Native Colonizing Species and Degraded Land Restoration in La Gran Sabana, Venezuela



We evaluated the ecological and reproductive characteristics of plant species occurring in severely disturbed areas that were revegetated with exotic grasses. We identified those species with the best combination of attributes that increase their probability of success in degraded lands. Fifteen degraded areas were studied in two different bioclimatic regions, a high premontane humid bioclimate and a low premontane humid bioclimate. The frequency of native colonizing species and the presence of arbuscular mycorrhizal colonization in their roots were evaluated. The sexual and breeding system, pollination mode, fruit set, and dispersal syndrome of ten of the most frequent colonizing species were also studied. The floristic survey of the colonizing species revealed a similarity to the reported flora of the treeless savannas that are dominant in the region. Bioclimatic conditions prevailing in the degraded lands seem to be an important factor for the presence of colonizing species and for species richness. All colonizing species studied were mycorrhizal, and for this reason the restoration program in these degraded areas should take mycorrhizae into account, reintroducing them or manipulating the soils to increase the mycorrhizal inoculum. We suggest Scleria cyperina and Trachypogon plumosus to start or promote the natural succession in the degraded areas from La Gran Sabana. Because their frequency is high and their reproductive system is less dependent on biotic factors, these species stand out in the studied areas.