科尔沁沙地榆树疏林的土壤空间变异特征

Study on the Soil Spatial Variability of Ulmus pumila Open Forest in Horqin Sandy Land

在科尔沁东部乌斯吐自然保护区内,以实施退耕还林10 a的沙地榆树疏林土壤为研究对象,利用地统计学方法分析土壤性状的相关性及其空间变异和分布格局。结果表明:土壤p H的空间变异性很弱,而土壤全氮、有机质、速效氮和速效磷具有中等程度的空间变异性;利用GS+软件自动拟合的变异函数的理论模型中,显示出土壤p H为球型模型、土壤全氮为线型模型、土壤有机质为线型模型、土壤速效氮为指数模型、土壤速效磷为高斯模型;土壤全氮和土壤有机质表现出纯块金效应,在小尺度上具有恒定的空间变异性,只受随机因素的影响,不受结构因素的影响,没有明显的变化规律,而土壤p H、土壤速效氮和速效磷的比值均小于25%,具有强烈的空间相关性,随机部分引起的空间变异性程度较低。除速效氮之外的其余4个土壤性状的空间分布较为均匀,表明土壤速效氮是科尔沁沙地榆树疏林恢复的关键性因子,经过历史上长期的人为干扰后,在地表植被的恢复过程中土壤养分的恢复并不同步。土壤的恢复比植被的恢复速度慢,榆树疏林草原生态系统的恢复需要长期的封山育林过程才能实现。

In order to ascertain the distribution rules of the Horqin sand soil with Ulmus pumila open forest after Grain for Green,this paper uses geostatistical methods to analyze the correlation,spatial variability and distribution of soil properties in Wusitu natural reserve area of eastern Horqin with Ulmus pumila open forest. The results show the spatial variability of soil p H is weak,but the soil total nitrogen,the soil organism,soil available N and available P have a medium spatial variability. If using the theoretical model of the GS ＋ and software automatically fitted variation function,the soil p H is spherical model,the soil total nitrogen and organism are linear model,the soil available N is exponential model,and the soil available P is Gaussian model. The soil total nitrogen and organism demonstrate a pure nugget effect with a constant spatial variability at a small scale. The pure nugget effect is only influenced by the stochastic factors not by the structural factors,and it has little obvious variation rules. However,the ratio of the soil p H,the soil available N and the soil available P is less than 25% with a strong spatial relevance. The random part caused little spatial variability. Only except the available nitrogen,the other four soil properties are uniform in spatial distribution. Therefore,it can infer the available nitrogen may be the critical element of the ecological restoration here. After the human＇s destruction for a long time in history,the restoration of land vegetation and soil nutrient are not synchronous. The latter is slower than the former. So the recovery of Ulmus pumila open forest grassy ecosystem requires a long-time closing hillside to facilitate afforestation.