Taking soil of seven-year-old forest of Eucalyptus dunnii Maiden in Jianyang City of Fujian Province as the research object, the spatial variation regulation of pH in different soil layers was analyzed by using geostatistics. The results show that the soil pH of E. Dunnii forest increases with the increasing of soil depth, the average of pH in 0-20, 20-40 and 40-60 cm soil layers is pH 3.57, pH 3.62 and pH 3.67 respectively, with a lower coefficient of variation of 3. 90% , 3.93% and 4.05% , respectively. The value of Co/( Co+C) of pH in 0-20, 20-40 and 40-60 cm soil layers is 0.389 6, 0.430 3 and 0.604 3 , respectively, meaning that the soil pH of the forest has the moderate spatial autocorrelation. By K-S nonparametric test, the pH of different soil layers of the forest assumes the normal distribution. The integrative comparisons of prediction errors of different semivariogranis with different trends show that the best model of spatial variation of pH in 0-20, 20-40 and 40-60 cm soil layers is 0-order Gaussian model, 1-order Exponential model and 1-order Spherical model, respectively. The results of Kriging optimal interpolation analysis show that the overall trend of spatial distribution of pH in different soil layers of E. Dunnii forest is decreasing from the west to the east, and the highest value appears in the southwest. The interpolation standard deviation of pH in different soil layers is small, and all appear the spatial distribution trends of taking the south and middle as center, and increasing gradually toward the northeast. According to these research results, it is conjectured that the acidification of soil in the E. Dunnii forest is more serious. And the spatial variation of pH in soil is influenced together by structural and random factors, while the distribution characteristics of interpolation standard deviation of pH in soil of the forest are probably related to quantity and setting of sample plots.%以福建省建阳市7年生邓恩桉(Eucalyptus dunnii Maiden)林地土壤为研究对象,应用地统计学方法分析了不同土层土壤pH的空间变异规律.结果表明:该邓恩桉林地土壤pH随土壤深度的增加而增大,0～20、20～40和40 ～60 cm土层的土壤pH均值分别为pH 3.57、pH 3.62和pH 3.67；土壤pH的变异系数较小,分别为3.90％、3.93％和4.05％.0～20、20～40和40～60 cm土层土壤pH的块金效应值分别为0.389 6、0.430 3和0.604 3,说明该林地土壤pH具有中等空间自相关性；经K-S非参数检验,该林地各层土壤pH服从正态分布.通过不同趋势效应下不同半方差函数模型预测误差的比较,确定该林地0～20、20～40和40～60 cm土层土壤pH空间变异最优模型分别适用0阶高斯模型、1阶指数模型和1阶球状模型.克里格最优插值分析结果表明:该邓恩桉林地各层土壤pH整体空间分布趋势均为由西向东递减,最高值出现在西南部；各层土壤pH插值标准差较小,且标准差分布均呈现以南部和中部为中心、向东北方向逐渐增大的趋势.根据研究结果推测:该邓恩桉林地土壤酸化程度较严重,其土壤pH的空间分布受结构因素和随机因素的共同影响,而土壤pH插值标准差的分布特征可能与采样点的数量和设置有关.
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