A peat-depth database for Canada (PDD-Can-1)

Abstract. Canadian peatlands hold an estimated ~25 % of the world's peatland carbon (C) stock. However, a more accurate calculation of C stock requires high-quality empirical datasets to refine numerical techniques, perform validation steps, and calculate the resulting uncertainties in prediction. Here, we present two databases (i) a compilation of 88,763 survey points of basal peat-depth across Canada, extracted from 844 publications (government reports, environmental impact assessments and scholarly journals), and (ii) a compilation of 436,923 survey points containing no peat. Many of these peat-depth survey points were digitized here for the first time. We showcase the peat-depth data by presenting a timeline of peat studies over the past ~100 years and discuss the motivation behind much of this peatland work across the country. Measurements of peat-depth across Canada range from 0–1200 cm and from relatively shallow wetlands in the Arctic tundra to deep fens and bogs in the southern temperate forests. Importantly, our compilation includes peat-depth measurements from regional soil or surficial material surveys, largely from environmental impact assessments. These datasets tend toward shallower peats in the range of 50–100 cm, and therefore represent transition areas, regions of shallow peat and/or forested peatlands that were not previously widely documented. There are five data-quality considerations: (i) some data have low precision geographic (latitude and longitude) coordinates; (ii) across the database, there are apparent issues with rounding, vague methodology and unclear definition of the mineral-peat interface; (iii) some peat-depth data were measured 100+ years ago, so there may be mismatches between the present-day condition of the peatland and the original measurements; (iv) there are notable spatial gaps and biases across Canada, including few data from the Hudson Bay Lowlands, overall sparse coverage north of ~55° and a patchwork of peat-depth data that is sometimes abruptly truncated at provincial/territorial borders; (v) we do not include a classification of peat-depth data into fens or bogs because this information is lacking in the original data or was unreliable. We finish by discussing potential uses for these databases along with future improvements. The databases are available at https://doi.org/10.5281/zenodo.17409850 (Dalton et al., 2025).