MARITIME CHAPARRAL COMMUNITY TRANSITION IN THE ABSENCE OF FIRE

• Published in: Madroño 2001-12, Vol.48 (4), p.221-229
• Main Authors: Van Dyke, Eric, Holl, Karen D., Griffin, James R.
• Format: Article
• Language: English
• Subjects: Chaparral; Coastal ecology; Forest canopy; Herbs; Plants; Seedlings; Shrubs; Soil ecology; Vegetation; Woodlands
• ISSN: 0024-9637; 1943-6297

Maritime chaparral stands on California's central coast are dominated by a number of endemic Arctostaphylos species and are the habitat for several other species of concern. Although chaparral is a fireadapted vegetation type, maritime chaparral occurs in densely populated regions where fire suppression prevents most stands from burning. In 2000, we re-sampled vegetation at six locations in north Monterey County's Prunedale sandhills that were sampled in 1975-1976 by Griffin (1978); this allowed us to document changes in community composition, canopy cover, and seedling abundance over a 25-year interval after more than 70 years of fire exclusion. Although species richness in the tree and shrub layers changed little between 1975-1976 and 2000, combined tree and shrub cover increased from 86 to 99%. Cover of Arctostaphylos pajaroensis J. Adams increased from 58 to 82%. Cover of Quercus agrifolia Nee and Heteromeles arbutifolia (Lindley) Roemer also increased significantly, whereas percent cover for most shrub species decreased, often dramatically. Species richness in the herb layer was markedly lower in the 2000 survey. Seedlings were rare under the dense canopy, although seedling abundance for Q. agrifolia and Mimulus aurantiacus Curtis increased. These results suggest that the long absence of fire in maritime chaparral stands may lead to dominance by one or two species and a gradual transition from chaparral to oak woodland. Land managers should consider the reintroduction of wildfire, or practices that mimic the effects of fire, to assure the long-term survival of maritime chaparral vegetation communities.