ABSTRACT

Water-limited ecosystems are especially sensitive to precipitation changes, and understanding the controls on land-atmosphere interactions and how they influence larger scale feedbacks will become increasingly important as climatic and other global changes continue to alter the water availability in these ecosystems. Despite comprising a relatively large percentage of the Earth's land surface, water-limited ecosystems are poorly represented in land-surface and global circulation models. This research will address water limited ecosystems function by linking small scale processes investigated in field and experimental efforts with large scale processes using a modeling approach that takes advantage of a simple conceptual framework combined with remote sensing products. Over a decade of field work has highlighted the importance of deep soil moisture in the functioning of water-limited ecosystems. Emergent hypotheses on the role of deep soil moisture in water-limited ecosystems will be addressed using a simple framework based on moisture in two soil layers (e.g. surface layer: 0 - 20 cm, deep layer: 20 - 60 cm). This robust framework is ideal for developing and testing hypotheses in both educational and research settings. Furthermore, the project will use this framework to test hypotheses in other uniquely water-limited ecosystems (e.g. snow-dependent subalpine, arctic tundra). Plot- to ecosystem- scale findings will be used to support hypothesis testing at larger scales using a modeling approach capable of multiple layers of moisture and incorporating remote sensing products.

Nearly 40% of the global land surface is classified as arid to semiarid; a percentage that is almost certain to increase based on current climate trends. Historically, these water-limited areas have also been locations of major population increase. This problematic combination of sustained climate change and population growth creates fundamental changes to native ecosystems that will undoubtedly have major impacts on watersheds and rivers; these impacts are likely to exacerbate further climatic changes. This research emphasizes monitoring in water-limited ecosystems to better predict the behavior and functioning of these ecosystems under global change and also better understand their contribution to global water, carbon, and energy cycling. Further, the project will engage students (especially underprivileged and underrepresented students) in the process of science as a means to ready them for the workforce. This is particularly crucial with the growing need to train students to effectively communicate the importance of scientific research to the general public. The simple two-layer moisture framework highlighted in this research is ideal for tackling both of these integrated research and educational challenges.

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