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21.
秦淮河上游水体大型底栖无脊椎动物群落结构及水质生物评价 总被引:4,自引:1,他引:4
2009年4月用D形网半定量采样法调查秦淮河上游25个点位的大型底栖无脊椎动物群落多样性,共获得63个大型底栖无脊椎动物分类单元;其中,水生昆虫5目12科30属,软体动物9科11属19种,寡毛纲2科7属9种。结果表明,生物指数(Biotic Index,BI)比Shannon-Wiener多样性指数的评价结果更接近实际情况,BI与ρ(TN)(r=0.44,p0.05)和ρ(NH3-N)(r=0.40,p0.05)之间显著相关,Shannon-Wiene多样性指数与ρ(TN)(r=-0.19,p0.05)和ρ(NH3-N)(r=0.44,p0.05)无显著性相关。生物评价表明秦淮河上游水质受到严重污染,句容地区的水质要优于南京。 相似文献
22.
本文通过一年的淡水藻类生态调查,用多样性和重现性指数,计算了浦东开发区川扬河和浦东运河若干断面的藻类群落数据。结果表明,有两个断面重污染,一个轻污染,其余符合三级国标。Wilhm污染分级显示,在轻度污染水域,多样性指数与污染无明显相关性。 相似文献
23.
The practice of environmental planning and protection frequently necessitates the quantification of ecological diversity. Traditional ‘ecological diversity indices’ are based on the abundances of species present. However, such indices are insensitive to taxonomic or similar differences. With equal species abundances they measure the species richness (species number) only. Conversely, so-called ‘biodiversity indices’ are based on species differences, but are insensitive to the abundance conditions. The quadratic entropy index is the only ecological diversity index, the value of which reflects both the differences ‘and’ abundances of the species. When a species list is given without abundance data, then, using the quadratic entropy index and postulating equal abundances, one gets the only biodiversity index derived from a traditional ecological index of diversity. Its extensive form is identical with the sum of differences or distances between the species present. This index trivially satisfies set monotonicity, an important property for biodiversity indices. 相似文献
24.
Characteristics of soil fauna community in the decomposition of Deyeuxia arundinacea litters北大核心CSCD
This study aimed to understand the soil fauna characteristics during the litter decomposition process of perennial herb Deyeuxia arundinacea. The litters were put in 6-, 30-, and 260-mesh litterbags to investigate their mass loss and the dynamics of soil faunal community during Aug. 2013 to Jul. 2014. Faster decomposition rate of Deyeuxia arundinacea in different meshes was found in the early period than in mid- and end-periods. Among different mesh sizes, 6-mesh had the fastest decomposition rate, followed by 30-mesh and 260-mesh. A total of 2218 individuals of soil fauna were obtained in different meshes, with 958, 737 and 523 individuals in 30-, 260- and 6-mesh respectively. Oribatida and Poduridae were the dominant groups, accounting for 73.22% of total individuals. The soil animal individual and group densities shared a very similar trend among the decomposition bags of three aperture sizes, all with obvious characteristics of seasonal dynamic distribution. During the 12 months of decomposition, the density of soil animal groups did not show significant difference between the 6 mesh and 260 mesh decomposition bags except for May. Correlation analysis showed that the group density was highly significantly correlated with average monthly temperature and rainfall, and the individual density significantly correlated with the average monthly temperature. The results indicated that the structure and diversity of soil fauna community of Deyeuxia arundinacea are influenced by hydrothermal conditions. The findings help in understanding the effect of soil fauna to perennial herb litter decomposition. 相似文献
25.
VIRGINIA GALLEGOS PÉRULA RAFAEL M. NAVARRO CERRILLO PILAR FERNÁNDEZ REBOLLOo GEMADEL VALLE MURILLO 《Environmental management》2003,31(1):0086-0099
The objective of this study was to examine postfire regeneration of tree, shrub, and dwarf shrub species, in relation to levels
of damage in four planted pine forests (Pinus pinea, Pinus pinaster) in Andalusia. A prefire vegetation map was used for detailing species composition, vertical structure, and density and another
for detailing the extent and intensity of fire damage. Between 3 and 7 years after the fires, an inventory was made of the
vegetation in each area, using the step-point method. The information thus obtained was used to determine the amount of cover
in the dwarf/shrub and tree layers, the frequency of species in each of the layers, floristic richness, and diversity (Shannon
index). The botanical composition of the dwarf and shrub layer was analyzed using TWINSPAN. Variables were poorly correlated
with level of fire damage, which suggests that the forests in this study followed the autosuccession model. Because of the
artificial origin or seminatural condition, regeneration of the dominant tree species is poor, and it seems unlikely that
forests will recover to their prefire state. Therefore action is recommended to restore these ecosystems. 相似文献
26.
