SELEÇÃO DE ESPÉCIES ARBÓREAS PARA REVEGETAÇÃO DE ÁREAS DEGRADADAS POR MINERAÇÃO DE PIÇARRA NA CAATINGA

Abstract

The piçarra (subsoil material mainly formed by silt, sand and gravel) is commonly used in the civil construction and activities related to the onshore oil production in the Caatinga biome. The revegetation of the piçarra mines at the end of exploration cycle is mandatory and generally demands the planting of native tree species. However, there is scarce information about tree species able to grow in these degraded environments. This study aimed to evaluate the development and survival of 20 tree species, including native and exotic spe-cies, and nodulating and non nodulating species, planted in five piçarra mines located in three cities in the state of Rio Grande do Norte, Brazil. The experiment was a split-split block design, where 10 nodulating tree species were compared with ten other non nodulating species in areas with and without addition of a 20 cm topsoil layer and/or 2 L cattle manure in the planting hole. Biometric measurements were made at the end of the dry and rainy seasons (February 2008 to February 2010) up to 660 days after planting. The addition of topsoil re-duced the survival of trees, especially of non nodulating species, likely due to the vigorous herbaceous regener-ation in this treatment. Conversely, the addition of manure favored the tree growth. The nodulating species outperformed the non nodulating in respect to survival rate, total height, trunk diameter, and growth rate. The native species with the best survival and development rates were Mimosa tenuiflora, Mimosa caesalpiniifolia, Caesalpinia ferrea and Tabebuia caraiba, and among the exotics were Azadirachta indica and Pseudosamanea guachapele.