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91.
Indicator taxa are often proposed as efficient ways of identifying conservation priorities, but the correlation between putative indicators and other taxa has not been adequately tested. We examined whether a popular indicator taxon, the butterflies, could provide a useful surrogate measure of diversity in a closely related but relatively poorly known group, the moths, at a local scale relevant to many conservation decisions (100-101 km2). We sampled butterflies and moths at 19 sites representing the three major terrestrial habitats in sub-alpine Colorado: meadows, aspen forests, and conifer forests. We found no correlation between moth and butterfly diversity across the 19 sites, using any of five different diversity measures. Correlations across only meadow sites (to test for correlation within a single, species-rich habitat) were also not significant. Butterflies were restricted largely to meadows, where their host plants occur and thermal environment is favorable. In contrast, all three habitats contained substantial moth diversity, and several moth species were restricted to each habitat. These findings suggest that (1) butterflies are unlikely to be useful indicators of moth diversity at a local scale; (2) phylogenetic relatedness is not a reliable criterion for selecting appropriate indicator taxa; and (3) a habitat-based approach would more effectively conserve moth diversity in this landscape and may be preferable in many situations where indicator taxa relationships are untested.  相似文献   
92.
Forest loss with accompanying urbanization is often permanent as forests are replaced by impervious concrete structures or surfaces. The remaining forest patches are usually isolated and too small to maintain viable populations of forest-dependent wildlife species. Consistent with the species-area function (S = cAz), extirpation of species should follow forest loss. However, this has rarely ever been tested in the urban landscape. We determined whether the observed number of forest-dependent bird extirpations occurring after forest loss matches that predicted by the species-area function in Vancouver (study area ∼126.7 km2), British Columbia, Canada. Prior to European settlement in 1859, Vancouver was covered completely by coastal western hemlock forest. Based on published historical maps of forest cover and present Landsat imagery of Vancouver, we estimated that approximately 87% of the forest area in Vancouver has been converted to urban development. Using the species-area function, we then predicted that approximately 14 bird species closely associated with lowland forest should have been extirpated. This figure is significantly greater than the three bird species known to have been extirpated in Vancouver. When we constrained the comparison to bird species closely associated with lowland forest and restricted in their distribution in British Columbia, we found a close match between the observed and predicted number of extirpations, suggesting that bird species closely associated with lowland forest and restricted in their geographic distribution are most prone to extirpation as a result of forest loss. Given that urban areas are situated in productive habitats with inherently high species richness, it is important that local land-use plans incorporate the conservation of habitat fragments from the onset and place particular emphasis on the regionally restricted forest-dependent species.  相似文献   
93.
Rapidly expanding water resource development in arid and semi-arid zones of Australia threatens the flow regime and ecological integrity of the few large dryland rivers and their immense floodplains. Efforts to manage and conserve the surface waters of these rivers are hampered by limited scientific data on the ecology of their flora and fauna and on their responses to the high natural variability of flow regime that typifies dryland rivers. Irregular floods connect channel and floodplain wetlands to differing degrees and for varying periods of time but the ecological significance of this connectivity is poorly understood. On Cooper Creek, a large dryland river in central Australia, we explored the degree to which assemblage composition varied with connectivity and hydrological regime. Shortly after protracted regional flooding, we sampled aquatic macroinvertebrate assemblages from the principal microhabitats in 12 channel and floodplain wetlands. Ephemeral and temporary lakes tended to have fewer taxa than semi-permanent channel or terminal lake habitats. Although hydrological connection had only recently been lost for some wetlands, there was already evidence of divergence in aquatic macroinvertebrate assemblage composition. Disruption of the natural variability in connectivity and hydrological regime by excessive water abstraction or river-flow regulation threatens the ecological integrity and aquatic macroinvertebrate biodiversity of dryland rivers. Preservation of the irregular flow regime and sporadic connectivity underpins conservation of the mosaic of floodplain wetlands that play such a crucial role in the ecosystem functioning of rivers such as Cooper Creek.  相似文献   
94.
This study compared soil physical, chemical, and biological characteristics between natural grassland and recently abandoned rice fields in order to identify those variables that might explain the observed increase of Camponotus punctulatus anthills in abandoned rice paddy fields from Northern Argentina. Mainly due to a reduction of macropores and mesopores, overall porosity decreased by around 6% and bulk density was about 7% greater, in the 0- to 10- and 10- to 20-cm layers of the abandoned rice fields. Carbon and nitrogen content from organic matter increased (29% and 41% respectively for the 0- to 20-cm horizon) during cultivation but decreased (38% and 24%) 2 years after the last rice harvest. Forty percent of natural grassland-organic matter and 30% of abandoned rice-organic matter mineralized in less than 2 years. There was a different community structure between the abandoned rice fields and the undisturbed natural grassland and only a 20.6% (i.e. only 19 species from a total of 92) overlap in species composition. The abundance of macrofauna was greater in abandoned rice fields (2,208 individuals m–2) in comparison to natural grasslands (288 ind m–2) due to higher densities of small earthworms and Camponotus punctulatus ants; however, the Shannon index showed lower values in comparison to natural grasslands. Earthworms and C. punctulatus in the abandoned rice fields showed a change in their 13C signature indicating a switch in diet from natural grassland organic matter (C4) to organic matter from rice (C3). Our results indicate that the effects of rice cultivation practices did not seem to produce any physical or trophic limitations to recolonization by the macrofauna. It seems that changes in overall soil conditions have favored a change in the construction behavior of C. punctulatus which, in combination with population increases, could explain the explosion in number of anthills.  相似文献   
95.
