Introduction:

Nutrient movement in high mountain forests generates information on their functioning and response to climate change effects. Nitrogen dynamics in these ecosystems has been poorly studied.

Objective:

To quantify N reservoirs in forest litter, topsoil (0-10 cm) and needle litterfall, and to measure temporal concentrations of nitrate and ammonium in topsoil and N resorption (ReabsN) in the Jocotilán (JO) and Tláloc (TL) mountains of central Mexico.

Materials and methods:

A total of 108 (JO) and 128 (TL) soil and needle litterfall samples were collected for one year. N and ReabsN reservoirs were compared between mountains using the Wilcoxon test (P < 0.05). Temporal trends of soil moisture, N and ReabsN forms were analyzed with linear mixed models, setting time and mountain as fixed factors.

Results and discussion:

Gravimetric moisture, total N, and nitrate and ammonium concentrations were not different between mountains. Total inorganic N (ammonium + nitrate) in JO was higher than in TL (46 vs. 41 mg∙kg-1). N in needle litterfall and soil were higher in JO, but ReabsN in TL was higher (60 vs. 55 %). Soil moisture, ammonium and ReabsN had a seasonal pattern of cubic trend (P < 0.05), denoting N pulses.

Conclusions:

Forests showed differences in N dynamics in needle litterfall, resorption and soil inorganic forms of N, indicating that it is possible to differentiate their functioning according to this nutrient.

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