Global recognition of climate change and its predicted consequences has created
the need for practical management strategies for increasing the ability of natural
ecosystems to capture and store atmospheric carbon. Mangrove forests, saltmarshes
and seagrass meadows, referred to as blue carbon ecosystems (BCEs), are hotspots
of atmospheric CO2 storage due to their capacity to sequester carbon at a far higher
rate than terrestrial forests. Despite increased effort to understand the mechanisms
underpinning blue carbon fluxes, there has been little synthesis of how management
activities influence carbon stocks and greenhouse gas (GHG) fluxes in BCEs. Here,
we present a global meta-analysis of 111 studies that measured how carbon stocks
and GHG fluxes in BCEs respond to various coastal management strategies. Research
effort has focused mainly on restoration approaches, which resulted in significant
increases in blue carbon after 4 years compared to degraded sites, and the potential
to reach parity with natural sites after 7–17 years. Lesser studied management
alternatives, such as sediment manipulation and altered hydrology, showed only increases in biomass and weaker responses for soil carbon stocks and sequestration.
The response of GHG emissions to management was complex, with managed sites
emitting less than natural reference sites but emitting more compared to degraded
sites. Individual GHGs also differed in their responses to management. To date, blue
carbon management studies are underrepresented in the southern hemisphere and
are usually limited in duration (61% of studies ❤ years duration). Our meta-analysis
describes the current state of blue carbon management from the available data and
highlights recommendations for prioritizing conservation management, extending
monitoring time frames of BCE carbon stocks, improving our understanding of GHG
fluxes in open coastal systems and redistributing management and research effort
into understudied, high-risk areas.
O’Connor JJ, Fest BJ, Sievers M, and Swearer SE. (2020). Impacts of management practices on blue carbon stocks and greenhouse gas fluxes in coastal ecosystems – A meta-analysis. Global Change Biology, 26, 1354-1366.
Michael Sievers 