Fire responses of three co-occurring Asteraceae shrubs in a temperate savanna in South America

Abstract

South American temperate savannas have undergone significant woody plant encroachment through changes in their disturbance regimes. We studied fire strategies and the spatial variation in individual fire responses of Eupatorium buniifolium, Baccharis medullosa and B. dracunculifolia, the dominant shrub species at El Palmar National Park, in areas with different fire history. In recently burnt sites, all Baccharis dracunculifolia individuals died, whereas all E. buniifolium and B. medullosa individuals sprouted. The relative growth rate was higher in E. buniifolium, which invested more biomass in shoots, and in B. medullosa, which invested more biomass in leaves. At the unburnt site, B. dracunculifolia showed the highest growth rate and leaf biomass. B. medullosa produced capitula immediately after fire, whereas E. buniifolium reproduction was delayed for 1 year. In both species, production of capitula and reproductive effort were higher in recently burnt sites. For B. dracunculifolia, production of capitula was lower and the reproductive effort was higher in burnt than in unburnt sites. Seedling establishment was extremely low for E. buniifolium, low for B. medullosa and high for B. dracunculifolia in both recently burnt sites. E. buniifolium behaved as a sprouter, B. medullosa as facultative sprouter and B. dracunculifolia as obligate seeder species. In order to control the increase and/or attain desirable population levels of these species, fire management practices in these savannas should consider individual species' responses, particularly to the time since the last fire.

Growth and performance of rupestrian grasslands native species in quartzitic degraded areas

“…* not significant. provavelmente também não atingiu maturidade sexual nesse período, embora seja uma espécie com grande capacidade de dispersão e estabelecimento via sementes em locais sujeitos a distúrbios frequentes (Gomes e Fernandes, 2002;Galindez et al, 2009;. A taxa de sobrevivência maior que 90% para todas as espécies evidenciou a adaptação das espécies estudadas aos rigores ambientais característicos dessas áreas degradadas quartzíticas.…”

Remoção dos frutos de Miconia albicans (sw.) Triana (Melastomataceae) por formigas na borda e no interior de um fragmento de Cerrado, Curvelo, MG

“…Atividades antrópicas têm influenciado a fisionomia dos ecossistemas savânicos, causando alteração no regime do fogo, erradicação de herbívoros nativos e introdução de plantas exóticas e de pastagens (GALÍNDEZ et al, 2009). Esta última atividade, juntamente com a agricultura, tem sido os maiores responsáveis pela fragmentação desse ecossistema.…”

Habitat and fire heterogeneity explain the co-occurrence of congeneric resprouter and reseeder Hypericum spp. along a Florida pine savanna ecocline

“…For instance, reseeders are predicted to persist in habitats where the fire frequency is greater than the age to maturity (Hawkes and Menges 1995;Pausas 2003;Vilà-Cabrera et al 2008). Reseeding plants are killed by fires, and recruitment occurs by seeds in the soil and canopy (Enright et al 1998;Keeley et al 2006;Galindez et al 2009). If fires occur repeatedly at an interval shorter than that required for these individuals to reach reproductive maturity, reseeding species may go locally extinct; the seed bank will become exhausted over time (Keeley and Zedler 1978;Wooller et al 2002;Watson et al 2009).…”