干旱荒漠区人工梭梭林土壤碳氮磷密度与生态化学计量特征

为了阐明人工梭梭林土壤碳氮磷密度及其生态化学计量特征演变规律,以吉兰泰荒漠区不同林龄(3,6,11,16年)人工梭梭林为研究对象,分析0—20,20—40,40—60 cm土层土壤有机碳(SOC)、全氮(TN)、全磷(TP)密度和生态化学计量特征。结果表明:(1)4种林龄人工梭梭林0—60 cm土层SOC、TN含量及其密度随林龄增加而升高,而TP含量及其密度随林龄增加而降低。其中,3,6年梭梭林SOC、TN含量及其密度随土层深度增加而升高,TP含量及其密度则与之相反;11,16年梭梭林SOC、TN、TP含量及其密度随土层深度增加而降低。(2)4种林龄梭梭林土壤C∶N、C∶P、N∶P分别为2.24~9.21,1.59~7.05,0.56~0.81,均属于中等变异水平,且变异系数随林龄和土层深度增加逐渐减小,说明土壤C∶N、C∶P、JP]N∶P趋于平稳状态。(3)林龄、土层深度及其交互作用显著影响SOC含量、SOC密度、C∶N、C∶P,对TN含量、TP含量、TN密度、TP密度、N∶P无显著影响。(4)土壤孔隙度(STP)与SOC密度呈显著正相关关系(P＜0.05),说明土壤孔隙度增加有助于SOC密度增加,提高土壤肥力。在干旱荒漠区建植梭梭林有利于提高土壤肥力,改善干旱荒漠区土壤环境。

Soil Carbon, Nitrogen and Phosphorus Densities and Ecological Stoichiometry Characteristics of Haloxylon ammodendron Plantations in Arid Desert Area

To investigate the evolution of planting years on soil carbon, nitrogen, phosphorus densities, and eco-chemical stoichiometry in Halaxylon ammodendron plantations, an age sequence of H. ammodendron stands (3, 6, 11 and 16 years) were selected in desert area of Jilantai, densities and stoichiometry characteristics of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) at soil depths of 0-20, 20-40, 40-60 cm were measured. The results showed that:(1) The contents and densities of SOC and TN in 0-60 cm soil increased with the increase of stand age, whereas the content and density of TP decreased with the increase of stand age. The SOC and TN contents and densities increased with the increase of soil depth in 3-year and 6-year plantations, and the content and density of TP were moving in exactly the opposite direction. The contents and densities of SOC, TN and TP increased with the increase of soil depth in 11-year and 16-year plantations. (2) The C:N, C:P and N:P ratios were 2.24~9.21, 1.59~7.05 and 0.56~0.81 with moderate spatial variation, and the coefficient of variation decreased with the stand age and soil depth, indicating that soil C:N, C:P and N:P ratios tended to remain stable. (3) Stand age, soil depth, and their interaction had a significant effect on SOC content, SOC density, C:N and C:P ratios, but had no significant effect on the N:P ratio and the contents and densities of TN and TP. (4) Soil porosity (STP) had a significant positive correlation with SOC density (P<0.05), indicating that the increase of soil porosity is helpful to increase SOC density and improve soil fertility. Plantation of H. ammodendron can improve soil fertility and soil environment in arid desert area.