Av. Martinez et Da. Perry, FACTORS INFLUENCING THE AVAILABILITY OF NITROGEN IN THINNED AND UNTHINNED DOUGLAS-FIR STANDS IN THE CENTRAL OREGON CASCADES, Forest ecology and management, 93(3), 1997, pp. 195-203
Soil N mineralized during 7-day anaerobic incubation at 40 degrees C (
'available' N) was compared at two soil depths and correlated to soil
and site factors in Douglas-fir stands with different combinations of
thinning and multinutrient fertilization. Available N expressed either
on an area basis (kg ha(-1)) or on a concentration basis (mg kg-l) at
the two depths did not vary significantly by stocking density, treatm
ent, or density-treatment interaction. There was a significant differe
nce between the soil depths, averaging 39 mg kg(-1) at 0-20 cm depth,
and 20 mg kg(-1) at 20-40 cm depth. Available N was positively correla
ted with total soil N, exchangeable Ca, and adjusted aspect (the forme
r two factors accounting for 46% of the total variation), and negative
ly with rock content and slope steepness. Stand density had no effect.
(C) 1997 Elsevier Science B.V.