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191.
192.
浦东新区土壤—食物链中的铜锌 总被引:1,自引:0,他引:1
本文调查了浦东新区污灌区、吹泥区和一般区三种处理土壤中Cu、Zn的水平和垂直分布,Cu、Zn分层现象不明显,水平差异较大,但三种关型土壤差异不显著。Cu在食物链中累积系数铰小,一般小于1.0,而Zn的累积程度较大,尤其是以人为消费者的食物链中,累积系数最高达到18。 相似文献
193.
Rachel Vallender Vicki L. Friesen Raleigh J. Robertson 《Behavioral ecology and sociobiology》2007,61(12):1797-1807
We examined two components of reproduction in a population of golden-winged warblers in the initial stages of hybridization
with blue-winged warblers. First, we used genetic analyses of mate choice to determine whether copulations outside the social
pairbond (extra-pair copulations; EPCs) occur in these species and their hybrids. Second, we compared several aspects of reproduction
(pairing success, clutch size, hatching success, fledging success, and loss of paternity) in nests raised by phenotypic golden-winged
warblers to those raised by hybrid individuals. Together, these data provide us with the first quantitative analysis of reproduction
within this hybrid system. Our data suggest several reasons why the level of hybridization between these species is likely
being underestimated. First, many birds in our population showed only subtle phenotypic signs of introgression indicating
that hybrid status can only be determined by close examination. Second, high rates of extra-pair paternity indicate that we
cannot base our estimates of hybridization on pairbond data alone. More than 30% of nestlings were the result of EPCs, occurring
in 55% of all nests. Third, there was no difference in the number of hybrid or “pure” golden-winged warbler males chosen as
social mates, relative to their abundance. Indeed, based on several components of nesting success, it appears as though hybrids
are having as great realized reproductive success as are phenotypic golden-winged warblers in our population. Accordingly,
we argue that hybrid reproductive success and extra-pair fertilizations are likely playing a major role in the ongoing hybridization
between blue-winged and golden-winged warblers. Studies such as this one are important to our understanding of the process
and implications of hybridization, and findings may be applicable to other hybrid zones. 相似文献
194.
195.
攀西地区水资源及可持续利用探讨 总被引:7,自引:0,他引:7
在分析攀西地区水资源特点的基础上,从资源开发结构调整、可持续发展和区域经济发展的角度阐述了该区水资源开发的迫切性。根据攀西地区水资源开发利用存在的问题,提出了该区水资源可持续利用的对策:统筹兼顾,综合利用;把建设全国能源基地与实现地方电气化相结合,因地制宜开发水能资源;以安宁河流域为重点,加快骨干水利工程建设;抓住机遇,多渠道、多途径开发水资源。 相似文献
196.
大连市水功能区的划分 总被引:1,自引:0,他引:1
从大连市水功能区划的背景出发 ,根据大连市自然环境和社会经济发展特点 ,对大连市供水工程与规划水源地状况以及水资源质量现状进行了调查分析 ,研究了大连市水功能需求状况 ,划定并提出了大连市水功能的划分 ,最后简要的介绍了成果验收情况 相似文献
197.
浦东新区工业结构的多目标优化研究 总被引:2,自引:0,他引:2
从经验和环境协调发展角度出发,用改进的多目标规划法研究浦东新区工业结构优化调整。以1989年为基准年,根据该年资料选取经济和环境影响较显著的十三个主要待业的产值为决策变量,设定调整目标,建立规划模型,并按照污染量增加率的不同设计方案。经过计算机数学模拟,提出既满足经济要求,又使污染量增加率尽可能降低的优化方案,将工业结构调整与污染控制结合起来,确定2000年规划年份的浦东新区工业结构优化。 相似文献
198.
