Water and energy fluxes from a woodland savanna (cerrado) in southeast Brazil

Abstract

a b s t r a c tStudy region: The area of woodland savanna (cerrado) is located in southeast Brazil (21 • 36 to 44 S, 47 • 34 to 41 W). Study focus: The cerrado sensu-stricto savanna evapotranspiration was observed using the eddy-covariance method over three years. New hydrological insights for the region: The first year total rainfall (R = 1664 mm) was 11% above the long-term rainfall (1498 mm) and the total evapotranspiration (ET = 1242 mm) and water equivalent of available energy (A v = 1835 mm) were approximately 4% and 2% greater, respectively, than in the second year when the rainfall total was 5% lower than the long-term average. In the third year despite the total rainfall (1259 mm) being 24% lower than the first year and 16% lower than the average, the totals of ET (1242 mm) and A v (1815 mm) were approximately the same.The small variation in the observed annual ET totals shows that in this cerrado vegetation the deep soil moisture content supports the ET in a dry year and the water available for recharging the soil profile and groundwater (∼R − ET) was dominated by the rainfall amount being significantly greater in the wet year (422 mm) than in the dry year (13 mm).

Woody encroachment and its consequences on hydrological processes in the savannah

“…Across the natural mosaic of tree biomass in the Cerrado vegetation, it is generally considered that the proportion of rainfall lost as evapotranspiration or recharging groundwater reserves and providing streamflow vary across the structural gradient as has been demonstrated worldwide [8,21,22,25,26]. If biomass increases due to woody encroachment, changes are also expected in the partitioning of rainfall in interception, stemflow and throughfall; this has never been assessed in the Cerrado vegetation where previous hydrological studies have mostly focused on evapotranspiration only [23,24,43].…”

“…Soils in the Cerrado are mostly oxisols or entisols (Quartzipsament), distrophic, acidic with low fertility, very deep and well drained (89%), with high infiltration and therefore efficient groundwater recharge [40]. The Cerrado is the moistest savannah in the world [41], with annual precipitation in 86% of the biome ranging from 1000 to 2000 mm [40] and evapotranspiration estimated between 700-1900 mm [24,42,43]. Such climate conditions permit savannah and forest as alternative stable states [44], with woody encroachment occurring after fire suppression.…”

Sensibilidade Do Modelo Distribuído Hidrológico Da Biosfera Às Propriedades Hídricas Do Solo Em Uma Pequena Bacia De Cerrado

“…Foram usados como forçantes do DBHM os dados meteorológicos diários de estações hidrometeorológicas do INMET localizadas na região ao redor da BHCP, junto com o conjunto de dados observados na torre micrometeorológica (Cabral et al, 2015) localizada no trecho mais a montante da BHCP. Também foram utilizados os dados de precipitação observada no vertedor.…”

“…(2015) por ser uma das reservas com maior área contígua de cerrado sensu-stricto. O solo da região é arenoso (87% da composição média é areia) a condutividade hidráulica é aproximadamente 300 mm/h e porosidade relativamente baixa (39%) Cabral et al (2015). …”

Physiological responses and soil water balance of clonal <i>Eucalyptus</i> under contrasting spacings and genotypes

“…In a region near the current study site, the native vegetation displayed an Ei of 8% (CABRAL et al, 2015), indicating how planted eucalyptus forests might further impact site water balance. T stand was the component that most contributed to the distribution of rainwater, with a general average of 65%.…”