Diferenças hidrometeorológicas e da vegetação de paisagens do sertão central do Brasil sob gradientes de perturbações antrópicas

Abstract

The Brazilian semiarid region is constantly changing land use due to the deforestation process, characterizing landscapes with different levels of human disturbance. Thus, the objective of this research was to investigate the patterns of energy fluxes in the Caatinga vegetation and in surfaces with land use modification as a result of the insertion of CAM agroecosystems or by the advance of the desertification process, establishing relationships with the seasonality of the species predominant. The experiment was conducted at Fazenda Algodões, municipality of Floresta - PE. The study period was from november 2017 to december 2020. Four experimental sites were evaluated: forest with preserved Caatinga vegetation (CAA), deforested area (ADA), area of regenerating Caatinga (REGE) and cactus area (CAM). Daily data of meteorological elements were obtained from micrometeorological towers installed in the respective experimental sites. The investigation of flux dynamics using the BERB technique contributed to estimate the magnitude and seasonal patterns of sensible heat (H) and latent heat (LE) among different ecosystems. The latter is used to determine evapotranspiration (ET) values. Monitoring of soil moisture was carried out using a capacitive probe in each area. The plant water dynamics were quantified by the relationships between internal precipitation, interception and stem runoff for the CAA plants. The results indicated that both surfaces had low LE values and high H values, mainly during the dry period. About 33% of the radiation balance (RN) received was used for LE, 62% for H and 5% for G in the preserved Caatinga, versus 32% of RN for LE, 62% for H and 6% for G in the regenerating Caatinga. While in the deforested area 37% of the NB received was destined for LE, 57% for the H and 6% for the G, versus 33% of the NB for LE, 63% for H and 4% for the G in the cactus area. For the Caatinga area, rainfall partition indicates that internal precipitation, trunk runoff and interception losses correspond to 83.14%, 0.49% and 16.37% of the precipitation, respectively. It was concluded that the variations of micrometeorological components were dependent on the water regime and soil water storage, and that the removal of native vegetation resulted in less energy available for the LE, with trends of higher values destined for the flows of H and G. The evapotranspiration for the regenerating Caatinga surfaces, deforested area and cactus was higher than the preserved 10 Caatinga area, due to the greater availability of water in the soil. Rainfall interception losses depend on rainfall characteristics, meteorological conditions and the characteristics of the forest they influence.