Impact of Fire on Carbon Stocks in a Peruvian Salt Marsh

Abstract:

There have been few studies of carbon (C) storage in Peru’s coastal wetlands, but the reports available indicate that they serve as valuable C sinks. Here we report on the impact of fire on C storage in a salt marsh of the Pantanos de Villa Wildlife Refuge in Lima. Situated in an arid climate, the Refuge is subject to frequent fires. We compared marsh areas dominated by Schoenoplectus Americanus (American bulrush), one burned in the previous year and a control site with no known history of recent burning. In both sites, we sampled five 1 m² plots, harvesting all vegetation before collecting three soil cores in each. Our 30 cm-deep soil cores were cut into 10 cm segments. Roots and rhizomes were separated from the soil matrix and analyzed as separate C pools.

C concentrations were measured with an elemental analyzer. The dry bulk density was used to calculate C density and stocks. C stocks in the control and burned areas decreased with depth and at all depths were substantially lower in the burned area as well as the living aboveground biomass. The average C stock in the living biomass was 53±8 and 2±0.5 tonnes ha^-1 in the control and burned areas, respectively. The average C stock over the 30 cm depth was 252±24 and 154±17 tonnes ha^-1 in the control and burned areas, respectively. The matrix contributed more to the C stock than the roots and rhizomes. Over the 30 cm depth, the matrix contributed 73% of the C in the control area and 77% in the burned area. Our results show that, per unit area, C storage of the S. Americanus marsh compares favorably to global averages, but is substantially reduced when burned. As most of the fires in the Refuge are of anthropogenic origin, the prevention of fire is imperative to maintain C stocks.