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Harvard Forest REU Symposium Abstract 2007
- Title: CO2 in Streamwater Shows Strong Response to Light and Flow Rate in Small Wetland
- Author: Eowyn C Connolly-Brown (Cornell University)
- Abstract:
We measured dissolved CO2 levels at multiple locations in a headwater stream (Bigelow Brook) with a small wetland created by beavers in the Harvard Forest. Our results confirm McInnis’s (2005) observation that the beaver swamp contains higher levels of dissolved carbon dioxide than upstream or downstream segments. CO2 concentration of streamwater was measured continuously by spraying water through an air-filled chamber and measuring CO2 in the air phase with an infrared gas analyzer. Chamber and water temperatures and wind speed were measured using thermocouples and a cup anemometer in order to calculate the air/water CO2 concentration ratio and to examine causes of CO2 variability. We found that the daily variation in CO2 concentration in the stream was not well predicted by temperatures or wind speed, but strongly correlated with photosynthetically active radiation (PAR), which we obtained from the Harvard Forest meteorological station. Over longer periods, stream flow rate also had an impact due to dilution effects, because of the low CO2 concentration in rainfall. We therefore conclude that the wetland’s dissolved CO2 concentration reflected the impact of both weather and microclimate factors including PAR over daily time scales and possibly soil temperature over longer time scales.
- Research Category: Forest-Atmosphere Exchange
