Decomposição da serrapilheira em área de restauração da Caatinga: efeitos da facilitação, estrutura da comunidade vegetal e sazonalidade

Abstract

The decomposition of litter is the main nutrient pathway between vegetation and soil. In forest ecosystems the vegetation community determines both the volume and quality of the litter, besides modifying abiotic conditions that directly affect the activity of detritivores organisms below the canopy. In semi-arid environments, such as the Caatinga in Northeastern Brazil, the environmental stress mitigation effect promoted by vegetation helps seedlings and the detritivore community to face limiting conditions, making facilitation relationships an important modulator of the plant community in this biome. In the present study, litter production and decomposition were measured during the dry and rainy seasons in Caatinga in order to assess: (I) How leaves of nurse species influence litter decomposition and nutrient cycling; (II) How the diversity of neighboring plants influence litter decomposition; and (III) The effect of the herbaceous community on leaf decomposition of tree species during restoration in the Caatinga. The results show that: (I) nurse plants have greater potential for tree-soil nitrogen transfer through leaf fall; (II) the functional traits of nurses leaves promote synergistic effects on litter decomposition; (III) the abundance of neighboring trees influences the decomposition of relatively less labile detritus; (IV) detritus from the herbaceous stratum positively affects the decomposition of tree leaves; (V) and that the quality of the litter and rainfall are determinants for the decomposition process in the Caatinga. Thus, the study assists in understanding the mechanism of nutrient supply in facilitating interactions between plants in the Caatinga and the importance of maintaining vegetation to promote efficient nutrient cycling, as well as highlighting the fundamental role of rainfall for the functioning of ecosystems in semi-arid environments.