Desertification, Soil Nitrogen Mineralization, and the Fractal Nature of Soil Spatial Variation in J. Occidentalis Communities of Central Oregon (Ecosystem Studies): VPW

这项研究测试了三个假设， 对土壤分形性质变化的否定 特性和土壤食物网在大山艾树/bluebunch 俄勒冈州中部的小麦草群落， 入侵植物为北美圆柏Juniperus occurentalis subsp. [咒语] 将通过在两个地点取样土壤来检验这些假设， 有和没有J. occurentalis，根据分形 取样设计;分析样品的有机碳，总量 氮、含水量、pH值、土壤动物和氮 矿化率;计算分形维数 通过将直线拟合到双对数半变异函数来获得数据;以及 比较半变异函数及其分形的形状 场地之间的距离。 这项研究具有重要意义 因为它验证了一个假设， 美国西南部表示，取消认证可能会发生， 草原生态系统中木本植物的入侵， 放牧增加了土壤的空间异质性 水和养分，但认识到土壤的分形性质 空间变化，即它们具有自相似性和细节 作为一个广泛的空间尺度，并试图将 土壤食物网结构的变化模式。 这项研究的结果将有助于了解 地理和生态过程的影响， 半干旱生态系统术语的使用。 该项目进一步促进了VPW 方案目标为妇女提供机会， 通过以下方式推进他们在科学或工程领域的职业生涯： 研究，并鼓励其他妇女追求事业， 这些领域通过调查人员的提高能见度， 学校里的榜样 本工程 有助于实现第二个目标的拟议活动 包括：讲授题为“土壤空间变异性 和森林生态学;”领导阅读和讨论小组; 提供咨询;并组织一系列客座研讨会， 妇女科学家提交的报告 土壤空间变异与森林生态学

The proposed research tests three hypotheses relating decertification to changes in the fractal nature of soil properties and to soil food webs in big sagebrush/bluebunch wheatgrass communities in central Oregon which are grazed and being invaded by Juniperus occidentalis subsp. occidentalis. The hypotheses will be tested by sampling soils in two sites, with and without J. occidentalis, according to a fractal sampling design; analyzing samples for organic carbon, total nitrogen, moisture content, pH, soil fauna, and nitrogen mineralization rates; calculating the fractal dimension of the data by fitting straight lines to log-log semivariograms; and comparing the shapes of the semivariograms and their fractal dimensions between the sites. The research is significant because it tests a hypothesis developed in deserts of the southwest U.S. stating that decertification may occur as invasion of wood plants in grassland ecosystems as the result of grazing, which increases the spatial heterogeneity of soil water and nutrients, but recognizes the fractal nature of soil spatial variation, i.e. that they have self-affinity and detail as a wide range of spatial scales, and attempts to relate the patterns of variation to the structure of soil food webs. The results of this research will contribute to understanding of geographical and ecological processes affecting the long term use of semi-arid ecosystems. The project furthers VPW program objectives to provide opportunities for women to advance their careers in science or engineering through research, and to encourage other women to pursue careers in these areas through the investigators' enhanced visibility as role models on the host campuses. In this project, the proposed activities which contribute to the second objective include: teaching a course entitled, "Soil spatial Variability and Forest Ecology;" leading reading and discussion groups; advising; and organizing a series of guest seminars to be presented by women scientists working in fields related to the subject of soil spatial variability and forest ecology.