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| Ecological stoichiometry of soil carbon,nitrogen and phosphorus in aLarix principis rupprechtii plantation |
| Bai Xiaofang1,2, Xu Fuli1,3, Wang Weiling3, Zhao Yafang1,2, Wang Lingling3, Sun Pengyue3 |
| 1. Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,712100,Yangling,Shaanxi,China;2. University of Chinese Academy of Sciences,100049,Beijing, China;3. Northwest A&F University,712100,Yangling,Shaanxi, China |
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Abstract Large areas of plantations have been cultivated in China since 1950s, which provide tremendous ecological and economic services such as soil and water control, wood production, carbon sequestration and environment protection. Many problems such as soil degradation, tree diseases and wood production decline, however, also appeared after several decades of cultivation due to lack of effective management practices, which seriously threatens the stability and sustainability of plantation development and imposes severe influence on ecological and economic achievements. As the main elements circulation and nutrients turn over pool for plant growth, soil is essential in forest management.The soil fertilization maintenance and promotion have been and still are of significant interest for plantation management. A number of studies concerning spatial pattern of soil nutrients have been conducted in woodland, while little is known about the temporal pattern of soil nutrient status and stoichiometric ratios in plantations which has the important implications for dynamic balance of soil nutrients. The objective of this study was to clarify the seasonal pattern of soil stoichiometric characteristics of a 20-year-old Larix principis rupprechtii plantation in Qinling. The soil organic carbon(C), total nitrogen (N), total phosphorous (P) contents and stoichiometric ratios were measured to explore their seasonal variation and vertical distribution. The results show that: 1) The contents of C,N and P decreased with soil depth throughout the entire growing season (May to October). The contents of C, N and P have obvious seasonally dynamic changes from May to October. Soil C and Nvaried greatly in the 0-20 cm soil layer (coefficient of variance (Cv) of C and N was 0.28 and 0.22,respectively) compared to 20-40 cm and 40-60 cm soil layers (Cvfor C 0.11 -0.18; for N 0.13 -0.14), while soil P fluctuated significantly in the 40 - 60 cm layer (0.18) in comparison with theother two layers. The contents of C and P in the 0-20 cm soil layer reached the top value in October.Also, seasonal variations of C (0.11 - 0.28) and N (0.15 - 0.22) were greater than P (0.06 -0.18). 2)C/N, C/P and N/P ratios in the 0 -20 cm soil layer was significantly higher than those in 20 -40 cm and 40 -60 cm layers (P<0.05). In these three soil layers, the seasonal variation of C/N was the smallest and not obvious. The seasonal variation of N/P was the biggest. In May, C/P and N/P in both 0 -20 cm and 20 -40 cm soil layers were significantly higher than in other months (P<0. 05). In May and June, C/P and N/P in 40 -60 cm soil layer were significantly higher than in July and August. 3) The relative analysis implies that the contents of C, N and P have obvious positivecorrelation (P<0.01). Moreover, C content and C/N, C content and C/P, N content and C/N, Ncontent and N/P, P content and C/P all have obvious positive correlations, but P content has norelation with N/P.
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Received: 08 April 2015
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