Chemistry and ectomycorrhizal communities of coarse wood in young and old-growth forests in the Cascade Range of Oregon

Coarse wood provides important ecosystem structure and function such as water and nutrient storage and critical habitat for the conservation of a variety of organisms, including ectomycorrhizal (EM) fungi. The chemistry and EM communities were compared in coarse wood samples collected from two advanced decay stages of logs in 12 paired young and old-growth stands in the Oregon Cascade Range. Average total C and nonpolar extractives were higher in young stands (15-55 years) (mean = 53.38%, 95% CI of 52.48-54.27 and mean = 8.54%, 95% CI of 6.92-10.16, respectively) compared with old-growth stands (200-500 years) (mean = 51.22%, 95% CI of 49.67-52.77 and mean = 6.75%, 95% CI of 5.88-7.62, respectively). Averages for total and extractable P were higher in old-growth stands (mean = 0.03%, 95% CI of 0.02-0.04 and mean = 82.91, 95% CI of 52.24-113.57, respectively) compared with young stands (mean = 0.02%, 95% CI of 0.02-0.02 and mean = 56.17, 95% CI of 45.84-66.50, respectively). Average pH and total N were highest in logs in the most advanced decay stage (mean = 4.17, 95% CI of 3.97-4.38 and mean = 0.35%, 95% CI of 0.29-0.40, respectively). No differences between log decay class or stand age were detected for water-soluble extractives, hemicellulose plus cellulose (or acid-hydrolyzable fraction), or acid-unhydrolyzable residue. Observed differences in average wood property values between decay stages and between young and old-growth stands were small and, although statistically significant, may not reflect an important difference in EM fungal habitat. EM communities were similar between young and old-growth stands and between logs in decay classes 4 and 5. Results suggest that down wood in advanced decay stages provides similar habitat for EM fungi in both old-growth and young, managed stands.