为了探究寒旱区湖泊中固氮菌的地区差异性,利用固氮菌特异性功能基因nif H对南海湖沉积物中的固氮菌进行测定并分析其与环境因子之间的相互作用关系.结果表明:不同湖区优势固氮菌群落组成存在差异,整体上由3门(蓝藻门、厚壁菌门、变形菌门)10属(蓝藻菌属、着色菌属、梭菌属、鱼腥藻属、红螺菌属、厌氧粘细菌属、荚硫菌属、柱孢藻属、根瘤菌属、假单胞菌属)组成;寒旱区特有的冰封期长、紫外线照射强等环境条件导致沉积物中的主导固氮菌为蓝藻门下的微生物.冗余分析结果表明:较高的C/N和TP是固氮菌生存的必要营养条件,可以促进固氮反应的顺利进行,较高的TN和NH3-N含量及较低的pH值会抑制表层沉积物部分固氮微生物的生长,较高的pH值尤其会抑制鱼腥藻属、荚硫菌属、蓝藻菌属、红螺菌属的生长.本研究通过探讨寒旱区固氮微生物在沉积物中的分布来研究固氮作用的潜在功能,进一步补充其在氮循环中的重要作用. 相似文献
199.
AIN VELLAK†‡ EVA-LIIS TUVI ÜLLE REIER REIN KALAMEES ELLE ROOSALUSTE MARTIN ZOBEL MEELIS PÄRTEL 《Conservation biology》2009,23(3):750-757
Abstract: The Global Strategy of Plant Conservation states that at least 60% of threatened plant species should be within protected areas. This goal has been met in some regions with long traditions of plant protection. We used gap analysis to explore how particular groups of species of conservation interest, representing different types of natural or anthropogenic rarity, have been covered by protected areas on a national scale in Estonia during the last 100 years. Species-accumulation curves indicated that plant species that are naturally rare (restricted global or local distribution, always small populations, or very rare habitat requirements) needed almost twice as many protected areas to reach the 60% target as plant species that are rare owing to lack of suitable management (species depending on grassland management, moderate forest disturbances, extensive traditional agriculture, or species potentially threatened by collecting). Temporal analysis of the establishment of protected areas suggested that grouping plant species according to the predominant cause of rarity accurately reflected the history of conservation decision making. Species found in very rare habitats have previously received special conservation attention; species dependent on traditional extensive agriculture have been largely ignored until recently. Legislative initiative and new nature-protection schemes (e.g., Natura 2000, network of protected areas in the European Union) have had a positive influence on all species groups. Consequently, the species groups needing similar action for their conservation are sensitive indicators of the effectiveness of protected-area networks. Different species groups, however, may not be uniformly conserved within protected areas, and all species groups should fulfill the target of 60% coverage within protected areas. 相似文献
200.
The distribution of ecological resources and their significance for males and females may vary considerably. Intersexual behavioural
interactions may lead, combined with particular resource configurations, to sexual spatial segregation. We investigated this
issue relative to host plant use in females of the purple-edged copper butterfly, Lycaena hippothoe. Males exhibited nectar resource-based territoriality, which is an uncommon mate-locating system in butterflies. They perched
and patrolled in large territories harassing every passing female. In our study system, the percentage of spatial dimension
shared for adult and larval resources was estimated at 50%, and males monopolised 28% of the nectar-rich zones. Under these
conditions of harassment, females travelled between nectar-rich zones for feeding and zones with suitable host plants for
egg laying, but often without nectar and hence with low male density. This is likely to limit their time budget and, potentially,
their realised fecundity as suggested by the low number of eggs found relative to population size. Females were also highly
specialised in selecting host plants under particular environmental conditions. Using test choice in experimental cages, we
showed that, in the absence of males, only micro-climatic conditions may significantly influencing egg-laying decisions. Moreover,
results of egg-rearing experiments under different temperature treatments suggested that eggs were laid in thermally suitable
micro-environments. The highly selective egg-laying behaviour can be viewed as a preference-performance choice. Knowledge
of individuals' behaviour, including sexual interactions, can be highly significant for our understanding of habitat use,
which in turn can be essential for conservation. We discuss this for L. hippothoe, a species of regional conservation concern. 相似文献