干旱区生态环境知识资源中心

Arbuscular mycorrhizas (AM) have an important role in plant succession and the rehabilitation of degraded ecosystems. In this work shrubs (Clusia pusilla) native of La Gran Sabana, were used as nurse plants to increase the deposition of seeds and mycorrhizal propagules transported by the wind to degraded lands. The recruitment of propagules caused by the shrubs would start the plant succession in severely degraded soils from which AM propagules have been lost. The effect caused by cuttings or by seedlings of C. pusilla in the recruitment of seedlings native of surrounding savannas subjected to different treatments were compared. Eight treatments were performed: a non mycorrhizal control (C), three AM treatments (M1, M2 and M3) where AM inocula were used, a treatment fertilized with P (TSP, 150kg/ha) and three treatments in which the different AM inocula and P were applied simultaneously (M+P). AM treatments were inoculated with Glomus manihotis (M1); an inoculum isolated from a savanna from La Gran Sabana (M2) and an inoculum isolated from a shrubland of the same locality. (M3). Results showed that the most effective treatment in promoting the growth of C. pusilla in the field was M3+P After 21 months in the field, in the treatments were cuttings were used as nurse plants a significant higher number of native plants were recruited in comparison with the treatments in which seedlings were used. Treatment M1+P produced a significantly higher number of recruitments than the control but not in comparison with the fertilized treatment. In conclusion, mycorrhizal and fertilized C. pusilla shrubs could be used as a viable strategy to restart the plant succession in degraded lands from La Gran Sabana, where due to the absence of both nutrients and mycorrhizal propagules, the spontaneous colonization by the natural vegetation has been stopped.