不同毛白杨无性系林分蓄积量的长期水氮耦合效应

【目的】研究不同田间持水量和纯氮施用量对毛白杨人工林单位面积上林分蓄积量的影响,确定毛白杨无性系最佳水氮组合方案。【方法】采用裂区试验设计在河北威县林地研究不同水氮耦合处理对不同无性系(BT17,B331,S86,1316)毛白杨林分蓄积量影响。【结果】1)无性系在不同纯氮施用量和田间持水量灌溉条件下单位面积上林分生长量有差异,S86无性系对高水肥处理响应较好,1316无性系响应较差。2)对杨树人工林进行水分灌溉管理措施时,应该设置田间持水量75%以上作为灌溉临界值同时灌溉临界值应考虑造林地区的环境条件、造林密度、林龄等因素。3)杨树人工林单位面积上纯氮施肥量范围是在100~400kg·hm^-2,且施肥量应当根据实验地区肥力等级状况进行酌量加减。【结论】在河北威县S86无性系是在田间持水量75%以上和每株施氮量160g的管理措施下能实现速生丰产的毛白杨无性系,建议在相近地区进行杨树人工林速生丰产林培育时候优先考虑。

Long Term Water-Nitrogen Coupling Effect on Stand Volume of Different Clones of Populus tomentosa

【Objective】 In Wei County nursery of Hebei province,we applied different irrigation and nitrogen addition treatments to study the long-term water-nitrogen coupling effect on stand volume of Populus tomentosa.【Method】 A split plot experiment design was used to study effects of different water-nitrogen coupling treatments in forest land on stand volume of different clones of P.tomentosa.【Result】 Results showed that: 1) different irrigation and nitrogen application had significantly different effects on stand volume of different clones.Clone S86 had better response mechanism under high water and fertilizer treatment,but it was opposite to clone 1316. 2) during irrigation to poplar plantation,the field capacity of more than 75% should be set as the critical value of irrigation,and the afforestation region of the environmental conditions,such as planting density,forests age and other factors,should be taken into account.3) It is suggested that the range of nitrogen fertilizer to poplar plantation should be between 100 kg·hm^-2 to 400 kg·hm -2,and the amount of fertilization should be adjusted to the fertility level in the experiment area.【Conclusion】 Through the comparative study,clone S86 is suitable for the experimental design in the area with field capacity of 75% and nitrogen application rate of 160 g per tree as a fast-growing among the 4 clones (BT17,B331,S86,1316).We suggest that the cultivation of fast-growing and high-yielding poplar plantations in the near areas should be given priority.The results provide scientific theoretical basis for directional cultivation of Populus tomentosa plantation,and put forward a scientific and reasonable variety (line) selection criteria with high-quality,fast-growing and high-yield.