| Agricultural sciences |
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| Effects of different planting-years of artificial Caragana intermedia shrubs on soil organic carbon, nitrogen and phosphorus stoichiometry characteristics in desert steppe. |
| Pan Jun1,2, Song Naiping1,2*, Wu Xudong1,3, Yang Xinguo1,2, Chen Lin1,2, Qu Wenjie1,2, Zhai Deping1,2 |
| (1. Breeding Base of State Key Laboratory for Preventing Land Degradation and Ecological Restoration, Ningxia University, Yinchuan 750021, China; 2. Union Research Center for Ecology and Exploition of Biological Resources in Western China, Ningxia University, Yinchuan 750021, China; 3. College of Agriculture, Ningxia University, Yinchuan 750021, China) |
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Abstract The thicketization of the shrub has become a common phenomenon in the arid and semi-arid steppe worldwide. The Caragana intermedia has been widely used to prevent grassland degradation because of its low transpiration rate, strong resistance and wide adaptability to the environment. The life activity of C. intermedia was not only restricted by water shortage, but also limited by soil nutrients and environmental stress. This paper revealed the balance and cycle process of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) in the soil, in which artificial shrub and grass were mixed planting. Therefore, the results can provide basic data for research on the balance and circulation of SOC, TN, TP in the soil of desert grassland ecosystems. The artificial C. intermedia shrubs in different planting-years (9 a, 17 a, 27 a) were taken as research objects, to analyze the contents and the ecological stoichiometry of SOC, TN, TP in the depth of 040 cm. The result showed that the SOC and TN contents of the artificial C. intermedia shrubs with different planting-years had significant differences in the vertical section (Pedge>outside. The contents of TP increased in all the parts of the shrubs with the planting-years, but the soil C/N ratio of each shrub decreased gradually. Furthermore, the soil C/P ratio first decreased and then increased on the edge and the inside of the shrubs, while gradually increased in the outside of the shrubs. The soil N/P ratio in the inside and outside of shrubs both showed increasing trends, and first decreased and then increased in the edge of the shurbs. The soil C/N ratio increased gradually with the increasing soil depth, while the C/P and N/P ratios first decreased and then increased as a whole. The N/P ratio had a significant negative correlation with the TP content (P<0.01), and significant positive correlations with the TN content and the C/P ratio (P<0.01). In conclusion, the soil nutrients in artificial C. intermedia shrubs show a significant surface accumulation and “fertile island” effect. As the growth of C. intermedia shrubs was affected by various factors, further research should be considered on the N/P stoichiometry characteristics of vegetation and soil ecosystem, and the relations between the limiting nutrients of soil N, P and the nutrient adaptability characteristics of vegetation.
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Published: 20 March 2015
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荒漠草原不同种植年限人工柠条林土壤碳氮磷化学计量特征
以荒漠草原不同林龄(9 a,17 a,27 a)人工柠条林为对象,研究不同土层深度以及柠条灌丛不同部位的土壤有机碳(soil organic carbon,SOC)、全氮(total nitrogen,TN)和全磷(total phosphorus,TP)含量及其生态化学计量特征变化规律.结果表明：不同林龄柠条灌丛各部位SOC和TN含量在垂直剖面上的分布具有统计学上的极显著差异(P边缘>外部；随着柠条林龄的增长,灌丛各部位土壤TP含量呈逐渐增加的趋势.随着林龄的增长,灌丛各部位土壤C/N均呈现逐渐降低的趋势；而土壤C/P在灌丛内部和边缘呈现先降低后增加的趋势,而在灌丛外部呈现逐渐增加的趋势；土壤N/P在灌丛内部和外部呈现逐渐增加的趋势,而在灌丛边缘呈现先降低后增加的趋势.随着土层深度的增加,土壤C/N呈逐渐增加的趋势,而C/P和N/P整体上呈先降低后增加的趋势.N/P与TP呈极显著负相关,而与TN和C/P呈极显著正相关.可见,人工柠条林在生长过程中土壤养分呈现明显的表聚性,柠条灌丛出现“肥岛效应”;由于柠条在生长过程中受到诸多因素的影响,还需加强植被与土壤生态系统N/P化学计量特征,土壤N、P养分限制和植被养分适应特征相互关系的研究.
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