JOURNAL OF ISOTOPES

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Soil Organic δ13C Change Along a Vertical Gradient in the Northern Slop of Tianshan Mountains

XU Wen-qiang1;LUO Ge-ping1;CHEN Xi1;FENG Yi-xing2;LI Chao-fan3   

  1. 1.State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; 2.Bureau of Land and Resources Reserve of Qiannan State, Duyun 558000, China; 3.Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
  • Online:2016-08-20 Published:2016-08-10

天山北坡土壤有机碳δ13C组成随海拔梯度的变化

许文强1;罗格平1;陈曦1;冯异星2;李超凡3   

  1. 1.中国科学院 新疆生态与地理研究所,荒漠与绿洲生态国家重点实验室,新疆 乌鲁木齐830011;2.贵州省黔南州国土资源储备局,贵州 都匀558000;3.中国科学院 南京土壤研究所,江苏 南京210008

Abstract:

Soil organic carbon (SOC) pool integrated the vegetation succession information from several years to thousands of years scales. It is an ideal tool to understand carbon isotope composition change and terrestrial ecosystem pathways. In this study, the Sangong river watershed was taken as a case. We had estimated the change of vegetation and soil organic along a vertical gradient using the carbon isotopic method, and analyzed the variations of mean SOC δ13C values with the annual precipitation, and researched the variations in SOC and δ13C values with profile depth in the study area. The results showed that the SOC δ13C decreased significantly with the increasing annual precipitation (R2=0.97) where the annual precipitation was less than 300 mm. When the annual precipitation was 300 mm~500 mm, the SOC δ13C was not significant changed with the increasing annual precipitation (R2=0.04). The enrichment effect of SOC δ13C with depth was significant in the sample site of pure C3 vegetation, that means lower layer SOC δ13C of profile was greater than the upper layer. The average difference of SOC δ13C between lower layer and upper layer was 1.01‰. The opposite trend of SOC δ13C was presented in the Desert and Shrubland sites. And that, the SOC δ13C value of upper layer closed to C4 vegetation source, and the lower layer closed to C3 vegetation source. Therefore, we can infer that the vegetation may have experienced from C3 to C4 in the sandy desert and terrene desert sites.

Key words: carbon isotope, δ13C value, C3 and C4 vegetation, enrichment effect of δ13C, Sangong river watershed

摘要:

本文选择天山北坡三工河流域作为研究区,基于碳稳定同位素技术,分析土壤有机碳(SOC)δ13C值随降雨量的变化,研究不同海拔梯度土壤剖面δ13C值随采样深度的变化。结果显示,三工河流域降雨量在300 mm以下的采样点,SOC δ13C值随降雨量的增加呈递减趋势(R2=0.97),而降雨量在300 mm~500 mm的采样点,δ13C值随降雨量变化不明显(R2=0.04);三工河流域纯C3植物采样点土壤剖面δ13C值随采样深度呈现明显的富集效应,即土壤剖面下层δ13C值大于上层,其平均差值为1.01‰,与其他相关区域研究结果一致;而沙质荒漠和土质荒漠采样点剖面下层与上层SOC δ13C平均差值为4.33‰,其变化趋势与纯C3植物采样点相反,且其表层δ13C值接近C4植物来源,底层接近C3植物来源,推断其地上历史植被可能经历了由C3到C4的演替过程。

关键词: 碳同位素, δ13C值, C3和C4植物, δ13C富集效应, 三工河流域