I am interested in the effects of contingency on plant community dynamics, particularly in the context of regeneration after disturbance.

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Current Research

Interactions between snowpack and competition in post-fire conifer regeneration


Interacting effects of multiple ecological drivers can have dramatic consequences for species recruitment and community assembly not evident from individual effects. To understand how post-fire conifer recruitment varies with interacting abiotic and biotic contingencies, we established an experiment in the Sierra Nevada, California. Working within the King Fire burned area, we crossed a manipulation of snowpack with a removal of surrounding shrubs, which may serve as competitors or facilitators of tree seedlings. We seeded two conifer species, Pinus ponderosa and Abies concolor, within these plots in two consecutive years, one relatively normal and the other with an unusually wet winter and hot summer, and tracked the survival and growth of these seedlings for multiple years. Overall, our results demonstrate that the competitive effect of shrubs on tree seedlings, which is often assumed to be pervasive in this system, is in reality highly context-dependent.

Post-fire regeneration on harsh soils is more resilient to climate change

Plant communities on harsh soils such as serpentine appear to be less sensitive to climate change. However, although disturbance from fire is an important part of grassland, chaparral, and forest communities, the resistance of these serpentine communities has primarily been studied in an undisturbed context. We compared two fires that burned fifteen years apart in a Mediterranean chaparral system to test whether shifting climate patterns—including a historically severe drought—had the same negative impacts on diversity of post-fire communities as it has on unburned communities, and whether those impacts varied by soil type. Our results thus far indicate that disturbance-following communities on harsh soils may be resilient to climate change, but slower recruitment from woody species may lead to eventual type conversion even on harsher soils.

Spatial and temporal contingency in rapid primary succession after dam removal on the Elwha River, Washington

In this study of naturally assembling plant communities after the largest dam removal thus far in the United States, I took advantage of the staged drawdown of the water (and consequent different timings of exposure of the previously inundated soil) as a natural experiment on the effects of temporal contingencies on revegetation. I found that spatial and temporal factors influenced initial community composition of both species and functional traits, and that communities shifted directionally but diverged through time in species composition as well as functional trait composition.


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Werner, Chhaya M., Susan P. Harrison, Gabrielle Bohlman, Rebecca Serata, and Hugh D. Safford. Post-fire regeneration on harsh soils is more resilient to global change. In prep.

Michael J. Koontz, Malcolm P. North, Chhaya M. Werner, Stephen E. Fick, and Andrew M. Latimer. Local variability of vegetation structure increases forest resilience to wildfire. PNAS, submitted. Preprint available.

Werner, Chhaya M., Derek J. N. Young, Hugh Safford, and Truman P. Young. Decreased snowpack and warmer temperatures reduce the negative effects of interspecific neighbors on regenerating conifers. Oecologia, submitted.

Young, Derek J. N, Chhaya M. Werner, Kevin R. Welch, Truman P. Young, Hugh D. Safford, and Andrew M. Latimer. 2019. Post-fire forest regeneration shows limited climate tracking and potential for drought-induced type conversion. Ecology, online.

North, Malcolm P., Jens T. Stevens, David F. Greene, Michelle Coppoletta, Eric E. Knapp, Andrew M. Latimer, … Chhaya M. Werner, Peter Wyrsch. 2018. Reforestation for Resilience in Dry Western Forests. Forest Ecology and Management 432:209-224.

Young, Truman P., Katharine L. Stuble, Jennifer A. Balachowski, Megan E. Lulow, Chhaya M. Werner, and Kristina Wolf. 2017. Experimental approaches to addressing climate change challenges in prairie restoration. Grasslands special issue: Climate change and grasslands 27(2) pp 10-15

Young, Truman P., Katharine L. Stuble, Jennifer A. Balachowski, and Chhaya M. Werner. 2017. Using priority effects to manipulate competitive relationships in restoration. Restoration Ecology 25(S2) pp 114-123.

Werner, Chhaya M., Kurt J. Vaughn, Katharine L. Stuble, Kristina Wolf, and Truman P. Young. 2016. Persistent asymmetrical priority effects in a California grassland restoration experiment. Ecological Applications 26(6) pp 1624-1632.

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I am a postdoc at the German Centre for Integrative Biodiversity Research (iDiv), studying plant community ecology.

My work combines experimental manipulations and computational analysis of landscape-scale data to identify the effects of initial conditions on plant communities, the persistence of these effects through time, and the impacts of projected climate change across the landscape.

I work in Anu Eskelinen’s lab in the Global Change and Biotic Interaction Ecology group at the Helmholtz Research center (UFZ) and under the Finnish Academy funded  project “Biotic modulators of plant community resistance and resilience to multiple global changes.” [CV]

Contact me: cwerner@ucdavis.edu

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News and Photos

Check out my latest research updates and photography on my blog