In partnership with research hydrologists Lorraine and Alan Flint of the USGS California Water Science Center, we are advancing our basic understanding of the water cycle in California’s geologically complex Coast Ranges (Flint et al. 2012b). We focus on rainfall-driven hydrology in the context of tectonically modified lithologies using a high-resolution (10 m) Basin Characterization Model (BCM) for the reserve now complemented by weather, soil moisture, stream flow and spring flow monitoring. This monitoring set-up captured unique data regarding the impacts of California’s recent drought on the water cycle. These included soil moisture measurements that we correlated to plant physiology and showed that due to accumulated climatic water deficits, soils actually dried out below the wilting point, often treated as a lower limit to soil moisture conditions. The development of the BCM was supported by TBC3 and is now used across all of California, including by the CA Department of Water Resources, and is available via the USGS for ecological research and climate adaptation applications. For relevant publications please refer to Flint et al. (multiple), Weiss et al. (multiple), Byrd et al. 2014, Andregg et al. 2015, Micheli et al. 2012.

FogNet is a collaborative fog water monitoring effort between UC Santa Cruz, Moss Landing Marine Laboratories, CSU Monterey Bay, Humboldt State Marine Labs, Bodega Bay Marine Labs, San Francisco State University, Pepperwood and the US Geological Survey. The goal is to quantify fog water deposition across a spatially extensive network using standard passive fog collectors and to sample fog water for chemical characterization using active fog collectors during summer advective fog events. Of particular interest has been the discovery of monomethyl mercury (MMHg) in fog water. PI Peter Weiss-Penzias (UC Santa Cruz) is testing the hypothesis that a volatile form of mercury (dimethyl mercury) produced in the coastal ocean can evade the sea water and be incorporated into cloud droplets, whereby it can deposit to terrestrial ecosystems and become an important contributor to MMHg to these environments. This project is in part NSF-funded via Peter Weiss-Penzias et al. Investigations on the cycling of mercury from the ocean to fog and deposition to land in coastal California (NSF 1333738). For relevant publications please refer to Caole et al. 2015, Fernandez et al. 2014, Torregrosa et al. (multiple), Scholl et al. 2014, Sahba et al 2015 and Weiss-Penzias et al. (multiple).

Principal Investigator David Ackerly (UC Berkeley, Department of Integrative Biology) and his lab are addressing the interaction of biotic and abiotic factors in the context of topographic environmental gradients and community composition, and their influence on seedling/sapling regeneration and successional trajectories in a changing climate. This study integrates observational, experimental and modeling approaches developed in the context of an emerging long-range study of California oak woodland dynamics. The project bridges a critical gap between statistical species distribution models and mechanistic studies of plant physiology and performance across climate gradients. The results will advance understanding of landscape-scale water deficits experienced by tree species with contrasting hydraulic strategies. This project is supported in part by NSF (1457400, see below). For relevant publications please refer to Ackerly et al., Cornwell et al., Papper et al.

Dawson, Ackerly and Thompson (UC Berkeley) utilized Pepperwood as a field site in this NSF-funded project (1441396) designed to take advantage of a once-in-a century Californian drought to study the effects of water stress in plant species growing in different habitats in order to evaluate how different plant adaptations lead to a spectrum of drought stress and susceptibility to ecosystem change. The project entailed physiological measurements as indicators of drought stress, specifically leaf water potentials, stomatal conductance, native embolism and canopy area. The effects of the drought on photosynthesis and plant carbon stores were evaluated using carbon isotopes as an indicator and sources of water used by the plants were determined using oxygen and hydrogen isotopes of water. Results will contribute to understanding of the physiological limits of native plant species to extreme drought stress that determine whether plants either survive or die. A follow-up NSF-funded project (1457400) is now underway to assess recovery of trees in the current El Niño rainy season, and to integrate physiological and ecohydrological models of soil moisture to better understand physiological dynamics in response to drought.

Pepperwood has become a hub for linking wildlife corridor analyses with quantitative wildlife camera studies from the Berryessa Blue Ridge range, through our own Mayacamas corridor, to Mount Tamalpais and the Marin Coast. In 2012, in collaboration with PI Dr. Susan Townsend, Pepperwood established the first Wildlife Picture Index array in North America to monitor top trophic level (mammal) ecosystem health and how it is affected by climate change and connectivity in the landscape. Preliminary findings show that meso-carnivores and top carnivores are residents year round, indicating that Pepperwood is potentially functioning as a source populations for the region. In addition to the 20 camera array on-site at Pepperwood, we oversee two additional arrays in partnership with Audubon Canyon Ranch and our local open space district in the Mayacamas range, and have now advised on an additional 5 arrays. We are currently working with Dr. Adina Merenlender (UC Berkeley and Hopland Research Extension Center) to combine land cover, land use, climate data, and camera data to recommend critical linkages for landscape-level conservation throughout the region. For relevant publications please refer to Townsend et al. 2012 and Merenlender et al. (multiple).