REU: Interactions in Time and Space Variability in a Chihuahuan Desert Ecosystem: Jornada LTER

本研究项目将检验沙漠化通过增加水氮的时空异质性而改变了以前相对均匀的水氮分布的一般假设，从而导致奇瓦瓦沙漠生态系统群落组成和生物地球化学过程的变化。拥有75年牧场研究历史的Jornada实验牧场（新墨西哥州南部）记录了植被覆盖的广泛变化——从多年生草地到几种灌木地——这是荒漠化的一个结果。这项工作将包括测量净初级产量、根系生长、分解、土壤水分动态、地表水文学、动物种群动态、动物产生的土壤扰动、氮循环过程和广泛生态系统中氮和碳的稳定同位素分布，从黑草甸到沙漠化，木蔷薇（Larrea tridentata），柏树（Flourencia cernua）和豆科植物（Prosopis gladulosa）的宿存灌木。将通过长期增水和水与养分的机械均质化来检验沙漠化的概念模型。这些研究的数据将用于参数化过程模型。水、风和气体输送的测量以及连续的导流实验将为沙漠景观模型提供数据。植被和土壤的卫星遥感数据将纳入约纳达盆地的动态地理信息系统模型。继续进行这一项目的体制支持仍然很好。设施非常好。涉及几名调查人员的三机构合作安排经过深思熟虑，应该证明是非常有益和富有成效的。这项研究项目的结果将产生对生态学广泛领域具有根本性意义的重大发现。此外，研究结果对未来更好地管理干旱区资源具有重要意义。

This research project will examine the general hypothesis that desertification has altered a previous, relatively uniform distribution of water and nitrogen by increasing their spatial and temporal heterogeneity, leading to changes in community composition and biogeochemical processes in Chihuahuan Desert ecosystems. The Jornada Experimental Ranch (southern New Mexico), with a 75-year history of rangeland research, has documented extensive changes in vegetation cover - from perennial grassland to several kinds of shrublands - which are one result of desertification. The work will include measurements of net primary production, root growth, decomposition, soil water dynamics, surface hydrology, dynamics of animal populations, animal-produced soil disturbance, nitrogen cycling processes, and stable isotope distributions of nitrogen and carbon in widespread ecosystems, ranging from black grama (Bouteloua eriopoda) grassland, to desertified, persistent shrublands of creosotebush (Larrea tridentata), tarbush (Flourencia cernua) and mesquite (Prosopis gladulosa). A conceptual model of desertification will be tested by long-term water augmentation and mechanical homogenization of water and nutrients. Data from these studies will be used to parameterize process models. Measurements of water, wind, and gaseous transport and run-on diversion experiments will provide data for a desert landscape model. Data derived from satellite remote sensing of vegetation and soils will be incorporated into a dynamic geographic information system model of the Jornada Basin. Institutional support remains excellent for the continuation of this project. Facilities are very good. The three-institution collaborative arrangement involving several investigators has been well thought out and should prove to be highly beneficial and productive. Results from this research project should yield major findings that are fundamental to the broad field of ecology. Additionally, results should be important to the future, better enlightened management of arid land resources.