Integrating measures of grassland function using Remote Sensing

草原提供重要的全球生态系统服务，对干扰和入侵很敏感，并且容易发生快速的功能崩溃。近几十年来，由于强烈的人类活动和气候变化，世界范围内的草地已经退化，这种退化不仅威胁到生态系统，而且对生态系统服务产生了负面影响。退化带来的压力强调了了解、评价和监测草地生态系统的必要性。几十年来，研究使用遥感工具来确定草地生长和生产力的单独测量，如覆盖度、生物量、叶面积指数、冠层高度、覆盖度、结构异质性以及燃烧和放牧效应。虽然这种方法提高了我们对如何孤立地监测草原群落特定要素的理解，但在评估生态系统健康及其服务方面继续取得进展的一个障碍是将不同的要素和方法整体地整合起来。因此，我的计划的长期目标是在保持可持续的草原生态系统的同时，为实现最佳和高质量的生态系统服务做出贡献。利用遥感和地理空间方法检测和有效评估有害物种的影响的方法的不确定性阻碍了草地综合评价。因此，我建议将木本植物入侵（WPE）纳入本提案的草地生态系统健康评价中。WPE是一种自然的生态系统过程，但由于气候变化的影响和对WPE机制缺乏明确认识，特别是在加拿大草原，WPE已成为草原生态系统健康的威胁，而在过去，加拿大草原的WPE并不是一个问题。利用遥感和空间技术了解草原WPE存在两个主要挑战。首先，木本植物覆盖具有高度的异质性，导致混合像元包含各种类型的覆盖。这是因为草原出现在不同的WPE阶段。其次，木本植物具有典型的健康植被光谱特征，难以与健康的生产性禾本科植物区分开。因此，我的五年目标是：1)开发利用遥感评估草原WPE的有效方法；2)利用遥感、地理信息科学和空间分析技术，了解草原WPE的驱动因素；3)将WPE纳入草地生态系统健康评价，促进WPE建模。我的研究致力于了解加拿大的草原生态系统，并努力保持它们在生态和经济上的健康。预期结果将揭示加拿大草原WPE学术的驱动因素，为问题提供潜在的解决方案，并获得维持草原生态系统服务的新知识。这个项目也将为培养高素质的人才提供一个很好的机会。

Grasslands provide vital global ecosystem services, are sensitive to disturbance and invasion, and are prone to rapid functional collapse. Grasslands worldwide have been degraded in recent decades due to intense human activity and climate change, and this degradation not only threatens ecosystems, but negatively affects ecosystem services. The pressures from degradation emphasize the need to understand, evaluate, and monitor grassland ecosystems. For decades, studies have used remote sensing tools to determine solitary measures of grassland growth and productivity, such as cover, biomass, leaf area index, canopy height, cover, structural heterogeneity, and burn and grazing effects. While this approach has advanced our understanding of how to monitor specific elements of the grassland community in isolation, a barrier to continued progress in assessing ecosystem health and its services is to integrate different elements and approaches holistically. Therefore, the long-term objective of my program is to contribute to achieving optimal and high-quality ecosystem services while maintaining sustainable grassland ecosystems. A comprehensive grassland assessment is hindered by uncertainties of understanding the expansion of unwanted species and the methods to detect and effectively assess their impacts using remote sensing and geospatial methods. Thus, I propose to focus on woody plant encroachment (WPE) and integrate this within grassland ecosystem health assessments for this proposal. WPE is a natural ecosystem process but has become a threat to grassland ecosystem health because of the effects of climate change and lack of a clear understanding of the WPE mechanisms especially in Canadian prairies, a location where WPE was not an issue in the past. There are two major challenges to understand WPE in grasslands using remote sensing and spatial techniques. First, woody plant cover is highly heterogeneous leading to mixed pixels that include various types of cover. This is because grasslands appear in various WPE stages. Second, a woody plant has typical healthy vegetation spectral features that are hard to separate from healthy productive grass species. Therefore, my five-year objectives are to 1) develop effective approaches to assess WPE in grasslands using remote sensing; 2) understand the drivers of WPE in grasslands using remote sensing, geographic information science, and spatial analytical techniques; and 3) integrate WPE into grassland ecosystem health assessment and facilitate WPE modelling. My research is devoted to understanding Canadian grassland ecosystems and I strive to keep them healthy ecologically and economically. The expected results will reveal the driving factors of WPE scholarly in the Canadian prairies, provide potential solutions for the issues, and gain new knowledge in maintaining grassland ecosystem services. This program will also provide a great opportunity for training high quality personnel.