Post-fire population dynamics of two tree species in high-altitude Polylepis forests of central ecuador Artikel uri icon

Open Access

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Abstract

  • Fire is considered the main cause for the patchy distribution of high-montane tropical forests growing below the upper limit of tree growth, but there are little quantitative data on the impacts of burning on the respective tree populations. This study compares adult tree survival as well as sapling (0.05-1.3 m) and seedling (< 0.05 m) recruitment of Polylepis incana, and the coexisting Gynoxis acostae in burned and unburned forest stands in the Paramo de Guamani, central Ecuador. In P. incana, adult survival after burning was low, whereas all G. acostae individuals survived through resprouting. Two years after fire, the density of P incana seedlings and saplings was higher than that of G. acostae, but still not sufficient for forest recovery. A sowing experiment revealed a significantly lower seedling emergence of both species in the burned than in the unburned plots. Seedling emergence was comparable to laboratory studies performed under optimal conditions, suggesting there was no evidence for climate constraining emergence at the given altitude. Interactions between seedling survival and burning for P incana indicate higher seedling survival after burning, which could not be shown for G. acostae. Our data imply that single fire events strongly decrease adult and seedling population sizes in P incana and thus may be the main reason for the discontinuous forest distribution below the upper distribution limit of the species. In contrast, the high resprouting potential of G. acostae explains its relatively high percentage in the remaining Ecuadorian P incana stands.

Veröffentlichungszeitpunkt

  • Januar 3, 2008