Water balance, nutrient and carbon export from a heath forest catchment in central Amazonia, Brazil

Abstract

Abstract:Carbon storage values in the Amazon basin have been studied through different approaches in the last decades in order to clarify whether the rainforest ecosystem is likely to act as a sink or source for carbon in the near future. This water balance, dissolved organic carbon (DOC) and nutrient export study were carried out in a micro-scale heath forest (Campina) catchment in central Amazonia, Brazil. For a 1-year study period (18 March 2007 until 19 March 2008, rainfall amounted to 3054 mm; of which, 1532 mm was evaporated by the forest (4.1 mm day À1 ). Rainfall interception loss amounted to 15.6% of gross rainfall. Surface runoff amounted to 485 mm, whereas another 1071 mm was discharged as regional groundwater outflow. Accumulated DOC exports in surface runoff amounted to 15.3 g m À2 year À1 , whereas the total carbon exported was 55.9 g m À2 . This is much higher than that observed for a nearby tall rainforest catchment in central Amazonia (DOC export < 20 g m À2 ). As Campina heath forest areas cover a significant proportion of the Amazon Basin, these differences in ecosystem hydrological carbon exports should be taken into account in future studies assessing the carbon budget for the Amazon Basin. Macro-nutrient exports were low, but those of calcium and potassium were higher than those observed for tall rainforest in the Amazon, which may be caused by a lower retention capacity of the heath forest ecosystem.

The canopy interception–landslide initiation conundrum: insight from a tropical secondary forest in northern Thailand

“…However, our values and variabilities are very similar to those reported in an open tropical Brazilian rainforest with many palm trees (10.2 ± 5.6 %) where similar magnitudes and numbers of storms were recorded (Germer et al, 2006). Interception losses in other native and secondary Amazonian forests have been reported in the range of about 6 to 22 % (Lloyd and Marques, 1988;Elsenbeer et al, 1994;Filoso et al, 1999;Tobón Marin et al, 2000;Bäse et al, 2012;Zanchi et al, 2015). Several studies in both native and plantation forests in southeast Asia that experience monsoon storms reported similarly low interception losses in the range of about 7 to 20 % (Sinun et al, 1992;Dykes, 1997;Konishi et al, 2006;Ziegler et al, 2009;Tanaka et al, 2015).…”

Effects of land‐cover changes on the partitioning of surface energy and water fluxes in Amazonia using high‐resolution satellite imagery

“…However, in order to better understand the impacts caused by land-cover changes, it is necessary to obtain detailed information on the partitioning of surface fluxes. Here, we highlight that alterations on flux partitioning over the Amazon can influence the atmospheric circulation and precipitation (PPT) in the tropics (Swann, Fung, & Chiang, 2012;Zanchi et al, 2015). Here, we highlight that alterations on flux partitioning over the Amazon can influence the atmospheric circulation and precipitation (PPT) in the tropics (Swann, Fung, & Chiang, 2012;Zanchi et al, 2015).…”

Are catchments leaky?

“…About 88% of catchment outflow is through groundwater, the consideration of which caused a fourfold increase in DOC and 14‐fold increase in DIC export. The map in (a) also shows the Reserva Biológica de Campina, the study catchment of Zanchi et al ()…”

“…Zanchi et al () reports on carbon and nutrient export from a microcatchment (0.065km 2 ) at Reserva Biológica de Campina in the white‐sand region of north‐central Amazonia (location shown in Figure a). Comprehensive hydrologic measurements ( P , canopy interception, sap flow, flux tower ET, soil moisture profile, water table level, streamflow, soil, stream and groundwater carbon, and major ions) suggest that river outflow accounted for ~31%, and groundwater outflow ~69% of total catchment discharge.…”

“…Note the presence of high-permeability zones 10s of meters below the stream beds along the main stem (point a to h) river export from small, leaky catchments to large river basins would grossly overestimate the capacity of the forests as carbon sinks, for the groundwater loss from the headwaters is likely imported into lower catchments where spring seeps and CO 2 outgassing can return a large amount of carbon to the atmosphere (Johnson, Lehmann, Couto, Filho, & Riha, 2006;Johnson et al, 2008;Neu et al, 2011). Zanchi et al (2015) reports on carbon and nutrient export from a microcatchment (0.065km 2 ) at Reserva Biológica de Campina in the white-sand region of north-central Amazonia (location shown in Figure 9a). Comprehensive hydrologic measurements (P, canopy interception, sap flow, flux tower ET, soil moisture profile, water table level, streamflow, soil, stream and groundwater carbon, and major ions) suggest that river outflow accounted for~31%, and groundwater outflow~69% of total catchment discharge.…”