Susceptibilidade ? desertifica??o no Estado do Rio de Janeiro baseada em ?ndices clim?ticos de aridez: Pr?ticas agroecol?gicas como alternativa de mitiga??o e preven??o

Sumario: Desertification is one of the major problems faced by humanity to achieve sustainable development. This phenomenon is defined as ?land degradation in arid, semi-arid and dry subhumid areas resulting from various factors, including climatic variations and human activities?. In terms of climate, aridity indices are considered reliable indicators, being utilized to delimitate areas susceptible to desertification in Brazil and worldwide. Although Brazil is extremely vulnerable to desertification, the Northeast of its territory is the priority for studies related to the topic. However, it is well known that other regions, especially those located in the boundary of the susceptible areas, are affected by land degradation exacerbated by severe droughts. Agroecology is considered a new proposal to combat this process by planning sustainable agriculture systems to ensure food security, protection of natural resources and safeguard human well-being. The present study aims to evaluate the susceptibility to desertification in the state of Rio de Janeiro (RJ) and propose agroecological practices as an alternative for its mitigation and prevention. For this, the climatic soil water balance (CSWB) of 94 rainfall stations was calculated with annual rainfall (R) data from 1961 to 2010 and annual air temperature (T) estimations obtained from the adjustment of a multiple linear regression model, which was, subsequently, used for the spatial interpolation of this variable, as a function of latitude, longitude and altitude. The resulted Potential Evapotranspiration (PET) data was used to calculate the aridity indices AI and D. R, PET, and water deficit (WD) determined by CWB calculations were then interpolated through minimum curvature method for the entire RJ state. AI indicated the presence of areas susceptible to desertification in 5% of Rio de Janeiro territory (2.305,8 km?) in Norte Fluminense and Baixadas Litor?neas regions, whereas D index, characterized only 431,06 Km? (1% of RJ) in the Norte Fluminense as susceptible. Nonetheless, both aridity indices (AI and D) demonstrated that Norte Fluminense and the east of Baixadas Litor?neas are the driest areas of the state, followed by Noroeste Fluminense and Metropolitana regions. Being Norte Fluminense more susceptible to desertification, a case study was performed through secondary data analysis and direct observations to propose agroecological practices to assist family farmers to combat desertification?s effects. In this perspective, the recovery and conservation of native vegetation in protected areas, improvement of irrigation systems, diversification of food production, agroecological management of the soil, among others, are considered powerful alternatives to improve life quality of rural communities and ensure environmental sustainability in facing desertification.