毛乌素沙地不同水分梯度根系垂直分布与土壤水分关系的研究

通过对毛乌素沙地不同水分梯度根系垂直分布的研究表明:不同水分梯度根系分布随土壤深度的增加呈指数形式下降,不同梯度由于土壤水分、植被根系类型的差异,不同水分梯度植被根系的空间分布也有差异,不同梯度根量随土壤垂直深度的模拟方程分别为:y=9.5736e-0.1341x,R2=0.8859(I);y=16.246e-0.2037x,R2=0.9301(II);y=32.001e-0.1904x,R2=0.9544(III);y=28.336e-0.1993x,R2=0.9484(IV)。不同水分梯度土壤含水率变化程度不同,同一水分梯度各层土壤含水率变化幅度亦有差异,0.1m土壤含水率变异系数最大,随着土壤深度增加变异系数减小,根据土壤含水率变异系数分析我们将各层土壤水分垂直变化划分为活跃层(0-0.1m)、次活跃层(0.2-0.6m)、相对稳定层(1m)(I、II、III);而对IV梯度划为活跃层(0-0.1m、1m)、相对稳定层(0.3m)。根系生物量垂直分布与其对应土壤含水率有明显相反的关系,土壤含水率的变化与根系生物量的变化趋于相反,当土壤含水率增大时相应区域根系生物量减小;反之则增加。随水分梯度的增加各梯度最高水分利用层逐渐向表层发展,从第I梯度0.4m的6.84到第IV梯度0.1m的14.33。

Relationship Between Soil Water Content and Vertical Distribution of Root System Under Different Ground Water Gradients in MaoWuSu Sandy Land

The vertical distribution of root system under different ground water gradients in MaoWuSu sandland were investigated.The results showed that: roots system under different ground water level decreased with the increasing of soil depth. Due to the difference of soil water content and vegetation roots type,the distribution of vegetation roots under different moisture content gradient was different.Simulation equation of roots under different gradient with soil vertical depth are: :y = 9.5736e-0.1341x R2= 0.8859(I),y = 16.246e-0.2037x R2= 0.9301(II),y = 32.001e-0.1904x R2= 0.9544(III)、y = 28.336e-0.1993x R2= 0.9484(IV);Soil water content variation was different under different ground water level.The variation of soil water content at each layer was different under the same ground water level.Variant coefficient of soil water content was the biggest at 0.1m depth,variant coefficient reduce with soil depth increased.According to analyzsis variant coefficient on soil water content the soil layers were divided: active layer(0-0.1m)、subactive(0.2-0.6m),relative stable layer(1m)(I,II,III)and gradient IV called active layer: active layer(0-0.1m、 1m),relative stable layer(0.3m).The relation between roots biomass vertical distribution and its ground level was obviously opposite.Variation of soil moisture was opposite to variation of roots biomass.When soil moisture increased,roots biomass at the same areas reduced.With the moisture gradient increased,the most used moisture layer was closed to soil surface,from gradient I 0.4m is 6.84 to gradient IV 0.1m is 14.33.