Carbon Dioxide (CO2) Fluxes from Terrestrial and Aquatic Environments in a High-Altitude Tropical Catchment

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Last modified date
  • June 17, 2020
Creator
  • Diego Riveros-Iregui (Corresponding Author)
  • Andrew Murray
  • Keridwen Whitmore
    • Affiliation: College of Arts and Sciences, Department of Geography
  • Chloe Schneider
    • Affiliation: College of Arts and Sciences, Department of Geography
  • Megan Raisle
    • Affiliation: College of Arts and Sciences, Department of Geography
  • Maribel Herrera
    • Affiliation: College of Arts and Sciences, Department of Geography
Abstract
  • *** This work was funded by the National Science Foundation under award 1847331: The role of small wetland connectivity in controlling greenhouse gas emissions and down-stream carbon fluxes from headwater tropical streams. *** Corresponding Author: Diego Riveros-Iregui
  • High-altitude tropical grasslands, known as “páramos", are characterized by their high solar radiation, high precipitation, and low temperature. They exhibit some of the highest rates of ecosystem carbon storage per unit area on Earth. Recent observations have shown that paramos may be a net source of CO2 to the atmosphere as a result of climate change; however, little is known about the source of this excess CO2 in these mountainous environments or whether specific landscape positions may be disproportionally contributing more CO2 than others. We evaluated the spatial and temporal variability of surface CO2 fluxes from adjacent terrestrial and aquatic environments based on a suite of field measurements performed over seven weeks. Our findings revealed the importance of hydrologic dynamics in regulating the magnitude and likely fate of dissolved carbon in the stream. While headwater catchments are known to contribute disproportionately larger amounts of carbon to the atmosphere than their downstream counterparts, our study highlights the spatial heterogeneity of CO2 fluxes within and between aquatic and terrestrial landscape elements in headwater catchments of complex topography. Stream carbon flux to the atmosphere appeared to be transport-limited (i.e., controlled by flow characteristics, turbulent flow, water velocity) in the upper reaches of the stream, and source limited (i.e., controlled by carbon availability) in the lower reaches of the stream. These findings represent first step in understanding ecosystem carbon cycling at the interface of terrestrial and aquatic ecosystems in high-altitude, tropical, headwater catchments.
Methodology
  • Our research site was located in the Cayambe-Coca Ecological Reserve, a páramo ecoregion in the northern Ecuadorian Andes (elevation 4,200 m). This páramo ecosystem exhibits a mean daily temperature of 5°C and a wide range of annual from 1,450 mm to 4,000 mm (Sanchez et al.,2017, Troya et al., 2004). The study watershed was a headwater catchment delimited to the west by the continental divide of the Andes Mountains, and draining to the east toward the Napo and Amazon Rivers. The site is characterized by alpine wetland complexes that are connected by well-defined, incised stream channels. This study focused on a 2.3-ha wetland (hereafter wetland) drained by a single outlet on the south end and into a stream channel cutting through complex topography (Figure 1). The outlet stream (hereafter stream reach) was 250 m long and flowed NNE-SSW. This stream reach was divided into upper and lower portions by a 4-m waterfall located 107 m downstream from the wetland outlet (Figure 1). Land cover is composed mainly of páramo vegetation communities, including grassland, scrublands, peatlands, and small pockets of high Andean forests that include dense shrubs. Mean peatland soil depth for the region is 4.6 m, with a mean estimated storage of 1,573 Mg C ha-1, believed to be at least 3,000 years old (Hribljan et al., 2016).
Date of publication
DOI
Kind of data
  • Numeric
Resource type
  • Dataset
Rights statement
  • In Copyright
License
  • CC0 1.0 Universal
Language
  • English

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