Carbon Stocks and Fluxes in Rangelands of the Río de la Plata Basin

PARUELO J. M.; PIÑEIRO, G.; BALDI, G.; BAEZA, S.; LEZAMA, F.; ALTESOR, A.; OESTERHELD, M

Rangeland Ecology and Management (ex JRM)

SOC RANGE MANAGEMENT

Año: 2010 vol. 63 p. 98 - 108

1550-7424

Grasslands are one of the most modified biomes on Earth. Land use changes had a large impact on carbon (C) stocks of grasslands.Understanding the impact of land use/land cover changes on C stocks and fluxes is critical to evaluate the potential of rangelandecosystem as C sinks. In this article we analyze C stocks and fluxes across the environmental gradients of one of the most extensivetemperate rangeland areas: the Rı´o de la Plata Grasslands (RPG) in SouthAmerica. The analysis summarizes information provided byfield studies, remote sensing estimates, and modeling exercises. Average estimates of aboveground net primary production (ANPP)ranged from240to 316 gC?m22 ? yr21.Estimates of belowgroundNPP (BNPP)weremore variable thanANPP and ranged from264to 568 g C?m22 ? yr21. Total Carbon ranged from 5 004 to 15 008 g C?m22. Plant biomass contribution to Total Carbon averaged13%andvariedfrom9.5%to27%among sites.The largestplantCstock corresponded tobelowgroundbiomass.Abovegroundgreenbiomass represented less than 7%of the plant C. Soil organic carbon (SOC)was concentrated in the slowandpassive compartments ofthe organic matter. Active soil pool represented only 6.7% of the SOC. The understanding of C dynamics and stocks in the RPGgrasslands is still partial and incomplete. Field estimates of ANPP and BNPP are scarce, and they are not based on a commonmeasurement protocol.Remotely sensed techniques have the potential to generate a coherent and spatially explicit databaseonANPP.However,morework is needed toimprove estimates of the spatialandtemporal variabilityof radiation use efficiency.The absence of aflux tower network restricts the ability to track seasonal changes in C uptake and to understand fine-scale controls of C dynamics.