Variations of soluble organic nitrogen and microbial nitrogen in deciduous forest soils along an urban–rural gradient

摘要: Abstract Soluble organic N and microbial pools in terrestrial ecosystems have been less studied than those of inorganic N. Therefore, cross-system variation their pool sizes seasonal dynamics, both absolute relative to pools, needs be quantified so that ecological importance different can evaluated. We measured extractable soil (ESON), biomass (MBN), the net production rates ESON red oak-dominated remnant forests, along an urban–rural gradient New York City metropolitan area. were interested (1) determining dynamics MBN, (2) examining whether contrasts land use (urban, suburban, rural) surrounding these forest remnants associated with amounts MBN. This field-based study was conducted continuously for 16 months. Yearly average concentrations ranged from 60 140 mg kg−1 matter (SOM), 3–4 times N, MBN 600 1100 SOM. There a considerable increase spring all plots across gradient. The expressed on areal basis (to depth 7.5 cm) 1.75 4.19 g N m−2. incorporated into gradually released later growing season (the mean decrease 1.11 3.82 N m−2). could important retention mechanism conserving when plant uptake may low. amplitude far as compared mineralization. These suggest closer coupling much more ESON. Both significantly higher rural soils urban soils, positively correlated SOM content. ESON, or this urbanization suggests form exported, budget mechanisms differentially affected by urban, suburban uses.