Contemporary distributions of saltmarsh diatoms in the Seymour–Belize Inlet Complex, British Columbia, Canada: Implications for studies of sea-level change

Surface diatom samples were collected from two saltmarshes in the Seymour–Belize Inlet Complex on the mainland coast of British Columbia to examine the controls on diatom distribution and provide training sets for regional studies of sea-level change. Cluster analysis and detrended correspondence analysis (DCA) were used to examine diatom distributions within and between the two marshes whilst canonical correspondence analysis (CCA) and partial canonical correspondence analysis (pCCA) were used to analyse species–environment relationships. The diatom assemblages were shown to be quite different between the two marshes, Waump and Wawwat'l. Q-mode cluster analysis separated the diatom assemblages from Waump into three zones corresponding to recognized vegetation zones; diatom zone C corresponds to the high marsh and is dominated by Pinnularia obscura, Caloneis bacillum and Diploneis ovalis, zone B spans the high- and mid marsh and is characterised by Fragilaria exigua, Nitzchia palea and D. ovalis, whilst zone A from the low marsh/tidal flat includes high frequencies of Diploneis smithii, Ctenophora pulchella and F. exigua. Three different diatom zones were recognised at Wawwat'l; two upper zones, E and F, corresponding to the mid-marsh which are dominated by mixed abundances of N. palea and Fragilaria construens var. venter, Navicula peregrina and Navicula clementis and zone D from the low marsh/tidal flat with increased frequencies of F. exigua and Achnanthes delicatula. At Waump, the major controls on diatom distribution were found to be elevation and to a lesser extent pH, whilst at Wawwat'l, the primary controls were grain size/organic content, conductivity and elevation. The results confirm that saltmarsh diatoms may have potential for future sea-level studies in this region. However, caution must be exercised as the significant difference in the diatom assemblages between the two marshes suggests that the diatoms are responding to a number of environmental variables on a local scale. Some of this variation may reflect highly seasonal changes in sedimentation and salinity resulting from the proximity of the marshes to adjacent streams which are subject to spring freshet. Local differences in elevation between the collected samples may also account for some of the assemblage variability. The results emphasize the great diversity and high sensitivity of intertidal diatom species to environmental controls.     

Assessment of the Sustainability of Wolverine Harvest in British Columbia,Canada

ABSTRACT Wolverines (Gulo gulo) are distributed across much of northern and western Canada and Alaska, USA, and they extend south into the mountainous western United States. Wolverines occur in most regions of British Columbia, Canada, with the highest population densities occurring in the interior mountainous areas. Wolverine populations in British Columbia have been primarily managed to provide a sustainable harvest for trappers and hunters. We used spatially based population estimates, population vital rate data, and spatially based harvest data to evaluate the sustainability of wolverine harvest (trapping and hunting) from 1985 to 2004. The median annual provincial wolverine harvest from 1985 to 2004 was 172 wolverines per year ( = 174.8), which was less than the median simulated estimate of provincial recruitment (195.9 wolverines/yr; = 209.7). Harvests in individual population units ranged from 0 to 280 over the 20-year period. Spatially, wolverine harvest was likely to have been unsustainable in 15 of the 71 population units with wolverines, and it was likely to have been sustainable in the remaining population units. Harvest in 5 of the other 56 population units was marginally sustainable and thus of potential management concern. To improve harvest management of wolverines in British Columbia, wildlife managers should focus on improved data collection and monitoring at a provincial scale, and they should work with trappers and hunters at regional scales to address issues specific to individual population units. Further research is required to improve the reliability of wolverine vital rate and population data.     

