Greenhouse gas budget of a poplar bioenergy plantation in Belgium: CO₂ uptake outweighs CH₄ and N₂O emissions

Abstract

Biomass from short‐rotation coppice (SRC) of woody perennials is being increasingly used as a bioenergy source to replace fossil fuels, but accurate assessments of the long‐term greenhouse gas (GHG) balance of SRC are lacking. To evaluate its mitigation potential, we monitored the GHG balance of a poplar (Populus) SRC in Flanders, Belgium, over 7 years comprising three rotations (i.e., two 2 year rotations and one 3 year rotation). In the beginning—that is, during the establishment year and during each year immediately following coppicing—the SRC plantation was a net source of GHGs. Later on—that is, during each second or third year after coppicing—the site shifted to a net sink. From the sixth year onward, there was a net cumulative GHG uptake reaching −35.8 Mg CO2 eq/ha during the seventh year. Over the three rotations, the total CO2 uptake was −51.2 Mg CO2/ha, while the emissions of CH4 and N2O amounted to 8.9 and 6.5 Mg CO2 eq/ha, respectively. As the site was non‐fertilized, non‐irrigated, and only occasionally flooded, CO2 fluxes dominated the GHG budget. Soil disturbance after land conversion and after coppicing were the main drivers for CO2 losses. One single N2O pulse shortly after SRC establishment contributed significantly to the N2O release. The results prove the potential of SRC biomass plantations to reduce GHG emissions and demonstrate that, for the poplar plantation under study, the high CO2 uptake outweighs the emissions of non‐CO2 greenhouse gases.

Estimation of Gross Primary Productivity (GPP) Phenology of a Short-Rotation Plantation Using Remotely Sensed Indices Derived from Sentinel-2 Images

“…Even though the important role of SRC plantations in bioenergy productions and carbon sequestration is well recognized by the scientific community [10,11], data on SRC productivity (e.g., Gross Primary Productivity (GPP)) and phenology are scarce and limited to small experimental areas.…”

The effects of cultivar and rotation length (5 vs. 10 years) on biomass production and sustainability of poplar (Populus spp.) bioenergy plantation

“…To conclude, this study showed that 10‐year rotation produced significantly more sustainable biomass in comparison to two, consecutive 5‐year rotation cycles. Other advantages of longer rotations arise from less impact on environment (Griffiths et al, 2019), a better GHG budget (creation of a GHG sink; Horemans et al, 2019) and positive influences on biodiversity (Griffiths et al, 2019), which together make them more similar to forest systems. Such rotations use the biological growth abilities of the trees more naturally.…”

Pectin and Xylan Biosynthesis in Poplar: Implications and Opportunities for Biofuels Production

“…In contrast, cellulosic ethanol derived from plants such as hybrid poplar can reduce net GHG emissions to nearly zero (Solomon et al, 2007 ). Researchers found that in a poplar short-rotation coppice in Belgium, the bioenergy plantation's high CO 2 uptake outweighed non-CO 2 greenhouse gas emissions (Horemans et al, 2019 ). The chemical properties and ubiquity of the secondary cell wall (SCW) have led to the SCW being marked as a biofuel source of interest.…”