Soil organic carbon storage and vertical distribution of carbon and nitrogen under different forest types in the Qinling Mountains

Abstract

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...

Analysis on Characteristics of Vegetation and Soil Bacterial Community under 20 Years’ Restoration of Different Tree Species: A Case Study of the Qinling Mountains

“…The discrepancies may be caused by various degree of forest canopy [33,34], temperature and precipitation [34], litter composition or root exudates [8]. In comparison with the results from , SOC in our study was lower, which may be related to the young tree age in our study [35]. C/N ratio is a sign of soil nitrogen mineralization ability, which is inversely proportional to the rate of soil organic matter decomposition [36].…”

The Influence of Land Use Patterns on Soil Bacterial Community Structure in the Karst Graben Basin of Yunnan Province, China

“…Therefore, the contents of TN and SOC in woodland were higher than those in shrubland and grassland. Further, soil nutrient contents decreased gradually with increasing soil depth because the soil's surface layer was the humus layer with rich litter, high nutrient content, a well-developed plant root system, good ventilation, and positive hydrothermal conditions [33][34][35][36].…”

Prediction of the vertical scaling of soil organic carbon in temperate forest soils using percolation theory

“…1 and 2, and the intercept on y-axis), but has no significant effect on the vertical scaling of SOC (shown as the slopes on the log-log plot), indicating that the vertical distribution of SOC is limited by the vertical transport of solute in temperate forest soils regardless of the carbon input from soil surface. 185 Figure 4: Vertical scaling of SOC content from 5 published datasets including a global dataset referenced from Jobbágy and Jackson (2000), and 3 field studies done in Hailun (Hao et al, 2015), and Qinling Mountains, China (Wang et al, 2015), and Hainich, Germany, (Braakhekke et al, 2011) 190 Figure 4 demonstrates the vertical scaling of SOC content with soil depth from published data (Wang et al, 2015, Hao et al, 2015, Jobbágy & Jackson, 2000, and Braakhekke et al, 2011. The scaling powers are -0.920, -1.097, -1.196, -1.062, and -1.038 from the 5 datasets (average is -1.063), comparing with the theoretical scaling, -1.149 in Eq.…”

“…Sources of the published data (Table 3) include 3 global databases of soil profile in temperate forest soils (National Soil 130 Characterization Database produced by the U.S. Department of Agriculture, World Inventory of Soil Emission Potential Database, and the Canadian Forest Service) summarized in Jobbágy and Jackson (2000), which cover 60 samples for the temperate deciduous forest, and 123 for the temperate evergreen forest across the world, and 3 field studies done in Hailun, China (Hao et al, 2015), Qinling Mountains, China (Wang et al, 2015), and Hainich, Germany, (Braakhekke et al, 2011). Soil depths were taken as the averaged depth of each soil interval, and the unit of SOC was converted from g kg -1 to g 100g -1 , 135 except data from Jobbágy and Jackson (2000), which was presented in relative proportion content throughout the first meter of soil in the original article.…”

“…The magnitude of SOC links to many factors including precipitation, temperature, soil properties (i.e. mineral content and mineral assemblage, Feller and Beare, 1997;Torn, 1997;Rasmussen and Southard, 2005), forest stands (Wang et al, 2015), and land use (Hao et al, 2015). Temperature mainly controls the decomposition of SOC through affecting microbial activity (Jobbágy and Jackson, 2000), and generally negatively correlates to SOC content, while 30 precipitation affects the production of plants as well as the decomposing process of plant litter into SOC, and has a positive correlation to SOC (Jobbágy and Jackson, 2000;Wang et al, 2002, Yang et al, 2007, Liu et al, 2016.…”