Lm. Aguilera et al., NITROGEN IN ECTOMYCORRHIZAL MAT AND NON-MAT SOILS OF DIFFERENT-AGE DOUGLAS-FIR FORESTS, Soil biology & biochemistry, 25(8), 1993, pp. 1015-1019
In an attempt to determine how stand age and mat-forming fungi affect
N chemistry in forest soils, soils with or without ectomycorrhizal mat
s were collected from five Douglas-fir Pseudotsuga menziesii (Mirb.)
Franco! forest stands, age 2-450 yr, in the Oregon Cascade Mountains.
A number of chemical and biological variables were measured in these s
oils, including: soil organic matter (SOM), pH, total N, inorganic N,
extractable NH4+ and NO3-, fungal hyphal length, numbers of bacteria,
and labile C and N. Total soil N and labile N both were significantly
greater in old-growth soils than in other soils, suggesting that fores
t soils become enriched in organic N with age. Labile C concentrations
were higher in mat than in non-mat soils of all age classes but were
significantly higher only in the older stands. This finding suggests t
hat ectomycorrhizal mat communities affect soil N with age both by sel
ectively removing organic N and by producing compounds with high C:N r
atios.