Doctoral Dissertation Research: Connectivity and Biodiversity Conservation in Rural Landscapes

大多数热带森林已经从大片森林转变为由农田、牧场、次生林、人工林和森林碎片组成的复杂马赛克。热带雨林的这种快速变化是土地利用/覆盖变化的最重要类型之一，也是栖息地丧失和物种减少的主要原因之一。与此同时，热带地区数以亿计的人依靠天然热带森林谋生或作为维持生计的“安全网”。为了了解复杂的农村景观维持生物多样性的潜力，迫切需要了解农村景观的组成和结构(景观格局)对关键生态过程(如分散性和功能连通性)的影响。本论文的研究就是针对这些重要问题展开的。调查人员将研究乡村景观如何有助于维持墨西哥塞尔瓦拉坎多纳热带雨林的区域树木生物多样性。这项研究将模拟不同农村土地覆盖对种子传播的影响，以及这一过程如何在景观和区域层面影响森林物种的功能连通性。研究将分为两个阶段：分类和建模。卫星图像的分类将侧重于揭示淹没在“非森林”或“农业用途”类别之下的复杂土地覆盖类别。变化分析将显示景观结构如何在时间和空间上发生变化。在建模阶段，将通过亚像素分类和实地调查来量化景观对分散体交叉点的“渗透性”。然后，模拟不同功能基团不同分散剂对林木种子在不同渗透率的不同覆盖层中的分散情况。最后，将评估景观和区域层面的整体功能连通性，以及尺度变化对功能连通性检测的影响。研究结果将展示乡村景观中土地利用在保护生物多样性方面的不同潜力，以及景观和区域层面的土地利用/覆盖趋势。本研究旨在更好地理解乡村景观的组成和结构如何影响景观和区域层面的种子扩散和功能连通性等生态过程。了解这些动态及其维持生物多样性关键进程的潜力，将有助于更好地管理整个热带地区的这类景观。它的主要贡献是：a)制定了一个连续的“梯度”分类程序；b)所产生的结果将把农村景观纳入生态过程的研究，并推动对热带地区以人为中心的综合保护的探索；c)所提供的工具将为保护和发展利益之间的谈判提供信息，并将提供一种替代分类和概念方法，以解决过去难以解决的冲突。

Most tropical forests have been transformed from large expanses of forest into complex mosaics composed of croplands, pastures, secondary forests, plantations, and forest fragments. This rapid transformation of tropical forests is among the most significant types of land-use/cover change and one of the major causes of habitat loss and species decline. At the same time, hundreds of millions of people in the tropics are dependent on natural tropical forest for their livelihood or as a subsistence 'safety net'. To understand the potential of complex rural landscapes to maintain biodiversity, an understanding of the effects of rural landscape composition and structure (landscape pattern) on key ecological processes (such as dispersion and functional connectivity) is critically needed. This dissertation research addresses these important issues. The investigators will examine how rural landscapes contribute to the maintenance of regional tree biodiversity in the tropical rainforest of the Selva Lacandona, Mexico. The study will model the effect of different rural land covers on the dispersion of seeds, and how this process can influence the functional connectivity of forest species at the landscape and regional level. The research will have two phases: classification and modeling. The classification of satellite images will focus on revealing the complex land cover classes submerged under the 'non-forest' or 'agricultural use' class. A change analysis will show how landscape structure has changed through time and space. In the modeling phase, the 'permeability' of the landscape to the crossing of dispersers will be quantified by a subpixel classification and field surveys. Then, the dispersion of tree seeds, mediated by different dispersers according to functional groups and through different land covers with differential permeability, will be simulated. Finally, the overall functional connectivity at the level of the landscape and the region will be assessed, together with the effect of the change of scale on the detection of functional connectivity. The outcomes will demonstrate the differential potentials of land uses in rural landscapes to conserve biodiversity and the land use/cover trends at the landscape and regional level.This study seeks to develop a better understanding of how rural landscape composition and structure can influence ecological processes such as seed dispersion and functional connectivity at the landscape and regional level. The understanding of these dynamics and their potential to maintain key processes for biological diversity would contribute to better management of such landscapes throughout the tropics. Its major contributions are: a) the development of a procedure for continuous "gradient" classification, b) the results produced will incorporate rural landscapes into the study of ecological processes and advance the search for an integrative people-centered conservation in the tropics, and c) the tools provided will inform negotiations among conservation and development interests and will provide an alternative classification and conceptual approach to address conflicts that have proven difficult to resolve in the past.