引入阔叶树种枯落叶对陕北风沙区针叶林土壤极化的防治效应

Control effects of introducing leaf litter of broad-leaved trees on soil polarization under pure stands of needle-leaved forests in the windblown sand region of northern Shaanxi

【目的】研究不同针、阔叶树种的种间关系,为通过针、阔混交或枯落叶客置来防治人工针叶纯林土壤的极化提供科学依据。【方法】在位于陕北黄土高原北部半干旱风沙区的靖边县,选择覆盖度达到90%～100%的22年生油松和25年生樟子松纯林,建立20 m×20 m的标准地,以5样方(1 m×1 m)混合采样法采集0～10 cm土层腐殖质土壤和附近不同针、阔叶树种的当年枯落叶后,进行室内混合培养试验。【结果】油松纯林会导致土壤养分含量、部分酶活性降低及真菌、放线菌数量明显减少的负向极化发展趋势,樟子松纯林会导致土壤部分酶(脲酶、蔗糖酶)活性降低和细菌数量明显减少的负向极化发展趋势。引入阔叶树种枯落叶防治油松纯林土壤极化的优先顺序为:引入白榆、沙棘和旱柳最好,其次为紫穗槐,而小叶杨、刺槐和柠条则均不适宜引入;引入阔叶树种枯落叶防治樟子松纯林土壤极化的优先顺序为:引入沙棘最好,其次为柠条,引入小叶杨和白榆效果不明显,而刺槐、紫穗槐和旱柳则均不适宜引入。【结论】不同阔叶树种枯落叶对针叶林地土壤性质的影响效应有明显差异;筛选出了防治陕北风沙区针叶林土壤极化的阔叶树种。

【Objective】 Study about the interspecific relationship can provide scientific basis for forming mixed forest or fertilyzing leaf litter with other tree speices to control soil polarizations of needl-leaved forest.【Method】 In Jingbian county which is situated in the semi-arid,windblown sand region of northern Shaanxi Province,after establishing standard plots（20 m×20 m） in forests of 22-year-old Pinus tabulaeformis and 25-year-old Pinus sylvestris var.mongolica whose coverage arrived at 90%-100% and sampling mixed humus soil of 0-10 cm depth with 5 small plots（1 m×1 m）in every forest and leaf litter of different needle or broad-leaved trees nearby,experiments of incubation mixing humus soil of pure forests with leaf litter were carried out in laboratory.【Result】 Pure forest of P.tabulaeformis would result in negative soil polarization including depletion in soil nutrients,decline in a few enzyme activities and amounts of fungi and actinomycetes.Pure forest of P.sylvestris var.mongolica would result in negative soil polarization including decline in a few enzyme activities and amounts of bacteria.The priority order of introducing other tree species to control soil polarization under forest of P.tabulaeformis is as follows：Ulmus pumila,Hippophae rhamnoides and Salix matsudana are better,Amorpha fruticosa second,but Populus simonii,Robinia pseudoacia and Caragana microphylla not suitable.The priority order of introducing other tree species to control soil polarization under forest of P.sylvestris var.mongolica is as follows：H.rhamnoides is better,C.microphylla second,P.simonii and U.pumila not significant,R.pseudoacia,A.fruticosa and S.matsudana not suitable.【Conclusion】 The effects of broad leaf litter on soil are very different and suitable tree species tree which can be introduced to control soil polarization under pure stands of needle-leaved forests in the windblown sand region of northern Shaanxi are selected.