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

9308065霍尔特一项关于栖息地破碎化的长期实验正在堪萨斯东部的草原森林交错带进行。 一个群岛的补丁，代表不同程度的破碎化，排列在6年的时间。在前六年的研究中，碎片化影响消费者的人口动态，和当地的持久性草本植物物种的克隆生命周期，但不影响当地物种丰富度或整体的演替率的措施。 预计在今后五年中，不成体系对演替动态的重大影响将开始显现，因为：1）存在从原始种子库中存在的物种到从外部源库（特别是乔木和灌木）定殖的物种的过渡，以及2）优势植物的高度正在增加，从而增强斑块内部和周围间隙生境之间的微环境差异，并因此增强边缘效应。 小型哺乳动物可能是木本植物群落建立的主导驱动因子，因此植物演替中的破碎化效应可能是小型哺乳动物群落破碎化效应的间接表现。 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、局部持久性和植物结构随破碎程度变化的动态。 它还将监测小型哺乳动物的空间分布，这些哺乳动物在减缓木本物种的入侵方面具有潜在的重要性，并使用围栏直接测量对幼苗存活率的影响。 这项研究是为数不多的栖息地破碎化的实验研究之一，并提供了一个系统，探索更普遍的问题，在生态dynamics.Research项目，如这是根本的更好地了解发生在社区内的关联过程。 这种理解将提供一个知识基础，了解随着景观更加细分，会发生什么。 它还可以提出维护系统完整性的改进措施。

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.