Restoration of retired agricultural land to wetland mitigates greenhouse gas emissions

Abstract

Retired farmland restoration is increasingly seen as a valuable opportunity to improve ecosystem functions in sensitive regions. For example, with expected mass retirement of cranberry farms in New England, there is increasing interest in restoring retired cranberry farms back to wetlands. To understand how restoration of retired cranberry farms to wetland ecosystems influences climate-related ecosystem functions, we assessed methane and carbon dioxide emissions from different post-farming management options, including an actively farmed cranberry bog, young and old retired cranberry bogs, young and old restored cranberry bogs, and a natural reference bog. In addition to methane and carbon dioxide, we measured key soil properties influential in greenhouse gas flux, including soil organic matter, moisture, pH, redox potential, and bulk density. Greenhouse gas flux differed significantly by site type, with the restored systems functioning similarly to the natural reference wetland while retired sites had fluxes similar to the actively farmed site. The older restored site had significantly lower emissions of both methane and carbon dioxide than the newly restored site, indicating that over a larger time scale, restored systems may transition from net carbon dioxide sources to sinks. Overall, the results of this study suggest that in addition to the many other ecological benefits, the restoration of wetlands may also play a role in climate change mitigation through their ability to store carbon.

Redox potential as a soil health indicator -- how does it compare to existing methods?

“…The trend of oxidized redox and low biological activity in the lab tests is in direct contrast with field observations, where high oxidation correlates with high respiration (Bartolucci et al, 2021). However, in field conditions, the redox was changing over time (with soil drying) and in our observations the redox changed between samples in an artificial drying-rewetting experiment.…”

“…In fully aerobic soils, oxygen serves as the electron acceptor, resulting in the production of CO 2 and H 2 O. The redox potential is controlled by the rates of reduction and oxidation processes in soil and is connected to soil respiration, for example in rewetted agricultural soils, where redox is a strongly correlated predictor of CO 2 flux (Bartolucci et al, 2021). Based on this, redox could be a promising indicator for soil carbon cycle (labile carbon pools) and structure (oxygen availability), two key components of soil health (Kibblewhite et al, 2008).…”

Trajectories of plant communities in Massachusetts, U.S.A. cranberry farms discontinued from agriculture

“…Increases in C and N stocks were smaller than increases in soil percent C and N because there was a concurrent decrease in soil bulk density and hence surface soil mass in C and N-rich surface soil layers. Soil percent C was similar to that observed in other active and actively restored former cranberry bogs (Bartolucci et al 2021). The changes to soil percent C and N in 21-49 year-old retired bog beds were generally similar to the changes observed in 30-35 year-old and 50-55 year-old restored wetlands in central New York (Ballantine et al 2009).…”

Flooding and ecological restoration promote wetland microbial communities and soil functions on former cranberry farmland

“…In previous studies, we have described the desirable impacts that active ecological restoration of retired cranberry farms has on both biogeochemical characteristics [ 50 , 51 ] and microbial community structure [ 11 ]. Here, we found that flooding also promotes beneficial wetland functions, even exceeding wetland restoration for soil organic matter formation and cation exchange capacity.…”