Impacts of grazing on greenhouse gas emissions from high elevation páramo peatlands.

High-elevation Andean peatlands hold particularly deep, dense carbon deposits even among peatlands and are a major regional carbon stock. These peatlands are often used for open-range cattle grazing, which has the potential to destabilize peat carbon stocks, releasing greenhouse gases (GHG) in the form of CO2 and CH4. There is currently very little information on the impacts of grazing on undrained or partially drained peatlands. We tested the hypotheses that (1) grazing increases GHG emissions (CO2 and CH4) from Andean peatlands in general when measured across a wide range of different vegetation types and water table depths and (2) the magnitude of impact of grazing on CO2 and CH4 emissions varies by dominant vegetation type. We conducted a survey of CH4 and CO2 fluxes at 31 high-elevation peatlands across Ecuador. We then quantified the influence of environmental parameters (water table depth, vegetation type, and grazing pressure) on GHG emissions. We found that heavier grazing intensities were associated with increased CH4 emissions and that the effect of grazing on CH4 emission was largest in areas with high water tables and sedge-dominated vegetation. Grazing in cushion plant-dominated peatlands also increased both gross primary productivity and ecosystem respiration, with the net effect of increasing CO2 release and an overall increase in global warming potential. Overall, our results support the hypothesis that grazing leads to increased GHG emissions from tropical Andean peatlands, with the effect size dependent on vegetation type, degree of drainage, and the intensity of grazing.