Dissertation Research: Temporal Scale and the Consequences of Habitat Fragmentation: The Birds of Pine-Oak Forests in the Oaxaca Valley

[9801587]在破碎化生态系统的研究中，空间尺度得到了很好的考虑，但时间尺度的影响在很大程度上被忽视了。大多数碎片化研究集中在101 - 102年的时间尺度上的人为碎片化情况。在这个时间尺度内，动物群预计仍处于放松的动态状态。然而，自然破碎的系统提供了一个机会来观察更古老的破碎方案（103 - 104年），潜在地允许分析平衡条件下的响应模式。墨西哥南部的瓦哈卡河谷是一个自然破碎的生态系统，是研究栖息地破碎化长期影响的理想场所。一万两千年前，潮湿的松栎林是整个地区的主要植被类型。这种森林类型现在仅限于高海拔地区。在本研究中，将对这些残存斑块中的留鸟群落进行清查，描述其分布格局以及与斑块特征相关的鸟类物种变异。分布数据将使用现有的历史标本数据和实地调查完成的调查。碎片将根据直接实地测量、专题地图咨询和遥感图像数据进行描述。我们已经在人为破碎化的生态系统中测试了强有力的新统计技术，这些技术将被应用于理解时间尺度对破碎化对鸟类的影响。进一步的分析将集中在分类群的功能群上，如喂养行会、系统发育谱系等，以提供对所涉及过程的更详细的了解。研究结果将用于设计保护生态系统鸟类多样性的保护区系统。

9801587 Peterson Spatial scale has been considered carefully in the study of fragmented ecosystems, but the effects of temporal scale have been largely overlooked. Most fragmentation studies focus on anthropogenically fragmented situations that were largely fragmented on a time scale of 101 - 102 yr. This is a time scale within which faunas are expected to still be in the dynamics of relaxation. Naturally fragmented systems, however, provide an opportunity to view older fragmentation schemes ( 103 - 104 yr), potentially allowing analysis of response patterns under equilibrium conditions. The Oaxaca Valley in southern Mexico represents a naturally fragmented ecosystem, ideal for the study of the long-term effects of habitat fragmentation. Twelve thousand years ago, humid pine-oak forest was the dominant vegetation type throughout the region. This forest type is now restricted to high elevations. In the proposed study, the resident bird communities in these relict patches will be inventoried, distribution patterns described and avifaunal variation related to patch characteristics. Distributional data will be compiled using existing historic specimen data, and inventories completed by field inventories. Fragments will be described based on direct field measurement, consultation of thematic maps, and data from remotely sensed imagery. Robust new statistical techniques, which we have tested in anthropogenically fragmented ecosystems, will be applied to understanding influences of temporal scale on effects of fragmentation on avifaunas. Additional analyses will focus on functional groups of taxa, such as feeding guilds, phylogenetic lineages, etc., to provide more detailed understanding of processes involved. Results will be applied to designing a reserve system for maximal preservation of the bird diversity of the ecosystem.