Doctoral Dissertation Research: Vegetation Dynamics and Biogeomorphic Influences in a Highly Eroded Landscape

博士论文研究：高度侵蚀景观中的植被动态和生物地貌影响

• 批准号: 9900967
• 负责人: Kathleen Parker
• 金额: $ 1万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9900967&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Vegetation; Dynamics

Although the impact of vegetation cover on erosional processes has been studied extensively, far less attention has been given to the effects of accelerated soil erosion on vegetation structure and composition. Research in relatively stable, arid badlands suggests that the steep environmental gradients caused by fluvial erosion create correspondingly graded vegetation communities, but few studies have examined vegetation responses to the frequent geomorphic disturbance that occurs in actively eroding landscapes as well as relationships among geomorphic processes, topographic variables, and edaphic (soil-related) characteristics, and vegetation patterns in humid environments. This doctoral dissertation research study will investigate those relationships through a case study in Providence Canyons, Georgia, a landscape that has experienced severe soil erosion and deep gully incision over the last 150 years because of careless cotton-farming practices. Aerial photographic analysis will be used to characterize vegetation and geomorphic change occurring both spatially and temporally on a landscape scale over the past 60 years. Complementing this broader-scale analysis will be focused examinations of geomorphic, topographic, and edaphic variables that have primary influences on vegetation patterns, including the nature and frequency of geomorphic disturbance that characterize a particular portion of the landscape; slope aspect, configuration and steepness; gradient; elevation above the valley floor; valley width; soil texture; and soil nutrient levels. The doctoral candidate will measure vegetative and soil characteristics in a broad range of sites exhibiting differing geomorphic disturbance regimes and topographic position and will relate the variables using canonical correspondence analysis, classification analysis, and discriminant function analysis. On an applied level, this study will assist landscape managers in the restoration of severely eroded landscapes. More broadly, because of the unique blend of geomorphic and topographic variables present in these landscapes, this study will increase our understanding of the influence of those variables on vegetation composition, structure, and dynamics. This study will strengthen existing links between geomorphologists and biogeographers and will enable geomorphologists to refine erosion models with more specific vegetation variables. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.

虽然植被覆盖对侵蚀过程的影响已经得到了广泛的研究，但对加速土壤侵蚀对植被结构和组成的影响的关注远远不够。在相对稳定的干旱荒地上的研究表明，河流侵蚀造成的陡峭环境梯度产生了相应的梯度植被群落，但很少有研究调查植被对频繁发生的地貌扰动的响应，以及在湿润环境中地貌过程、地形变量、土壤特征和植被模式之间的关系。这篇博士论文研究将通过对佐治亚州普罗维登斯峡谷的案例研究来调查这些关系，普罗维登斯峡谷在过去的150年里经历了严重的土壤侵蚀和深深的沟壑切割，因为粗心的棉花种植实践。航空摄影分析将用于表征过去60年来在空间和时间上发生的景观尺度上的植被和地貌变化。为补充这一更广泛的分析，将重点检查对植被模式有主要影响的地貌、地形和土壤变量，包括具有景观特定部分特征的地貌扰动的性质和频率；坡度、形状和陡度；梯度;海拔：高于谷底的高度；山谷宽度;土壤质地;土壤养分水平。该博士候选人将在广泛的地点测量植被和土壤特征，这些地点表现出不同的地貌干扰制度和地形位置，并将使用规范对应分析、分类分析和判别函数分析将变量联系起来。在应用层面上，本研究将有助于景观管理者修复严重侵蚀的景观。更广泛地说，由于这些景观中存在着独特的地貌和地形变量的混合，这项研究将增加我们对这些变量对植被组成、结构和动态的影响的理解。这项研究将加强地貌学家和生物地理学家之间现有的联系，并将使地貌学家能够用更具体的植被变量来完善侵蚀模型。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。