A Spatial Model to Estimate Habitat Fragmentation and Its Consequences on Long-Term Persistence of Animal Populations

The increasing use of the landscape by humans has led to important diminutions of natural surfaces. The remaining patches of wild habitat are small and isolated from each other among a matrix of inhospitable land-uses. This habitat fragmentation, by disabling population movements and stopping their spread to new habitats, is a major threat to the survival of numerous plant and animal species. We developed a general model, adaptable for specific species, capable of identifying suitable habitat patches within fragmented landscapes and investigating the capacity of populations to move between these patches. This approach combines GIS analysis of a landscape, with spatial dynamic modeling. Suitable habitat is identified using a threshold area to perimeter ratio. Potential movement pathways of species between habitat patches are modeled using a cellular automaton. Habitat connectivity is estimated by overlaying habitat patches with movement pathways. The maximum potential population is calculated within and between connected habitat patches and potential risk of inbreeding within meta-populations is considered. The model was tested on a sample map and applied to scenario maps of predicted land-use change in the Peoria Tri-county region (IL). It (1) showed area of natural area alone was insufficient to estimate the consequences on animal populations; (2) underscored the necessity to use approaches investigating the effect of land-use change spatially through the landscape and the importance of considering species-specific life history characteristics; and (3) highlighted the model's potential utility as an indicator of species likelihood to be affected negatively by land-use scenarios and therefore requiring detailed investigation.     

林格曼数监测存在的问题及时间——林格曼数计算方法的探讨

分析并讨论了目前国内关于锅炉烟尘林格曼数（黑度级）监测计算几种取值方法存在的问题，对时间－林格曼数这一新的取值方法进行了探讨。     

入海河流对近岸海域海湾影响分析

利用污染指数法及相关系数法对盘锦市境内的河、海水质进行对比分析，从而得出近岸海域海湾水质主要受入海河流水质影响的结论。     

滇池细菌总数与有机碳、氮、磷的调查研究

通过对滇池水体一年多的定点采样工作,重点调查研究了草海、外海表层水中细菌数量及有机营养盐碳、氮、磷的季节变化规律,分析探讨了细菌总数与环境条件和有机营养盐之间的某些关系.对滇池富营养治理提出了一些建议,并提出利用微生物学的方法参与这一研究.     

东海区带鱼伏季休渔效果及其资源的合理利用

根据2002-2003年东海区带鱼年龄鉴定资料,并引用以往的带鱼渔业生物学研究结果,作为估算带鱼死亡系数和建立动态综合模型所需的有关参数值估算的依据,从而运用Ricker动态综合模型分析了在现行渔业条件下东海区带鱼伏季休渔效果和带鱼资源利用状况以及变更渔业利用情况对带鱼渔业所产生的影响。结果表明:在现行渔业下(tc=0.5a,F=2.61/a),东海区实施3个月的伏季休渔制度能使年平均资源量增加87%,年产量增加29%,渔获平均体重增加42%;带鱼资源的利用虽处于捕捞过度状态之中,但尚能承受较大的捕捞压力,资源结构利用不合理之处是捕捞大量的幼鱼群体,渔获个体依然过小,渔获平均体重仅为75g/ind.;单位补充量渔获量(Y/R)随tc变化的影响大于随F的变化,建议在维持现有伏季休渔制度下,应逐渐降低捕捞强度,并以提高起捕规格放大网目尺寸作为今后一个时期首选的渔业管理目标,应是较为现实的资源合理利用措施。     

Measurement of respiration amount of white birch(Betula platyphylla) population in the mountainousregion of Beijing

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Influence of chlorsulfuron herbicide on size of microbial biomass in the soil

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An approach to the fluctuation mechanism of ecotone

In this paper,the relationship among land productivity,population pressure and the fluctuation mechanism of ecotone is analyzed,taking coumties and banners of southeast Inner Mongolia plateau as an example,which is the most fragile part in the farming and husbandry interleaving belt of north China due to its severe desertification degree and low level of economic development.The Cv for the total output value of agriculture decreases from southeast to northwest,with the same rule as which the overloading population cumulated distributes,and both indicators have close relation with the high linear coefficient of 0.83.These reveal the fluctuation mechanism for ecotone:fluctuation of the level of economic development is a scientific and practical measure both to weakness degree and to instability of ecotone,because it is a synthesized response to the variation of climate as well as irrational land uses,which reinforce and magnify the fluctuation.In detail,the heavier the population overloading,the severer the grassland reclamation,the stronger the dependence of regional productivity on rainfall,the lower the level of economic development,the rougher the fluctuation of ecotone,but the weaker the PRED system.     

西藏自治区的土地、粮食和人口

本文讨论了西藏自治区土地系统、农业发展、人口增长和它们之间的相互关系。指出西藏土地类型复杂多样,极少土地能用于种植业,单位产量亦不高。人均占有粮食不足300kg,若干牧区不足50kg。粮食生产不能满足人口增长的需求。这种趋势在今后30年内仍将继续下去。 为了解决土地—粮食—人口三者之间关系的不协调,需采取若干切实措施。文中亦强调人口控制的必要。