Studying Plant and Insect Response to Environmental Change: A Love Story

By Jessica Dawn Pratt

EPA Fellow Jessica Pratt examines sagebrush.

EPA STAR Fellow Jessica Dawn Pratt

As a native Midwesterner, I was not impressed with the brown and shrubby coastal sage scrub ecosystem that covered hillsides around my new home when I moved to southern California in September of 2005. It was drab, short and prickly compared to the northern hardwood forests to which I was accustomed.

But, as an ecologist, I was excited to live in a “biodiversity hotspot,” a place that rivals the species diversity of many tropical forests and is home to numerous endemic and endangered plant and animal species.

I quickly learned that September was the end of the summertime drought that characterizes California’s Mediterranean climate. As I watched the brown and shrubby hillsides come to life with the winter rains, I fell in love with the coastal sage scrub ecosystem.

In addition to being incredibly diverse and unique, the coastal sage scrub ecosystem also faces many threats, including development, habitat fragmentation, pollution, climate change, invasive species, and wildfire. So, in 2008 when I began the Ph.D. program in Ecology & Evolutionary Biology at the University of California, Irvine, I was determined to work on questions related to its conservation and restoration. A Science to Achieve Results (STAR) Fellowship from EPA allowed me to do just that.

My graduate research examines how California sagebrush (Artemisia californica), an icon of the coastal sage scrub ecosystem, is responding to environmental changes like climate change and nitrogen pollution, and how the response of this important plant species affects the animals that depend on it.

It is my hope that understanding how important species respond to environmental change – and how those responses “scale up” throughout the ecosystem to affect other species – will help us predict and mitigate the impacts.

The first part of this work, published online in Global Change Biology and summarized on UC Irvine’s web site, shows that sagebrush in the southern part of its range will adjust better to climate change than sagebrush in the north.

To determine this, plants collected from a 400-mile stretch of coastal California were grown in experimental plots in Orange County where we tested their response to altered precipitation. Populations from southern sites, where year-to-year rainfall amounts have historically been rather variable, were more flexible to altered precipitation than populations from the north, where precipitation has been more predictable. The findings indicate that a species’ response to climate change won’t always be equal across its range.

Moreover, we saw that year-to-year variability in rainfall at weather stations across the species range is increasing more rapidly in the north, in the very regions where plants may be the least able to tolerate this effect of climate change. As such, including southern sagebrush in northern restoration plantings may be one way to ensure that we give this species an opportunity to adapt to our changing climate.

As we move forward with habitat conservation and restoration in this era of change, it may be prudent to consider the flexibility of the plants that we use in such endeavors so that the greening up of California’s shrubby hillsides each fall may continue long into the future.

About the Author: Jessica Pratt is a Ph.D. Candidate in Ecology & Evolutionary Biology at the University of California, Irvine. Her research examining plant and insect community responses to environmental change in Southern California is funded through the EPA’s STAR Fellowship Program.