Human Transformation of California: Botany, History, and Sociology
Barbour, Michael .
The transformation of California forests.
HUMAN-CAUSED changes to California forests include dramatic
type conversions but also subtle shifts in dominance and tree age structure. Virtually every forest has been modified: low elevation riparian forests, coast redwood forests, mixed evergreen forests at moderate elevations, and conifer forests in the lower and upper montane zones. The modifications are due to a change in fire regimes, extensive timber harvest, grazing by domesticated livestock, introduction of exotic species (including trees and shrubs), and atmospheric pollutants. The evidence for change comes from repeat photography, old and current maps of forest distribution, old and current plot data, and comparisons with conifer forests in Baja California that still experience surface wildfires with a 25-50 yr return interval. Analyses of these types of data allow one to estimate ecosystem-scale impacts, such as to
hydrology, wildlife, productivity, and biotic richness. Seen from a distance--as in a plane flying at a high elevation--California forests appear to be green and healthy. But closer examination reveals
frayed, damaged, and thinned vegetation cover that requires restoration programs in order to enhance ecosystem sustainability.
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1 - University of California, Department of Plant Sciences, Mail Stop 1, 1 Shields Avenue, University of California, Davis, California, 95616, USA
Presentation Type: Symposium or Colloquium Presentation
Date: Tuesday, August 1st, 2006
Time: 10:30 AM