Seedling habitat structure in dry Chaco forest (Argentina)

We hypothesized that seedlings of different dominant species in the dry Chaco forests of Córdoba Province were restricted to patches with particular microenvironmental conditions. To test this hypothesis, the seedling habitat was characterized by measuring physical and biotic microhabitat variables such as incident light, distance to the nearest neighbour, and herb, thallophyte, and litter cover. Seedlings of the different dominant species established in different patches representing a broad range of microhabitat conditions. Open, arid microsites with high percentages of incident light were occupied by Cercidium praecox, Larrea divaricata and Prosopis spp. seedlings. These species colonize open patches in the forest, taking advantage of the low competition environment and establishing during the brief favourable period before the dry season. In contrast, seedlings of Celtis pallida, Capparis atamisquea, Mimozyganthus carinatus andAcacia furcatispina tend to establish in closed, canopied microsites, with lower incident light and better moisture and nutrient conditions. These species may benefit from the conditions underneath the canopies. Distance to the nearest neighbour did not restrict seedling establishment when the neighbours were herbs, but the nearest shrub exerted a strong influence, depending on the seedling species as well as the shrub species. Facilitation could be an important mechanism in the regeneration of species in the dry Chaco forests