Dissertation Research: The Ecological Implications of HabitFragmentation: A Field Manipulation of Patch Size and Connectivity

生境破碎化现象极为普遍，是指原生植被的残余面积缩小，并与相邻的连续生境分离。这种现象对地球的生物多样性构成最严重的威胁之一。生境碎片的生态观测表明，物种多样性随斑块大小的减小而减小。动物经常使用碎片之间的植被连接，并被认为可以增加物种在碎片中持续存在的可能性。然而，迄今为止发表的研究有几个主要的局限性：通常在隔离之前没有测量斑块；很少有证据表明动物优先使用斑块之间的连接；生物的基本生活史特征往往没有与它们对栖息地破碎化的数值响应相联系。在野外条件下通过实验操纵片段大小和连通性，并将操纵样地中的物种反应与相邻对照样地的物种反应进行比较的研究尚未发表。这里提出的研究将在美国科罗拉多州博尔德附近的原生混合草地上进行，包括实验性地创建三种大小的栖息地斑块，并控制其与相邻连续栖息地的连接是否存在。模拟了边缘条状序列、廊道序列、分散斑块序列、分散斑块序列和四核序列4种土地转化破碎化基本序列的空间格局。4个序列同时将相同面积的草地从完整生境转化为清除生境，但完整生境的空间形态在不同序列之间存在差异。通过研究昆虫动力学，他将能够研究破碎化过程阻碍或增强动物种群数量的程度。除了研究实验区和对照区植物和昆虫物种丰富度和多样性的总体模式外，他还将比较三种表现出不同程度的敏捷性和摄食方式的焦点昆虫物种的运动反应。研究结果将有助于他们理解特定空间结构的生态影响，并可能指导生态学家以及设计师和规划者在土地利用项目方面的决策。

The phenomenon of habitat fragmentation, when remnants of native vegetation are reduced in size and separated from adjacent, continuous habitat, is extremely widespread and poses one of the most serious threats to the earth's biological diversity. Ecological observations of habitat fragments have shown that in general, species diversity decreases as patch size decreases. Vegetated connections between fragments are often used by animals, and are presumed to increase the probability of species' persistence in fragments. However, studies published to date have several major limitations: Patches are typically not measured prior to isolation; it has rarely been shown that animals preferentially use connections between patches; and organisms' basic life history characteristics are often not examined in relation to their numerical response to habitat fragmentation. No studies are published which have experimentally manipulated both fragment size and connectivity under field conditions and compared species' responses in the manipulated plots to those in adjacent control plots. The research proposed here, to be done in native mixed- grass prairie near Boulder, Colorado, USA, involves experimentally creating habitat patches of three sizes and manipulating presence or absence of connectivity to adjacent, continuous habitat. The research will also simulate the spatial configurations in four basic sequences of land transformation and fragmentation: edge strip sequence, corridor sequence, dispersed patch sequence, dispersed patch sequence and four nuclei sequence. The four sequences will simultaneously convert equal areas of grassland from intact to cleared habitat, but the spatial configuration of the intact habitat will vary among sequences. By studying insect dynamics, he will be able to examine the extent to which animal populations are impeded or enhanced by fragmentation processes. In addition to examining overall patterns of plant and insect species richness and diversity in experimental and control plots, he will compare the movement responses of three focal insect species which exhibit different degrees of vagility and modes of feeding. The results will contribute to their understanding of the ecological implications of particular spatial configurations, and will potentially guide ecologists as well as designers and planners in their decisions regarding land use projects.