CAREER: The effects of non-rainfall moisture inputs on dryland ecosystem functions

旱地的广义定义是年平均降水量低于蒸发需要量三分之二的地区，占全球陆地面积的近40%，是地球上最大的陆地生物群落。全球约有25亿人居住在旱地，因此旱地具有重要的社会经济意义。非降雨降水成分（如雾和露）对旱地生态系统的影响是水文学中研究最少的方面之一。量化和确定旱地系统的各种非降雨水分来源对于预测未来气候变化下非降雨成分将如何变化以及旱地生态系统将如何作出相应的反应是不可或缺的。通过使用新兴技术、全面的实地观测和基于过程的建模，该项目将为了解旱地生态系统中非降雨投入的起源和影响迈出关键一步。该项目将包括广泛的社区外展，并教育各级学生（K-12，本科生和研究生），包括那些在STEM领域代表性不足的学生。这些拓展和教育活动包括针对三年级至九年级学生的教育模块开发、针对高中生的真实研究体验、针对高中教师的暑期教师培训项目、针对本科生的海外研究体验以及针对研究生的专业发展。尽管非降雨降水很重要，但维持旱地生态系统所需的非降雨投入的数量仍不清楚。此外，对于旱地系统，非降雨水的具体来源（例如，海水与当地地下水）以及雾和露的相对贡献尚不清楚。量化和确定旱地系统的各种非降雨水分来源对于预测未来气候变化下非降雨成分将如何变化以及旱地生态系统将如何作出相应的反应是不可或缺的。本研究的总体目标是通过稳定同位素（2H、17O和18O）和模型分析来评估非降雨输入对旱地生态系统功能的影响。实地研究将在纳米比亚一个长期存在的国际站（戈巴布研究和培训中心）进行，因为其独特的生态位置、事先的研究和在拟议地点进行实地研究的现有后勤。

Drylands, broadly defined as areas where mean annual precipitation is less than two-thirds of evaporative demand, account for nearly 40% of the global land surface and represent the largest terrestrial biome on the planet. Globally, ~2.5 billion people reside in drylands, and therefore drylands are socioeconomically important. The effect of non-rainfall precipitation components (e.g., fog and dew) on dryland ecosystems is one of the least studied aspects in hydrology. Quantifying and identifying the various sources of non-rainfall moisture to dryland systems are integral to predict how non-rainfall components will change under future climate change and how dryland ecosystems will respond accordingly. Through the use of emerging technology, comprehensive field observations and process-based modeling, this project will provide a key step toward understanding the origins and effects of non-rainfall inputs in dryland ecosystems. This project will include broad community outreach, and educate students at all levels (K-12, undergraduate and graduate), including those underrepresented in the STEM fields. These outreach and educational activities include education module development for third through ninth grade students, authentic research experiences for high school students, a summer teacher-training program for high school teachers, research abroad experience for undergraduate students, and professional development for graduate students. Despite the importance of non-rainfall precipitation, it remains unclear as to the amount of non-rainfall input that is needed to sustain dryland ecosystems. Furthermore the specific sources of non-rainfall water (e.g., ocean water vs. local groundwater), and the relative contribution of fog and dew, are not known for dryland systems. Quantifying and identifying the various sources of non-rainfall moisture to dryland systems are integral to predict how non-rainfall components will change under future climate change and how dryland ecosystems will respond accordingly. The overarching goal of this proposed research is to evaluate the effects of non-rainfall inputs on dryland ecosystem functions through stable isotope (2H, 17O and 18O) and modeling analyses. The field research will be conducted at a long-standing international station in Namibia (Gobabeb Research and Training Center) due to its unique ecological location, prior research and existing logistics for conducting field research at the proposed site.