How does the spatial structure of habitat loss affect the eco-epidemic dynamics?

Habitat loss is considered as one of the primary causes of species extinction, especially for a species that also suffers from an epidemic disease. Little attention has been paid to the combined effect of habitat loss and epidemic transmission on the species spatiotemporal dynamics. Here, a spatial model of the parasite–host/prey–predator eco-epidemiological system with habitat loss was studied. Habitat patches in the model, instead of undergoing a random loss, were spatially clustered by different degrees. Not only the quantity of habitat loss but also its clustering degree was shown to affect the equilibrium of the system. The infection rate and the probability of successful predation were keys to determine the spatial patterns of species. The epidemic disease is more likely to break out if only a small amount of suitable patches were lost. Counter-intuitively, infected preys are more sensitive to habitat loss than predators if the lost patches are highly clustered. This result is new to eco-epidemiology and implies a possibility of using spatial arrangement of suitable (or unsuitable) patches to control the spread of epidemics in the ecological system.     

不同农作制对四川紫色丘陵区地表径流氮、磷流失的影响

以小麦(Triticum aestivum)-玉米(Zea mays)轮作制为基础,通过在仁寿县建立18个径流小区监测试验,对4种不同农作制与4种施肥水平下各小区径流水样中的氮、磷含量进行了分析.探讨了四川紫色丘陵区坡耕地氮、磷流失系数及其影响因素.结果表明,氮流失总量随施氮量而增加,在增量施肥+横坡种植方式下最大,为0.326 kg·hm~(-2);氮流失总量和流失系数在优化施肥+横坡种植+秸秆覆盖+植物篱方式下最小,其流失总量为0.270kg·hm~(-2),流失系数为0.009%0磷流失总量和流失系数在不同处理方式下总体上虽较为接近,但增量施肥+横坡种植方式下磷的流失总量最大,为0.020kg·hm~(-2);而优化施肥+横坡种植+秸秆覆盖+植物篱最小,为0.015kg·hm~(-2).研究表明,优化施肥、横坡种植、秸秆覆盖和植物篱拦蓄地表径流作用明显,是遏制耕地氮、磷流失的有效途径.     

Use of Basic Biological Information for Rapid Prediction of the Response of Species to Habitat Loss

Abstract:  Much research has focused on identifying traits that can act as useful indicators of how habitat loss affects the extinction risk of species, and the results are mixed. We developed 2 simple, rapid-assessment models of the susceptibility of species to habitat loss. We based both on an index of range size, but one also incorporated an index of body mass and the other an index combining habitat and dietary specialization. We applied the models to samples of birds (Accipitridae and Bucerotidae) and to the lemurs of Madagascar and compared the models' classifications of risk with the IUCN's global threat status of each species. The model derived from ecological attributes was much more robust than the one derived from body mass. Ecological attributes identified threatened birds and lemurs with an average of 80% accuracy and endangered and critically endangered species with 100% accuracy and identified some species not currently listed as threatened that almost certainly warrant conservation consideration. Appropriate analysis of even fairly crude biological information can help raise early-warning flags to the relative susceptibilities of species to habitat loss and thus provide a useful and rapid technique for highlighting potential species-level conservation issues. Advantages of this approach to classifying risk include flexibility in the specialization parameters used as well as its applicability at a range of spatial scales.     

Expanding the Global Network of Protected Areas to Save the Imperiled Mediterranean Biome

Abstract:  Global goals established by the Convention on Biological Diversity stipulate that 10% of the world's ecological regions must be effectively conserved by 2010. To meet that goal for the mediterranean biome, at least 5% more land must be formally protected over the next few years. Although global assessments identify the mediterranean biome as a priority, without biologically meaningful analysis units, finer-resolution data, and corresponding prioritization analysis, future conservation investments could lead to more area being protected without increasing the representation of unique mediterranean ecosystems. We used standardized analysis units and six potential natural vegetation types stratified by 3 elevation zones in a global gap analysis that systematically explored conservation priorities across the mediterranean biome. The highest levels of protection were in Australia, South Africa, and California-Baja California (from 9–11%), and the lowest levels of protection were in Chile and the mediterranean Basin (<1%). Protection was skewed to montane elevations in three out of five regions. Across the biome only one of the six vegetation types—mediterranean shrubland—exceeded 10% protection. The remaining vegetation types—grassland, scrub, succulent dominated, woodland, and forest—each had <3% protection. To guard against biases in future protection efforts and ensure the protection of species characteristic of the mediterranean biome, we identified biodiversity assemblages with <10% protection and subject to >30% conversion and suggest that these assemblages be elevated to high-priority status in future conservation efforts.     

