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

这项拟议的研究测试了三个假说，这些假说与俄勒冈州中部大型鼠尾草/蓝丛冰草群落中土壤性质的分形性变化和土壤食物网有关，这些群落正在被西方杜松亚种放牧和入侵。西方人。这些假设将通过两个地点的土壤样本来验证，根据分形抽样设计，在有和没有西方斑潜蝇的情况下；分析样本的有机碳、总氮、水分含量、pH、土壤动物和氮矿化率；通过将直线拟合到对数对数半方差图来计算数据的分维；并比较了不同地点的半方差函数的形状及其分维。这项研究意义重大，因为它检验了美国西南部沙漠中提出的一种假说，即放牧可能会导致草原生态系统中的木本植物入侵，从而增加土壤水分和养分的空间异质性，但认识到土壤空间变异的分形性质，也就是说，它们具有广泛的空间尺度的自亲和性和细节，并试图将变化模式与土壤食物网的结构联系起来。这项研究的结果将有助于理解影响半干旱生态系统长期利用的地理和生态过程。该项目进一步推动了VPW项目的目标，为女性提供通过研究提升她们在科学或工程领域的职业生涯的机会，并通过调查人员作为东道主校园榜样的更高知名度，鼓励其他女性在这些领域追求职业生涯。在该项目中，有助于第二个目标的拟议活动包括：教授题为“土壤空间变异性和森林生态学”的课程；领导阅读和讨论小组；提供咨询；组织一系列嘉宾研讨会，由从事土壤空间变异性和森林生态学相关领域工作的女科学家主持。

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.