$CO_{2}$ uptake is offset by $CH_{4}$ and $N_{2}O$ emissions in a poplar short rotation coppice

The need for renewable energy sources will lead to a considerable expansion in the planting of dedicated fast-growing biomass crops across Europe. These are commonly cultivated as short-rotation coppice (SRC), and currently poplar (Populus spp.) is the most widely planted. In this study we report the greenhouse gas (GHG) fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) measured using eddy covariance technique in an SRC plantation for bioenergy production. Measurements were made during the period 2010-2013, i.e. during the first two rotations of the SRC.The overall GHG balance of the four years of the study was an emission of 1.90 (± 1.37) Mg CO2eq ha−1; this indicated that soil trace gas emissions offset the CO2 uptake by the plantation. CH4 and N2O contributed almost equally to offset the CO2 uptake of -5.28 (±0.67) Mg CO2eq ha−1 with an overall emission of 3.56 (± 0.35) Mg CO2eq ha−1 of N2O and of 3.53 (± 0.85) Mg CO2eq ha−1 of CH4. N2O emissions mostly occurred during one single peak a few months after the site was converted to SRC; this peak comprised 44% of the total N2O loss during the two rotations. Accurately capturing emission events proved to be critical for deriving correct estimates of the GHG balance. The nitrogen (N) content of the soil and the water table depth were the two drivers that best explained the variability in N2O and CH4 respectively. This study underlines the importance of the non-CO2 GHGs on the overall balance. Further long-term investigations of soil trace gas emissions should monitor the N content and the mineralization rate of the soil, as well as the microbial community, as drivers of the trace gas emissions.

Publication year:2016

Keywords:A1 Journal article

BOF-keylabel:yes

BOF-publication weight:10

CSS-citation score:2

Authors:International

Authors from:Higher Education

Accessibility:Open