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[目的]探讨边缘效应对贺兰山东坡直翅目昆虫群落的影响。[方法]样带法采集取样,采捕过程中针对采捕的不同种类及生境中的具体情况,采用网捕法、徒手捕捉、诱捕法等。采集时将昆虫标本毒死后带回实验室,制作针插标本,根据相关文献专著鉴定并记录直翅目昆虫的种类和数量。并通过物种丰富度、Shannon-Wiener多样性指数、均匀性指数、优势度指数、群落相似性指标和多度值对调查数据进行了分析。[结果]斑翅蝗科、斑腿蝗科和癞蝗科个体数量分别占总数的42.65%、29.15%和12.76%,构成研究区域直翅目昆虫的优势类群。直翅目昆虫数量沿疏林草地、边缘和荒漠草地依次增加,边缘多样性高于疏林草地和荒漠草地内部,且边缘与疏林草地差异显著;无论是疏林草地还是荒漠草地,直翅目昆虫群落多样性都是随着距边缘距离的增加而降低。在疏林草地-荒漠草地过渡带出现了栖息地广布种、利用边缘的栖息地广布种、利用边缘的栖息地特异种和逃避边缘的栖息地特异种4种边缘反应类型。[结论]该研究可为直翅目昆虫生物多样性的保护和开发利用及保护生物学的发展提供数据和理论基础。 相似文献
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Craig A. DeMars Daniel K. Rosenberg Joseph B. Fontaine 《Biological conservation》2010,143(6):1485-19602
With recent emphasis on sustainable agriculture, conservation of native biota within agricultural systems has become a priority. Remnant trees have been hypothesized to increase biological diversity in agro-ecosystems. We investigated how remnant Oregon white oak (Quercus garryana) trees contribute to conserving bird diversity in the agro-ecosystem of the Willamette Valley, Oregon, USA. We compared bird use of isolated oak trees in three landscape contexts - croplands, pastures, and oak savanna reserves - and ranked the relative importance of four factors thought to influence bird use of individual trees: (i) tree architecture; (ii) tree isolation; (iii) tree cover in the surrounding landscape; and (iv) landscape context, defined as the surrounding land use. We evaluated species-specific responses and four community-level responses: (i) total species richness; (ii) richness of oak savanna-associates; (iii) tree forager richness; and (iv) aerial and ground forager richness. We documented 47 species using remnant oaks, including 16 species typically occurring in oak savanna. Surprisingly, landscape context was unimportant in predicting frequency of use of individual trees. Tree architecture, in particular tree size, and tree cover in the surrounding landscape were the best predictors of bird use of remnant trees. Our findings demonstrate that individual remnant trees contribute to landscape-level conservation of bird diversity, acting as keystone habitat structures by providing critical resources for species that could not persist in otherwise treeless agricultural fields. Because remnant trees are rarely retained in contemporary agricultural landscapes in the United States, retention of existing trees and recruitment of replacement trees will contribute to regional conservation goals. 相似文献
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可采森林资源日趋零散,旧的生产工艺已远远适应不了经济发展的需要,工艺改革势在必行。本文分析了旧生产工艺的种种弊端,提出了“移动式机库存车,移动式宿营车住宿,随车液压吊装原条”的新生产工艺模式,并着重介绍了按这一模式进行实践的效果,证明了新工艺具有一定的先进性和可操作性。 相似文献
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后屋面散射光(包括一部分直射光)对黄瓜生长有很大的影响.与对照相比,处理平均单株叶面积增加8.07%,叶面积系数增加7.81%,叶绿素a+b增加15.54%;定植后70天株高、茎粗和展开叶片数与对照差异极显著;定植后两个月的根、茎、叶干重分别增加36.89%、46.37%和50.00%,产量提高21.16%. 相似文献
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Anthony Weinberg Philip Gibbons Sue V. Briggs Stephen P. Bonser 《Biological conservation》2011,(1):227-233
The process of natural regeneration is critical for sustaining remnant native vegetation and the ecosystem services it supports. We quantified the extent and pattern of Eucalyptus regeneration within remnant vegetation in a fragmented agricultural landscape in south-eastern Australia. Eucalyptus regeneration was absent at 42% of sites. Using an information-theoretic approach, we explored 13 possible models of Eucalyptus regeneration across multiple scales. The explanatory variables in the four models with empirical support (and their summed Akaike weights) were: grazing intensity (1.0), native ground cover (0.99), remnant area (0.83), tenure (0.67), canopy cover (0.21) and vegetation type (0.11). Averaging across these four models we predicted that the probability of Eucalyptus regeneration was highest (0.95) in relatively unmodified remnant native vegetation, that is, remnant vegetation on public land where grazing was light and the understorey was dominated by native plants. In contrast, the predicted probability of Eucalyptus regeneration was lowest (0.12) in small remnants on private land where grazing was heavy. Our results suggest that a large proportion of all remnant native vegetation in this landscape will disappear under existing land management and farming practices. Reducing grazing pressure within intensively grazed remnants appears to be the single most effective management intervention that will mitigate this threat. This will require a shift in conservation priorities away from large, intact remnants where regeneration does not appear to be affected, to poorer quality remnants—often small remnants or scattered trees—where regeneration is typically absent. 相似文献
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Wild service tree [Sorbus torminalis (L.) Crantz] is a forest tree widespread in Europe, characterized by a scattered distribution. Its hermaphroditic flowers
are pollinated by insects, and outcrossing is the prominent mating system, also due to the presence of gametophytic self-incompatibility.
Genetic diversity and differentiation of 22 populations from northwestern Italy were investigated by means of variation scored
at 53 polymorphic RAPD (Random Amplified Polymorphic DNA) loci. Populations differed in genetic variation, with Shannon diversity
index ranging from 0.166 to 0.469. According to Analysis of Molecular Variance (AMOVA), most of the genetic variation was
found within populations (61.78%) with a significant proportion of variance attributable to genetic differences between regions
(23.60%) and between populations (14.62%). Evidence for isolation by distance was found in the set of populations sampled.
The effect of habitat fragmentation on genetic variation was also evaluated. The efficacy of RAPD markers in analysing genetic
variation, and the contribution of the results in terms of the preservation of biodiversity are discussed. 相似文献
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