COS 99-6
Does plant meristem number limit post-fire resprouting?
Post-fire resprouting from underground storage reserves is an essential persistence strategy for plants in fire prone habitats. However, it is difficult to disentangle the relative contribution of new assimilates and storage reserves to post-fire resprouting. Furthermore, frequent fire tends to promote small statured plants at the expense of larger plants. To better understand what limits resprouting and regulates size-dependent success, we tested the hypothesis that post-fire resprouting in large individuals will be more limited by meristem number than in small individuals. Thus, we predicted that suppressing supplementary shoots would result in larger negative consequences to growth in large plants, relative to small. With this purpose, we measured the height of all shoots of 200 Oxydendron arboretum and Persea palustrus at the beginning of the growing season. All plants were coppiced at 5cm above ground level to simulate fire-induced topkill. Plants were assigned to “coppiced” (removal of all stems except the largest) or “uncoppiced” (all stems remain intact) treatments. After topkill, height was measured and coppicing treatments were performed for maintenance at 2-week intervals for 20 weeks. Biomass was estimated using allometric equations, and we analyzed the relationship between “pre-burn” size and biomass of the largest stem of each treatment.
Results/Conclusions
Contrary to our hypothesis, we found that the pattern of biomass accumulation in a lone stem was not significantly different than the largest stem of the uncoppiced treatments. Our data suggest that availability of new assimilates limit resprouting more strongly than does meristem number. If all but one stem was removed, and as a result storage reserves were funneled into that remaining stem, ostensibly this lone stem would have increased growth. However, this was not what we observed. Therefore, we believe that early resprouting is more limited by new assimilates and that meristem number is equally important over all size classes. Elucidating the mechanisms underlying these resprouting patterns is important for understanding the dynamics of plant persistence and community composition in fire-prone systems.