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Harvard Forest Symposium Abstract 2006
- Title: Carbon Monoxide Uptake Kinetics in Unamended and Long-Term Nitrogen Amended Temperate Forest Soils
- Primary Author: Paul Steudler (Marine Biological Laboratory)
- Abstract:
Carbon monoxide (CO) is a chemically active trace gas that plays a critical role in tropospheric chemical processes. The effect of nitrogen (N) additions on the dynamics of carbon monoxide consumption in temperate forest soils is poorly understood. To explore the consequences of long-term N additions on atmospheric carbon monoxide consumption in soils, we measured soil CO profiles, potential rates of CO consumption and uptake kinetics in temperate hardwood and pine control plots and plots that had amendments of 50 and 150 kg N ha-1y-1 for more than 15 years. CO concentrations in the soil profiles were above atmospheric levels in the high N plots of both stands suggesting that in these forest soils the balance between consumption and production may sometimes be shifted so that either production increased or consumption decreased. Highest potential rates of CO consumption were measured in the organic horizons and decreased with soil depth. Additions of N affected the rates differently in the two stands. CO consumption increased in all but one soil depth of the hardwood N amended plots while in the pine N amended plots CO consumption decreased in all soil depths. CO enzyme affinities increased with depth in the soil profiles of both control plots. However, enzyme affinities in the most active soil depths (organic and 0-5 cm mineral) decreased in response to addition of low levels N in both stands suggesting an adaptation by the microbial community to N inputs. The response to high levels of N was mixed between stands. Enzyme affinities dramatically increased in these two soil depths in the hardwood stand. In the pine stand, affinities decreased in the organic horizon, but increased slightly in the 0-5 cm mineral soil. These findings indicate that long-term addition of N either by fertilization or deposition may alter the size, composition and/or physiology of the community of CO consumers so that their ability to act as a sink for atmospheric CO changes. These changes could have a substantial effect on the lifetime of greenhouse gases such as CH4 and therefore the future of Earth’s climate.
- Research Category: Forest-Atmosphere Exchange
