CAJ | 학술논문

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。
비교퇴경조건하류역간토양유궤탄밀도（SOCD）적변화，유조우리해황토고원구역토양유궤탄원/회효응적변화궤리。재황토구릉구학구，자북향남종비사암구、풍식수식교착구、수식구분별선취오분지구、전요구、연구삼개전형치리소류역，연구료파지퇴경위림초지후SOCD변화급기영향인소。결과표명：（1）류역내，림초지SOCD현저대우파경지，표층0~10 cm고우아표층10~20 cm，차차이현저（P<0.05）。（2）류역간，동일토지이용방식SOCD인류역존재현저차이（P<0.05）。종북도남，파경지화임지SOCD기본정증가적추세，파경지표층SOCD분별시0.54、0.56 kg·m-2화0.61 kg·m-2，임지SOCD의차위0.64、0.90 kg·m-2화1.05 kg·m-2；이초지선략유하강후우정증가적추세，분별위0.71、0.67 kg·m-2화0.73 kg·m-2。（3）상대우파경지，류역간동일퇴경방식SOCD적증폭존재일정적공간분이。퇴경환림방식하SOCD적증폭종북도남의차변대，유오분지구류역표층적18.8％변화도연구류역적72.7％；퇴경환초SOCD적증폭교소，종32.1％변화도20.1％。가견，재황토구릉구학구，퇴경방식불부영향류역내SOCD함량적변화，이차영향류역간SOCD증폭적변화，저일변화여남북류역적기후조건、생물인소（세근생물량）、토양성질이급토양침식강도밀절상관。
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.