Arboreal vegetation, coarse woody debris, and disturbance history of mature and old-growth stands in a coniferous forested wetland

We quantified the forest age and tree size structure of an old-growth and mature stand in a coniferous forested wetland in central New York, USA. We also determined the volume and decay class distribution of standing and downed coarse woody debris. The old-growth stand contains eastern white pine (Pinus strobus L.) &gt 400 years old and other species &gt 200 years old. Live tree basal area in the old-growth area (36$\text{m}^{2}\cdot \text{ha}^{-1}$) was dominated by approximately equal amounts of balsam fir (Abies balsamea (L.) Miller.), eastern white pine, and northern white-cedar (Thuja occidentalis L.; 11, 10, and 10$\text{m}^{2}\cdot \text{ha}^{-1}$, respectively), but eastern white pine was less abundant in the mature stand. Snag basal area was 7$\text{m}^{2}\cdot \text{ha}^{-1}$in the old-growth and mature stands and was dominated by balsam fir and northern white-cedar. Total coarse woody debris (CWD) volumes were 145 and 83$\text{m}^{3}\cdot \text{ha}^{-1}$in the old-growth and mature stand, respectively. The decay class distribution in each area was skewed toward advanced decay classes. Most CWD was in the form of logs and snags in both areas, but snag volume in the old-growth area was approximately 3 times that in the mature stand (75 vs. 26$\text{m}^{3}\cdot \text{ha}^{-1}$). In both stands, balsam fir and northern white-cedar each accounted for 21-30% of total CWD. Eastern white pine contributed 28% of the CWD in the old-growth area but was not present as CWD in the mature stand. Both forests are uneven-aged, with the earliest species establishing in the 1600s and 1750s for the old-growth and mature stands, respectively. No species exhibited major growth releases in the old-growth or mature stands, but several exhibited moderate releases. The age and diameter distributions of the old-growth area suggest that no stand-initializing disturbances have affected the forest for at least 250 years. Instead, fine-scale treefall gaps created by single or multiple treefalls are the dominant mode of regeneration in this forest.