Trade-offs in the implementation of silvopastoral systems: Windbreak counter-effect, wind speed and cloud cover

Abstract This work aimed to improve the description of the windbreak counter-effect (WbCe) tin he implementation of silvopastoral systems under different cloudy conditions (clear sky and cloudy). A silvopastoral system with nuclei in which 5% and 10% of the pasture area is occupied by agroforestry nuclei was used (SPSnu5 and SPSnu10) and compared with treeless pasture (TLP) during summer in southern Brazil. The microclimatic variables analyzed were air temperature, wind speed, relative humidity, black globe temperature and Heat Load Index (HLI) at two heights, 20 and 120 cm. The wind speed was about twice as high in the TLP because there was no wind barrier through the nuclei. Air temperatures were higher on days with clear skies. SPSnu had a slightly lower temperature under most conditions. Humidity was similar in all treatments. TLP had lower HLI values than SPSnu5 and SPSnu10 under both cloudy conditions. SPSnu10 had the worst conditions for thermal comfort in the area 'around the nuclei'. Although the young nuclei did not provide shade, but blocked wind increasing HLI. Air temperatures were slightly lower under the SPSnu treatments, the lower wind speed and lack of shade from the growing trees worsened thermal comfort in both SPSnu, even on cloudy days, due to WbCe. Therefore, the phase of adoption of silvopastoral systems is a critical moment for the thermal comfort of livestock, even on cloudy days. Producers must be aware of this trade-off on hot days and avoid paddocks with young trees even on cloudy days as HLI increases.