Microclima de sistema silvipastoril em diferentes orientações de encostas

Abstract

Knowledge of the microclimate is essential for the planning and implementation of silvopastoral systems, since its success depends on the balance in the competition for environmental resources between the tree component and the forage species. The objective was to characterize the influence of topography, as well as the combined effect of the exposure face and the tree component on the microclimatic conditions of a silvopastoral system in the initial phase of establishment. The study was carried out in Jerônimo Monteiro, ES (Latitude: 20 ° 50'27 "S; Longitude: 41 ° 22'22" W) in a pasture area, delimited according to the exposure face (north, south, northeast and southwest) and recovered by different silvopastoral system models. The evaluations took place in campaigns of 20 days in three periods, with the first two aiming to characterize the variation of climatic conditions in relation to the dry and rainy seasons, while the third aimed to characterize the combined effect of the dry season and the tree component. Microclimatic characterization was performed by measuring global solar radiation, radiation balance, air temperature, relative humidity, surface temperature and soil temperature at 2, 5, 10 and 20 cm deep. From the temperature and relative humidity data, the vapor pressure deficit was determined. The soil moisture content was determined using the gravimetric method, taking a soil sample (0 to 20 cm deep) at five points around each weather station. In the third campaign, the leaf area index (IAF) of the eucalyptus rows was determined by means of a canopy analyzer model (LAI-2.050 - LI-COR), connected to a model datalogger (LAI-2.050 - LI- COLOR). The data were analyzed using descriptive statistics and linear regression. The different slope exposure faces caused differences in the radiation regime of opposite sides. The shading caused by the tree component changed the hourly dynamics of radiation incidence, especially on the south-facing slopes. The radiation regime of each slope provided the formation of distinct microclimate conditions between the slopes, especially after the establishment of the slvipastoral system. The main microclimate differences were evidenced on clear days and on an hourly scale.