Sedgwick Reserve

01 Jul, 05 AM - 10 Oct, 09 AM

In California, late April/early May is when rainfall typically ends and water availability for plants begins to decline. Wildfires typically occur during this drought period when plant moisture content is at its lowest. However, in coastal California, rainfall is not the only source of moisture as seasonal fog commonly occurs during the late summer months when shrubs are experiencing peak drought stress. This ?occult precipitation? has the potential to influence shrub moisture content, alter plant flammability and modify patterns of fire on the landscape. This project seeks to determine whether shrubs can utilize fog water during periods of drought by sampling the isotopic composition of xylem water from chaparral and coastal sage scrub species across two summer drought periods. Along with the plant isotope data collection, I will monitor live fuel moisture content as a proxy for plant flammability. By following the fuel moisture trends of these species and their water use, I will be able to evaluate the relationship between fog water and plant flammability. Project Description: The schedule of visits will be every two weeks from the end of June through October (when school starts). It will consist of visiting a coastal sage scrub site near the old airstrip and a chaparral site off of Figueroa Mountain road used previously by Keely Roth and myself for a project last summer. The species I am monitoring are Artemisia californica and Baccharis pilularis for coastal sage scrub and Adenostoma fasiculatum and Ceanothus cuneatus for chaparral. On each of the dates of sampling I will record phenology and sample twigs for live fuel moisture content from 8 individuals of each species. Four of those individuals will also have twig samples measured for xylem pressure potential and stem water isotopes. The isotope collection consists of taking a 4 inch long section of stem, shaving off the bark and quickly placing in a sealed scintillation vial. These four individuals will also have 20 gram soil samples taken from beneath the plant for gravimetric soil moisture measurements and fine root collection. Once the soil has been dried and weighed, I will return it to to original location. In addition to the biweekly sampling of plants I will also collect soil samples from a core to extract soil water for isotope analysis. This will consist of a core drilled down 1 meter into the soil profile and subsampling five 20ml vials worth of soil from each core. The rest of the soil will be placed back in the hole. In all I will take 6 cores in July and 6 cores in September.

Visit #29024 @Sedgwick Reserve

Approved

Under Project # 25531 | Research

Seasonal fog and the effects on moisture content in shrubs

graduate_student - University of California, Santa Barbara

Reservation Members(s)

Nathan Emery Jul 1 - Oct 10, 2012 (102 days)
Group of 4 Undergraduate Student Jul 1 - Oct 10, 2012 (102 days)

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