Klamath Forest, Fire, and Climate History

Postglacial vegetation and fire history of the Klamath Mountains, southwestern Oregon and northwestern California

The Klamath Mountains of northwestern California and southwestern Oregon are recognized for their extraordinary plant diversity; yet the explanation for this diversity is unclear, though it likely results from a combination of geological, ecological and historical factors.  Little is known about the role of long-term climate and climate variability in maintaining the biological diversity through the last 15,000 years (following deglaciation of the region).  We also have a poor understanding of how past climate has affected the vegetation and fire history in different geological settings.  A recent study of the vegetation history on diorite/serpentine soils in the northern Klamath Mountains suggests that vegetation communities were strongly affected by variations in climate occurring on centennial and millennial time scales, whereas studies from the eastern Klamath Mountains on ultramafic soils show little vegetation response to such changes.  It is hypothesized that different substrates in the Klamath region have influenced the sensitivity of different plant communities to past variations in fire and climate and will likely affect their response to future climate change as well.  To test this hypothesis, the project is developing a network of postglacial vegetation and fire records from lake sites on different substrates in the Klamath Mountain region in order to examine the ecosystem response to past climate changes of different duration and intensity.

Fire management, post-fire "salvage" logging and thinning of the forest understory have become important regional and national issues in the aftermath of the Biscuit Fire in 2002.  The study focuses on reconstructing the fire and vegetation history of the Klamath Mountain region to (1) provide valuable information on the ecological response of biologically diverse ecosystems to climate changes occurring on multiple time scales; (2) improve our understanding of the historical context for present-day biological diversity; and (3) provide prehistoric fire reconstructions to help inform fire-management planning efforts.