摘要
准确描述森林土壤含水量的空间异质性并确定合理取样量,对理解林地生态和水文过程有重要意义。本研究结合传统统计学和地统计学方法,调查分析了在土壤湿润、干旱两种情况下的华北落叶松林土层(0~10cm、10~20cm和20~30 cm)土壤含水量的空间异质性,并用蒙特·卡罗抽样法确定了土壤含水量的合理取样量。结果表明,土壤湿润时各土层土壤含水量的变异系数均小于土壤干旱时,且均属中等变异。不同土壤湿度下各土层土壤含水量的空间结构有所差异,土壤湿润时各土层土壤含水量的块金值均高于土壤干旱时;土壤干旱时0~10 cm土层土壤含水量表现为较强的空间自相关,其他土层及土壤湿润时各土层土壤则表现为中等强度的空间自相关;土壤变湿润后,土壤含水量的变程在0~10 cm和10~20 cm土层增加明显,但在20~30 cm土层变化较小。在90%置信区间下,若将评估误差控制在10%以内,0~10 cm、10~20 cm和20~30 cm土层土壤所需的最少取样数量在土壤干旱时分别为7、5和7个,在土壤湿润时分别为4、4和7个,即土壤干旱时所需的最少取样量大于土壤湿润时。考虑到研究区内存在频繁而明显的季节性干旱,在制定合理、高效的土壤含水量取样方案时,应考虑林地土壤含水量的空间异质性,并采取土壤干旱时的取样量。
Describing the spatial heterogeneity of forest soil water content accurately and determining optimal sample sizes are of great significance for the accurate understanding of forest ecological and hydrological processes.In this study,the spatial heterogeneity of soil water content in different soil layers(0-10 cm,10-20 cm,and 20-30 cm)of a Larix principis-rupprechtii plantation was analyzed by combining traditional statistics and geo-statistics methods and analyses of the observed data under drought and wet soil conditions.The reasonable sample sizes for soil moisture content in each soil layer with error levels under 10%were calculated using the Monte Carlo simulation sampling method.The results showed that soil water content had evident spatial heterogeneity under both drought and wet conditions.The coefficient of variation in soil water content in all soil layers under wet conditions was lower than that under drought conditions;however,the variation was moderate in all cases.The spatial distribution of soil water content in each soil layer varied along with the soil moisture conditions.The nugget value of soil moisture in the 0-10 cm,10-20 cm,and 20-30 cm soil layers was higher under wet conditions than that under drought conditions.The spatial autocorrelation of the 0-10 cm soil layer under drought conditions was strong,whereas it was moderate in the other soil layers under soil drought conditions and in all soil layers under wet conditions.When the soil moisture changed from dry to wet conditions,the range of soil water content increased evidently in the 0-10 cm and 10-20 cm soil layers but changed marginally in the 20-30 cm soil layer.The reasonable sample size under dry conditions was greater than that under wet conditions.Under the 90%confidence level,if the estimation error was controlled to within 10%,the minimum sample size for the 0-10 cm,10-20 cm,and 20-30 cm soil layers was 7,5,and 7 under soil drought conditions,and 4,4,and 7 under wet conditions,respectively.This implies that the minimum sample size under drier soil conditions should be greater than that under wetter soil conditions.Owing to the frequent and evident seasonal droughts in the study area,the spatial heterogeneity of soil water content should be considered,and the minimum sample size under dry soil conditions should be adopted,when designing a reasonable and efficient soil moisture sampling plan.
作者
刘帆
刘泽彬
马水莲
郭建斌
丁志宏
LIU Fan;LIU Zebin;MA Shuilian;GUO Jianbin;DING Zhihong(Key Laboratory of Forestry Ecology and Environment of National Forestry and Grassland Administration,Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry,Beijing 100091,China;College of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,China;Xixia Forestry Farm of Liupan Mountain Forestry Bureau,Guyuan,Ningxia 756400,China;Liupan Mountain Forestry Bureau,Guyuan,Ningxia 756401,China)
出处
《森林与环境学报》
CSCD
北大核心
2021年第5期487-494,共8页
Journal of Forest and Environment
基金
中央级公益性科研院所基本科研业务费专项资金项目(CAFYBB2020QB004,CAFYBB2021ZW002)
国家自然科学基金项目(41971038,U20A2085)。
关键词
华北落叶松林
土壤含水量
空间异质性
合理取样量
Larix principis-rupprechtii plantation
soil water content
spatial heterogeneity
reasonable sample size
