O estabelecimento de plantações de cactáceas forrageiras pode reduzir a expansão das áreas em processo de desertificação?

Abstract

Understanding the main hydrodynamic and biophysical consequences of land use change has been investigated by many researchers. However, little is known about how the establishment of forage cactus plantations can minimize the impacts promoted by anthropogenic actions especially in areas in the process of desertification. In this context, the objective of this research is to investigate the vegetation cover, the hydrodynamic and meteorological variables of an area of caatinga with anthropic disturbance (CPA) in comparison to an area with signs of desertification (AID) and another with cacti agroecossystem, Opuntia stricta (Haw.) Haw.) Forage palm, Mexican Elephant Ear clone. The experiment was conducted at Fazenda Algodões (8.31 ° S, 38.51 ° W and 348 m), in the municipality of Floresta - PE, during the period of August 2016 and August 2017. CPA and ACC were used three linear PAR sensors (SQ-321 Calibration Line Quantum Net10 sensors, Apogee, Logan, Utah, USA), both coupled to the structure of the micrometeorological towers. In AID, ICV was monitored by means of a ceptometer (AccuPAR, LP-80, Decagon Devices, Pullman, USA). In addition, soil analysis was carried out to characterize the physical-water properties at the beginning of the experiment, and measurements of soil water content were made over time. Daily data of the meteorological elements were obtained from three micrometeorological towers installed one in each area (CPA, AID and AAC). The results showed that the change in the soil use of caatinga areas with anthropogenic disturbance by areas with signs of desertification implied a reduction in plant cover from 41% to 17%. The water storage variation (CAS) followed the precipitation behavior, being higher in the caatinga area with anthropic disturbance (μ = 0.109 m3 m-3), even presenting a history of small animal rearing. The mean air temperature (Tm) indicates that there is a greater heat absorption in the cactaceous agroecosystem area (8.3°C) which resulted in higher air heating in that environment. The seasonality of relative air humidity (RAH) was influenced by the vegetation cover type, resulting in a higher mean for the area with signs of desertification (μ = 64.5%) and a lower one for the caatinga area with anthropic disturbance (μ = 62.0%). However, the interaction between the high temperature and the low relative humidity of the air resulted in a high vapor pressure deficit (VPD) for the area of cacti agroecosystems (μ = 1.54 kPa). The radiation balance (Rn) varied in response to water availability after rainfall events, presenting lower values for the area with signs of desertification (μ = 9.8 MJ m -2 day -1). Thus, the results suggest that the establishment of agricultural areas with forage cactus plants Opuntia stricta (Haw.) Haw can reduce the expansion of the environments in Desertification process, especially in the semi-arid region.