陕北黄土区不同林地土壤有机碳含量研究

Study on the soil organic carbon content of different vegetation types in loess region of Northern Shaanxi Province,China

为探究黄土高原植被恢复对深层土壤碳库的影响,选取退耕还林第一县陕北吴起县金佛坪流域5种植被恢复类型(山杏林(Armeniaca sibrica),油松林(Pinus tabulaeformis)、沙棘林(Hippophae rhamnoides)、刺槐林(Robinia pseudoacacia)、小叶杨林(Populus simonii))和以自然恢复为主的荒草地为研究对象,通过调查0~1000 cm土层土壤有机碳含量,并计算土壤有机碳储量,分析不同植被类型的土壤有机碳剖面分布和差异。结果表明:在总体上,土壤有机碳在0~60 cm出现快速下降,60~1000 cm出现不明显的波动变化,其中40~260 cm土层,小叶杨林地土壤有机碳含量明显最高。不同植被恢复都具有固碳效益,且不同植被土壤有机碳含量差异显著(P<0.05)。不同植被土壤有机碳储量:小叶杨(18年)(301.51 t·hm^(-2))>刺槐(19年)(249.86 t·hm^(-2))>沙棘(18年)(242.14 t·hm^(-2))>山杏(8年)(226.08 t·hm^(-2))>油松(5年)(182.91 t·hm^(-2))>荒草地(160.45 t·hm^(-2)),这可能是由于不同树龄和植被类型导致的结果。深层(100~1000 cm)土壤有机碳储量占0~1000 cm剖面有机碳储量的73%~84%。深层土壤有机碳含量颇丰,在今后碳汇评估中不容忽视。

To investigate the effect of vegetation restoration on deep soil carbon pools in the Loess Plateau,five different vegetation restoration types(Armeniaca sibirica,Pinus tabuliformis,Robinia pseudoacacia,Populus simo-nii and Hippophae rhamnoides)and natural restoration-based barren grassland were selected from Jinfoping water-shed of Wuqi county,Northern Shaanxi.The distribution and differences of soil organic carbon profiles under dif-ferent vegetation restoration types were analyzed by investigating the soil organic carbon content in 0-1000 cm soil layer and calculating the soil organic carbon storage.The results showed that:in general,soil organic carbon de-creased rapidly in 0-60 cm and an insignificant fluctuating change from 60-1000 cm,with the highest soil organic carbon content evident in 40-260 cm soil layer,in P.simonii forestland.There were significant differences in soil organic matter content among different vegetation restoration(P<0.05).Soil organic carbon storage of different vegetation types:P.simonii(18 years)(301.51 t·hm^(-2))>R.pseudoacacia(19 years)(249.86 t·hm^(-2))>H.rhamnoides(18 years)(242.14 t·hm^(-2))>A.sibirica(8 years)(226.08 t·hm^(-2))>P.tabuliformis(5 years)(182.91 t·hm^(-2))>Grassland(160.45 t·hm^(-2)),which may be the results of different tree ages and vegetation types.Soil organic carbon storage of deep layer(100-1000 cm)accounted for 73%-84%of organic carbon storage of 0-1000 cm profile.The content of organic carbon in deep soil is abundant,which should not be ignored in the future carbon sink assessment.