多气候情景下中国森林火灾风险评估

森林火灾风险主要取决于致灾因子、承灾体以及防灾减灾能力,综合评估和预测森林火灾风险是制定科学的林火管理政策的基础.本文基于经典自然灾害风险模型和可获取数据构建森林火灾风险评估模型与指标体系,评估过去和未来的森林火灾风险.未来气候情景数据包括RCP 2.6、RCP 4.5、RCP 6.0和RCP 8.5下5个全球气候模式(GFDL-ESM2M、HadGEM2-ES、IPSL-CM5A-LR、 MIROC-ESM-CHEM和NorESM1-M)日值数据.根据最高温度、最小相对湿度、平均风速和每日降水量分别计算1987—2050年历史观测数据和未来气候情景下各格点每日火险天气指数系统中各个指数.结果表明: 1987—2010年,森林火灾风险高和很高的区域分别占21.2%和6.2%,主要分布在大兴安岭和长白山地区、云南大部分区域和南方零散分布的区域.森林火灾可能性高和很高的区域主要分布在东北和西南地区,分别占森林面积的13.1%和4.0%.与观测时段相比,2021—2050年RCP 2.6、RCP 4.5、RCP 6.0和RCP 8.5情景下森林火灾可能性高和很高的区域分别增加0.6%、5.5%、2.3%和3.5%,华北地区增幅明显.气候变化引起的森林火灾高风险区域有些增加,RCP 8.5情景下增幅最明显(+1.6%).     

Classification of natural forest communities of coastal British Columbia, Canada

In comparison to countries with a tradition of vegetation studies, a comprehensive, hierarchical classification of plant communities in the province of British Columbia has not yet been developed. Such a classification is needed for systematic ecological studies and coordinated conservation of vegetation. As the culmination of fifty years of detailed surveys, tabular and multivariate analyses of 3779 relevés of natural, old-growth, submontane, montane and subalpine forest communities in coastal British Columbia were used to develop a hierarchy of vegetation units according to the Braun-Blanquet approach. At the highest level, we distinguished seven orders: Quercus garryana, Pseudotsuga menziesii-Mahonia nervosa, Tsuga heterophylla-Rhytidiadelphus loreus, Tsuga mertensiana, Thuja plicata-Tiarella trifoliata, Populus trichocarpa, and Pinus contorta-Sphagnum. Diagnostic table, ordination, and elimatic and edaphic regimes were used to show floristic affinities among the orders and to interpret their relationships to regional environmental gradients. Plant communities of each order were briefly characterized by their floristic composition, physiognomy, succession, and environment. The synopsis for all delineated vegetation units (order, suborder, alliance, and association) of coastal British Columbia is included.     

Impacts of climate change on fire activity and fire management in the circumboreal forest

Forest fires are a significant and natural element of the circumboreal forest. Fire activity is strongly linked to weather, and increased fire activity due to climate change is anticipated or arguably has already occurred. Recent studies suggest a doubling of area burned along with a 50% increase in fire occurrence in parts of the circumboreal by the end of this century. Fire management agencies' ability to cope with these increases in fire activity is limited, as these organizations operate with a narrow margin between success and failure; a disproportionate number of fires may escape initial attack under a warmer climate, resulting in an increase in area burned that will be much greater than the corresponding increase in fire weather severity. There may be only a decade or two before increased fire activity means fire management agencies cannot maintain their current levels of effectiveness.     

Multiscale Habitat Use by Wolverines in British Columbia,Canada

ABSTRACT Wolverine (Gulo gulo) distribution in British Columbia, Canada, includes multiple-use lands where human use and resource extraction may influence habitat selection. We evaluated seasonal habitat use by resident adult wolverines using radiotelemetry locations from 2 multiple-use landscapes in British Columbia. Food, predation risk, and human disturbance hypotheses were considered in logistic regression analyses of used and random landscapes. Male wolverine habitat associations were most supported by the food hypothesis in both summer and winter. Moose (Alces alces) winter ranges, valley bottom forests, and avalanche terrain were positively associated with winter male wolverine use. Habitat use by male wolverines in winter was also negatively associated with helicopter skiing areas in the Columbia Mountains. Habitat associations of females were more complex; combinations of variables supporting food, predation risk, or human disturbance hypotheses were included in most supported models from both summer and winter in both study areas. Females were associated with alpine and avalanche environments where hoary marmot (Marmota caligata) and Columbia ground squirrel (Spermophilus columbianus) prey are found in summer. Roaded and recently logged areas were negatively associated with female wolverines in summer. In the Columbia Mountains, where winter recreation was widespread, females were negatively associated with helicopter and backcountry skiing. Moose winter ranges within rugged landscapes were positively associated with females during winter. Our analysis suggests wolverines were negatively responding to human disturbance within occupied habitat. The population consequences of these functional habitat relationships will require additional focused research. Our spatially explicit models can be used to support conservation planning for resource extraction and tourism industries operating in landscapes occupied by wolverines.     

