Dissertation Research: Phosphorus Cycling in Semiarid Woodlands: Potential Consequences of Global Climate Change

本项目验证了全球变暖改变磷循环并触发松-桧生态系统生物反馈机制的假设。目的是量化土壤温度升高和湿度降低对生物地球化学磷循环的影响以及优势植物物种对林地演替的响应。将对不同温度和湿度处理下的土壤进行初步实验室研究。在为期一年的野外研究中，对亚利桑那州中北部一个早期演替区和一个成熟的松柏群落的土壤气候进行了控制。复制因子设计将用于测试无机、有机、微生物和植物有效磷库和通量的变化。土壤磷酸酶活性将作为有机磷矿化的一个指标进行检测。小松、杜松和蓝草的磷重吸收效率将被用作测量植物内部磷循环变化对土壤变暖的响应。该项目将确定土壤气候变化介导的无机和有机过程以及植物和微生物的生物活性，这是了解气候变化条件下磷动态和生态系统功能的关键。本研究可视为全球变化条件下区域尺度生物地球化学磷循环的一个案例研究。

This project tests the hypothesis that global warming alters phosphorus cycling and triggers biological feedback mechanisms in pinyon-juniper ecosystems. The intention is to quantify the consequences of increased soil temperature and decreased moisture on biogeochemical phosphorus cycling and the response of dominant plant species relative to woodland successional development. An initial laboratory study will be conducted with soils incubated under various temperature and moisture treatments. During a one year field study, soil climate will be manipulated in an early successional and a mature pinyon-juniper community of north- central Arizona. A replicated factorial design will be used to test for changes in inorganic, organic, microbial, and plant available phosphorus pools and fluxes. Soil phosphatase activity will be examined as an indicator of organic phosphorus mineralization. Phosphorus reabsorption efficiency in pinyon, juniper, and blue grama will be used as a measurement of plant internal changes in phosphorus cycling in response to a soil warming. This project will identify the inorganic and organic processes mediated by an altered soil climate and the biological activity of plants and microbes that are key to understanding phosphorus dynamics and ecosystem function under conditions of climate change. This research may be viewed as a case study for biogeochemical phosphorus cycling at a regional scale under conditions of global change.