11:00 〜 11:15
[BCG05-06] Forest-to-Solar-Farm Conversion Turns a Methane Sink into a Source Due to Soil Compaction
キーワード：Methane flux, Land-use change, Soil compaction, Solar photovoltaic farm, Soil carbon flux, Forest-to-solar conversion
The conversion of forested land to solar photovoltaic (PV) farms is an emerging land-use change with significant implications for ecosystem greenhouse gas (GHG) fluxes. This study investigated the impact of forest-to-solar-farm conversion on methane (CH4) fluxes at the 66-hectare Sheng-Feng solar farm in eastern Taiwan. Using two years of field measurements, we analyzed changes in soil CH4 fluxes following the transition from a forest plantation to a solar farm, focusing on the effects of soil disturbance and compaction.
The study site was part of a ~500 ha forest plantation, of which 66 ha were converted into a solar farm. Monthly soil CH4 flux measurements were conducted within the solar farm, while a neighboring section of the remaining plantation served as a reference site. The plantation functioned as a typical net CH4 sink, with microbial oxidation playing a dominant role in uptaking atmospheric CH4. In contrast, measurements at the converted solar farm site revealed a distinct shift, with the area now acting as a CH4 source. Monthly CH4 flux measurements showed sporadic yet significant CH4 emissions, particularly following rainfall events, when compacted soils restricted drainage and created anaerobic microsites conducive to methanogenesis. The estimated annual soil CH4 flux transitioned from -4.3 kgC ha-1 y-1 (net sink) in the plantation to +87.6 kgC ha-1 y-1 (net source) in the solar farm, demonstrating a notable reversal in CH4 cycling. Soil compaction during site preparation altered soil porosity and water infiltration rates, promoting transient water saturation and localized CH4 production.
This study highlights the unintended GHG consequences of renewable energy infrastructure development on former forested lands, particularly in relation to CH4 dynamics. While solar farms contribute to carbon offset via clean energy generation, their potential to become CH4 sources due to soil compaction warrants further attention. These findings emphasize the need for sustainable land management strategies that mitigate CH4 emissions when repurposing forested landscapes for renewable energy projects.
The study site was part of a ~500 ha forest plantation, of which 66 ha were converted into a solar farm. Monthly soil CH4 flux measurements were conducted within the solar farm, while a neighboring section of the remaining plantation served as a reference site. The plantation functioned as a typical net CH4 sink, with microbial oxidation playing a dominant role in uptaking atmospheric CH4. In contrast, measurements at the converted solar farm site revealed a distinct shift, with the area now acting as a CH4 source. Monthly CH4 flux measurements showed sporadic yet significant CH4 emissions, particularly following rainfall events, when compacted soils restricted drainage and created anaerobic microsites conducive to methanogenesis. The estimated annual soil CH4 flux transitioned from -4.3 kgC ha-1 y-1 (net sink) in the plantation to +87.6 kgC ha-1 y-1 (net source) in the solar farm, demonstrating a notable reversal in CH4 cycling. Soil compaction during site preparation altered soil porosity and water infiltration rates, promoting transient water saturation and localized CH4 production.
This study highlights the unintended GHG consequences of renewable energy infrastructure development on former forested lands, particularly in relation to CH4 dynamics. While solar farms contribute to carbon offset via clean energy generation, their potential to become CH4 sources due to soil compaction warrants further attention. These findings emphasize the need for sustainable land management strategies that mitigate CH4 emissions when repurposing forested landscapes for renewable energy projects.