晋西黄土区不同密度油松人工林保育土壤功能评价

Evaluation on Soil Conservation Function of Pinus tabulaeformis Plantation with Different Densities in the Loess Area of Western Shanxi Province

研究晋西黄土区不同密度油松林保育土壤功能变化规律及差异性,评价其保育土壤功能,以加强林分管理和生态恢复建设。以山西吉县蔡家川流域4种不同密度(925,1325,1750,2250株/hm^(2))油松人工林为研究对象,对其土壤容重、孔隙度等物理性质、有机质等化学性质以及坡面径流泥沙量进行测定和分析,确定了12项评价指标,采用熵权法(EWM)对各密度油松林地的保育土壤功能进行综合评价。结果表明:(1)4种林分密度的油松人工林,土壤容重、总孔隙度、非毛管孔隙度、毛管孔隙度、全氮、全磷、氨氮、硝氮和速效磷均存在显著差异(P<0.05);(2)林分密度变化会不同程度地改变油松林土壤物理性质、土壤养分和径流泥沙量等12项指标,其中土壤容重、径流量、泥沙量均随林分密度增大呈现先下降后上升的趋势;土壤有机质、全氮、全磷、硝氮、速效磷,随林分密度增大呈先增加后减少的趋势;(3)不同密度油松林地的土壤物理结构、土壤肥力和产流产沙均随密度变化呈现一定的变化规律,随着林分密度增大,土壤结构改良状况和土壤肥力呈现先上升后下降的趋势;径流泥沙量表现为先减小后增大地趋势;(4)对不同密度油松人工林保育土壤功能评价表明,4种密度油松林中,随着油松林林分密度的增加,保育土壤功能呈现先增强后减弱的趋势。密度为1750株/hm^(2)的油松林地保育土壤功能相对较好。从保育土壤角度出发,建议将1750株/hm^(2)作为晋西黄土区油松人工林经营密度,该密度油松林能较好保持水土,改善林地土壤质量。

This paper aimed to study the changing laws and differences of soil conservation functions of Pinus tabulaeformis forests with different densities in the loess area of western Shanxi Province,and to evaluate their soil conservation function,so as to strengthen forest stand management and ecological restoration.Four kinds of P.tabulaeformis plantations with different densities(925 plant/hm^(2),1325 plant/hm^(2),1750 plant/hm^(2) and 2250 plant/hm^(2))in the Caijiachuan watershed of Jixian County,Shanxi Province were taken as the research objects.The soil bulk density,porosity and other physical properties,organic matter and other chemical properties as well as the amount of slope runoff and sediment were measured and analyzed,and 12 evaluation indicators were determined,and the entropy weight method(EWM)was used to evaluate comprehensively the soil conservation functions of each P.tabulaeformis forests.The results showed that:(1)There were significant differences in soil bulk density,total porosity,non-capillary porosity,capillary porosity,total nitrogen,total phosphorus,ammonia nitrogen,nitrate nitrogen and available phosphorus among the four kinds of P.tabulaeformis plantation(P<0.05).(2)The change of stand density would change the 12 indicators of soil physical properties,soil nutrients and runoff and sediment volume of the P.tabulaeformis forest.Among them,soil bulk density,runoff and sediment volume all decreased first and then increased with the increasing of forest density.Soil organic matter,total nitrogen,total phosphorus,nitrate nitrogen and available phosphorus showed the opposite tendency with the increasing of forest density.(3)The soil physical structure,soil fertility,runoff and sediment yield of different P.tabulaeformis forests all showed certain change laws with the change of density.The improvement of soil structure and soil fertility increased first and then decreased with the increasing of forest density.With the increasing of forest density,the amount of runoff and sediment decreased first and then increased.(4)The evaluation of soil conversation function of P.tabulaeformis plantations with different densities showed that the soil conservation function of P.tabulaeformis forest increased firstly and then decreased with the increasing of density.The conservation soil function of P.tabulaeformis forest land with a density of 1750 plant/hm^(2) was relatively good.From the perspective of soil conservation,it was recommended that 1750 plant/hm^(2) should be used as the management density of P.tabulaeformis plantations in the loess area of western Shanxi.This density could better maintain water and soil and improve the soil quality of forest land.