Effect of habitat and substrate quality on Douglas fir litter decomposition in western Oregon

Linear regression models were developed for Douglas fir needle, female cone, branch, and bark decomposition in seven stands representing four mature vegetation types in western Oregon. Rate constants (k) for annual weight loss of needles ranged from 0.22 to 0.31 year −1 , from 0.047 to 0.083 year −1 for cones, from 0.059 to 0.089 year −1 for branches, and from 0.005 to 0.040 year −1 for bark. The decomposition constant (k) of needles had a negative linear correlation (P < 0.01) with maximum plant moisture stress and temperature growth index of the seven stands. In comparing substrate quality of needle and woody litter components, k was more closely correlated with lignin content than with C:N ratio.