Root‐associated fungi not tree density influences stand nitrogen dynamics at the larch forest–tundra ecotone

Abstract Greater tree density and forest productivity at the tundra–taiga ecotone (TTE) are expected with climate warming, potential feedbacks to system. Yet, competition for nitrogen (N) may impact TTE dynamics. will likely increase N demand, while reducing supply through soil shading slower decomposition rates. We explored whether characteristics of roots root‐associated fungi important acquisition responded changes in were related above‐ground stand cycling. measured rooting depth, uptake forms among layers ectomycorrhizal (EcM) colonization composition along a natural gradient monodominant larch Larix cajanderi northeastern Siberia. tested relationships between root fungal characteristics, stand‐level cycling parameters. Overall, there was preferential ammonium compared glycine or nitrate. Nitrogen greatest shallow soils organic horizon chemistry, parameters, but direction these depended on form. Uptake different forms, depth EcM not density, correlated chemistry In addition EcM, abundance dark septate endophytes other ascomycetous taxa positively Synthesis . There little parameters suggesting intraspecific amplified increased density. was, however, strong dynamics regardless Together, this suggests an role broadscale patterns forests independent warming.