人工防护林对风沙土有机碳动力学的影响

选取塔里木沙漠公路沿线定植年限为5、7、10、13、16 a的防护林,运用物理化学提取法及傅里叶变换红外光谱仪,研究人工防护林对风沙土发育过程中土壤有机碳动力学的影响。结果表明:(1)随定植年限增加,土壤碳储量变化不大;(2)土壤有机碳在0~50 cm随深度增加而降低,50 cm以下变化不大;(3)随防护林定植年限的增加,表层土壤(0~10 cm)中总有机碳(TOC)、微团聚体有机碳(OCMIA)、腐殖质有机碳(OCHS)、抗氧化性(OCNa Cl O)和抗酸解性有机碳(OCHCl)均有所升高,其中TOC、OCMIA、OCHS逐年增加,而OCNa Cl O和OCHCl在5~7 a时增加较快,以后趋于稳定,且各碳组分(OCHCl除外)在不同定植年限防护林风沙土间的差异极显著(P0.01),OCHCl差异显著(0.01P0.05);(4)所有碳组分极显著相关,其中OCMIA、OCHS与TOC的相关性比OCHCl、OCNa Cl O高;(5)惰性碳库中OCMIA和OCNa Cl O占总有机碳的比例较高,OCHS相对含量随定植年限增加而升高;(6)腐殖质结构中C=O相对含量(C=O/C-O-C)先降低后升高,脂族链聚亚甲基碳含量占末端甲基碳的比例(CH2/CH3)7 a时最高,后3个年限变化不大。因此,人工防护林引起了土壤有机碳累积,特别是惰性碳库在表层累积,腐殖化程度增加,提高了土壤固碳能力并促进了风沙土的发育。

Effects of Artificial Shelter Forest on Dynamic Change of Organic Carbon Pool of Aeolian Sandy Soil

This study investigated the dynamic change of organic carbon pool of aerolian sandy soil in the shelter belts planted for 5,7,10,13 and 16 years respectively along the Taklimakan Desert Highway.The results are as follows:① The total organic carbon content was changed slightly with the increase of plantation years;② The soil organic carbon content was decreased only in soil layer of 0-50 cm in depth, and changed slightly in soil layer deeper than 50 cm;③ The change of topsoil (0-10 cm) showed that the contents of total soil organic carbon (TOC),micro-aggregate organic carbon (OCMIA), humus organic carbon (OCHS), resistance to oxidation carbon (OCNaClO) and resistance to hydrolysis carbon (OCHCl) were increased with the increase of plantation years, TOC,OCMIA and OCHS were increased year by year, and OCNaClO and OCHCl were increased after the plantation for 5 to 7years.Except OCHCl, all other carbon fractions were changed with the increase of plantation years (P ＜ 0.01), and OCHCl was changed with significant difference (0.01 ＜ P ＜ 0.05);④ There were the significant correlations among all kinds of SOC fractions, in which the correlations between OCMIA and TOC, and OCHS and TOC were higher than those between OCHCl and TOC, and OCNaClO and TOC;⑤ The proportions of content of OCMIA and OCNaClO were higher than those of OCHS and OCHCl, and the relative content of OCHS was increased with the increase of plantation years;⑥ The relative content of functional C =O groups (C =O/C-O-C) was decreased at first and then increased, and the ratio of polymerization methylene in carbon branched chain to methyl at the end of the carbon chain (CH2/CH3) was the highest in the 7-year-old shelter forest.This indicated that the soil organic carbon accumulation occurred in the artificial shelter forest, especially the inert carbon pool accumulation in topsoil, and the humufication degree was increased.Thus the soil carbon sequestration capacity and the aeolian sandy soil development could be improved.