The main forest areas of Shaanxi Province lie in the Qinling Mountains. These forests have important ecological and economic significance. The distribution patterns of soil organic carbon (SOC) , total nitrogen (TN) , and SOC storage in the soil profiles have not been systematically studied. The objective of this study was to estimate SOC, TN, and SOC storage for six forest types in the Matoutan forest farm and in the Xinjiashan forest farm of the Qinling mountain range. All forest types in this study were natural secondary forests: namely Quercus aliena var acuteserrata (Matoutan forest farm) , Pinus tabulaeformis Carr, Pinus armandii Franch, pine鄄oak mixed forest, Picea asperata Mast, and Quercus aliena var acuteserrata (Xinjiashan forest farm). Five replicate samples were taken in an " S冶 pattern for each forest type. The profiles were divided into 0-10, 10-20, 20-40, and 40-60 cm groups and then sampled, summing up to 72 soil samples. The physical and chemical properties of the soils were measured using conventional methods. The results were analyzed using univariate analysis of variance. Differences among forest types and soil horizons were analyzed with SPSS statistics 18.0. The http: / / www.ecologica.cn results showed that the content of SOC and TN of different soil layers decreased with increasing soil depth in all six soil profiles. The accumulation and decomposition of SOC and TN differed between forest types. Among the six forest types, the SOC and TN contents of Picea asperata Mast and pine鄄oak mixed forest were higher than in the others, and that of Quercus aliena var. acuteserrata (Xinjiashan forest farm) was the lowest. The SOC and TN content in the intervals of the six forest soils were 13.46-26.41 g / kg and 4.47-9.51 g / kg, respectively, and the order was Picea asperata Mast > pine鄄oak mixed forest > Quercus aliena var acuteserrata (Matoutan forest farm) > Pinus tabulaeformis Carr > Pinus armandii Franch > Quercus aliena var. acuteserrata (Xinjiashan forest farm). The ratio of carbon to nitrogen (C / N) ranged from 5. 93 to 15.47, the mean C / N was in the order of pine鄄oak mixed forest > Pinus armandii Franch > Pinus tabulaeformis Carr > Picea asperata Mast > Quercus aliena var acuteserrata (XinJiashan forest farm) > Quercus aliena var acuteserrata (MaToutan forest farm). SOC storage of the 0-60 cm layer of the six soils was 150.94 t / hm 2 for Picea asperata Mast > 135.28 t / hm 2 for Quercus aliena var acuteserrata (Matoutan forest farm) > 124.93 t / hm 2 for Pine鄄oak mixed forest > 109.24 t / hm 2 for Pinus armandii Franch > 102. 15 t / hm 2 for Quercus aliena var acuteserrata (Xinjiashan forest farm) > 96. 62 t / hm 2 for Pinus tabulaeformis Carr, which was greater than the national average SOC storage (96. 0 t / hm 2). SOC storage was influenced by SOC content, soil bulk density (BD) , soil thickness, and volume of gravel; therefore, the distribution regularity in the soil profile was poorer. Correlation analysis showed that there were highly significant positive correlations between SOC...

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The main areas of forest in Ningxia Province lie in the Helan and Liupan mountain ranges. These forests have important ecological and economic significance. The fertility of forest soil in these areas has not been systematically studied.The objective of this study was to evaluate soil fertility under six forest types in the Su鄄Yukou forest zone of the Helan mountain range and in the Xi鄄Xia and Die鄄Diegou forest zones of the Liupan mountain range. The natural forest types were Pinus tabulaeformis 伊 Populus davidiana, Picea crassifolia 伊 Populus davidiana, Potentilla parvifolia, and Larix principis鄄 rupprechtii. The planted forest types were Quercus liaotungensis and Larix principis鄄rupprechtii. Five separate profiles ( replications) were sampled in an ' S爷 pattern for each soil type. The profiles were divided into A, B, and C horizons and then sampled, making a total of 18 soil samples. Soil physical and chemical properties were measured with conventional methods. The results were analyzed using univariate analysis of variance. Differences among forest types and soil horizons