Moisture effect on carbon and nitrogen mineralization in topsoil of Changbai Mountain, Northeast China

Abstract

Changbai Mountain Natural Reserve (1,985 km<sup>2</sup> and 2,734 m a.s.l.) of Northeast China is a typical ecosystem representing the temperate biosphere. The vegetation is vertically divided into 4 dominant zones: broadleaved Korean pine forest (annual temperature 2.32°C, annual precipitation 703.62 mm), dark coniferous forest (annual temperature –1.78°C, annual precipitation 933.67 mm), Erman's birch forest (annual temperature –2.80°C, annual precipitation 1,002.09 mm) and Alpine tundra (annual temperature –3.82°C, annual precipitation 1,075.53 mm). Studies of soil carbon (C) and nitrogen (N) mineralization have attracted wide attention in the context of global climate change. Based on the data of a 42-day laboratory incubation experiment, this paper investigated the relationship between soil moisture and mineralization of C and N in soils with different vegetation types on the northern slope of the Natural Reserve Zone of Changbai Mountain. The elevation influence on soil C and N mineralization was also discussed. The results indicated that for the given vegetation type of Changbai Mountain the C and N mineralization rate, potential mineralizable C (C0) and potential rate of initial C mineralization (C<sub>0</sub>k) all increased as the soil moisture rose. The elevation or vegetation type partially affected the soil C and N mineralization but without a clear pattern. The moisture-elevation interaction significantly affected soil C and NO<sub>3</sub><sup>–</sup>-N mineralization, but the effect on NH<sub>4</sub><sup>+</sup>-N mineralization was not significant. The complex mechanism of their impact on the soil C and N mineralization of Changbai Mountain remains to be studied further based on data of field measurements in the future.