PARENT SESSION
Poster Session #42: Restoration of Public Lands.
Wednesday, August 7. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Effect of solarization on weed seedbanks in coastal sage scrub.

Nenzen, Hedvig^*,1, Nenzen, Cheryl¹, Gilbert, Griffith¹, ¹ Whittier College, Whittier, CA

ABSTRACT- Competition between non-native invasive annuals and native species is a significant problem in coastal sage scrub restoration. Weed abatement practices include herbicide application, hand clearing, a pre-emergent herbicide application, and solarization.. In order to test the effectiveness of solarization as a weed abatement option, five 100 m2 plots were watered and covered with plastic from June 1999 through June of 2000. Soil samples were collected from plots in fall of 2000, treated with combinations of heat and charred wood, and incubated over the spring of 2001 to promote seed germination. Seed banks of invasive species, as indicated by germinated seeds, were significantly lower in solarized samples than non-solarized samples. In addition to quantifying seed banks, the numbers of invasive individuals were sampled pre-solarization and one and two years post solarization. In the first post-solarization year, the number of weedy grasses in solarized plots was significantly lower than the number of individuals in adjacent non-solarized areas. However, the number of weedy dicots was not significantly different. These results suggest that solarization is more effective in controlling grasses and that input of seeds of grasses is low enough such that the seed bank is not replaced at a rate high enough to regenerate pre-solarized seed bank levels.

KEY WORDS: Coastal Sage Scrub, Invasive Species, Seedbanks