PARENT SESSION
Poster Session #59: Fire Ecology II.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC
122
Vegetation response of a semiarid grassland watershed to prescribed fire.
PENDLETON, BURTON*,1, PENDLETON, ROSEMARY1, WHITE, CARLETON2, LOFTIN, SAMUEL3, 1 Rocky Mountain Research Station, Albuquerque, NM2 Department of Biology, Albuquerque, NM3 Los Alamos National Laboratories, Los Alamos, NM
ABSTRACT- The Bernalillo Watershed Protection Project was begun in 1953. Prior to this, heavy runoff and erosion from monsoonal rains caused catastrophic damage to small communities below. Erosion control features constructed by the Soil Conservation Service and the U. S. Forest Service consisted of terracing, furrow plowing, pitting, check dams, and grass seeding. These measures resulted in the stabilization of the watershed and a gradual increase in perennial grass cover. Aerial photographs document the expansion of juniper (Juniperus monosperma) woodland into the Bernalillo watershed grassland over the last 50 years. In 1995, fire was re-introduced into the grassland as a means of maintaining perennial grass cover and preventing the expansion of the juniper woodland community. A second fire was conducted in January of 1998. Except for periods of drought, total vegetative cover at the site generally increased during the years from 1995 to 2000. Drought conditions in 1995 and 2000 resulted in a temporary reduction in both vegetative and grass cover of unburned plots. Vegetative cover and perennial grass cover of burned plots declined initially following both fires, but recovered fully within 2 to 3 years. The number of juniper per plot, censused in February of 2002, averaged 22.75 for control plots and 7.25 for burned plots. Average size of live juniper was greater on burned plots, indicating that fire was effective in reducing juniper recruitment. Burned plots also contained significantly fewer cholla (Opuntia imbricata) than did unburned plots. Burning did not reduce the number of Opuntia phaeacantha patches, but did significantly reduce their size. Cover of broom snakeweed (Gutierrezia sarothrae), the most common woody plant on the site, initially declined following both burns, but was equal to that of unburned plots within 2 years. Prescribed fire appears to be an effective means of reducing recruitment of woody perennials while maintaining perennial grass cover.
KEY WORDS: Juniperus monosperma, fire, semiarid grassland, watershed