岷江流域不同土地利用方式下紫色土有机碳储量特征

以岷江中下游流域紫色土为研究对象,按流域分上中下游区段3个抽样层采样,研究不同土地利用方式下紫色土有机碳储量特征,为紫色土退化评估及地力维护提供参考.结果显示,紫色土有机碳总量以林地(14.151g/kg)显著高于果园地(9.458g/kg)、菜园地(8.542g/kg)、草坡地(7.875g/kg),以玉米地(6.226g/kg)最低.水溶性有机碳含量呈现林地>果园地>菜园地>草坡地>玉米地趋势.同时,流域上、中、下游紫色土有机碳总量总体上差异显著,且以上游区段紫色土有机碳总量最高.流域中下游紫色土有机碳总量变化较大,其中,林地以下游高于中游,果园及草坡地以中游高于下游.菜园地、玉米地在3个区段上差异未达显著水平.岷江流域紫色土有机碳储量总体特征表现上游最高,中下游变化复杂,下游略高于中游区域.图1表4参10

Soil Organic Carbon Storage of Purplish Soil in Different Land Uses in the Minjiang River Valley, Sichuan

The Minjiang River,running through the Sichuan Basin as a key tributary to the Yangtze River,is characterized dominantly with purplish soil distribution that is very important for the agriculture along its middle and lower reaches.However,dense population and irrational land uses result in serious degradation of purplish soil.So as to evaluate the tensity of degradation and scavenge for productivity improvement,this study aimed to survey the soil organic carbon content and distribution in the regions of different land uses in the upper,middle and lower reaches of the Minjiang River.The results showed that significant differences could be found in the total organic carbon contents of purplish soil under forestland,orchard,vegetable garden,grass slope and maize field,as 14.151 g/kg,9.458 g/kg,8.542 g/kg,6.226 g/kg and 7.875 g/kg,respectively.The dissolved organic carbon contents of the soil also showed the same decreasing trend,that is,forestland>orchard>vegetable garden>grass slope>maize field.The total organic carbon content of purplish soil was highest in the upper reaches of the river,but the variation in the content was found relatively large in the middle and lower reaches.Furthermore,the content of forestland was higher in the lower reaches than that in the middle,and the contents of vegetable garden and grass slope were higher in the middle than those in the lower reaches.Fig 1,Tab 4,Ref 10