Applied nucleation under high biodiversity silvopastoral system as an adaptive strategy against microclimate extremes in pasture areas

Abstract

This study aimed to assess the influence of the high biodiversity silvopastoral system (SPSnu) on the microclimate, pasture production, and pasture chemical composition. Microclimate variables and pasture production and chemical composition were measured in pared paddocks under SPSnu and treeless pasture (TLP) in a commercial farm during four seasons in Southern Brazil. SPSnu measurements were subdivided into two areas: around the nuclei (AN) and area inter-nuclei (IN). In the TLP paddocks, we plotted fictitious nuclei with the same areas and distributions of SPSnu, however without trees. For the microclimate measurements, these areas were noted when shaded or unshaded by the nuclei trees. In each season, the microclimate variables air temperature (AT, °C), relative humidity (RH, %), illuminance (Ilu, lux), wind speed (WS, m/s), and soil surface temperature (SST, °C) were measured. In addition, botanical composition (%), pasture production (kg/DM/ ha), and pasture chemical composition were evaluated. The SPSnu provided the lowest values of microclimate variables in all seasons (p < 0.05), except for the relative humidity. Winter had the highest thermal amplitude in the systems. The highest difference between SPSnu and TLP for AT (4.3 °C) and SST (5.2 °C) was measured during the hot seasons (spring and summer). In contrast, during cold seasons (autumn and winter) it observed highest thermal amplitude between SPSnu and TLP. Overall, the highest annual pasture production was observed in the SPSnu (p < 0.05). During the summer, the SPSnu areas showed the highest values of crude protein and dry matter (p < 0.05). During the winter, the TLP showed the lowest values (p < 0.05) of pasture production and dry matter. It was observed that SPSnu improved the microclimate at the pasture level, influencing pasture production and pasture chemical composition. The enhanced microclimate can partially mitigate some of the effects of climate change on pastoral agroecosystems, creating conditions for ecological rehabilitation of ecosystem processes and services. These conditions could be amplified to a biome level through a payment for ecosystem services program.

Keywords: Agroforestry; Biometeorology; Pasture shading; Thermal amplitude; Thermal environment.