黄土丘陵区不同退耕方式土壤有机碳密度的差异及其空间变化  

Spatial Variations in Soil Organic Carbon Density Under Different Restoration Practices in Loess Hilly-gully Region

作　　者：李俊超[1] 郭胜利[1,2,3] 党廷辉[1,2,3] 张彦军[2] 李娜娜[2] 

机构地区：[1]西北农林科技大学资源环境学院,陕西杨凌712100 [2]西北农林科技大学水土保持研究所,陕西杨凌712100 [3]中科院水利部水土保持研究所,陕西杨凌712100

出　　处：《农业环境科学学报》2014年第6期1167-1173,共7页Journal of Agro-Environment Science

基　　金：国家自然科学基金(41071338);中国科学院西部行动计划项目(KZCX2-XB3-13)

摘　　要：比较退耕条件下流域间土壤有机碳密度（SOCD）的变化，有助于理解黄土高原区域土壤有机碳源/汇效应的变化机理。在黄土丘陵沟壑区，自北向南从砒沙岩区、风蚀水蚀交错区、水蚀区分别选取五分地沟、砖窑沟、燕沟三个典型治理小流域，研究了坡地退耕为林草地后SOCD变化及其影响因素。结果表明：（1）流域内，林草地SOCD显著大于坡耕地，表层0~10 cm高于亚表层10~20 cm，且差异显著（P〈0.05）。（2）流域间，同一土地利用方式SOCD因流域存在显著差异（P〈0.05）。从北到南，坡耕地和林地SOCD基本呈增加的趋势，坡耕地表层SOCD分别是0.54、0.56 kg·m-2和0.61 kg·m-2，林地SOCD依次为0.64、0.90 kg·m-2和1.05 kg·m-2；而草地先略有下降后又呈增加的趋势，分别为0.71、0.67 kg·m-2和0.73 kg·m-2。（3）相对于坡耕地，流域间同一退耕方式SOCD的增幅存在一定的空间分异。退耕还林方式下SOCD的增幅从北到南依次变大，由五分地沟流域表层的18.8％变化到燕沟流域的72.7％；退耕还草SOCD的增幅较小，从32.1％变化到20.1％。可见，在黄土丘陵沟壑区，退耕方式不仅影响流域内SOCD含量的变化，而且影响流域间SOCD增幅的变化，这一变化与南北流域的气候条件、生物因素（细根生物量）、土壤性质以及土壤侵蚀强度密切相关。Studying spatial variation of soil organic carbon density（SOCD）is helpful for exploring the mechanisms of carbon sequestration under different restoration practices in the Loess Plateau. Wufendigou, Zhuanyaogou, and Yangou watersheds were selected across the hilly-gully region of Loess Plateau from North to South. Changes in SOCD in these three watersheds were analyzed during conversion of cropland into grassland and woodland. In the same watershed, SOCD was higher in woodland and grassland than in sloping farmland, and greater in surface（0~10 cm）than in subsurface（10~20 cm）（P〈0.05）. Under the same land use, SOCD showed significant spatial distribution（P〈0.05）among three watersheds. From North to South, SOCD changed from 0.54 kg·m-2 to 0.56 kg·m-2, and to 0.61 kg·m-2 for sloping farm-land, from 0.64 kg·m-2, to 0.90 kg·m-2 and to 1.05 kg·m-2 for woodland, and from 0.71 kg·m-2, to 0.67 kg·m-2 and to 0.73 kg·m-2 for grassland. Compared to the sloping farmland, percent increase in SOCD caused by converting cropland into woodland or grassland had spa-tial variations from North to South. In woodland, the percentage was 18.8%in Wufendigou watershed to 72.7%in Yangou watershed, where-as in grassland it ranged from 32.1%（North）to 20.1%（South）. Our results indicate that SOCD is closely related with climate condi-tions , biological factor（the fine- root biomass）, soil properties and soil erosion intensity in hilly-gully region of the Loess Plateau.

关 键 词：土壤有机碳密度 小流域 空间变异 退耕还林(草) 黄土丘陵区 

分 类 号：S153.6[农业科学—土壤学]