|Sierra forests that burned at high severity are important habitat for wildlife. Photo by Brendan McGarry / PRBO.|
The role of fire in the Sierra Nevada has garnered considerable debate, both popular and legal. The majority opinion seems to be that wildfire is bad, if not often catastrophic or tragic. Certainly when property and life are lost that is true. However, within our National Forests and Parks in the Sierra, fire has been a primary force shaping ecosystems: it mediates competition within and among ecological communities, and it promotes diversity. In contrast, the effects of nearly a century of fire suppression range from thickets of young conifers that choke out stands of aspen and black oak, to lodgepole pines that invade valuable meadows.
There is another effect of fire suppression in the Sierra Nevada: the overall area burned by wildfire each year appears to be increasing. This trend is likely due to a build-up of fuels, as well as to changing climatic conditions, and points to the growing need to understand how to manage areas affected by wildfire. To this end, PRBO’s Sierra Nevada program brings an objective, science-driven approach to provide reliable information. Now more than ever, our science is crucial to help guide the way toward meeting diverse and often competing objectives that land managers face across the Sierra Nevada.
|Black-backed Wood-pecker is one of the species that thrive in post-fire habitat. Photo by Tom Grey / www.tgreybirds.com.|
The debate surrounding fire extends to what is done after the last embers are extinguished. Management activities that now shape the regeneration of burned areas include removal of fire-killed trees, inhibition of shrubs and broadleaf trees that flourish after fire, and planting of conifer species. Such activities can profoundly influence what habitat exists in an area for years to come—and how the future Sierra Nevada ecosystem is affected by fire.
For the past four years PRBO biologists have trudged through burned landscapes to document bird communities. From the “rattles” of nesting Black-backed Woodpeckers to the “zips” of Lazuli Buntings in re-sprouting manzanitas, we have listened carefully to what the birds are telling us, and it’s a rather resounding chorus. Areas that have burned hot and killed the majority of trees support a unique avian community; many bird species that are rare or declining in the region reach their greatest abundance in areas that have burned at moderate to high severity. Wildfire is a critically important “ecosystem driver”—necessary for maintaining biodiversity in the Sierra Nevada. High-severity burned areas are also where important habitat elements that were degraded over the past century (dense stands of snags, a rich herbaceous understory, groves of oak and aspen) now flourish.
Management recommendations from PRBO’s study include:
Burned areas are not blank slates or catastrophic wastelands. They are unique components of the Sierra ecosystem and represent opportunities to shape forest composition for decades to come. In addition, fire will likely play a critical role in aiding these forests’ adaptation to a changing climate: by reducing tree densities, fire reduces competition for light, nutrients, and water, allowing forests to withstand more variable future conditions.
As debates over these often maligned but ecologically important areas in the Sierra Nevada continue, PRBO’s innovative science and outreach provide a true and needed heading.