不同林龄樟子松人工林根际与非根际土壤生态化学计量特征

  目的  探究辽西北沙地不同林龄樟子松Pinus sylvestris var. mongolica人工林根际与非根际土壤碳(C)、氮(N)、磷(P)质量分数及生态化学计量特征关系，为该地区的樟子松林培育、经营及管理提供理论依据。  方法  采用时空互代的方法，在辽西北章古台地区选取6个林龄(10、20、30、40、50和60 a)的樟子松人工林作为研究对象，分析各林龄下根际与非根际土壤碳、氮、磷质量分数及化学计量比的差异和影响因素。  结果  辽西北沙地樟子松人工林土壤贫瘠，根际土壤碳、氮、磷质量分数均高于非根际土壤，根系对养分的富集与平衡维持作用明显。林龄、根际以及二者之间的交互作用，对土壤碳、氮、磷质量分数及其生态化学计量比影响显著。樟子松人工林土壤C∶N主要受到土壤全氮的影响，土壤C∶P主要受土壤有机碳的影响，土壤N∶P受土壤全氮的影响大于全磷。各林龄樟子松人工林土壤C∶N均远高于全国平均水平，表现为氮限制，其中60 a过熟林氮限制更为强烈。樟子松人工林根际土壤氮、磷限制存在一定程度的协同性。  结论  各林龄樟子松生长均受到氮限制，相较于根际土壤，非根际土壤氮更为缺乏。在森林经营过程中，应充分考虑根际与非根际土壤的差异性，建议对辽西北沙地樟子松人工林施用氮肥、引入固氮植物以解除氮限制，并注意根系磷肥的补充。图1表5参28

Ecological stoichiometric characteristics of rhizosphere and non-rhizosphere soil of Pinus sylvestris var. mongolica plantations at different ages

  Objective  The purpose is to explore the relationship between C, N, and P contents in rhizosphere and non-rhizosphere soil and ecological stoichiometric characteristics of Pinus sylvestris var. mongolica plantations at different ages in sandy land of northwest Liaoning Province, so as to provide theoretical basis for cultivation and management of P. sylvestris var. mongolica plantations in this area.  Method  Using space-temporal exchange method, six P. sylvestris var. mongolica plantations (10, 20, 30, 40, 50 and 60 a) were selected in Zhanggutai area to analyze the differences and influencing factors of C, N, P contents and stoichiometric ratio between rhizosphere and non-rhizosphere soil of different stand ages.  Result  The soil of P. sylvestris var. mongolica plantation in the sandy land of northwest Liaoning was poor, and the contents of C, N, and P in rhizosphere soil were higher than those in non-rhizosphere soil. The root system had a significant effect on nutrient enrichment and balance maintenance. Stand age, rhizosphere, and their interaction had significant effects on soil C, N, P contents and their ecological stoichiometry. Soil C∶N of the P. sylvestris var. mongolica plantation was mainly affected by total N, soil C∶P was mainly affected by soil organic carbon, and soil N∶P was more affected by total N than total P. The soil C∶N ratio of P. sylvestris var. mongolica plantation at all ages was much higher than that of the national average level, which was manifested as N limitation, especially in the 60 a over mature forest. The limitation of N and P in rhizosphere soil of P. sylvestris var. mongolica plantation was synergistic to some extent.  Conclusion  The growth of P. sylvestris var. mongolica at all ages is restricted by N, and non-rhizosphere soil is more deficient in N compared with rhizosphere soil. In forest management, the difference between rhizosphere and non-rhizosphere soil should be fully considered. It is suggested that N fertilizer and N-fixing plants should be applied and introduced to P. sylvestris var. mongolica plantations in sandy land of northwest Liaoning to relieve N limitation, and P fertilizer should be added to the root system. Ch, 1 fig. 5 tab. 28 ref.]