摘要
溶解性有机质(dissolved organic matter, DOM)是土壤有机碳的重要组成部分,可以有效地评价干旱区沙漠化土壤植被恢复状况.然而,对于不同恢复方式、不同植被类型(如草地、灌木丛、针叶林、落叶林等)沙地土壤中DOM的演变特征与光谱学特性缺乏认知.本研究以毛乌素沙地为例,采集3种土地利用类型(裸沙地、配土改良地和植被覆盖地)的表层土壤,采用紫外吸收光谱、三维荧光光谱和平行因子模型法,结合主成分分析法探究了不同土地改良措施和植被覆盖类型下土壤中DOM的来源、含量与组分特征.结果表明,不同土地利用类型和不同植被覆盖下土壤DOM含量和溶解性有机碳(DOC)/土壤有机碳(SOC)值存在较大差异,相较于裸沙地,配土改良和植被覆盖显著提高了DOC的含量,但DOC/SOC的比值降低, SOC的稳定性有所提升;且乔木覆盖地中有机碳的稳定性略高于草地及灌木地.平行因子分析(PARAFAC)结果表明,裸沙地DOM主要由类蛋白质(C3)组成,而配土改良和植被覆盖地则以类腐殖酸(C1和C2)为主.相关性分析表明, C1与C3及C2与C3均为极显著负相关关系(P<0.01).这说明C3组分与C1、C2组分的来源不同.在不同的植被类型之间,类腐殖酸物质(C1与C2)的总占比为乔木>草本>灌木,且恢复年限越长,腐殖质类物质的相对含量越高.相比于裸沙地和配土改良地,植被覆盖地土壤DOM的荧光指数(FI值)下降、自生源指数(BIX值)与腐殖化指数(HIX值)显著提高,呈现明显的陆源特征,证实了有机碳稳定性的增强.且乔木区域土壤的腐殖化程度相较于灌木地和草地更高.总之,植被恢复过程,特别是乔木的种植,较配土改良地和裸沙地可有效增加DOM的含量,提高DOM的稳定性,有利于土壤有机碳的固存.本研究为毛乌素沙地的治理改善提供一定的理论支持和参考依据.
Vegetation restoration is one of the most effective methods to control soil desertification. The change of the input and decomposition of soil organic matter(SOM) in the process of vegetation restoration not only affects the restoration of its own ecosystem, but also affects the biogeochemical cycle of soil carbon. In addition, the soil texture and the conversion and accumulation of organic carbon are also improved by vegetation restoration. Dissolved organic matter(DOM), an important component of SOM, can effectively evaluate the vegetation restoration status of desertification soil in arid area.However, the evolution and spectral characteristics of DOM in sandy soil with different restoration methods and vegetation types(such as grassland, shrub, coniferous forest, deciduous forest, etc.) are not well understood. Mu Us Sandy Land is located in the transition zone between desert steppe and forest steppe in the northwest of China, which is one of the four typical sand areas in China. In recent years, the restoration of Mu Us Sandy Land has achieved obvious results through engineering technologies such as sand-fixing plants, aerial seeding and soil recombination. In this study, the surface soil of three types of soils(sandy land, newly improved land and plant-covered land) was collected in Mu Us Sandy Land. In the present study, the source, content and composition of the DOM of soil under different land improvement measures and vegetation types(sandy land, SL;newly improved land, NL and plant-covered land, PL) in Mu Us Sandy Land were investigated using ultraviolet-visible spectral(UV-Vis) and fluorescence excitation-emission matrix spectrophotometry(EEM) with parallel factor analysis(PARAFAC), the correlation analysis and principal component analysis(PCA). Results showed that DOM content and DOC/SOC value were significantly under different types of land and vegetations cover. The proportion of dissolved organic carbon in shrub land and tree land showed an opposite trend to its content of dissolved organic carbon. Compared with bare sandy land, soil modification and vegetation cover significantly enhanced the content of DOC and the stability of SOC. Moreover, the stability of organic carbon in arbor covered land was slightly higher than that in grassland and shrub land. PARAFAC showed that the DOM of sandy land was mainly composed of tryptophan-like(C3), while the DOM of modified soil and vegetation covered land was mainly composed of humic acid-like(C1 and C2).Negative correlation between C1 and C3, C2 and C3(*P < 0.01). Among different vegetation types, the total proportion of humic acids(C1 and C2) was in the order: Arbor>herb>shrub, and relative content of humic acid increased with the increased restoration years. DOM fluorescence index(FI value) decreased, biological index(BIX value) and humification index(HIX value) significantly increased in vegetation-covered soil, compared with SL and NL, which indicated obvious terrigenous characteristics, confirming the enhancement of organic carbon stability. The humification degree of soil in arbor area was higher than that in shrub land and grassland. Overall, compared with NL and SL, vegetation restoration process, especially the planting of arbor can contribute to the storage of soil organic carbon, increasing the content and the stability of DOM. This study provides a theoretical support and reference for the improvement of Mu Us Sandy Land management and it helps to provide a scientific basis for the accurate evaluation of soil improvement and ecological effects of vegetation restoration in sandy land. It will provide theoretical support for understanding the biogeochemical cycle of carbon in sandy land.
作者
贾汉忠
刘子雯
石亚芳
杨康杰
付广军
祝凌燕
Hanzhong Jia;Ziwen Liu;Yafang Shi;Kangjie Yang;Guangjun Fu;Lingyan Zhu(College of Natural Resources and Environment,Northwest A&F University,Yangling 712100,China;Shaanxi Academy of Forestry,Yulin 719000,China;College of Environmental Science and Engineering,Nankai University,Tianjin 300350,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2021年第34期4425-4436,共12页
Chinese Science Bulletin
基金
国家自然科学基金(21737003,41877126)
陕西省重点研发项目(2019ZDLNY01-02-01)资助。
关键词
植被恢复
溶解性有机质
毛乌素沙地
荧光特性
平行因子分析
soil improvement
dissolved organic matter
Mu Us Sandy Land
fluorescence
parallel factor analysis
作者简介
联系人:祝凌燕,E-mail:zhuly@nankai.edu.cn。
