A Rapid Method to Assess, Map, and Develop Standards for Old Growth: Catchacoma Primary Hemlock Forest, Ontario, Canada

All eastern hemlock-dominated forests in Ontario could be gone by 2075 given current trends, which demands rapid assessment to locate these endangered ecosystems. To date, however, neither the Canadian or Ontario governments have developed field assessment protocols or minimum standards for identifying old-growth forests that provide density and biomass estimates for the primary features of these forests. This study focused on the Catchacoma Forest, Canada’s largest eastern hemlock forest, and represents a first step towards establishing minimum standards for old-growth eastern hemlock forests in the Great Lakes-St. Lawrence Forest region. Rectangular plots were systematically placed along evenly spaced east–west transects at a 2% sampling intensity for the 181 ha study area and assessed for mother trees (MTs) and cut stumps. By a factor of 15X, the method developed was more efficient for covering larger areas compared to randomly placed and intensively sampled plots typically used for long-term ecological studies. Mean integrity (stumps/ha) was 0.006/ha and mean MT density was 149/ha with a range of 0–533/ha. Four MT forest types were identified including: eastern hemlock-dominant (47%; 194 MT/ha), white pine-dominant (26%; 123 MT/ha), other MT species-dominant (9%; 169 MT/ha), and eastern hemlock–white pine co-dominant (8%; 133/ha). MTs were absent from roughly 10% of the study area.