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

这项研究项目将检验这样一个普遍假设，即荒漠化通过增加水和氮的时空异质性，改变了以前相对均匀的水和氮的分布，导致奇瓦瓦沙漠生态系统的群落组成和生物地球化学过程发生变化。Jornada实验牧场(新墨西哥州南部)有75年的牧场研究历史，它记录了植被覆盖的广泛变化--从多年生草原到几种灌木丛--这是荒漠化的结果之一。这项工作将包括测量净初级生产力、根系生长、分解、土壤水分动态、地表水文学、动物种群动态、动物产生的土壤干扰、氮循环过程以及广泛生态系统中氮和碳的稳定同位素分布，范围从黑色格拉玛(Bouteloua Eriopoda)草原到沙化的持久灌木丛(Larrea Tridentata)，塔尔布希(Flourencia Cernua)和麦斯奎特(Prosopis Gladulosa)。沙漠化的概念模型将通过长期的水量增加和水和养分的机械均质化来检验。这些研究的数据将被用来对过程模型进行参数化。对水、风和气体传输的测量以及连续的导流实验将为沙漠景观模型提供数据。来自植被和土壤卫星遥感的数据将纳入约尔纳达盆地的动态地理信息系统模型。对于该项目的继续下去，机构支持仍然是极好的。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，应该被证明是非常有益和富有成效的。这一研究项目的结果应该会产生对广泛的生态学领域具有基础的重大发现。此外，结果应该对未来更好地开明地管理干旱土地资源很重要。

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 chreosotebush (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 dynamics 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 finding that are fundamental to the broad field of ecology. Additionally, results should be important to the future, better enlightened management of arid land resources.