Abstract Detail


Floreani Buzbee, Raphaela E. [1], Ackerly, David [2], Cushman, Hall [3].

Coastal plant community composition shifts and microclimate variation in response to tule elk herbivory.

Species distributions are expected to shift across large spatial and temporal scales as species migrate to keep pace with anthropogenic climate change. Within a plant community, taxa from warmer regions or exposures will become more prevalent with increased warming and/or aridification. Eventually, community composition will be increasingly dominated by species from lower latitudes or elevations that are better adapted to the novel local climate. This process may be influenced or accelerated by disturbances or environmental processes that alter the availability of microclimates.  Coastal California grasslands are among the most species rich temperate plant communities and are home to several species of conservation concern. Recent models based on future climate scenarios identify parts of the California coast as a possible climate refugium for plant diversity where warming will be buffered by maritime influences of the Pacific Ocean. However, this projection reflects stability in relation to surrounding areas and does not necessarily predict how species distributions will respond. Grazing by native and introduced herbivores has complex effects on plant community composition and structure in these mesic grasslands which may, in turn, influence how the ecosystem will respond to climate change.  This study utilizes a 24-year old exclusion experiment at the Tule Elk Preserve in Point Reyes National Seashore, California, to investigate the interactive effects of grazing and microclimate on a coastal California grassland plant community. Tule elk (Cervus canadensis nannodes) is a native herbivore that was extirpated and then reintroduced in 1980 after over a century of cattle grazing. By combining fine-scale climatic data with plant community metrics across paired grazed and ungrazed plots, we seek to test the following hypotheses: (1) that the presence of elk herbivory is correlated with higher soil temperatures and lower soil moisture; (2) since grazing generally decreases woody cover, there will be fewer available microclimates in grazed sites; and (3) grazed sites will have higher proportions of xeric-adapted plant species compared to ungrazed sites.  If grazed plots are warmer and/or drier than ungrazed sites and these hypotheses are supported, then it is possible that grazed plant communities are already adjusting (or may be better suited for adaptations) to future climate conditions. These results could also suggest that grazed sites will be more resistant or resilient to climate change.  Altered species distributions have the potential to reassemble current patterns of biodiversity presenting novel challenges for biodiversity-focused conservation efforts and land management. A better understanding of coincident influences of grazing and climate change can assist in ongoing efforts to protect, manage and steward biodiversity into an uncertain climate future.

1 - University of California, Berkeley, Department of Environmental Science, Policy and Management, Berkeley, CA
2 - University of California, Berkeley, Department of Environmental Science, Policy and Management,, Berkeley, CA
3 - University of Nevada, Reno,, Department of Natural Resources & Environmental Science,, Reno, NV

none specified

Presentation Type: Poster
Number: PEC041
Abstract ID:1066
Candidate for Awards:Ecological Section Best Graduate Student Poster

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