Carbon dioxide and methane fluxes in grazed and undisturbed mountain peatlands in the Ecuadorian Andes

Abstract

Peatlands are widespread throughout the tropical Andean paramo. Despite the large carbon stocks in these ecosystems, carbon dioxide (CO2) and methane (CH4) flux data are lacking. In addition, cattle grazing is widespread in the paramo and could alter gas fluxes. Therefore, our objectives were to measure CO2 and CH4 fluxes with the static chamber technique in an undisturbed and in an intensively cattle grazed peatland in the mountains of Ecuador. We found that hummocks in the undisturbed site had higher net ecosystem exchange (NEE), gross primary production (GPP), ecosystem respiration (ER), and CH4 fluxes, compared to lawns. In contrast, microtopography at the grazed site did not predict CO2 fluxes, whereas vegetation cover was correlated for all three metrics (NEE, ER, and GPP). At low vegetation cover, NEE was positive (losing carbon). CH4 emissions in the undisturbed site were low (8.1 mg CH4 m-2 d-1). In contrast, CH4 emissions at the grazed site were much greater (132.3 mg CH4 m-2 d-1). This is probably attributable to trampling and nutrient inputs from cattle. In summary, the two peatlands differed greatly in CO2 and CH4 exchange rates, which could be due to the variation in climate and hydrology, or alternatively to intensive grazing by cattle.