Managed stands generally contain little coarse woody debris compared to natural forests. This study addresses the potential of retained cut wood to increase the amount of substrate available for a variety of saproxylic fungi.Fruit bodies of fungi were recorded from 270 cut high stumps and logs of spruce, birch, aspen and oak over nine years of initial succession. A total of 1565 occurrences of 148 species, seven of which were red-listed, were found. Numbers of species were significantly higher on logs than on stumps. Annual diversity peaked four to seven years after logging, sooner on logs than on stumps. Numbers of species were positively related to substrate diameter, but not to the level of shade/sun-exposure, while the presence of some individual species were significantly affected by one or both of these factors. Comparisons with data from the literature indicated no fundamental differences between fungal communities on cut wood and on naturally dead substrates. We conclude that cut wood left on site, especially logs, may mimic dead wood from trees that die swiftly from natural causes and support diverse fungal communities, both in shaded stands and in open logging sites. Substrates generated by slow self-thinning processes in natural forests however, are probably difficult to mimic in managed stands.  相似文献   
96.
The distribution of organic carbon, microbial biomass and activity, from the surface down to 70 cm, was investigated through three semiarid Mediterranean soils: (1) a Typic Calcixeroll covered with a native pinewood (NP), (2) a Typic Calcixerept under a mature pine plantation (PP) on abandoned agricultural terraces and (3) a Typic Haploxerept under a grassland (GS). NP and GS had the highest and lowest soil organic carbon (SOC) pools, respectively. Both of them had decreasing SOC contents with depth. PP, which held intermediate SOC levels, showed an increase in total organic C and humic substances C with depth due to their mineralization in the anciently ploughed topsoil layer. The soils were similarly ranked as regards their microbial biomass and activity: NP>PP>GS. In general, the microbial communities were less dense and active towards the deeper horizons. More specifically, PP and GS had a very populated and active top 20-cm layer, which was attributed to the dense root system of their grass cover. NP maintained high microbial biomass and activity levels from 0 to 70 cm, progressively diminishing along with shrub root density (e.g. microbial biomass C dropped from 2342 to 394 mg kg−1 soil). The latter soil presented the sharpest drop of its microbial properties with depth, what was considered an indicator of its quality. Generally decreasing patterns of microbial biomass and activity were not always coincident with previously published gradients of microbial metabolic abilities and genetic structure. This reinforces the need of combining biomass, activity and biodiversity measurements if the ecosystem's functioning is to be fully understood and a real monitoring of degradation processes and restoration strategies is to be achieved.  相似文献   
97.
1 INTRODUCTIONUnderthescopeofCBD ,sustainableutilizationofbiologicalresourcesisanimportantcomponent.Itisthekeyinconvincingpeoplethatitisnecessarytoconservebiodiversityforawellbeingofmankindandforthefuturegenerationuses.Intellectualproperty (IP)andownershipofbiologicalmaterialshasasignificantimpactonthede velopment,implementationandinvestmentinconserva tionandutilizationofbiologicaldiversity .Biologicalma terialor“bioproperty”hasledtothedevelopmentofin tellectualproperty (patents,plan…  相似文献   
98.
Investigation of higher plant diversity in different age cutovers indicated those diversity indices of herb, xylophyta and advanced plants increased gradually in the cutovers from 1984 to 1994, and diversity indices had obviously positive correlation with richness and evenness.  相似文献   
99.
新疆野生苹果表型多样性研究   总被引:18,自引:2,他引:16  
对中国新疆霍城野生苹果林进行了性状调查,结果表明:各性状均普遍存在多样性,性状变异系数大部分大于0.2%,充分表现出变异具有一定的广度和宽度。其中抗逆性和冠密度2个性状处于显著变异状态,不同生态条件影响了各个性状的变异系数大小和百分率的多少,群体中存在着多样性。通过聚类分析证明性状变异与野生苹果分布地点有较大关系。新疆野生苹果所处的生态条件复杂,遗传变异类型丰富,整个野生群体可以看作是该树种的基因库,是苹果中不可再造的宝贵种质资源。  相似文献   
100.
黄元河  潘乔丹  卢贞燕  梁显堂 《安徽农业科学》2012,40(3):1409-1411,1414
经调查,金钟山国家级自然保护区共有野生药用植物187科651属1 126种(包括变种),其中珍稀保护药用植物有5种。在生活型上,多年生草本类最多(422种),占该区药用植物总数的37.48%;在药用部位上,全草(株)类、根类和叶类药用植物最多,分别占该区药用植物总数的32.50%、26.02%和16.79%。  相似文献   
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