Background: Natural wetlands can mitigate ongoing increases in atmospheric carbon by storing any net balance of organic carbon (peat) between plant production (carbon uptake) and microbial decomposition (carbon release). Efforts are ongoing to quantify peat carbon stored in global wetlands, with considerable focus given to boreal/subarctic peatlands and tropical peat swamps. Many wetlands in temperate latitudes have been transformed to anthropogenic landscapes, making it difficult to investigate their natural/historic carbon balance. The remaining temperate swamps and marshes are often treated as mineral soil wetlands and assumed to not accumulate peat. Southern Ontario in the Laurentian Great Lakes drainage basin was formerly a wetland-rich region that has undergone significant land use change since European settlement. Results: This study uses southern Ontario as a case study to assess the degree to which temperate regions could have stored substantial carbon if it had not been for widespread anthropogenic land cover change. Here, we reconstruct the full extent and distribution of natural wetlands using two wetland maps, one for pre-settlement conditions (prior to 1850 CE) and the other for modern-day patterns of land use (2011 CE). We found that the pre-settlement wetland cover decreased by about 56% with the loss most significant for marshes as only 11% of predicted pre-settlement marshland area remains today. We estimate that pre-settlement wetlands held up to ~ 3.3 Pg of carbon relative to ~ 1.3 Pg for present-day (total across all wetland classes). Conclusions: By not considering the recent carbon loss of temperate wetlands, we may be underestimating the wetland carbon sink in the pre-industrial carbon cycle. Future work is needed to better track the conversion of natural wetlands globally and the associated carbon stock change.
Bibliographical noteFunding Information:
Funding for this research was provided by the Connaught International Scholarship for Doctoral Students (University of Toronto) to E. Byun and Grants from the Natural Sciences and Engineering Research Council (Canada) to S. Finkelstein and S. Cowling.
EB, SF, and SC designed the study. PB contributed data from DUC. EB assembled datasets, performed analyses, and wrote the manuscript. All authors reviewed the results, discussed, and revised the manuscript. All authors read and approved the final manuscript. We thank John Riley for collecting the data for the SEO peatland survey, and we acknowledge Peatland Research and Data housed at McGill University. We also thank Jim McLaughlin and Maara Packalen for helpful discussions. The authors declare that they have no competing interests. The SEO peatland data and SOLRIS datasets are publicly available [24 , 27]. DUC pre-settlement wetland reconstruction was made available through a data-sharing agreement. All co-authors have consented to publication. Funding for this research was provided by the Connaught International Scholarship for Doctoral Students (University of Toronto) to E. Byun and Grants from the Natural Sciences and Engineering Research Council (Canada) to S. Finkelstein and S. Cowling. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
© 2018, The Author(s).
All Science Journal Classification (ASJC) codes
- Global and Planetary Change
- Management, Monitoring, Policy and Law
- Earth and Planetary Sciences (miscellaneous)
- Earth and Planetary Sciences(all)