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• 1. [Article] Biomass dynamics of dead Douglas-fir and western hemlock boles in mid-elevation forests of the Cascade Range

  The rate and manner of bioniass loss from decomposing Douglas-fir and western hemlock boles in mid-elevation forests of the central Cascade Range were measured. Bole bark and wood were considered separately. ...

  Citation × Citation Citation Abstract Copy Title: Biomass dynamics of dead Douglas-fir and western hemlock boles in mid-elevation forests of the Cascade Range Author: Graham, Robin Lee Lambert The rate and manner of bioniass loss from decomposing Douglas-fir and western hemlock boles in mid-elevation forests of the central Cascade Range were measured. Bole bark and wood were considered separately. Loss of bole wood due to respiration was measured by change in bole wood density. Loss of bole wood due to fragmentation - was measured by change in bole volume. Bole species, position (upright or prostrate), and diameter affected the rate of bole decomposition with regard to both fragmentation and respiration. Douglas-fir boles decomposed slower than western hemlock boles. For both species, upright boles decomposed faster than prostrate boles (k 0.031 yr versus 0.012 for Douglas-fir wood and k= 0.090 yr versus 0.021 for western hemlock wood). Fragmentation proceeded at a faster rate than respiration for both prostrate and upright Douglas-fir boles. Decomposing prostrate boles of western hemlock did not fragment. Upright western hemlock boles had substantial fragmentation losses. Seven to thirteen percent of the wood of an upright western hemlock bole was lost each year to fragmentation. The relationship between bole size and decomposition rate was complex. For upright boles, decomposition rates increased as bole diameter decreased. Prostrate boles showed no relationship between bole diameter and decomposition rate. Bark loss rates of prostrate boles were similar for both species (k= 0.02 yr). Upright boles lost their bark faster than prostrate boles (k 0.038 yr to 0.14). Bark was lost faster from small than large boles. The decomposition data for all boles were quite variable. A computer simulation model was built to attempt to examine the question of how the quantity and type of wood and bark of dead boles would vary in a Douglas-fir/western hemlock forest as the stand developed. No age trends were apparent from the model output. The amount and type of dead bole wood fluctuated within a given range which was determined by the stochastic fluctuations in annual mortality. Title: Biomass dynamics of dead Douglas-fir and western hemlock boles in mid-elevation forests of the Cascade Range Author: Graham, Robin Lee Lambert The rate and manner of bioniass loss from decomposing Douglas-fir and western hemlock boles in mid-elevation forests of the central Cascade Range were measured. Bole bark and wood were considered separately. Loss of bole wood due to respiration was measured by change in bole wood density. Loss of bole wood due to fragmentation - was measured by change in bole volume. Bole species, position (upright or prostrate), and diameter affected the rate of bole decomposition with regard to both fragmentation and respiration. Douglas-fir boles decomposed slower than western hemlock boles. For both species, upright boles decomposed faster than prostrate boles (k 0.031 yr versus 0.012 for Douglas-fir wood and k= 0.090 yr versus 0.021 for western hemlock wood). Fragmentation proceeded at a faster rate than respiration for both prostrate and upright Douglas-fir boles. Decomposing prostrate boles of western hemlock did not fragment. Upright western hemlock boles had substantial fragmentation losses. Seven to thirteen percent of the wood of an upright western hemlock bole was lost each year to fragmentation. The relationship between bole size and decomposition rate was complex. For upright boles, decomposition rates increased as bole diameter decreased. Prostrate boles showed no relationship between bole diameter and decomposition rate. Bark loss rates of prostrate boles were similar for both species (k= 0.02 yr). Upright boles lost their bark faster than prostrate boles (k 0.038 yr to 0.14). Bark was lost faster from small than large boles. The decomposition data for all boles were quite variable. A computer simulation model was built to attempt to examine the question of how the quantity and type of wood and bark of dead boles would vary in a Douglas-fir/western hemlock forest as the stand developed. No age trends were apparent from the model output. The amount and type of dead bole wood fluctuated within a given range which was determined by the stochastic fluctuations in annual mortality. Close