Publications
The changing anthropogenic diets of American black bears over the past century in Yosemite National Park
American black bears in Yosemite National Park now consume human foods at the same rate as they did over a century ago, despite a four-million-fold increase in annual park visitors. This significant reduction in anthropogenic diet reliance was achieved through targeted management strategies, including closing artificial feeding areas and implementing a $500,000 annual conflict mitigation program starting in 1999. Researchers analyzed carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes in bear tissues to track dietary shifts over time. The findings highlight the success of park management in curbing human-bear conflicts while maintaining ecological balance, offering a model for other protected areas.
Factors Associated with the Severity of Intersecting Fires in Yosemite National Park, California, USA
A study on Yosemite National Park's Illilouette Creek basin reveals that reburn fires tend to increase in severity, with high-severity burns often converting vegetation to montane chaparral. The research found no significant link between fire return interval and initial fire severity but identified associations with the number of years since the last burn, burning index, and previous fire severity. These factors interact to influence reburn severity, offering insights for ecosystem management. The study analyzed 28 fires larger than 40 ha from 1973 to 2011, providing a data-driven understanding of fire dynamics in this UNESCO World Heritage Site.
Climatic water deficit, tree species ranges, and climate change in Yosemite National Park
Research on Yosemite National Park reveals that projected increases in climatic water deficit (Deficit) due to climate change may significantly alter forest structure and composition. The study found a 23% increase in Deficit from present (1971–2000) to future projections (2020–49), with species like Pinus monticola and Tsuga mertensiana potentially facing disproportionate impacts. Using high-resolution spatial data, the study correlated tree species distributions with actual evapotranspiration (AET) and Deficit across a 2300-meter elevation gradient, showing that species differentiation intensifies under higher Deficit conditions. The research also highlights the importance of fine-scale soil and topographical data in improving vegetation-change projections in heterogeneous mountainous landscapes.
Fire regimes, forest change, and self‐organization in an old‐growth mixed‐conifer forest, Yosemite National Park, USA
A 2125-hectare old-growth mixed-conifer forest in Yosemite National Park exhibited frequent, low-severity fires with a median return interval of 10 years and an average burn extent of 115 hectares before Euro-American settlement. These fires created small canopy openings (<0.2 ha) and showed self-organizing behavior, with area burned increasing tenfold when an area had not been affected by the previous fire. Post-1905 fire suppression led to a significant increase in forest density, basal area, and a shift toward shade-tolerant, fire-intolerant species. The study suggests that restoring frequent, low-severity burns can mimic historical conditions, reducing surface fuels and creating small canopy openings characteristic of the reference forest.
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