Fire, water, and biodiversity in the sierra nevada: A possible triple win

Reducing the risk of large, severe wildfires while also increasing the security of mountain water supplies and enhancing biodiversity are urgent priorities in western US forests. After a century of fire suppression, Yosemite and Sequoia-Kings Canyon National Parks located in California’s Sierra Nevada initiated programs to manage wildfires and these areas present a rare opportunity to study the effects of restored fire regimes. Forest cover decreased during the managed wildfire period and meadow and shrubland cover increased, especially in Yosemite’s Illilouette Creek basin that experienced a 20% reduction in forest area. These areas now support greater pyrodiversity and consequently greater landscape and species diversity. Soil moisture increased and drought-induced tree mortality decreased, especially in Illilouette where wildfires have been allowed to burn more freely resulting in a 30% increase in summer soil moisture. Modeling suggests that the ecohydrological co-benefits of restoring fire regimes are robust to the projected climatic warming. Support will be needed from the highest levels of government and the public to maintain existing programs and expand them to other forested areas

Simulation modeling of visitor flows: where have we been and where are we going?

Section: Workshop: Travel simulation modeling for recreation plannin

38 CHAPTER 3 Fire as a Physical Process

Where there’s smoke, there’s fire. In many California ecosystems, the process of decomposition is too slow to completely oxidize accumulated organic material, and another process, such as fire, steps in to perform that role. The mediterranean climate in California, with its hot, dry summers and cool, wet winters, is not conducive to decomposition. When it is warm enough for decomposer organisms to be active, it’s too dry. Conversely, when it’s wet enough, it’s too cold. As a result, decomposition is unable to keep up with the deposited material, and organic debris begins to accumulate. This debris becomes fuel available for the inevitable fire that will occur. All that is needed is a sufficient amount of fuel, an ignition source, and weather conditions conducive to burning. In this chapter we will look at fire as a physica

Great Gray Owls (\u3ci\u3eStrix nebulosa\u3c/i\u3e) in Yosemite National Park: on the Importance of Food, Forest Structure, and Human Disturbance

We studied great gray owls (Strix nebulosa Forster) in Yosemite National Park, California, measuring variables that could potentially influence patterns of occurrence and conservation of this state endangered species. We found that owl presence was closely tied to habitat (red fir (Abies magnifica A. Murray) and the abundance of meadows), prey, and snags across the landscape. We also found that indicators of human recreational activities negatively influenced owl distribution and habitat use. Great gray owls appear to prefer mid-elevation red fir forest with meadows that are drier and more productive in terms of small mammal populations. That these areas also have the highest human activity presents a paradox, both for individual owls and for the future conservation and management of this California endangered species. The extent to which human recreation in natural areas affects animal behavior, species distribution, and productivity is a growing issue in natural area management. We present information that will allow land managers to better understand how existing natural resources, coupled with human recreation, influence the distribution and habitat use of the great gray owl