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991.
992.
Ying Hu Liu De Li Liu Min An Yin Lian Fu Ren Sen Zeng Shi Ming Luo Hanwen Wu Jim Pratley 《Ecological modelling》2009
Many plant species defend themselves against herbivorous insects indirectly by producing and releasing induced volatiles to attract natural enemies of the herbivores. In this paper, we consider the recruitment of natural enemies attracted by plant-induced volatiles and introduce the An–Liu–Johnson–Lovett model into the Lotka–Volterra model in an attempt to add this missing vital link in tritrophic interaction. Increase in attraction strength of plant-induced volatiles to the natural enemy leads to high fluctuation amplitude of plant biomass and herbivore population. When the attack strength of natural enemies reaches a certain level, fluctuation amplitude of plant biomass and herbivore population will decrease and plant biomass will approach to its environmental carrying capacity. The simulation demonstrates that plant volatile compounds induced by insects have led to the introduction of a third tritrophic level, e.g., natural enemies, into the plant–herbivore system, resulting in the coexistence of plants, insects, and natural enemies during the evolution process. 相似文献
993.
A fuzzy analytic hierarchy process (FAHP) approach to eco-environmental vulnerability assessment for the danjiangkou reservoir area,China 总被引:4,自引:0,他引:4
The Danjiangkou reservoir lies in the upper Hanjiang basin and is the source of water for the Middle Route Project (MRP) under the South-to-North Water Transfer Scheme (SNWT) in China. The eco-environment of water resource areas plays an important role in water conservation and purification and would have significant implications for the economic prosperity in Hanjiang basin as well as for the SNWT. Focusing on the Danjiangkou Reservoir Area (DRA), this study established an environmental information system database. Based on the database, an eco-environmental vulnerability assessment method using integrated fuzzy AHP (FAHP) and GIS was developed for the DRA. According to eco-environmental conditions and anthropic effects, vulnerability was classified into five levels: potential, light, medium, heavy and very heavy. The eco-environmental vulnerability distribution and major problems of the eco-environment were analysed and discussed. The results indicated that eco-environmental vulnerability in the DRA was moderate overall. Regions with lower eco-environmental vulnerability were located in Qinling Mountain area in the northwest, Daba Mountain area in the south and the area immediately surrounding Danjiangkou Reservoir in the east. Two regions with very high eco-environmental vulnerability were located in the north of Danjiangkou Reservoir in Henan province and in the western part of Shanxi province. On the basis of analysis of distribution of the different factors of eco-environmental vulnerability, different environmental protection measures were proposed for different areas. This study demonstrated that the proposed method was an effective approach for the assessment of environmental vulnerability. The results gained closely reflected the reality of the eco-environmental vulnerability of the DRA. 相似文献
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995.
氯代芳香化合物的KOW与对数拓扑指数和路径指数的相关性 总被引:3,自引:1,他引:2
本文用1gKow表征氯代芳香化合物的生物降解能力,并分别以对数拓扑指数(LTI)和路径指数(PI)为自变量,建立了新的预测模型。结果表明,回归方程的预测值与实验值十分吻合,相关系数接近于1,平均标准偏差小于0.1。 相似文献
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997.
Application of the simplified toxicity identification evaluation procedures to a chemical works effluent 总被引:5,自引:0,他引:5
Toxicity of a Chemical Works effluent from the Southeast China to the Daphnia magna was compared to determine the most representative aqueous fraction for simplified toxicity identification evaluation (TIE) studies. Toxicity characterization procedures revealed that the primary toxicant(s) was a nonpolar organic compound. Toxicity was recovered through C18 solid-Phase extraction and concentration steps. Gas chromatography-mass spectroscopy of these concentrates revealed the presence of chlorobenzene, nitrobenzene, naphthalene, 1-chloro-3-nitrobenzene, 1-chloro-4-nitrobenzene, 2-naphthol and aniline. The mass balance approach of TIE implicated the seven chemicals as the primary toxicants. The simplified TIE procedures can save our cost and time. The significance of the TIE results may indicate a more widespread problem what chemical(s) has priority to be controlled when being discharged. 相似文献
999.
基于分区的多目的地TCM模型及其在游憩资源价值评估中的应用——以九寨沟自然保护区为例 总被引:28,自引:3,他引:25
作为评估户外游憩价值的经典方法,旅行费用法穴TCM雪主要存在3种基本模型,即分区旅行费用法穴ZTCM雪、个人旅行费用法穴ITCM雪和随机效用法穴RUM雪。尽管这3种模型在理论和实践上都已相当成熟,却均无非常完善的方法来解决广为存在的多目的地环程旅行问题,致使该问题成为TCM研究应用中的难点和热点。论文根据九寨沟的实际情况,首次提出应用基于分区的多目的地TCM模型穴MZTC雪来评估九寨沟的游憩价值,得到2002年九寨沟自然保护区的总游憩价值为15.61×108元,人均1246.10元;其中消费者剩余为4.71×108元,人均375.92元,与国外最新游憩价值综述研究的结果非常接近。 相似文献
1000.