A influência da riqueza de espécies sobre a decomposição da serrapilheira em um projeto de restauração da caatinga

Abstract

Several studies have been conducted in the Caatinga in view of the high level of degradation, fragmentation of this habitat and desertification process. When implementing a restoration experiment it is of utmost importance to understand the various mechanisms that improve the growth and survival of the transplanted species, among them, the cycling of nutrients and factors that influence and increase the speed of this process.The study was conducted in a large-scale, long-term Caatinga Restoration experiment in the Conservation Unit, Açu National Forest, Assu-RN, administered by the Chico Mendes Institute for Biodiversity Conservation - ICMBio. Comprising 16 tree species, native to the Caatinga, 155 plots of 104 m² (8 x 13 m), communities with 32 individuals and five levels of richness: monocultures, combinations of 02, 04, 08 and 16 species, and control plots. It is part of a worldwide network, called TreeDiv (http://www.treedivnet.ugent.be/), which together with 27 other experiments implemented in more than 20 countries that test the effect of native species diversity on the functioning of planted forests. Thus, test whether: (I) Does the richness of tree species influence the process of burlap decomposition in the experiment? (II) Does the species composition of the plots of the experiment influence the process of burlap decomposition? (III) Do these effects differ between the dry and rainy season? For this purpose, we deployed litterbags containing detritus at three levels of lability (Amburana cearensis leaves, more labile; Combretum leprosum leaves, intermediate; and pine bark, more recalcitrant) in all 155 plots. The implementation of litterbags was carried out during the dry and rainy seasons. The results indicated that not photodegradation, but the rainy season has a greater effect on the decomposition of the burlap. The rainy season proved to be significant in all analyses; factors such as precipitation, temperature, and humidity would thus be contributing to the acceleration of the speed of this process in the cycling of nutrients and the better use of these in soil nutrition, improving the conditions for the growth and survival of the species in the experiment.