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111.
Chile has more than half of the temperate forests in the southern hemisphere. These have been included among the most threatened eco-regions in the world, because of the high degree of endemism and presence of monotypic genera. In this study, we develop empirical models to investigate present and future spatial patterns of woody species richness in temperate forests in south-central Chile. Our aims are both to increase understanding of species richness patterns in such forests and to develop recommendations for forest conservation strategies. Our data were obtained at multiple spatial scales, including field sampling, climate, elevation and topography data, and land-cover and spectrally derived variables from satellite sensor imagery. Climatic and land-cover variables most effectively accounted for tree species richness variability, while only weak relationships were found between explanatory variables and shrub species richness. The best models were used to obtain prediction maps of tree species richness for 2050, using data from the Hadley Centre’s HadCM3 model. Current protected areas are located far from the areas of highest tree conservation value and our models suggest this trend will continue. We therefore suggest that current conservation strategies are insufficient, a trend likely to be repeated across many other areas. We propose the current network of protected areas should be increased, prioritizing sites of both current and future importance to increase the effectiveness of the national protected areas system. In this way, target sites for conservation can also be chosen to bring other benefits, such as improved water supply to populated areas. 相似文献
112.
Rare species have restricted geographic ranges, habitat specialization, and/or small population sizes. Datasets on rare species distribution usually have few observations, limited spatial accuracy and lack of valid absences; conversely they provide comprehensive views of species distributions allowing to realistically capture most of their realized environmental niche. Rare species are the most in need of predictive distribution modelling but also the most difficult to model. We refer to this contrast as the “rare species modelling paradox” and propose as a solution developing modelling approaches that deal with a sufficiently large set of predictors, ensuring that statistical models are not over-fitted. Our novel approach fulfils this condition by fitting a large number of bivariate models and averaging them with a weighted ensemble approach. We further propose that this ensemble forecasting is conducted within a hierarchic multi-scale framework. We present two ensemble models for a test species, one at regional and one at local scale, each based on the combination of 630 models. In both cases, we obtained excellent spatial projections, unusual when modelling rare species. Model results highlight, from a statistically sound approach, the effects of multiple drivers in a same modelling framework and at two distinct scales. From this added information, regional models can support accurate forecasts of range dynamics under climate change scenarios, whereas local models allow the assessment of isolated or synergistic impacts of changes in multiple predictors. This novel framework provides a baseline for adaptive conservation, management and monitoring of rare species at distinct spatial and temporal scales. 相似文献
113.
对普通级SD大鼠和KM小鼠肠道内鞭毛虫分别作了观察,从大鼠检出10种肠道鞭毛虫:鼠唇鞭毛虫(Chilomastix bettencourti),人肠滴虫(Enteromonas hominis),西蒙氏贾第虫(Giardia simoni)鼠六鞭虫(Hexamita muris),似单尾滴虫(Monocercomonoidies sp),人五毛滴虫(Pentatrichomonas hominis 相似文献
114.
包头市草坪蛴螬种类调查及药效防治试验 总被引:2,自引:1,他引:1
蛴螬是危害草坪的主要害虫。近几年,包头地区草坪地下害虫蛴螬发生严重。采用随机挖土取样法,对包头市草坪地下害虫蛴螬种类进行调查。结果查到3科7属7种,其中华北大黑金龟为优势种群。采用不同的农药种类对蛴螬进行防治试验,田间试验结果显示,40%甲基异柳磷EC、48%乐斯本EC对蛴螬防效好。 相似文献
115.
Staline Kibet 《Forest Ecology and Management》2011,261(6):949-957
The Kenyan coastal forests make up one of the World 25 Biodiversity Hotspots. They consist of over 140 fragments (the majority with areas less than 0.5 km2) of the once extensive Zanzibar-Inhambane lowland moist forest. The over 60 known Mijikenda sacred Kaya forests and groves scattered along the coastal hinterland form the greater part of this ecosystem. The forests are of biological and cultural significance, and this has been recognized nationally and internationally, with some now listed as World Heritage Sites. The forests are protected by councils of Kaya elders who regulate use of their resources. Increasing human population and subsequent rise in demand for forest products and land for settlement has put a strain on these relic forests. Farm encroachment and extraction of forest products in different Kaya forests have affected the vegetation ecology at varying levels. This study investigated the spatial species distribution, association and regeneration potential of commonly utilized plants in one of these traditionally managed ecosystems. A modified nested plot method was used to collect data in the field.Using TWINSPAN multivariate, and indicator species analysis, two plant communities (Asteranthe and Bridelia) and an undifferentiated vegetation type were identified. Species association in Asteranthe consisted largely of forest dependant species, with a significant presence of woody climbers. It was comprised of two sub-communities namely Manilkara and Scorodophloeos. In contrast the second plant community, Bridelia, was dominated by light demanding species. It comprised one sub-community (Catunaregam) and a seral stage (Keetia). The species diversity and richness was higher in the Asteranthe community compared to Bridelia. Some of the forest species commonly utilized by the local people were observed to regenerate both in open and closed forest habitats while others had seedling recruitment confined to closed forest.Despite some coastal forests showing physiognomic similarity, detailed study shows intra-variation linked to topography, exposition, type and intensity of human perturbation both currently and in the distant past. Clearly, vegetation patterns of coastal forests of eastern Africa change at fairly short intervals.Recruitment of forest specialists is likely to decline if closed forests are opened up by farm encroachment, however their less specialized counterparts can pioneer in re-colonization of disturbed sites if conservation is strengthened. There is need to invigorate traditional management systems of forests with cultural significance by recognizing and giving increased legal mandates to the local custodians. 相似文献
116.
117.
天然落叶松林树种组成的优化 总被引:1,自引:0,他引:1
为研究天然落叶松林的树种组成,对黑河地区122块样地的蓄积量和生长量进行聚类分析,并对分析结果和树种组成进行频率分析。研究结果表明:要保证天然落叶松林的高产,落叶松在林分中的比例应占绝对优势,但不完全是100%。落叶松断面积在阴坡应控制在90% ̄95%,在阳坡应控制在85% ̄90%;落叶松株数在阴坡应控制在86% ̄92%,在阳坡应控制在80% ̄85%。 相似文献
118.
文山县泰昌珍稀濒危植物园建设的意义及其可行性 总被引:1,自引:0,他引:1
位于文山县西北部,拟由私营企业文山泰昌花木场承建的文山泰昌珍稀植物固总规模63hm^2。文章论述了植物固建设对开展古老、珍稀、濒危物种种质资源的收集、迁地保存、驯化、繁育栽培以及发展经济等方面的重要意义。谊植物固划分为珍稀濒危植物展示区、繁育试验示范区、森林生态防护区、生活服务区。分析了建因的基本条件及其可行性。 相似文献
119.
一串红是目前最主要的一种花坛花卉。介绍了一串红的形态特征、生态习性,并对其品种选择、繁殖与栽培技术等三方面进行了详细的阐述。 相似文献
120.
荧光原位杂交检测野生六出花(Alstroemeria aurea) 染色体命运* 总被引:4,自引:2,他引:2
利用从野生六出花(Alstroemeria aurea) 中分离的一个种特异性串联重复序列(A001-I) 作荧光原位杂交的探针, 检测野生六出花染色体在其一系列杂交后代中的命运。试验结果表明, 除最长的一对染色体外, 该方法能够检测到在其一系列杂种后代中其余7 对染色体是否存在。 相似文献