Abrupt fire regime change may cause landscape‐wide loss of mature obligate seeder forests

Obligate seeder trees requiring high‐severity fires to regenerate may be vulnerable to population collapse if fire frequency increases abruptly. We tested this proposition using a long‐lived obligate seeding forest tree, alpine ash (Eucalyptus delegatensis), in the Australian Alps. Since 2002, 85% of the Alps bioregion has been burnt by several very large fires, tracking the regional trend of more frequent extreme fire weather. High‐severity fires removed 25% of aboveground tree biomass, and switched fuel arrays from low loads of herbaceous and litter fuels to high loads of flammable shrubs and juvenile trees, priming regenerating stands for subsequent fires. Single high‐severity fires caused adult mortality and triggered mass regeneration, but a second fire in quick succession killed 97% of the regenerating alpine ash. Our results indicate that without interventions to reduce fire severity, interactions between flammability of regenerating stands and increased extreme fire weather will eliminate much of the remaining mature alpine ash forest.     

Bored Bivalves in Upper Triassic (Norian) Event Beds,Northeastern British Columbia,Canada

Skeletobionts are important components of most shallow marine ecosystems. Prior to the fossils reported herein, evidence of skeletobionts was absent from Upper Triassic successions on the northwestern margin of Pangaea. The boring Talpina ramosa is reported from bivalve body fossils from the Upper Triassic (Lower Norian) lower Pardonet Formation at Pink Mountain in northeastern British Columbia. This Ichnotaxon penetrates through both the outer and inner surface of articulated and disarticulated bivalve shells preserved within sharp-based event beds. The occurrence of these trace fossils underscores the paucity of borings, bioerosional structures, and encrusting taxa from Triassic successions in the western Pangaean realm. Due to erosional removal of shallow water strata by a post-Triassic unconformity, these event beds provide the only available information regarding the ecological health of Late Triassic depositional systems in the study area.     

The Abundance and Distribution of Wolverines in British Columbia,Canada

ABSTRACT The abundance and distribution of carnivores and their habitat are key information needed for status assessment, conservation planning, population management, and assessment of the effects of human development on their habitat and populations. We developed a habitat quality rating system, using existing wolverine (Gulo gulo) distribution, wolverine food, ecosystem mapping, and human development data. We used this and empirically derived estimates of wolverine density to predict wolverine distribution and abundance at a provincial scale. Density estimates for wolverines in high-quality habitat averaged 6.2 wolverines/1,000 km² (95% CI = 4.2–9.5). We predicted mean densities ranging from 0.3/1,000 km² in rare-quality habitat to 4.1/1,000 km² in moderate-quality habitat. Our predicted population estimate for wolverines in British Columbia was 3,530 (95% CI = 2,700-4,760). We predicted highest densities of wolverines in interior mountainous regions, moderate densities in interior plateau and boreal forest regions, and low densities in mainland coastal regions and drier interior plateaus. We predicted that wolverines would be rare on Vancouver Island, along the outer mainland coast, and in the dry interior forests, and absent from the Queen Charlotte Islands, interior grassland environments, and areas of intensive urban development.     

Diatom (Bacillariophyceae) assemblages in tidal environments of Vancouver Island,British Columbia,Canada

To understand distributions of coastal diatoms along Vancouver Island, British Columbia, Canada, this paper describes diatom assemblages observed in 47 surface sediment samples from intertidal environments. One hundred and eighty-four diatom taxa were identified from five transects crossing tidal flats, salt marshes, and freshwater forests in Tofino, Ucluelet, and Port Alberni. Distributions of the diatom assemblages were consistent with those reported elsewhere in the Pacific Northwest, but a few diatom taxa show different trends in their distributions. For example, one benthic species Denticula subtilis shows widespread distributions along the transect in Tofino. An ordination shown by Detrended Correspondence Analysis (DCA) using a combined dataset indicated overlapped scatter plots of diatom assemblages, suggesting that assemblages with similar species compositions are observed in more than one location. Hierarchical and k-means clustering analyses using Euclidean distance recognized unique small groups along each transect. Rank abundance curves show different trends for richness and evenness of diatom assemblages among the five transects.     

