Department of Environmental Sciences, University of Virginia, VA, USA.
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA.
Sci Rep. 2020 Apr 30;10(1):7325. doi: 10.1038/s41598-020-64094-1.
Awarding CO offset credits may incentivize seagrass restoration projects and help reverse greenhouse gas (GHG) emissions from global seagrass loss. However, no study has quantified net GHG removal from the atmosphere from a seagrass restoration project, which would require coupled C stock and GHG flux enhancement measurements, or determined whether the creditable offset benefit can finance the restoration. We measured all of the necessary GHG accounting parameters in the 7-km Zostera marina (eelgrass) meadow in Virginia, U.S.A., part of the largest, most cost-effective meadow restoration to date, to provide the first seagrass offset finance test-of-concept. Restoring seagrass removed 9,600 tCO from the atmosphere over 15 years but also enhanced both CH and NO production, releasing 950 tCOe. Despite tripling the NO flux to 0.06 g m yr and increasing CH 8-fold to 0.8 g m yr, the meadow now offsets 0.42 tCOe ha yr, which is roughly equivalent to the seagrass sequestration rate for GHG inventory accounting but lower than the rates for temperate and tropical forests. The financial benefit for this highly successful project, $87 K at $10 MtCOe, defrays ~10% of the restoration cost. Managers should also consider seagrass co-benefits, which provide additional incentives for seagrass restoration.
授予 CO 抵消信用额度可能会激励海草恢复项目，并有助于扭转全球海草损失导致的温室气体（GHG）排放。然而，尚无研究量化海草恢复项目从大气中去除的净 GHG，这需要耦合 C 储量和 GHG 通量增强测量，或确定可抵消费用的抵消效益是否可以为恢复提供资金。我们在美国弗吉尼亚州测量了所有必要的 GHG 核算参数，包括 7 公里长的 Zostera marina（鳗草）草地，这是迄今为止最大、最具成本效益的草地恢复项目之一，为首次海草抵消融资概念验证提供了依据。恢复海草在 15 年内从大气中去除了 9600 吨 CO，但也增强了 CH 和 NO 的产生，释放了 950 吨 COe。尽管将 NO 通量增加了两倍，达到 0.06 g m yr，将 CH 增加了 8 倍，达到 0.8 g m yr，但现在草地每年抵消 0.42 tCOe ha yr，这大致相当于 GHG 清单核算的海草封存率，但低于温带和热带森林的速率。这个非常成功的项目的财务效益为 87000 美元，每吨 COe 为 10 美元，可抵免约 10%的恢复成本。管理者还应考虑海草的共同效益，这为海草恢复提供了额外的激励。
