Measuring ecologically important quantities at relevant operational scales: An example using the dusky flycatcher in selectively logged forests in Idaho

Effective management of forest wildlife requires information about habitat features that can be altered by operations, if those habitat features promote reproductive success and survival, and if changes in organism density influence reproductive success and survival. Habitat selection studies often provide the first type of information, although relatively few studies examine how different selection decisions or densities of organisms influence fitness measures or measure habitat features at relevant operational scales. We examined patterns of habitat selection and estimated how habitat use, territory size, and conspecific density were associated with territory success (probability of a territory producing one or more fledglings) for the dusky flycatcher in 2002–2003 on eight study plots in managed grand fir (Abies concolor) forests in Idaho, USA. Flycatchers selected territories with greater cover of deciduous vegetation in two different height strata (1–2 and 3–4 m) and reduced cover of conifers less than 4 cm dbh compared to what was available. While flycatchers selected habitat characteristics at the territory scale, model selection results did not support any associations between vegetation features and territory success. Territory success had weak positive associations, for a given territory size, with conspecific density, although the relationship was highly variable. An interaction between territory size and density was not supported. These results are consistent with the view that avian breeding habitat selection occurs at multiple scales, and that the nest site scale may explain more of the variance in reproductive success than larger scales. Our results suggest that operational management of vegetation features, which often occurs at the stand scale, may not influence variation in critical demographic metrics. Increasing total shrub cover of commonly used plant species should benefit the dusky flycatcher, as well as other shrub-nesting forest birds, but stand-level habitat alterations alone cannot be relied upon to increase reproductive success, an important component of population change.     

家庭蚕桑适度规模经营的实践探索

推地蚕桑适度规模经营是提高蚕桑生产经济效益的一项主要途径。海宁市对蚕桑适度规模经营进行了试点实践和调查,并就提出该课题的依据,可能性,典型蚕户的经营分析,适度规模经营的指标,优缺点进行了有益探讨。     

微博书评引领高校图书馆的信息服务模式探析

阐述高校图书馆开展信息服务工作的现状及意义,微博书评引领高校图书馆信息服务的优势、微博书评创新高校图书馆信息服务的模式及其微博书评引领高校图书馆信息服务应注意的问题。     

Arthropods as surrogates of diversity at different spatial scales

This study evaluates the effectiveness of taxonomic, colonization and trophic groups of arthropods from native forests of the Azores archipelago as surrogates of the diversity of other arthropod groups and of the remaining arthropods. Consistency in the performance of surrogates was tested across three spatial scales and using two measures of diversity. Pitfall and beating samples from 109 transects, 18 forest fragments and seven islands were analysed. The results showed that Araneae, Hemiptera and small orders taxonomic groups; native, endemic and introduced colonization groups; and the herbivores trophic group were consistent surrogates of the remaining diversity across the three spatial scales analysed, for both alpha and dissimilarity diversities. However, none of the subsets considered was significantly related with all of the other subsets at any of the three spatial scales. The effectiveness of surrogacy was dependent on the spatial level considered, and groups behaved inconsistently depending on the measure of diversity used. The value of a group as a diversity surrogate should be evaluated for a study area for a given spatial scale and diversity measure, in accordance with the scale and measure that will be used for biodiversity assessments and monitoring programs in that area.     

贵阳喀斯特地区夏旱特征分析

[目的]揭示贵阳喀斯特地区夏旱强度指数变化的多尺度时空分布规律,分析夏旱变化的周期特征和突变点,为工农业生产服务。[方法]利用1951～2004年共54a8个站6～8月日降水量资料,计算了贵阳喀斯特地区夏旱强度指数。采用Morlet小波函数,时贵阳喀斯特地区夏旱强度指数时间序列进行了小波分析。[结果]贵阳喀斯特地区夏旱强度指数序列变化具有明显的周期和突变点,夏旱强度指数存在22a的周期特征;2～3a的周期震荡也很明显;并且存在着2a的主周期。[结论]根据主周期进行预测,干旱程度将加重。同时,还分析了夏旱的分布特征、形成的环流形式和物理因子。     

对城西川流域坝系建设规模及工程布局的探讨

通过对城西川流域社会自然条件、水土流失治理现状、坝系建设潜力、减沙目标、淤地目标进行综合分析,确定该流域坝系建设的规模为:骨干坝14座、中小型淤地坝8座、48座,骨干坝与淤地坝配置比例为1∶4。根据建设规模提出该流域工程布局的原则、思路与方案。