Longevity and reuse of black bear dens in managed forests of coastal British Columbia

We evaluated longevity and reuse of denning structures by American black bears (Ursus americanus) in coastal temperate rainforests of British Columbia from 1992 to 2010 to assess potential impacts of forest management on these critical habitat features over time. We identified 67 dens during a 4-yr intensive radio-telemetry study (1992–1995): 40 dens of 21 radio-collared black bears and 27 dens found incidentally. Dens occurred in or beneath large diameter trees or wooden structures derived from trees (i.e., logs, root boles, and stumps; = 143 cm diameter, SD = 49 cm). Longevity of dens varied by type, tree species that formed the den, and forest management that occurred at or near the den. Twenty-four of 28 dens of radio-collared bears that were monitored were still usable in 2010, whereas only 5 of 14 dens found incidentally were still usable in 2010. We assessed reuse of bear dens 3 times following initial identification: during the radio-telemetry study, again in 2000, and finally in 2010. Radio-collared bears reused dens from previous years on 7 of 25 potential occasions during the course of the radio-telemetry study. Upon assessment in 2000 and 2010, 17 of 24 (71%) available dens first used by radio-collared bears were reused at least once between 1993 and 2010. The high rate of reuse may indicate low availability of den structures in our study area. Because black bears in coastal British Columbia only used trees or structures derived from trees for winter dens and forest harvesting reduces the supply of these necessary structures, conservation and recruitment of suitable den trees is necessary if maintaining black bear populations is a management goal in these areas. © 2011 The Wildlife Society.     

Aboriginal burning for vegetation management in northwest British Columbia

The Gitksan and Wet'suwet'en peoples of northwest British Columbia occupy the upper drainage of the Skeena River and the western headwaters of the Fraser River. They live in a region of diverse topography, vegetation, and climate. Berry patch burning was the most important traditional vegetation manipulation. Black huckleberry and lowbush blueberry patches were burned to stimulate growth of new stems and production of berries, while preventing invasion by other shrub species and conifers. Maintenance of berry patches by burning was discontinued in the 1930s and 1940s because of fire suppression by the British Columbia Forest Service. Spring burning on south facing slopes, village sites, and garden sites was also practiced, and continues to the present. It occurs in aspen, pine, or grass dominated seral communities, or cottonwood floodplain forest, and is intended to control brush and encourage growth of grass.     

Ordination of epiphytic bryophyte communities in a wet-temperate coniferous forest,South-Coastal British Columbia

Three coniferous tree species (Pseudotsuga menziesii, Tsuga heterophylla, and Thuja plicata) at Capilano Canyon, British Columbia, were studied for their epiphytic communities. Quantitative data were obtained for fourteen bryophyte species by sampling at heights of 0.5 m, 1 m and 2 m above ground level. Scapania bolanderi is an abundant and widely distributed species; Dicranum fuscescens, Bazzania denudata, Lepidozia reptans and Hypnum circinale are also common. An environmentally uniform study area was chosen to minimize the effects of factors other than bark and elevation on the distribution of epiphytes. In general, tree species are similar in terms of their epiphytic assemblages, but ordination methods using quantitative data exposed compositional variation that may be explained by differences in microclimate and bark-type. In this respect, the results point the way to further studies to examine epiphyte associations in closer detail, and to relate these associations to specific factors in the microenvironment.Nomenclature for vascular plants follows Hitchcock & Cronquist (1973); bryophyte nomenclature follows Schofield (1976) for mosses and Stotler & Crandall-Stotler (1977) for hepatics.We thank Dr. W. B. Schofield for aiding in bryophyte identification.