplankton isotope values led to a large uncertainty in the assessed KDD contributions in benthic organisms. These results highlighted the importance of the KDD as a widespread and stable year-round food source in coastal kelp populated regions.</span></span>
文摘The HoekeBrown criterion was introduced in 1980 to provide input for the design of underground excavations in rock.The criterion now incorporates both intact rock and discontinuities,such as joints,characterized by the geological strength index(GSI),into a system designed to estimate the mechanical behaviour of typical rock masses encountered in tunnels,slopes and foundations.The strength and deformation properties of intact rock,derived from laboratory tests,are reduced based on the properties of discontinuities in the rock mass.The nonlinear HoekeBrown criterion for rock masses is widely accepted and has been applied in many projects around the world.While,in general,it has been found to provide satisfactory estimates,there are several questions on the limits of its applicability and on the inaccuracies related to the quality of the input data.This paper introduces relatively few fundamental changes,but it does discuss many of the issues of utilization and presents case histories to demonstrate practical applications of the criterion and the GSI system.
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.
