Extended Data Fig. 8: Inorganic nitrogen availability at Trail Valley Creek.
From: Arctic soil methane sink increases with drier conditions and higher ecosystem respiration
Plant-available nitrogen (N; mean ± standard deviation, n = 5) for lichen, shrub, and tussock sites at Trail Valley Creek during 2019. The presence of nitrate (NO3−) and negative correlation between ammonium (NH4+) and NO3− indicates nitrification is an active process at Trail Valley Creek. During nitrification, NH4 is oxidized to NO3− via several intermediates. The low amounts of NH4 in early summer (June) under shrub and tussock indicate NH4+-limitation, due to high microbial N demand (for example, through nitrification) and plant N demand during onset of the plant growth phase, but a lifting of N-limitation in late summer when plant N demand is lower during the senescence period.
