justin valliere

Justin Valliere

Postdoctoral Researcher

UCLA La Kretz Center for California Conservation Science



 I am a plant ecologist whose research is motivated by a passion for conservation and an interest in the processes that determine plant community composition. Multiple factors of global change, such as biological invasions, nitrogen (N) deposition and climate change pose a significant and growing threat to native ecosystems. A major challenge in conservation also continues to be bridging the gap between science and management. The goal of my research is to explore the impacts of human-caused global change on plant communities, identify mechanisms of change and inform land management and restoration. By studying disturbed and novel ecosystems, I aim to better understand the processes driving community assembly, while building on our capacity to predict changes under future global change. My research approach integrates biogeochemistry, community ecology, ecophysiology and soil ecology, and I utilize observational studies, manipulative field experiments and greenhouse studies to test hypotheses at multiple scales.


I earned my Ph.D. at the University of California, Riverside, studying ecological impacts of anthropogenic N deposition and drought on California’s severely threatened coastal sage scrub plant community.  Currently, I am pursuing two major research projects. The first is an exploration of potential adaptation to N pollution and climate in invasive plant species of southern California. The other aims to evaluate methods for restoring native plant and soil microbial communities of invaded and disturbed ecosystems that will be resistant to drought and re-invasion.

Curriculum Vitae


high school student mentored by ucla la kretz center postdocs wins state science fair

High school student mentored by UCLA La Kretz Center postdocs wins state science fair

Like many high schoolers, Tai Michaels has plenty of hobbies. He runs cross country. He’s on the speech and debate team. He struggles with Spanish class at times. His favorite band is The Killers. He’s also doing scientific research to protect Southern California from future wildfires, working hand-in-hand with postdoctoral scholars at UCLA’s La Kretz...

eco-evolutionary consequences of global change on invasive plant species

Eco-Evolutionary Consequences of Global Change on Invasive Plant Species

Human activities are dramatically impacting ecosystems worldwide due to air pollution – and resulting changes to climate and nitrogen cycling – and the spread of nonnative plant species. These drivers of global change may have strong and interactive ecological effects, but the evolutionary impacts of these factors are poorly understood. La Kretz postdoc Justin Valliere is currently exploring potential adaptation to nitrogen pollution and climate in common invasive plant species of California. This study will have important implications for invasive plant management under predicted global change.

ecological impacts of nitrogen deposition on coastal sage scrub of the santa monica mountains

Ecological Impacts of Nitrogen Deposition on Coastal Sage Scrub of the Santa Monica Mountains

California’s native ecosystems are increasingly impacted by nitrogen deposition resulting from air pollution, particularly in the greater Los Angeles area. This project, led by La Kretz postdoc Justin Valliere, extends an ongoing collaboration between the National Park Service, the U.S. Forest Service and the UCLA, with the goal of understanding the ecological impacts of nitrogen pollution on the severely threatened coastal sage scrub plant community of the Santa Monica Mountains.


Repeated mowing to restore remnant native grasslands invaded by nonnative annual grasses: upsides and downsides above and below ground

Justin M. Valliere, Susan Balch, Carole Bell, Carlos Contreras, Bridget E. Hilbig

Published Work | 2018 | Restoration Ecology

High N, dry: Experimental nitrogen deposition exacerbates native shrub loss and nonnative plant invasion during extreme drought

Justin M. Valliere, Irina C. Irvine, Louis Santiago, Edith B. Allen

Published Work | 2017 | Global Change Biology