Jump to main content or area navigation.

Contact Us

Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Clinal Variation in Artemisia californica Traits and Implications for Herbivore Communities, Invasion Resistance, and Plant Adaptation in a Changing Climate

EPA Grant Number: FP917241
Title: Clinal Variation in Artemisia californica Traits and Implications for Herbivore Communities, Invasion Resistance, and Plant Adaptation in a Changing Climate
Investigators: Pratt, Jessica Dawn
Institution: University of California - Irvine
EPA Project Officer: Just, Theodore J.
Project Period: August 1, 2010 through July 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010)
Research Category: Academic Fellowships , Fellowship - Global Change



The way in which a keystone plant species responds to environmental change has important implications for its associated biotic community. If there is geographic variation in plant responses to environmental change, then conservation and management decisions to mitigate climate impacts will need to occur on a local or population-level scale. I aim to understand how higher trophic levels respond to variation in plant traits of Artemisia californica along a four-fold precipitation gradient across 700 km of the species range.


The way in which a plant species responds to environmental change has implications for the community of organisms that interact with that species. This project aims to assess geographic variation in plant traits and plant-herbivore interactions in Artemisia californica. Understanding how plant trait variation affects higher trophic levels will inform land management decisions in light of climate change and help predict community-wide impacts of conservation strategies, such as assisted migration.


I will use a series of common garden experiments and manipulative field studies to examine geographic variation in plant traits and plant-herbivore interactions of Artemisia californica, a keystone plant species in California’s endangered coastal sage scrub habitat. Cuttings of Artemisia californica collected from populations across the range of the species are being grown in a common garden experiment where I have manipulated precipitation. I will measure morphological, physiological, and chemical traits of plants from across the species range in order to understand how these plants respond not only to changes in precipitation, but also nitrogen deposition and herbivore pressure. In addition, I will monitor arthropod communities on plants in the common garden environment to examine community-level consequences of plant response to environmental change.

Expected Results:

In a common garden setting, I have documented clinal variation in plant growth rate and resistance to herbivores. Plants can allocate available resources to growth, defense, and reproduction. Ecological theory predicts that tradeoffs occur between investment in growth and defense and that these tradeoffs are more evident in a resource poor environment. I predict that geographic variation in the strength of these tradeoffs will affect plant-herbivore interactions and result in different emergent communities that associate with Artemisia californica across its range. In addition, management approaches, such as assisted migration of Artemisia californica, may be necessary to mitigate the impacts of climate change on coastal sage scrub communities if Artemisia californica populations are locally adapted to current climate conditions.

Potential to Further Environmental/Human Health Protection:

Understanding geographic variation in plant traits and plant-herbivore interactions will allow us to better understand how a plant species as a whole will respond to environmental change, and how the response of the plant will affect higher trophic levels. If adaptation to climate is detected across the species range, then my results will inform adaptive management programs, such as assisted migration. Data from this study will provide land managers with important information about how adaptive genetic variation can ensure the long-term success of restoration projects as well as an indication of what is required to maintain evolutionary potential in natural and restored populations.

Supplemental Keywords:

climate adaptation, community genetics, plant-herbivore interactions, assisted migration, assisted colonization, restoration, coastal sage scrub, Artemisia californica,

Top of Page

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

Jump to main content.