Postdoctoral Fellowship: EAR-PF: Assessing the net climate impact of tropical peatland restoration: the role of methane

Perryman, Clarice R, Durham NH

Investigators

Abstract

Peatlands are globally important carbon stores, containing double the amount of carbon stored in forests worldwide. Draining peatlands for agriculture and forestry encourages microbial decomposition of peat carbon, releasing this stored carbon into the atmosphere as carbon dioxide (CO2). Peatland drainage is particularly widespread in Southeast Asia, where over 90% of peat swamps have been disturbed, resulting in peatland CO2 emissions on par with regional fossil fuel emissions. Blocking drainage canals to raise water levels should reduce CO2 emissions by discouraging microbial decomposition. As such, “peatland rewetting” through canal blocking has been proposed as a low-cost natural climate solution and many countries including Indonesia have committed to rewetting vast areas of degraded peatlands to combat climate change. However, peatland rewetting stands to increase methane (CH4) emissions, as microbes that produce CH4 thrive under water-logged conditions. Increased CH4 emissions may partially offset the climate benefits of peatland rewetting due to the high global warming potential of CH4. Measurements of CO2 and CH4 emissions after rewetting tropical peatlands are extremely scarce, which is a major limitation for policy and planning. This research aims to quantify CH4 and CO2 emissions from rewetted peatlands in Indonesia. Dr. Clarice Perryman will collect new emissions data to assess how future greenhouse gas emissions vary across different tropical peatland rewetting scenarios and identify important variables controlling emissions from rewetted peatlands. The results of this research will help guide peatland management through determining the spatial scale and timing of peatland rewetting that will provide greatest greenhouse gas emissions reductions. Research findings will be broadly disseminated to local communities, partner NGOs, and the research community via public presentations and research publications. Dr. Perryman also aims to promote belonging, accessibility, justice, equity, diversity, and inclusion (BAJEDI) in the geosciences through mentoring undergraduate and graduate students on related research in Indonesia and at her host institution. Peatland rewetting is gaining popularity as an effective and low-cost natural climate solution as rewetting stands to reduce high CO2 emissions from peatlands drained for agriculture and logging. Even though rewetting reduces CO2 emissions, increased CH4 emissions post-rewetting can cause rewetted peatlands to remain a net greenhouse gas source with a net positive (warming) radiative forcing for several decades. Despite the great potential and widespread enthusiasm for peatland rewetting, field measurements of greenhouse gas emissions from rewetted peatlands are extremely sparse. This is particularly true for tropical peatlands in Southeast Asia, including those in Indonesia which has recently committed to rewetting vast areas of degraded peatlands to mitigate wildfire risks and CO2 emissions. This research will quantify CH4 and CO2 emissions from rewetted peatlands in Indonesia. Dr. Clarice Perryman will use this new data to upscale emissions from plot to landscape level to assess how future greenhouse gas emissions and net climate impact vary across different tropical peatland rewetting scenarios. The fellow will measure CO2 and CH4 emissions at peatland sites in Indonesia before and after drainage canal blocks are installed to assess emissions at sub-daily to annual timescales. Dr. Perryman will determine abiotic (e.g. hydrology, geochemistry) and biotic (e.g. vegetation, microbial community composition) factors controlling CH4 emissions at the plot scale relevant to upscaling emissions to landscape-level using existing geospatial datasets. Finally, the fellow will apply these new data and process-level insights to assess the net climate impact of tropical peatland rewetting at decadal to century scales. Using a variety of methods, including direct emissions measurements, stable isotope measurements, and microbiome analyses, this research will improve predictions of how microbial systems mediating CH4 cycling will respond to land use change in tropical peatlands. The research will provide critical datasets of CH4 and CO2 emissions and their abiotic and biotic controls from rewetted tropical peatlands. Dr. Perryman will engage in knowledge co-production and transfer with communities and partner NGOs in Indonesia and promote BAJEDI through mentoring undergraduate and graduate students on related research in Indonesia and at her host institution. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.