Nitrification potentials and landscape, soil and vegetation characteristics in two Central Appalachian watersheds differing in NO3− export

Topographic variation of soil nitrogen mineralization and microbial biomass in Japanese cedar (Cryptomeria japonicaD. Don) stands at Myougodani watershed, Toyama, Japan

“…In general, tree species composition and topography are considered to be the major factors affecting the spatial variability of soil N transformation and microbial biomass on small spatial scales, such as within a watershed or a landscape (Zak and Pregitzer 1990;Garten et al 1994;Christ et al 2002;Oyanagi et al 2002). Recently, in several studies, prediction of the spatial patterns of N transformation within forest watersheds using vegetation factors and topographic factors has been successfully achieved (Garten et al 1994;Hutchinson et al 1999;Christ et al 2002;Venterea et al 2003).…”

“…Recently, in several studies, prediction of the spatial patterns of N transformation within forest watersheds using vegetation factors and topographic factors has been successfully achieved (Garten et al 1994;Hutchinson et al 1999;Christ et al 2002;Venterea et al 2003). On the other hand, when the tree species composition is constant (e.g.…”

“…On the other hand, in several studies, it was demonstrated that the telTain attributes derived from GIS analysis were a good predictor of the spatial pattern of N transformation in heterogeneous watersheds in terms of tree species composition (Garten et al 1994;Christ et al 2002;Venterea et al 2003). In those studies, the terrain attributes were closely related to the spatial pattern of the tree species composition, and thus the spatial pattern of N transformation was controlled by interactions between the topography and vegetation (Venterea et al 2003).…”

Acidification and Nutrient Cycling

“…Since then, a number of publications have explored the symptoms of N saturation, as described by Aber et al (1998), on the FEF (Peterjohn et al 1996, Fenn et al 1998, Fernandez and Adams 2000. Additional research at FEF has focused on the possible effects of N saturation on plants (Gilliam et al 2001a, Christ et al 2002 and soils (Peterjohn et al 1998;1999;Gilliam et al 2001a, b) of these hardwood stands. These studies have provided compelling evidence to corroborate Stoddard's earlier conclusions based on stream chemistry from WS4 -some of the forest stands of FEF are demonstrating symptoms of N saturation, including WS3 and possibly WS7.…”

“…Net nitrification on WS3, WS4, and WS7 was 141, 114, and 115 kg N ha -1 yr -1 , respectively (Gilliam et al 2001b, Christ et al 2002, and essentially equal to 100% of net mineralization for these watersheds. These rates do not differ significantly among watersheds.…”