What make Panicum maximum Jacq. successfully invade the Dadu mountain area after fire?
Date Issued
2009
Date
2009
Author(s)
Ho, Chen-Ying
Abstract
Previous studies showed that Miscanthus sinensis, a native plant, was the dominant species of Acacia confuse forest after recurrent of burning in Dadu and Tiehchen mountain area. But recent survey reported that Panicum maximum, a perennial grass in the family of Poaceae and listed as one of the twenty most noxious invasive plants in Taiwan has replaced the role of M sinensis in those areas. As a result of recurrent burning, A. confuse forest has been gradually replaced by the grassland of P. maximum. In this study, I compared morphological, photosynthetic, growth and life history characters of field growing P. maximum and M. sinensis and conducted greenhouse experiments to understand the mechanisms contributing to the invasion of P. maximum after burning. Field growing P. maximum had significant higher specific leaf area (cm2/g) and net photosynthetic rates but lower water use efficiency than M. sinensis. In comparison of the two species, after burning or been pruned, I found that M. sinensis had better recovery ability in drought season, but P. maximum grew faster in wet season. The fruiting period of P. maximum was mainly in wet season, but M. sinensis mainly in dry season. In comparison to M. sinensis, P. maximum had significantly longer flowering and fruiting period and heavier seeds, but lower germination percentage. Greenhouse experiments revealed that under high water or high light availability P. maximum grew much faster, accumulated significantly more biomass, and produced more litters than M. sinensis. It indicates that P. maximum could have more coverage and inflorescence than M. sinensisin favorable conditions. However, under low water condition, P. maximum was more susceptible to drought than M. sinensis. P. maximum grew much better than M. sinensis in full light condition and much taller in shading environment after pruning. These results suggest that with the advantage of the morphological and photosynthetic traits in combination with longer wet season in Dadu mountain area, P. maximum can resprout and grow faster than M. sinensis in wet season which may help the species in competition for resource uptake after fire. In addition, a longer fruiting period of P. maximum might contribute to a larger seed bank which might enable the species to have more seedlings germinated than M. sinensis. Though M. sinensis is drought tolerant, the advantages of drought tolerance ability can not expressed in the area due to a short dry season. Due to its higher growth rate, P. maximum produces more litters than M. sinensis which would help inducing fire during dry season. The burning events create new space that P. maximum can easily invade again. The invasion of P. maximum makes the area prone to fire in dry season. As a result of recurrent burning, P. maximum replaces M. sinensis becoming the most dominant species in Dadu mountain area.
Subjects
Panicum maximum
Miscanthus sinensis
fire
Dadu mountain
photosynthetic gas exchange
resprout ability
plant growth
SDGs
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