California Institute for Water Resources
California Institute for Water Resources
California Institute for Water Resources
University of California
California Institute for Water Resources

Assessment of water storage for management of California’s oak woodlands

Summary:

Oak woodlands are one of the most biologically diverse habitats in California, spread across ten percent of the state. They are also increasingly stressed in a warming and drying climate. Understanding water movement and storage is especially important for the prediction of ecosystem health in these systems, and we are applying a suite of novel approaches to better understand water storage and movement in semi-arid coastal oak woodlands. Our goal with this project is to understand possible mechanisms for oak resilience to future shifts in temperature and drought conditions.

Investigator:

Margaret Zimmer, Twitter: @margaret_zimmer
Assistant Professor in Earth and Planetary Sciences
UC Santa Cruz

Project description:

Oak woodlands cover approximately ten percent of California, represent one of the most biologically diverse habitats in the state, and provide a broad range of vital ecosystem services. At the heart of these systems are the oak trees. Throughout their multi-century lifespans, oak trees provide a multitude of services, including water redistribution to shallow soil zones, habitat for high fungal diversity, and shade and sustenance for mammals in otherwise sparsely vegetated landscapes. Without oak trees, these unique ecosystems could not thrive. Thus, the conservation of these ecosystems and their iconic oak trees are and will continue to be a critical policy and management priority to the state of California.

How ecosystems process and route water governs drought resilience, groundwater recharge, water resource availability, and landslide, flood, and wildfire risks. Understanding water movement and storage is especially important for the prediction of ecosystem health in a warming and drying climate. Yet our understanding of the processes that ultimately determine water availability in California’s diverse ecosystems is limited.

For this project, we are applying a suite of novel isotopic, geophysical, and ecohydrologic approaches to better understand water storage and movement in a semi-arid coastal watershed in California’s southern Diablo Mountain Range. At the University of California’s Blue Oak Ranch Reserve, we are quantifying precipitation inputs, the above and below-ground physical and biological architecture, and the resulting water flowpaths.

We are also investigating the subsurface depth from which oak trees take up water to determine if this depth of plant-water uptake changes seasonally or in response to variable wetness conditions, such as droughts or excess precipitation. Our goal is to understand possible mechanisms for oak resilience to future shifts in temperature and drought conditions.

Preparing ground penetrating radar in the field. Photo by Noah Lyman.
Preparing ground penetrating radar in the field. Photo by Noah Lyman.

Surveying topography at Blue Oak Ranch Reserve. Photo by Kerri Johnson.
Surveying topography at Blue Oak Ranch Reserve. Photo by Kerri Johnson.

Running seismic refraction. Photo by Margaret Zimmer.
Running seismic refraction. Photo by Margaret Zimmer.

Coyote Knoll at Blue Oak Ranch Reserve. Photo by Kerri Johnson.
Coyote Knoll at Blue Oak Ranch Reserve. Photo by Kerri Johnson.

Webmaster Email: faith.kearns@ucop.edu