LTREB: Long-term Studies of Population and Community Ecology in an Experimentally Fragmented Landscape

一项关于栖息地碎片化的长期实验正在堪萨斯州东部的草原森林交错带进行。在6年内排列了一个代表不同程度碎片化的补丁群岛。在研究的前六年，碎片化影响了消费者种群的动态，以及具有克隆生命周期的草本植物物种在当地的持久性，但不影响当地物种丰富度的衡量标准或总体演替速度。预计在接下来的五年中，片断化对演替动态的实质性影响应该开始出现，因为：1)正在从原始种子库中的物种过渡到从外部来源池中定居的物种，特别是乔木和灌木；2)优势植物的身高正在增加，从而加强了斑块内部与周围间隙生境之间的微环境差异，从而增强了边缘效应。小型哺乳动物可能是木本植物物种建立的主要驱动因素，因此植物演替中观察到的片断化效应可能是小型哺乳动物群落片断化效应的间接表现。该项目将利用地面调查、树冠分析技术、航空摄影和遥感技术，记录植物群落组成、当地持久性和植物建筑作为碎片化程度的函数的动态。它还将监测小型哺乳动物的空间分布，这些小型哺乳动物对减缓木本物种的入侵具有潜在的重要意义，并使用封闭物直接测量对幼苗存活的影响。这项研究是为数不多的栖息地破碎化实验研究之一，为探索生态动力学中更一般的尺度问题提供了一个系统。这样的研究项目对于更好地理解群落内发生的关联过程是基础的。这一理解将提供一个关于景观更细微碎片化的预期的知识基础。它还可能为维护系统完整性提出改进措施。

9308065HoltA long-term experiment on habitat fragmentation is underway in the prairie-forest ecotone in eastern Kansas. An archipelago of patches, representing different levels of fragmentation, was arrayed within a period 6 years. During the first six years of the study, fragmentation influenced consumer population dynamics, and the local persistence of herbaceous plant species with clonal life cycles, but did not affect measures of local species richness or the overall rates of succession. It is expected that during the next five, substantial effects of fragmentation upon successional dynamics should begin to appear, because: 1) there is a transition underway from species present in the original seed pool to species colonizing form external source pools, particularly trees and shrubs, and 2) the stature of the dominant plants is increasing, thereby enhancing microenvironmental differences between patch interiors and the surrounding interstitial habitats and hence edge effects. It is also expected that small mammal may be dominant driving factors in woody species establishment, and so fragmentation effects observed in plant succession may be indirect manifestations of fragmentation effects on the small mammal community. This project will document dynamics in plant community composition, local persistence, and plant architecture as a function of the degree of fragmentation, using both ground surveys, canopy analysis technology, aerial photography, and remote sensing. It will also monitor the spatial distributions of small mammals that are potentially important in slowing the invasion of woody species, and to use exclosures to directly measure effects on seedling survivorship. This study is one of the very few experimental studies of habitat fragmentation, and provides a system for exploring more general issue of scale in ecological dynamics.Research projects such as this are fundamental to the better understanding of the associative processes that occur within communities. This understanding will provide a knowledge base on what to expect as landscapes are more finely fragmented. It may also suggest ameliorative measures for maintaining system integrity.