Microclimate and soil moisture in a silvopastoral system in southeastern Brazil

Abstract

In this study, the microclimate changes in silvopastoral systems are quantified at different time and spatial scales and compared with single-pasture systems. The study was conducted in a silvopastoral system in São Carlos, Brazil (22°01' South and 47°53' West). The silvopastoral system consisted of grass pastures [Urochloa (sin. Brachiaria) decumbens cv. Basilik] lined with strips of native trees spaced at 17 m. Continuous microclimate measurements (air temperature, relative humidity, wind speed, and incident photosynthetically active radiation) were carried out from September 2010 to September 2012 at two positions of the silvopastoral system (2.0 and 8.5 m from the rows of trees) and at a pasture under full sunlight, located in an adjacent area. The soil moisture was monitored weekly from 24 March 2010 to 1 April 2012 at distances of 0.0, 2.0, 4.75, and 8.5 m from the rows of trees. The rows of native trees reduced wind speeds (46% reduction) and changed the photosynthetically active radiation incidence pattern on the pasture (up to 40% reduction of incidence at the point nearest to the trees). The combined action of these factors promoted thermal and air humidity changes on the pasture at the different points measured. With respect to soil moisture, there was greater soil moisture removal at the sampling points near the rows of native trees under the silvopastoral system, mainly due to enhanced exploration by tree roots at greater depths in dry spells or early dry periods, when compared with the midpoints between the rows.

Microclimate in understories of a mango orchard and a degraded area in the Eastern Amazon

“…Minimum air temperature in the understory was 0.16ºC lower in degraded area than in the mango orchard. Similar results were observed by Pezzopane et al (2015), in São Carlos, São Paulo State, where minimum air temperature was 0.10ºC lower in the forest understory with less vegetative cover than the other. In areas with less vegetation, minimum air temperature is usually lower, because having less vegetation facilitates the passage of longwave radiation (coming from Earth), leading to atmospheric cooling.…”

“…The mango orchard reduced mean air temperature in the understory by 0.37ºC in comparison to the degraded area. Similar results were observed in São Carlos, where average air temperature was reduced by 0.25ºC in the forest understory with more vegetation coverage in comparison with the other understory (Pezzopane et al, 2015). This was lower than the results found in Jussari, Bahia State, where the reduction of the average air temperature was 1.25°C in the understory of the forest areas and a shaded cacao crop (Theobroma cacao L.) (Pinheiro et al, 2013).…”

“…Reduction of maximum air temperature in understories has been observed in other studies, where the mean reduction was 0.77ºC in forest understories, in São Carlos, São Paulo State (Pezzopane et al, 2015) and 2.20ºC, in the understory of macadamia nut trees (Macadamia integrifolia Maiden & Betche), in São Mateus, Espírito Santo State (Pezzopane et al, 2010), in relation to other environments outside of the understory.…”

“…The presence of trees reduces the average air temperature by 1.25ºC (Pinheiro et al, 2013), the maximum air temperature by 0.77ºC (Pezzopane et al, 2015), the air thermal amplitude by 2.40ºC, and the vapor pressure deficit of the understory by 0.34 kPa (Pezzopane et al, 2010). Therefore, planting trees may ameliorate understory microclimate (Pezzopane et al, 2010;2015;Pinheiro et al, 2013), especially in degraded areas with a history of land use changes.…”

Influence of pastoral systems on Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae) and the entomopathogen Metarhizium anisopliae (Metsch.) Sorokin

“…Some studies have shown that shadow promoted by trees in silvopastoral systems reduce solar radiation, avoid soil moisture loss and increase air humidity (Paciullo et al, 2008;Law et al, 2011;Pezzopane et al, 2015) which contribute to entomophathogen establishment (Meyling et al, 2009).…”