Effects of snow absence on available N pools and enzyme activities within soil aggregates in a spruce forest on the eastern Tibetan Plateau

Winter climate change has great potential to affect the functioning of terrestrial ecosystems. In particular, increased soil frost associated with reduced insulating snow cover may impact nitrogen (N) dynamics in cold ecosystems, but little is known about variability these effects among aggregates. A manipulation experiment was conducted investigate absence on N cycling within aggregates a spruce forest eastern Tibetan Plateau China. The extractable available (ammonium and nitrate), net mineralization rate, cycling-related enzyme activities (urease, nitrate reductase, nitrite reductase) were measured large macroaggregate (>2 mm), small (0.25–2 microaggregate (<0.25 mm) during early thawing period years 2016 2017. Snow availabilities reductase activity microaggregate, did not urease or any aggregate fractions. Regardless manipulations, both inorganic higher than other two effect size sampling year significant mineral N, activity. Our results indicated that exerts largest its dependent winter conditions (e.g., temperature). Such findings have important implications for snow-covered subalpine forests experiencing pronounced change.