CARBON SEQUESTRATION IN DOUG-FIR FORESTS ON GLACIAL AND VOLCANIC SOILS IN THE PACIFIC NORTHWEST University of Washington Soils Lab A.B. Adams & Rob Harrison Funded by DOE CENTER FOR RESEARCH ON ENHANCING CARBON SEQUESTRATION IN TERRESTRIAL ECOSYSTEMS CSITE

C SEQUESTRATION RELATED HYPOTHESES Fertilizer increases tree biomass accumulation Fertilizer increases soil carbon transport to deeper depths in the soil profile Following fertilization, volcanic sites (fine-textured) soil carbon accumulation > and deeper than glacial (coarse) soil

FOUR (surface, A, B & C) LYSIMETERS INSTALLED IN CONTROL AND UREA FERTILIZED PLOT WITH SMC GLACIAL SITES Port Gamble - est. 1975; fertilized w/ 200 lbs/acre at 8 yrs and every 4 yrs after up to 1200 lbs/acre; thinned to 300 tpa Cedar River - est. 1972; fertilized w/ 200 lbs/acre at 8 yrs and every 4 yrs after up to 1200 lbs/acre; thinned to 60% of basal area VOLCANIC SITES Mud Mountain - est. 1980; fertilized w/ 200 lbs/acre at 8 yrs and every 4 yrs after up to 1,200 lbs/acre; thinned to 300 tpa Radio Hill - est. 1980; fertilized w/ 200 lbs/acre at 8 yrs and every 4 yrs after up to 1,200 lbs/acre; thinned to 300 tpa

LEACHATE COLLECTIONS FROM 4 TENSION LYSIMETERS AT ONE PLOT A horizon least reliable B horizon color varies C or deep B horizon most predictable (good yield and colorless) O horizon darkest

As horizons were extracted and sieved with the 25mm screen, the components were weighed in the field. This is material from the Bw horizon of Barneston (glacial)

As seen with this rocky Barneston soil, pits were dug to roughly a meter. Depths from the midpoint of each side to tops and bottoms of each horizon were measured. Means of these 4 measurements were used as water displacement levels for horizons.

Poulsbo soil series, Port Gamble, WA Sandy glacial with E horizon Very thin E horizon Deep sand Sand very compacted at lower depths Thin forest floor Low understory cover Olympic Mts. rainshadow effect

POULSBO SANDY LOAM SPODIC HORIZON

Undetermined volcanic soil series, Mud Mt. , WA Undetermined volcanic soil series, Mud Mt., WA. Ashy loam with no rocks Thick forest floor Decaying roots and tunnels present Low bulk densities even at deepest depths

Winston soil series, Radio Hill, WA. Ashy loam with some rocks Deep ashy loam Deep lysimeter in or just above 2C glacial horizon Some rocks Larger forest floor At all plots, 3mm sieve used to screen for soil to pack around porous ceramic lysimeter cups This is Radio Hill (ashy loam).

COARSE FRAGMENT DISTRIBUTION FOR BARNESTON AT CEDAR RIVER INSTALLATION ALDERWOOD

COARSE FRAGMENT DISTRIBUTION FOR 3 DEPTHS AT RADIO HILL INSTALLATION SHOWING DOMINANCE OF THE <2mm COMPONENT

SUMMARY DOC detected in epipedon decreases with depthDIC exhibits spatial and temporal variation Texture is a factor in results, but study does not consider mineralology Volcanic soils have lower percent of hydrophilic (labile) substances, particularly in deeper lysimeters Fertilizer may have more effects on C dynamics with finer textured soil (volcanic)