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乌鲁木齐南山小渠子土壤螨类群落结构研究 总被引:1,自引:0,他引:1
[目的]研究乌鲁木齐南部山区不同土地利用类型下土壤螨类群落结构特征及季节动态变化规律,为开展人类活动对市郊旅游胜地土壤环境质量影响的生物学评价提供科学依据。[方法]采用常规野外采样方法和改良的Ttdlgren分离法对该山区针叶林、山地草原、阔叶林、山地灌木林、山地耕地及居民点6种不同生境土壤螨类群落结构特征、季节动态及其与环境要素的关系进行分析。[结果]共获得土壤螨类7135只,隶属蜱螨亚纲的4亚目57科87属,其中甲螨亚目5785只54属38科,占总采集量的81.08%:中气门亚目1077只19属14科,占总采集量的15.09%;前气门亚目270只4属4科,占总采集量的3.78%;无气门亚目3只1属1科,占总采集量的0.04%。其中,小奥甲螨属为优势类群,占总捕获量螨类的10.06%,盖头甲螨属和真前翼甲螨属为亚优势属,占总捕获量的12.27%。礼服甲螨属、滑缝甲螨属、珠足甲螨属、洼甲螨属和懒甲螨属等35属为常见类群,占总捕获量的76.73%;优势类群和常见类群共占总数量的98.96%。广缝甲螨属、龙足甲螨属、卷甲螨属、沙足甲螨属和缰板鳃甲螨属等19属均为稀有类群,仅占总捕获量的0.94%。土壤螨类个体数和类群数组成在不同生境、不同土层以及不同季节间具有显著差异(P〈0.05)。其中,个体数的水平分布依次为针叶林〉山地灌木林〉山地草原〉山地耕地〉阔叶林〉居民地;垂直分布具有明显的表聚性,即表层〉中层〉下层。个体数量的季节变化依次为秋季〉冬季〉夏季〉春季。[结论]该山区不同生境土壤螨类群落组成及时空分布动态之间均存在显著差异(P〈0.05).这与植被类型、土壤环境因素及人为干扰程度等有关。 相似文献
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对一种花生收获机的轮边减速器进行了设计与研究,在总体方案分析的基础上,进行了轮边减速器主要零件基本参数设计,建立了基本的实体模型,并进行了有限元分析,完成了轮边减速器的总体设计。 相似文献
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基于债务结构的研究视角,以德国和PIIGS五国为例,构建主权债务可持续性模型,量化研究债务自身结构、宏观经济结构以及财政支出结构对债务可持续性的影响,并运用向量自回归模型进行检验.研究结果表明:适度地提高长期债券所占比重(以65%-75%为宜),同时降低短期债务的比重(不超过15%),改善宏观经济结构并促进国内就业,扩大固定资产投资的财政支出,均有助于抑制债务规模的持续扩张,维持主权债务的可持续性. 相似文献
106.
Satoshi Chiba 《Biological conservation》2010,143(6):1558-9501
Although a large number of studies have shown that rats have a serious effect on island ecosystems, questions remain regarding how their invasion alters native species diversity and assemblage patterns on islands. In particular, a long history of invasions makes it difficult to understand the impact of rat invasion. In the present study, I investigate how an increase in predation by black rats (Rattus rattus) alters the assemblage characteristics of land snails on the Ogasawara Islands in the West Pacific. Radical declines in many land snail species have occurred since 2006 due to increasing predation by black rats. The frequency of shells with predation scars was greater on larger species and on those living on the trees and in a shallower position in the litter, suggesting greater predation pressure on these species. As a result of this selective predation, large species living on trees and in shallower parts of the litter declined. Accordingly, when black rats increased on the island, small species and species with a burrowing microhabitat became dominant in the land snail assemblage. The present findings can be used to aid in predicting the effects of rat eradication and in estimating the assemblage patterns and diversity prior to rat invasion. 相似文献
107.
Members of the general public interact with wildlife in many ways, and an inability to distinguish between species can have significant implications for conservation. For example, attempts by environmentally-concerned private citizens to control invasive species may cause collateral damage unless people can reliably distinguish native fauna from the invader. We tested the Australian public’s ability to distinguish invasive cane toads (Bufo marinus) from native frogs at egg, tadpole, subadult and adult life-history stages. Errors were common, especially for eggs and tadpoles (27-31% error rates) and less so for subadult and adult toads and frogs (5-43% error rates). Accuracy of identification was higher in people living in areas where toads occur (compared to other parts of Australia or overseas), and similar in men and women (but with a decrease in older men). Ability to identify anurans was increased by toad-identification awareness programs and membership of “toad-busting” community groups, but direct killing of cane toads by the general public may inflict substantial “friendly fire” on native frogs. In the absence of any clear evidence for ecological benefits from toad-killing, we suggest that such collecting activities should be conducted only in areas where toads are known to occur, and under the supervision of trained personnel (to identify any anuran before it is killed), rather than as an ad hoc activity pursued independently by local residents. More generally, conservation activities that involve public participation should carefully evaluate the potential rates and consequences of species misidentification by well-intentioned but untrained people. 相似文献
108.
Steven Alan Wakelin Guixin Chu Richard Lardner Yongchao Liang Mike McLaughlin 《Pedobiologia》2010,53(2):149-68
Long-term diversity-disturbance responses of soil bacterial communities to copper were determined from field-soils (Spalding; South Australia) exposed to Cu in doses ranging from 0 through to 4012 mg Cu kg−1 soil. Nearly 6 years after application of Cu, the structure of the total bacterial community showed change over the Cu gradient (PCR-DGGE profiling). 16S rRNA clone libraries, generated from unexposed and exposed (1003 mg Cu added kg−1 soil) treatments, had significantly different taxa composition. In particular, Acidobacteria were abundant in unexposed soil but were nearly absent from the Cu-exposed sample (P<0.05), which was dominated by Firmicute bacteria (P<0.05). Analysis of community profiles of Acidobacteria, Bacillus, Pseudomonas and Sphingomonas showed significant changes in structural composition with increasing soil Cu. The diversity (Simpsons index) of the Acidobacteria community was more sensitive to increasing concentrations of CaCl-extractable soil Cu (CuExt) than other groups, with decline in diversity occurring at 0.13 CuExt mg kg−1 soil. In contrast, diversity in the Bacillus community increased until 10.4 CuExt mg kg−1 soil, showing that this group was 2 orders of magnitude more resistant to Cu than Acidobacteria. Sphingomonas was the most resistant to Cu; however, this group along with Pseudomonas represented only a small percentage of total soil bacteria. Changes in bacterial community structure, but not diversity, were concomitant with a decrease in catabolic function (BioLog). Reduction in function followed a dose-response pattern with CuExt levels (R2=0.86). The EC50 for functional loss was 0.21 CuExt mg kg−1 soil, which coincided with loss of Acidobacteria diversity. The microbial responses were confirmed as being due to Cu and not shifts in soil pH (from use of CuSO4) as parallel Zn-based field plots (ZnSO4) were dissimilar. Changes in the diversity of most bacterial groups with soil Cu followed a unimodal response - i.e. diversity initially increased with Cu addition until a critical value was reached, whereupon it sharply decreased. These responses are indicative of the intermediate-disturbance-hypothesis, a macroecological theory that has not been widely tested in environmental microbial ecosystems. 相似文献
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