Doctoral Dissertation Research: Integrating Image Spectroscopy and Microbial Biogeochemistry to Analyze Woody Shrub Encroachment

本博士论文旨在研究半干旱区灌木入侵对植物和土壤养分动态的景观效应。灌木入侵是全球旱地生态系统的持续威胁，通过改变植物群落多样性、净初级生产力和土壤功能，从根本上改变了生态系统过程。本博士论文研究项目将采用创新的方法，将高光谱遥感数据与土壤生物地球化学和微生物参数野外测量相结合，推断叶片化学，量化灌木入侵对旱地养分动态的影响。该项目将更全面地了解微生物群落和植物群落的空间动态，它们是由生物地球化学循环联系在一起的。该项目包括一个强大的教育组成部分，为K-12培训提供机会，并为当地服务不足的社区提供持续的外展和教育倡议。此外，K-12教师将参与以探究为基础的STEM课程开发。作为博士论文研究改进奖，该奖项将为有前途的学生提供支持，使他们能够建立强大的独立研究事业。高光谱成像为研究生态系统结构的大尺度变化及其对生态系统服务的影响提供了独特的机会。该博士生将整合土地覆盖遥感数据产品与植物和土壤养分动态的原位测量，以确定灌木入侵如何影响亚利桑那州东南部景观中的植物化学，土壤微生物群落和活动以及生态系统过程。这个项目的结果将确定(1)土壤养分、地形和灌木和草的丰富度之间的联系；(2)灌木入侵对景观尺度养分动态的潜在影响；(3)利用成像光谱为土地管理实践提供信息。这种综合方法提供了在景观尺度上对土壤养分有效性和生物地球化学循环进行革命性研究的机会，并监测不同植被入侵管理策略的效果。

This doctoral dissertation research will investigate the landscape-scale effects of shrub encroachment on plant and soil nutrient dynamics in a semi-arid region. Shrub encroachment, a persistent threat to dryland ecosystems worldwide, fundamentally alters ecosystem processes by changing plant community diversity, net primary productivity, and soil functioning. This doctoral dissertation research project will use innovative methods that combine hyperspectral remotely sensed data with field measures of soil biogeochemistry and microbial parameters to infer foliar chemistry and quantify the impacts of shrub encroachment on nutrient dynamics in drylands. The project will provide a more holistic understanding of the spatial dynamics of microbial communities and plant communities that are linked by biogeochemical cycling. The project includes a strong educational component by providing opportunities for K-12 training and ongoing outreach and education initiatives with local underserved communities. In addition, K-12 teachers will be involved in inquiry-based STEM curriculum development. As a Doctoral Dissertation Research Improvement award, this award will provide support to enable a promising student to establish a strong independent research career.Hyperspectral imagery offers a unique opportunity to study large scale shifts in ecosystem structure and their effects on ecosystem services. The doctoral student will integrate land cover remote sensing data products with in situ measurements of plant and soil nutrient dynamics to determine how shrub encroachment affects plant chemistry, soil microbial communities and activity, and ecosystem processes, across the landscape in southeastern Arizona. Outcomes from this project will determine (1) the link between soil nutrients, topography and the abundance of shrubs and grasses; (2) the potential effects of shrub encroachment on landscape-scale nutrient dynamics; and (3) the utility of imaging spectroscopy to inform land management practices. This integrative approach offers the opportunity to revolutionize research on soil nutrient availability and biogeochemical cycling at landscape scales, and monitor the effects of different vegetation encroachment management strategies.