宁夏黄土区典型坡面表层土壤有机碳含量的空间变化特征及尺度效应  

Spatial Variation and Scale Effect of Surface Soil Organic Carbon Content on Typical Slopes in the Loess Region,Ningxia

作　　者：韩新生 刘广全[1] 许浩[2] 董立国[2] 郭永忠[2] 安钰[2] 万海霞[2] 王月玲[2] Han Xinsheng;Liu Guangquan;Xu Hao;Dong Liguo;Guo Yongzhong;An Yu;Wan Haixia;Wang Yueling(China Institute of Water Resources and Hydropower Research,Beijing 100038;Institute of Forestry and Grassland Ecology,Ningxia Academy of Agriculture and Forestry Sciences Ningxia Key Laboratory of Desertification Control and Soil and Water Conservation Research Center for Ecological Restoration and Multi-Functional Forestry of Ningxia,Yinchuan 750002)

机构地区：[1]中国水利水电科学研究院,北京100038 [2]宁夏农林科学院林业与草地生态研究所、宁夏防沙治沙与水土保持重点实验室、宁夏生态修复与多功能林业综合研究中心,银川750002

出　　处：《林业科学》2024年第1期19-31,共13页Scientia Silvae Sinicae

基　　金：国家重点研发计划课题(2023YFF1305104);宁夏重点研发计划(引才专项)(2022YCZX0054);国家自然科学基金黄河水科学研究联合基金项目(U2243601);中国水利水电科学研究院R&D项目(SC0202A012018,SC0145C022023)。

摘　　要：【目的】定量认识土壤有机碳(SOC)含量在坡面上的空间异质性及尺度效应,探索“由点及面”估算坡面平均SOC含量的精确便捷途径,为细致刻画坡面土壤资源状况、全面理解生态系统碳循环、制定土壤高质量管理方案提供科学基础。【方法】在宁夏半干旱黄土丘陵区,选择3个相邻的由退耕还林工程形成的典型坡面,从坡顶向坡脚设置连续样点,调查各样点的土地利用、植被特征、立地条件及表层(0^20 cm)SOC含量,分析其坡向差异、坡位变化;以“离坡顶的水平距离或相对距离”为自变量,以表层SOC含量的顺坡滑动平均值为因变量,定量描述坡面尺度效应;再以坡面上任一样点表层SOC含量与坡面平均值的比值为因变量,实现由“点”到“面”的尺度上推。【结果】研究区表层SOC含量存在明显的坡向差异、坡位变化、尺度效应。表层SOC含量的坡面平均值在南坡(7.60 g·kg^(-1))最高,东坡(6.42 g·kg^(-1))次之,西坡(5.65 g·kg^(-1))最低,其坡位间变幅在东坡(15.95 g·kg^(-1))最大,其次为西坡(11.34 g·kg^(-1)),最小为南坡(9.72 g·kg^(-1)),说明东坡的坡面效应最强,其次为西坡,南坡最弱。东坡、西坡、南坡表层SOC含量的坡位变化大致相同,均由坡顶向下逐渐减小,至离坡顶水平距离200、150、280 m(相对距离0.73、0.45、0.76)后趋于稳定,主要与坡面“上部为自然状态的坡地+林草植被+恢复年限长、下部为人工梯田+林农植被+扰动频繁”的空间格局有关。在东坡、西坡、南坡上,距坡顶水平距离每增加100 m,SOC含量的滑动平均值分别变化-3.40、-2.50、-1.51 g·kg^(-1);距坡顶相对距离每增加0.1,SOC含量的滑动平均值分别变化-0.96、-0.75、-0.55 g·kg^(-1)。构建3个坡向不同坡位样点表层SOC含量与坡面平均值的比值随离坡顶水平距离或相对距离增加而变化的数量关系(R^(2)>0.7,P<0.001),籍此可由坡面上任一样点表层SO【Objective】A quantitative acknowledge on the spatial variation and scale effect of soil organic carbon(SOC)content provides basis to accurately and conveniently estimate the average SOC content of the whole slope,comprehensively understand the status of soil resources and the ecosystem carbon cycle,and propose high-quality soil management programs.【Method】Three adjacent typical slopes formed by the project of returning farmland to forestland were selected in the small watershed of Zhongzhuang within the semi-arid loess hilly region of Ningxia.After multiple sample points were set up in succession from the top to the foot on slopes,the land use,vegetation characteristics and site conditions were investigated,the surface soil samples(0-20 cm)were collected to test the SOC content,and the slope aspect difference and slope position variation were analyzed.Taking the horizontal distance or relative distance from slope top as the independent variable,the slope scale effect was quantitatively described by the slope moving average of the surface SOC content as the dependent variable,and the ratio of the surface SOC content of any point on the slope to the average value of the slope as the dependent variable to realize the scale from‘point’to‘slope’.【Result】The surface SOC content had obvious slope difference,position variation and scale effect in the study region.The average surface SOC content was the highest on the southern slope(7.60 g·kg^(−1)),followed by the eastern slope(6.42 g·kg^(−1))and the western slope(5.65 g·kg^(−1)).However,the variation range of surface SOC content of the eastern slope(15.95 g·kg^(−1))was the largest,followed by the western slope(11.34 g·kg^(−1)),and the smallest was the southern slope(9.72 g·kg^(−1)),indicating that the slope effect was the strongest on the eastern slope,followed by the western slope and the southern slope.The pattern of position variation in surface SOC content was roughly the same among the three slopes,which gradually decreased from

关 键 词：黄土丘陵区 立地条件 土地利用 土壤有机碳含量 坡面变化 尺度效应 

分 类 号：S153.621[农业科学—土壤学]