生态转型模式对吕梁山红枣经济林土壤团聚体及其有机碳分布的影响

Effects of ecological transition patterns on the distribution of soil aggregates and organic carbon in jujube economic forest in Lvliang Mountain

为探究吕梁山区红枣经济林不同生态转型模式对土壤团聚体及其有机碳分布的影响,试验选取该地区5种主要的生态转换模式,分别为枣林撂荒(AF)、枣林补种黄芪-柴胡(MM)、补种苜蓿(AL)、补植油松(CP)、补植侧柏(PO),并以清耕枣林为对照(CK),测定并分析各样地0~20 cm土层中土壤团聚体稳定性、团聚体有机碳与土壤总有机碳含量及其相关性。结果表明:(1)与CK相比,除AF模式外,其他生态模式提高了>2.0 mm及>0.25 mm团聚体含量,增量分别为3.75%~9.31%和1.68%~10.36%;同时提高了团聚体的平均重量直径、几何平均直径,增量分别为0.05~0.19、0.03~0.10 mm,CP模式提高幅度最大;(2)所有生态模式显著提高了土壤有机碳含量,增量为0.24~4.72 g·kg^(-1),提高幅度为9.25%~182.10%,同时提高了土壤各粒径团聚体有机碳含量;(3)土壤有机碳的贡献率主要来自于>0.25 mm团聚体,所有生态模式均提高了土壤>0.25 mm团聚体有机碳的贡献率,增量为4.20%~22.96%;(4)土壤有机碳及>0.25 mm团聚体有机碳含量与土壤团聚体稳定性参数呈显著正相关关系,红枣林补植油松模式最有利于土壤有机碳、>0.25 mm团聚体有机碳含量及团聚体稳定性的提高。

In order to investigate effects of ecological transition patterns on the distribution of soil aggregates and organic carbon in jujube economic forest in Lvliang Mountain,five ecological transformation modes were selected,namely jujube forest abandoned farmland(AF),jujube forest replanting with Astragalus-Bupleurum(MM),replanting with alfalfa(AL),replanting with Chinese pine(CP),replanting with Platycladus orientalis(PO),and jujube forest under clear-cutting operation was used as the control(CK).The stability of soil aggregates in 0~20 cm soil layer,the organic carbon content of soil and the organic carbon content of soil aggregates in 0~20 cm soil layer were assessed.The results showed that:(1)Except for AF model,other ecological models increased the ratios of>2.0 mm aggregates and>0.25 mm aggregates by 3.75%~9.31%and 1.68%~10.36%,respectively.Mean weight diameter and geometric mean diameter were increased by 0.05~0.19 mm and 0.03~0.10 mm,CP treatment performed best.(2)All ecological patterns significantly increased soil organic carbon content by 0.24~4.72 g·kg^(-1),the increase rate was 9.25%~182.10%,and increased the organic carbon content of soil aggregates of all grain sizes.(3)The contributions of soil organic carbon were mainly from>0.25 mm aggregates,which were increased by 4.20%~22.96%in all ecological models.(4)The organic carbon content of soil and>0.25 mm soil aggregates were significantly positive correlated with soil aggregate stability parameters.Soil organic carbon content,>0.25 mm soil aggregates organic carbon content and soil aggregate stability parameters in the Chinese pine model were the highest in all ecological transformation modes in Lvliang Mountain.