Experimental assessment of the impacts of fire and agriculture on the carbon dynamics of a páramo grassland in northern Ecuador

Prescribed fires, associated to extensive cattle raising, and the expansion of crop agriculture are two of the main threats to the integrity and functionality of páramo ecosystems in the Northern Andes. In addition to affecting plant and animal communities, these practices could significantly affect soil carbon storage and hydrological regulation. In this study, we present results from a field experimental assessment of the impacts of fires and potato cultivation on carbon dynamics in a grassland ecosystem in the páramo of Northern Ecuador. Using the static chamber method and a portable gas analyzer, we characterized carbon dynamics in 27 experimental 6.25 m 2 plots, randomly assigned to control, vegetation burning, or potato cultivation treatments. Unlike Control plots, Burning and Potato plots predominantly lost carbon during the first half of the experiment, and then shifted to negative values of net carbon exchange (NEE) around day 150. Specifically, NEE in the potato plots decreased from an average of 0.9 g CO 2 m -2 hr -1 during the first 150 days of the experiment, to −0.6 g CO 2 m -2 hr -1 during the second half of the study. Corresponding values for burning treatment plots represent a decrease from 0.5 g CO 2 m -2 hr -1 during the first half of the experiment to −0.3 g CO 2 m -2 hr -1 in the second half. Low rates of NEE in Control plots suggest that daytime carbon uptake capacity may be reduced under the evaluated conditions, although annual carbon balance cannot be inferred from the present dataset. These results underscore the need to further evaluate the practice of anthropogenic fires in páramos and limit the expansion of agriculture, as critical strategies for the long-term maintenance of páramo ecosystem services.