Collaborative Research: RUI: Facilitation, Competition and Woody Patch Dynamics in a Savanna Parkland

9815796 BarnesSavanna研究强调树木对土壤、小气候和草的影响。树与树之间的相互作用以及这些相互作用如何影响萨卡纳的功能和动力学，人们知之甚少。此外，稀树草原的研究主要是在个体树木散布在草地基质中的情况下进行的。然而，树和灌木岛屿的形成是一种常见的，但很少研究的现象，在许多干旱的土地ecosystem.This合作项目将量化的机制，促进和竞争之间的相互作用的上层树，蜂蜜牧豆树，并在德克萨斯州中南部的亚热带稀树草原生态系统相关的林下灌木。该项目的目标是阐明与草地和开放的稀树草原的外貌转变为封闭的树冠刺林地斑块动态的机制。的具体目标是阐明与乔木灌木岛屿的启动和发展的机制，并预测如何在这些岛屿的物种相互作用的变化，随着时间的推移，在地形多样的景观。这项研究的方法将涉及选择性去除和相互移植实验相结合，将与资源（光，养分和土壤水分）的操纵和植物生长，叶片化学，叶片气体交换，植物/土壤水的关系和同位素丰度的测量相结合。研究结果将提高我们的能力，概括的作用，促进和竞争的演替和机制的木本植物增加草原和稀树草原，提高我们的能力，代表和parameterizing空间明确的模拟模型的乔木-灌木-草地生态系统，并直接有助于发展一个良好的基础，监测，管理和操纵草原和稀树草原生态系统。

9815796BarnesSavanna research has emphasized tree effects on soils, microclimate and grasses. Little is known of tree-tree interactions and how these might influence sacanna function and dynamics. Furthermore, savanna research has largely been conducted where individual trees are scattered throughout a grassy matrix. However, the formation of tree and shrub islands is a common, but little-studied phenomenon in many arid land ecosystems.This collaborative project will quantify mechanisms of facilitative and competitive interactions between an overstory tree, honey mesquite, and associated understory shrubs in a subtropical savanna ecosystem in south-central Texas. The goal of the project is to elucidate mechanisms of patch dynamics associated with the physiognomic transformation of grassland and open savanna to closed-canopy thorn woodland. The specific objectives are to elucidate the mechanisms associated with the initiation and development of tree-shrub islands, and to predict how species interactions in these islands change across topoedaphically diverse landscapes over time. The approach to this research will involve a combination of selective removal and reciprocal transplant experiments that will be coupled with manipulations of resources (light, nutrients and soil moisture) and measurements of plant growth, foliar chemistry, leaf gas exchange, plant/soil water relations and isotopic abundances. Results will increase our ability to generalize the roles of facilitation and competition in succession and mechanisms of woody plant increase in grasslands and savannas, enhance our ability to represent and parameterize spatially explicit simulation models for tree-shrub-grass ecosystems, and contribute directly to the development of a sound basis for monitoring, managing and manipulating grassland and savanna ecosystems.