祁连山区成土过程驱动的土壤地形序列土壤有机碳固存特征  

Soil Organic Carbon Sequestration Driven by Pedogenesis Along Soil Toposequence in Qilian Mountains

作　　者：谷俊 杨飞[1,3] 李德成 宋效东[1] 张甘霖[1,2,4] GU Jun;YANG Fei;LI Decheng;SONG Xiaodong;ZHANG Ganlin(State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;University of Chinese Academy of Sciences,Beijing 100049,China;Qinghai Province Key Laboratory of Physical Geography and Environmental Process,Qinghai Normal University,Xining 810008,China;Key Laboratory of Watershed Geographic Sciences,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所),南京210008 [2]中国科学院大学,北京100049 [3]青海师范大学/青海省自然地理与环境过程重点实验室,西宁810008 [4]中国科学院南京地理与湖泊研究所/流域地理学重点实验室,南京210008

出　　处：《土壤》2023年第4期871-879,共9页Soils

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0306-02);国家自然科学基金项目(42007001)资助。

摘　　要：土壤有机碳(SOC)含量和动态是有机碳输入输出平衡和土壤固持能力共同作用的结果,前者主要受生物气候条件控制,而后者则主要受黏粒及无机矿物等土壤理化属性的影响。本研究通过沿海拔梯度选择表土地形序列作为“自然试验场”,探究祁连山区SOC含量及组分变化的控制因素。研究发现:该地形序列土壤母质主要来源于黄土沉积,土壤黏土矿物以绿泥石和水云母为主,指示该区域的整体弱风化特征。在巨大的水热梯度影响下,地形序列内土壤成土强度差异明显,低海拔地区土壤含有碳酸盐,随着海拔上升,碳酸盐物质逐渐淋失,SOC和铁铝氧化物含量增加。进一步分析发现,铁铝氧化物是SOC含量及组分方差的主要解释变量。偏相关分析显示,当控制铁铝氧化物后,气候对SOC含量及组分的影响不显著。这表明气候对SOC的影响可能主要通过影响土壤属性,造成铁铝氧化物等属性的差异,间接影响SOC的长期固存,且该机制主要作用于矿物结合态有机碳(MOC)组分。本研究对理解SOC固存及其对气候变化的动态响应有重要启示。Storage and dynamics of soil organic carbon(SOC)are the results of input-output balance and soil retention capacity for SOC,which are mainly controlled by bio-climatic conditions,and by soil physiochemical properties such as clay content and soil minerals,respectively.A soil toposequence along an altitudinal gradient was constructed as a natural experiment,aiming to explore the controlling factors for SOC and its fractions in the Qilian Mountains.It is found that soil parent material of this topographic sequence is mainly derived from loess deposits.Chlorite and hydromica are the dominant clay minerals,pointing to the relatively weak chemical weathering intensity of the study region.Meanwhile,the large hydrothermal gradient drives the differences in pedogenic intensities within the topographic sequence.Carbonates exist in soils from the low altitude area;with the rise of altitude,the carbonate is leached away while the contents of iron and aluminum oxide and SOC increase.Further analysis revealed that Al/Fe-oxide was the main explanatory variable for the variance of SOC and its fractions.Partial correlation analysis showed that once the effect of Al/Fe-oxides was controlled,the effects of climate on SOC and its fractions were insignificant.This indicated that the effect of climate on SOC took place mainly via its influence on soil properties,resulting in differences in properties such as Fe and Al oxides.This mechanism mainly occurs in mineral-associated organic carbon(MOC)fraction and make an influence on long-term sequestration of SOC.This study has great implications for understanding the preservation of SOC as well as its responses to climate changes.

关 键 词：土壤地形序列 土壤有机碳 铁铝氧化物 祁连山 

分 类 号：S159.2[农业科学—土壤学]