建设用地空间错配理论、机制与效益损失:基于湖北省的实证

研究建设用地空间错配特征及内在机制,对纠正土地资源错配、优化土地资源配置机制具有现实意义。基于资源错配理论对土地资源错配理论开展梳理,提出建设用地错配机制假说,运用边际分析法和计量方法构建建设用地空间错配测度模型及机制检验模型,并以湖北省为例进行实证研究。结果表明:①1996—2017年湖北省建设用地过度错配与短缺错配并存,空间错配程度总体上有所改善,但局部地区错配程度加剧。②土地负外部性扩散、非均衡发展、非市场化供应、土地财政依赖等加剧了建设用地空间错配,优化产业结构、减少政府腐败、发展多元所有制等有利于降低建设用地空间错配程度。③1996—2017年湖北省建设用地空间错配效率损失由6.92%下降到3.84%,年均减少2.03%,效率损失得到缓解。④从损失值看,湖北省建设用地空间错配效率损失严重,1996—2017年累计经济损失达3.90×10^4亿元。主要结论:建设用地空间错配测度模型兼顾了土地配置的效率与公平,可以作为建设用地空间错配程度衡量的有效方法;建设用地空间错配已经成为阻碍经济增长的重要因素之一,纠正建设用地空间错配,能有效促进区域经济增长;土地市场配置和政府主导配置均会带来建设用地空间错配,建设用地配置中一个“有效的市场”与“有为的政府”结合十分必要且迫切。     

煤矿风井噪声控制的声学设计和阻力损失计算研究

煤矿风井空气流量大 ,噪声辐射强 ,正确合理的消声器声学设计和阻力损失计算是噪声控制成功的关键。     

混凝处理防止膜污染的作用与机理

通过膜过滤混凝上清液的方法 ,并比较膜进水和透过水中有机物相对分子质量分布的变化 ,探讨了混凝防止膜污染的作用和机理 .结果表明 ,相对分子质量大于 10 0 0的有机物是造成膜污染的主要因素 ,而相对分子质量小于 10 0 0的有机物对膜污染的影响较小 .尽管混凝能有效地去除相对分子质量较大的有机物 ,但混凝防止膜污染的效果与其投加量有密切的关系 .较低的混凝投加量 (2 5mg·L- 1 )防止膜污染的效果较差 ,较大的投加量 (>5 0mg·L- 1 )防止膜污染的效果较好 .UV2 54能更好地反映有机物对膜污染的影响程度 ,如何有效地去除这类有机物是防止膜污染的关键 .混凝防止膜污染的效果与去除相对分子质量大于 10 0 0的UV2 54的程度密切相关 .试验结果表明 ,混凝去除这类有机物的效果达到 5 0 %时 ,可有效地防止膜污染     

渗滤液与城市污水合并处理过程的有机物去除特征

以上海老港垃圾填埋场调蓄池的渗滤液,及其经厌氧甲烷化垃圾填埋柱循环回灌处理后的出水和其再经过混凝处理后的出水等3种不同处理水平的渗滤液为研究对象,分别以不同的比例与城市污水混合,采用好氧活性污泥法合并进行处理,对进出水的COD、UV254吸光度和溶解性有机物的分子量分布及污泥的脱氢酶活性进行了测定分析．结果表明：当渗滤液混合比例小于10％时,出水的COD和UV254吸光度随混合比例线性升高,污泥的活性相应线性降低;而当混合比例大于20％时．污泥活性阶跃降低,出水COD和UV254吸光度的升高超出线性范围．渗滤液混合比例为20％与比例为5％的混合污水相比．分子量1k～4k的溶解性有机物去除率显降低．渗滤液与城市污水合并处理的混合比例大于10％时,微生物的有机物降解能力会受到严重损害,且常规的渗滤液生物和物化预处理不能减轻此种损害．     

超小型液体旋流分离器的研究

这是用超小型液体旋流分离器从水中分离固体粒子的性能实验。在旋流分离器下向流排出口内插入一个圆锥流量调节器。实验中使用的固体粒子为玻璃球 ,平均粒子径为 4 84 μm。通过实验发现了装有圆锥流量调节器旋流分离器有较好的性能 ,与普通型的相比 ,其压力损失约减少 7% ,分离效率增加 10 %。     

大气质量污染损失率评价模型参数的GA优化

设定各项污染物在大气环境质量污染损失率评价模型中有相同参数值,采用具有全局优化的遗传算法(GA)对模型中的参数进行优化,得出了对各种大气污染物均适用的大气环境质量污染损失率计算公式及大气环境质量综合评价模型。该模型与其他多种评价模型用于大气环境实例进行评价比较,结果表明:该评价方法不仅原理直观,评价结果准确,而且计算简便,实用性强。