Traços fenotipicos e adaptativos como critério de seleção de mudas de especies arboreas nativas para subsidiar ações de reflorestamento na caatinga

Abstract

The selection of native forest species for the ecological restoration of degraded environments is a challenge for restoration ecology and requires technical knowledge regarding the introduction of species in the field and their management, especially in environments with high water restrictions, as is the case of the Caatinga. The Caatinga, a semi-arid region located in Northeastern Brazil, faces serious degradation problems due to deforestation and other anthropogenic actions. About 89% of the Caatinga has some level of degradation, threatening its biodiversity and ecosystem services; therefore, ecological restoration actions in this region are urgent. Given this context, the general objective of this study was to evaluate the initial development, survival, and growth of native tree species seedlings under different management conditions to support the selection of species to be used in the reforestation of the Caatinga. The present research has two distinct stages: the first stage is a greenhouse experiment and the second stage is directly in the field. The evaluation of the initial development of the seedlings in the greenhouse and the underground system of the species included two species that present underground storage structures (Astronium urundeuva M. Allemão (aroeira) and Amburana cearensis M. Allemão (cumaru)) and two that do not (Libidibia ferrea Mart. (jucá) and Tabebuia aurea S. Manso (craibeira)). The experiment on the survival and development of seedlings in the field was conducted at the São João do Cariri Experimental Station, PB, Brazil, and consisted of three treatments: irrigated short-root seedlings (RCI) and non-irrigated short-root seedlings (RCNI), planted in the rainy season, and non-irrigated long-root seedlings (RLNI), planted in the dry season. The results obtained in the greenhouse showed differences in seedling performance among species, regardless of the presence of the storage structure. The aroeira stood out positively in all analyzed variables; the craibeira had moderate growth, with a high root/shoot ratio; the cumaru had the lowest overall performance, with low biomass accumulation and slow growth; and the jucá presented, in the first three months, investment in shoot and root length growth, while in six months, it invested in the accumulation of biomass and phytomass. Regarding the field experiment, it can be highlighted that in terms of survival and development, the RCI treatment had the highest survival rate (80%) and development, followed by RLNI (60%) and RCNI (45%). Although RCI has the highest cost due to irrigation, it showed the best results. RCNI is cheaper but presents low survival, which may compromise reforestation over the years, especially if the following years are drier. RLNI, despite the high initial cost of seedling production, is a viable alternative in areas without irrigation with the potential for better results in the long term. Thus, it is concluded that the initial growth of the seedlings is determined by the intrinsic genetic potential of each species, regardless of the presence of storage structures. The choice of plant management conditions in reforestation actions should not be guided solely by the initial cost, but rather by a careful cost-benefit analysis that considers environmental conditions and the availability of financial resources. Keywords: desertification; dryland; ecosystem services; restoration; semi-arid.