Fall River Long-term Productivity Study : Predictions of Pre-harvest Biomass and Nutrient Pools K....
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- Fall River Long-term Productivity Study : Predictions of
Pre-harvest Biomass and Nutrient Pools K. Petersen, B. Strahm, C.
Licata, B. Flaming, E. Sucre, J. Forcier, Rob Harrison, College of
Forest resources, University of Washington; Thomas A. Terry,
Weyerhaeuser Company; Constance A. Harrington, U.S.D.A. Forest
Service, PNWRS Biomass and Nutrient Content Sampling Methodology A
comparison of site-specific allometric equations for estimating
pre-harvest above-ground biomass with the Gholz equations (Gholz et
al. 1979) for estimating biomass showed an ~14% difference between
the estimates. This emphasizes the importance of developing models
on a site by site basis. Site Features Soil Series: Boistfort
(volcanic parent material) 50 yr. site index: 130 ft. (40 m) Slope:
10% Aspect: West Site area: 12.24 ha Map Source:
http://wwwflag.wr.usgs.gov/USGSFlag/Data/maps/Washington.gifhttp://wwwflag.wr.usgs.gov/USGSFlag/Data/maps/Washington.gif
McDonald Tree Farm owned by Weyerhaeuser Company Location: Section
2/11,T14N, R6W Pacific County, Washington Site History Western
Hemlock was the dominant species at harvest in 1952 and 1953. The
unit was replanted in 1953 and 1954 with Douglas-fir seedlings at
886 tpa. Naturally regenerating hemlock increased tpa to 905. The
stand was precommercially thinned to a tpa of 494 in 1971.
Approximately 1800 kg N/ha was applied as urea fertilizer over the
course of the 1953-1999 rotation. The stand was harvested in 1999
according to a plan to study the effects of various management
treatments on soil processes, nutrient cycling, and Douglas-fir
productivity over a 40 year stand rotation. Works Cited: Gholz,
HL,Grier CC, Campbell AG, and Brown AT. 1979. Research Paper 41,
Forest Research Lab, School of Forestry, Oregon State University,
Corvallis, OR Estimated preharvest distribution of biomass and
pools of C and N in the above-ground portion of the forest system
for each tree species Conclusions Establishment of accurate
estimates for preharvest biomass and elemental pools allows for
comparisons of biomass, C, and N pools in a spatial and temporal
context. It is critical to develop site-specific allometric
equations for estimating biomass. Future work will include
estimating the biomass and nutrient content of 5 th year trees to
determine the effects of competing vegetation control. Photo above
depicts1999 Preharvest stand conditions Acknowledgements Funding
for the Fall River Long-term Productivity Study was made possible
through grants from the National Council for Air and Stream
Improvement (NCASI) and the Olympic Natural Resource Council.
Collaboration with the USDA Forest Service PNW Research Station
Olympia Lab and the Stand Management Cooperative has been
invaluable to this research. Also, wed like to thank Dongsen Xue of
UW Analytical Laboratory Services for his assistance. Finally, we
express thanks to Weyerhaeuser Company for continued support of
this project. For additional information on details of the Fall
River Long-term Productivity Study please visit the following web
address: http://soilslab.cfr.washington.edu/LTSP_FallRiver/ 30
Douglas-fir (15-80.1 cm dbh) and 11 Western hemlock (20-61.7cm dbh)
were selected for predicting the biomass of the 12.24 ha stand. All
7533 trees were measured for dbh and a subset of 30 trees in each
of the 48 treatment plots were measured for height. The dry biomass
of each sample tree was estimated by wet weighing and then dry
weighing randomly selected subsamples of tree components.
Allometric models were used to estimate stand biomass based on the
7533 dbh measurements. Forest Floor (FF) was sampled by compositing
organic matter 5 cm was sampled along 3 randomly located 15 m x.3 m
transects in each of the 48 treatment plots. Samples were ranked by
decay classes of 1-5, with 5 representing the most advanced stage
of decay. Soil cores were taken to depth of 91.5 cm at 2 randomly
located subplots per 48 plots, and then the samples were separated
by horizon and depth interval. Understory was sampled from 5
randomly located 2 m radius circular subplots in 48 equal-area
treatment plots. Results and Discussion Estimated pools for the
preharvest forest system Douglas-firWestern hemlock The bole and
needles of live trees contributed the most N from the live tree
proportion of the system. The largest pool of N was contained in
the soil to 91.9 cm depth as is expected at a high productivity
site in the Pacific Northwest. The second largest N pool at the
site was in tree boles. The A horizon contained the greatest
proportion of N of the soil horizons sampled. Live Tree Component
kg dry biomass/ha kg C/hakg N/hakg dry biomass/ha kg C/hakg N/ha
Needles44002335895100263973 Live Branches1780088524611500561017
Dead Branches9200446318370018283 Bole
wood182200889011401262006172493 Bark20600106878312100606842 Total
live above- ground 235000118426138716000079682667 Standing dead
trees 26021241519499304 Snags6687328321302414859 Total dead
Above-ground 92894524264973241513 Total live and dead above- ground
244289122950141316497382097680 System Componentkg dry biomass/hakg
C/hakg N/ha total live and dead above-ground for both tree
species4092622050472093 understory221955 forest floor 5
cm14300072000309 Soil 0-15.7 cm (A)~184980924903855 -25.7 cm
(B1)~89802449012241 -45.7 cm (B2)~138676693383693 -65.7 cm
(B3)~84474422372668 -91.9 cm (B4)~85758428792984 total soil 0-91.9
cm~58369029184515441 total site (12.24
hectares)~99295259613718301