Tuesday, August 4, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Background/Question/Methods In the last century, anthropogenic influences have enabled the invasion of exotic species in chaparral and California sage scrub (CSS) ecosystems, resulting in vegetation type conversion, species loss, and reduced fire-return interval. The objective of this study was to determine how germination of selected herbaceous fire-followers would react to increased temperatures predicted by climate models, with and without the presence of fire. I measured mean time to germination (MTG) and germination proportion in two common fire-following forbs (Calystegia macrostegia [South Coast Morning Glory] and Hemizonia fasciculata [Clustered Tarweed]), two uncommon fire-following forbs (Daucus pusillus [Rattlesnake Weed] and Lupinus succulentus [Hollowleaf Annual Lupine]), and two exotic species (Silybum marianum [Blessed Milk thistle] and Sonchus asper [Spiny Sow thistle]).
Results/Conclusions Treatment group and an interaction of treatment group and species were the significant predictors of meant-time-to-germination (MTG <- treatment + treatment*species). Species was the only significant predictor of proportion of successful germination (proportion of germination <- species). The exotic herbs, Sonchus asper and Silybum marianum, had the highest proportion of germinated seeds at 63.13% and 44.20%, respectively. The shortest MTG occurred in treatment groups mimicking current spring and summer temperatures. Heat-shock prior to germination had no significant effect on germination proportion or MTG, which suggests that wildfire heat is not a germination trigger for these species. With increased temperatures in this region, competition among native and exotic herbs is likely to change. This study is a preliminary insight into how germination of selected species will be impacted.
Results/Conclusions Treatment group and an interaction of treatment group and species were the significant predictors of meant-time-to-germination (MTG <- treatment + treatment*species). Species was the only significant predictor of proportion of successful germination (proportion of germination <- species). The exotic herbs, Sonchus asper and Silybum marianum, had the highest proportion of germinated seeds at 63.13% and 44.20%, respectively. The shortest MTG occurred in treatment groups mimicking current spring and summer temperatures. Heat-shock prior to germination had no significant effect on germination proportion or MTG, which suggests that wildfire heat is not a germination trigger for these species. With increased temperatures in this region, competition among native and exotic herbs is likely to change. This study is a preliminary insight into how germination of selected species will be impacted.
