The system measures the concentration of CO2 within an open- field plot, releasing CO2 as required from an on-site tank; release of CO2 is based on the direction and speed of the wind as measured by a weathervane at the center of the plot (Hendry et al., 1993). [...] This makes sense in the context of the present analysis as observations from the same study are held at the same conditions with respect to irrigation, solar irradiance, the chemical composition of the air and soil, location, and other factors. [...] Upon adding dummy variables for type of experiment in the Controls (1) specification, CO2 is positive and statistically significant at the 5% level of significance and temperature is negative and statistically significant at the 10% level. [...] In the No Controls (2) specification with the interaction term, none of the terms are statistically significant, CO2 and temperature are negative, and the interaction term is positive. [...] Adding the study year to the regression in the Controls+Year (1) specification leaves the coefficient on CO2 unchanged over the specification without the year variable and does not change the lack of statistical significance.
Authors
- Pages
- 32
- Published in
- Canada
