栽植密度对毛白杨林地土壤垂直方向养分的影响

Planting densities and vertical soil nutrients in a Populus tomentosa stand

【目的】研究栽植密度对毛白杨Populus tomentosa林地土壤养分的影响。【方法】在3种不同栽植密度[行距×株距分别为2 m×2 m(T1)、4 m×3 m(T2)和4 m×5 m(T3)]下,对10年生毛白杨速生丰产林试验地0~5、5~10、10~20、20~40、40~60和60~100 cm共6个土层的有机质、碱解氮、有效磷和速效钾质量分数进行了分析。栽植密度对土壤养分的影响用单因素分析法,数据间的多重比较用Ducan法。【结果】0~20 cm土层有机质、碱解氮、有效磷和速效钾所占比例分别为69%、79%、71%和74%;不同栽植密度下土壤养分质量分数不一致:T2栽植密度下有机质在0~5 cm处最高,为15.44 g·kg^-1,显著高于T1,在5~20 cm土层处3栽密度间有机质差异显著(P<0.05),大小依次为T3、T2、T1,在20~100 cm土层处T1显著低于T3和T2(P<0.05);碱解氮在T2下为14.5~142.7 mg·kg^-1,高于T1和T3(除5~10 cm);有效磷为1.3~12.4 mg·kg^-1,5~40 cm土层T2显著高于T1和T3(P<0.05),40~100 cm土层大小依次为T3、T2、T1;栽植密度对速效钾无显著影响(P>0.05)。【结论】10年生毛白杨林地土壤养分富集在0~20 cm土层,栽植密度为2 m(行距)×2 m(株距)的养分低于栽植密度为4 m×3 m和4 m×5 m,养分质量分数随栽植密度和不同土层的变化而变化。

[Objective]To explore the effects of planting densities on soil nutrients of different soil layers for a Populus tomentosa plantation.[Method]10-year-old S86 clones were used to study the soil nutrient characteristics with three planting densities(T1:2 m×2 m;T2:4 m×3 m;and T3:4 m×5 m)for six soil layers(0-5,5-10,10-20,20-40,40-60,and 60-100 cm).In mid-October 2016,soil samples were collected,and the contents of carbon(C),available nitrogen(N),available phosphorus(P),and available potassium(K)were determined and in total there were 3 treatments with 3 replicates,then one-way ANOVA and Duncan’s multiple comparison tests were used to determine significant differences.[Result]The proportions of nutrients in the 0-20 cm layer compared to the 0-100 cm layer were:C(69%),N(79%),P(71%),and K(74%).The content of soil nutrients varied for the three planting densities.The highest C content found in T2(15.44 g·kg^-1 in the 0-5 cm layer)was significantly higher(P<0.05)than T1;the C content in the 5-20 cm layer was significantly different(P<0.05)than other densities in the order of T3>T2>T1;and in the 40-100 cm layer,the T1 content was significantly lower(P<0.05)than other densities.The N content in T2 was 14.5-142.7 mg·kg^-1.The P content was 1.3-12.4 mg·kg^-1 with the content of T2 being significantly higher(P<0.05)than other layers from 5-40 cm;however,in the 40-100 cm layers the content was T3>T2>T1.Planting density,though,had no significant effect on K content(P>0.05).[Conclusion]Nutrient content varied according to planting density and soil layers with the soil nutrient content of 10-year-old P.tomentosa clone S86 gathered in the 0-20 cm layer for the 2 m×2 m density having a lower nutrient content than the 4 m×3 m and 4 m×5 m densities.