Aquatic insect diversity in the Chandrabhaga, an important headwater stream of Garhwal Himalayas, was surveyed for a period
of twelve months (October 1999 to September 2000). All the important physico-chemical environmental variables (temperature,
water velocity, hydromedian depth, transparency, turbidity, total dissolved solids, pH, alkalinity, dissolved oxygen, free
CO2, nitrates, phosphates, sodium and potassium) of the aquatic ecosystem were measured monthly for one year. Aquatic insects
were sampled from three sites (S1, S2 & S3) of the headwater stream Chandrabhaga. Aquatic insects of Chandrabhaga were represented by the members of the orders of Ephemeroptera,
Trichoptera, Coleoptera, Diptera, Plecoptera and Odonata. The maximum density of aquatic insects was recorded in the month
of March (4,165 ind. m−2) and minimum in the month of August (680 ind. m−2). The annual contribution of Trichoptera (38%) and Ephemeroptera (32%) was observed to be maximum, while Odonata contributed
minimum (2%) to the total aquatic insect density. The present study on the relationship between physico-chemical environmental
variables and the density of aquatic insects revealed that the velocity of water, hydromedian depth, turbidity and dissolved
oxygen in addition to composition and texture of the bottom substrates have significant impact on benthic aquatic insects’
density and their diversity. The ecological relevance of the measured hydrological attributes was investigated by composing
their degree of correlation with insects density and diversity. The diversity index (Shannon–Weiner) of aquatic insects dwelling
in the Chandrabhaga river ranged from 2.54 to 3.86. Some of the natural and anthropogenic environmental factors contributing
towards the degradation of the watershed of the Chandrabhaga have been identified, and ameliorative measures for the conservation
of the aquatic insect diversity have been suggested. 相似文献
27.
Moses Elleason Zhuoli Guan Yiming Deng Aiwu Jiang Eben Goodale Christos Mammides 《Ambio》2021,50(5):1058
The International Union for Conservation of Nature (IUCN) classifies protected areas into six categories, ranging from strict nature reserves to areas where multiple human uses are permitted. In the past, many researchers have questioned the effectiveness of multiple-use areas, fueling an unresolved debate regarding their conservation value. The literature so far has been inconclusive: although several studies have found that strictly protected areas are more effective, others have found the opposite, and yet others that the two types do not differ. To help resolve this debate, we reviewed the literature on protected areas and conducted our own analysis using > 19 000 terrestrial protected areas worldwide. We found that the differences between strictly protected areas and areas in which multiple human uses are permitted are often small and not statistically significant. Although the effectiveness of protected areas worldwide varies, other factors, besides their assigned IUCN category, are likely to be driving this pattern.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01426-5) contains supplementary material, which is available to authorized users. 相似文献
28.
29.
黄河三角洲河口区浮游植物组成及多样性分析 总被引:1,自引:0,他引:1
通过对2010年5月、8月、11月黄河三角洲主要河口浮游植物的调查,该水域共有浮游植物42种,以硅藻门所占比例较大;细胞密度为5.3×107~2.41×109ind/m3;生物多样性H为0.56~1.4,植物物种丰度指数D为0.06~0.36,均匀度指数J值均在0.5以上。结果表明:与莱州湾、渤海湾海域相比,黄河三角洲主要河口区浮游植物具有一定的淡水特征,种类组成及数量差异较大。黄河三角洲主要河流入水口处浮游植物的Shannon-Weaver多样性指数、Pielou均匀度指数与莱州湾、渤海湾海域相比差别不大,均较低。渤海水域主要河流入水口处营养状态均为中营养型以下,且春季好于夏秋两季,表现出一定的季节趋势。 相似文献
30.
In this paper, the evolution of cooperation is studied by a spatially structured evolutionary game model in which the players are located on a two-dimensional square lattice. Each player can choose one of the following strategies: “always defect” (ALLD), “tit-for-tat” (TFT), and “always cooperate” (ALLC). Players merely interact with four immediate neighbors at first and adjust strategies according to their rewards. First, the evolutionary dynamics of the three strategies in non-spatial population is investigated, and the results indicate that cooperation is not favored in most settings without spatial structure. Next, an analytical method, which is based on comparing the local payoff structures, is introduced for the spatial game model. Using the conditions derived from the method as criteria, the parameter plane for two major parameters of the spatial game model is divided and nine representative regions are identified. In each parameter region, a distinct spatiotemporal dynamics is characterized. The spatiotemporal dynamics not only verify that the spatial structure promote the evolution of cooperation but also reveal how cooperation is favored. Our results show that spatial structure is the keystone of the evolution of intraspecific diversity. 相似文献