Population biology and regeneration of forbs and shrubs after fire in Brazilian <Emphasis Type="Italic">Campos</Emphasis> grasslands |
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Authors: | Alessandra Fidelis Sandra Cristina Müller Valério DePatta Pillar Jörg Pfadenhauer |
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Institution: | 1.Vegetation Ecology,Technische Universit?t München,Freising,Germany;2.Laboratory of Quantitative Ecology,Universidade Federal do Rio Grande do Sul,Porto Alegre,Brazil;3.Department of Ecology,Universidade de S?o Paulo,S?o Paulo,Brazil |
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Abstract: | Fire is an important factor in several ecosystems, affecting plant population biology. Campos grasslands are under constant influence of disturbance, mostly grazing and fire. However, few studies evaluated the effect
of fire on plant population biology of grassland species. Therefore, we aim to analyze the effect of fire on the population
biology of four species, from different functional groups and regeneration strategies: Chaptalia runcinata (forb, resprouter, absence of belowground organ), Vernonia flexuosa (forb, resprouter, presence of rhizophore), Eupatorium ligulaefolium (shrub, resprouter, presence of xylopodium) and Heterothalamus psiadioides (shrub, obligate seeder). Seven plots were established in different sites in southern Brazil: frequently burned (FB) and
excluded from fire since 6 years (E). All plots were subjected to controlled burns during summer. Before experiments, populations
were sampled. Further observations were carried out after 90 and after 360 days of fire experiments. In addition, we counted
the number of seedlings and resprouters recruited after fire. Heat shock experiments were conducted with two species (H. psiadioides and V. flexuosa), as well as the study of the bud bank of the following species: E. ligulaefolium and V. flexuosa. The obligate seeder species had all individuals killed by fire and established only after 1 year. Resprouters, however,
showed new stems immediately after fire. E. ligulaefolium and V. flexuosa showed only vegetative regeneration from belowground organs and more individuals in excluded sites 1 year after the fire.
The bud bank of E. ligulaefolium tended to be larger in excluded sites, whilst V. flexuosa showed an opposite result. High temperatures did not enhance nor kill seeds from both studied species. Vegetative regeneration
was the most important strategy for all studied species, except for H. psiadioides, the obligate seeder species. Fire thus, plays an important role on population structure and demography, being also important
for plant recruitment. |
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