Soil Physical And Chemical Spatial Variation In Picea Crassifolia Forest Of Qilian Mountain

Researching spatial variation of forest soil physical and chemical properties isable to realize the soil environmental of forest, to provide scientific instruction for thework of tending of woods,at the same time to protect the forest and forest soilresources is of great significance.This peaper based on the soil of Picea crassifoliaforest in Qilian Mountain,use the method of combining the field sampling andlaboratory analysis,researched soil physical and chemical properties of spatialvariability in Picea crassifolia forest.The main results as follows:（1）The soil temperature of Picea crassifolia forest in Qilian Mountain has a greatvariability in profile of0⁴0cm,the variation coefficient of0¹0cm,10～20cm,20～40cm respectively are:22.79%,24.10%,31.39%,both of them are moderatevariation.With the deepening of the soil,soil temperature gradually reduced,the soiltemperature variation coefficient decreased aslo.In the same altitude soil temperature is obviously less than the air temperature.Atelevational gradient,soil temperature fluctuated decrease with the elevationsrise,changing trends like air temperature changes in forests.Correlation analysisshowed that soil temperature and air temperature in0.01level is significantlyrelated,the correlation coefficient is0.834.（2）In0¹0cm,10～20cm, and20～40cm of soil layer,the content of soil organicmatter are13.52±2.46%,11.12±1.43%,9.17±1.29%;the variation coefficient are18.23%,12.83%,14.10%,both of them are moderate variation.In the soil verticalsection,the of organic matter have significantly reduced trend with the soil depthincreased.At the altitude of2500～3100m,the average of soil organic matter is10.73±3.143%,the maximum and the minimum respectively are15.77%and6.55%,coefficient of variation is29.30%,is moderate variation.Whether the west,theeast,or the middle of Qilian Mountain,soil organic matter all increased gradually with the elevations rise.（3） Picea crassifolia forest in Qilian Mountain soil bulk average are0.645±0.055g/cm³,0.702±0.055g/cm³,0.810±0.061g/cm³in vertical section.At samealtitude range,soil bulk has an obvious increase trend with the depth of profileincreased.Soil bulk has a weak variability in the layer of0～10cm,10～20cm,20～40cm.In altitudinal gradients,soil bulk performance for weak variability,variationcoefficient is6.55%.In the same altitudinal gradients,soil bulk show a trend of risingfirst and down after with the elevations rising.（4）At elevational gradient,0～10cm,10～20cm,20～40cm soil moisture contentrespectively are:47.50%±15.99%,34.85%±13.30,31.91%±11.08, variation coefficientare:33.67%,38.16%,34.73%,all belong to moderate intensity variation.The change ofsoil moisture in vertical section belongs to reduce type,it’s mainly decided by soilbulk and porosity.Picea crassifolia forest soil moisture has an increase trend with the elevationsrising at the elevational gradient,.（5）In the same altitude range soil pH has an obviously increase trend with theprofile depth increased.After statistical analysis,the average of soil pH are:7.63±0.29,7.74±0.24,7.86±0.29in the layer of0～10cm,10～20cm,20～40cm,and thevariation coefficient are3.85%,3.13%,3.66%.At the altitude of gradient,except for2650m soil is the neutral,other altitude rangeare in weak alkaline.（6）Soil total N,total P,NH₄⁺-N,in all the layer are moderate variation,total K isweak variability,NO₃^--N performance for strong variability.In the soil layer,thevariation coefficient decreases gradually with the deepness increased, show that thedeeper soil total N,NH₄⁺-N content is more stable.Coefficient of variation NO₃^--N hasa gradually increased trend with the increase of layer,it says that the deeper soil isNO₃^--N the more unstable.Variation coefficients of total P,total K fluctuation changein the soil profile,no significant increase or decrease trend.In the same altitude,soil total N,NH₄⁺-N gradually decreases with the profile depth increase,and total P,total Kgradually increase with the profile depth increase,NO₃^--N is fluctuation change.Soil total N,total P,total K,NH₄⁺-N,NO₃^--N of Picea crassifolia forest in QilianMountain change range in altitudinal gradients respectively are:0.36%～0.51%,0.060%～0.084%,1.950%～2.126%,9.46～15.60mg·kg-1,2.74～10.21mg·kg-1.Except for the total K is weak variability,the other four are medium variationand variation coefficient respectively are11.80%,12.59%,2.98%,16.97%,37.21%.Atthe altitude of gradient,the change of soil total N,total P,total K,NH₄⁺-N,NO₃^--Nbelong to polynomial.