吕梁山撂荒枣林不同生态转型模式对土壤团聚体稳定性及胶结物质的影响

Effects of different ecological transition patterns on soil aggregate stability and cementing substances in jujube economic forest in the Lvliang Mountain

  • 摘要: 吕梁山撂荒枣林的生态转型是黄土高原生态修复的重要内容。土壤团聚体是土壤结构的基本单元, 其组成和稳定性是评价土壤质量的重要指标, 土壤胶结物质是团聚体形成的重要物质基础。本研究通过探究吕梁山红枣经济林不同生态转型模式样地土壤团聚体和胶结物质含量的变化揭示土壤团聚体的形成机制。以枣林撂荒为对照(CK), 选取枣林补种苜蓿(AL)、补种药材(MM)、补植油松(CP)、补植侧柏(PO) 4种不同生态转型模式样地土壤为研究对象, 分析<0.053 mm、0.053~0.25 mm、0.25~2 mm和>2 mm 4个不同土壤粒径水稳性团聚体的分布比例和稳定性特征, 测定土壤有机碳、富里酸、胡敏酸、多糖、总球囊霉素相关土壤蛋白和易提取球囊霉素相关土壤蛋白6种团聚体有机胶结物质以及无机胶结物质碳酸钙的含量, 并通过冗余分析探究团聚体胶结物质与团聚体分布比例和稳定性的响应关系。结果表明, 1)与CK相比, 4种生态转型模式提高了>2 mm和0.25~2 mm的团聚体含量, 增量分别为1.61%~5.29%和1.59%~5.45%; 此外, 团聚体的平均重量直径和几何平均直径也有所增加, 其增量分别为0.05~0.16 mm和0.02~0.08 mm, 其中CP模式增量最大; 团聚体破坏率有所下降, 降幅为24.85%~66.15%。2)与CK相比, 4种生态转型模式均提高了6种有机胶结物质含量, 降低了无机胶结物质(碳酸钙)含量。3)胡敏酸和易提取球囊霉素相关土壤蛋白对团聚体分布比例和稳定性变化的解释率分别为59.0%和14.8%, 达显著水平(P<0.05), 其中胡敏酸的贡献率最高, 为71.0%。综上所述, 不同生态转型模式均提高了土壤团聚体稳定性及有机胶结物质含量, 其中CP模式效果最优, 且胡敏酸是影响土壤团聚体分布比例和稳定性变化最显著的胶结物质。研究结果对于指导撂荒枣林生态转型和促进黄土高原区的生态恢复具有重要意义。

     

    Abstract: The ecological transformation of abandoned jujube forests in the Lvliang Mountain is an important part of the ecological restoration of the Loess Plateau. Soil aggregates are the basic unit of soil structure, and their composition and stability are important indicators for evaluating soil quality, and soil cementing material is an important material basis for the formation of aggregates. This study reveals the formation mechanism of soil aggregates by investigating the changes in the content of soil aggregates and cementing material in different ecological transition modes of red jujube economic forests in the Lvliang Mountain. Taking jujube forest abandonment as the control (CK), four different ecological transition model plots were selected as the research objects, including Medicago sativa (AL), medicinal herbs (MM), Pinus tabuliformis (CP) and Platycladus orientalis (PO), the distribution proportion and stability characteristics of water-stable aggregates with particle size <0.053、0.053~0.25、0.25~2 mm and >2mm were analyzed. The contents of six aggregate organic cementing substances and inorganic cementing material calcium carbonate were determined in soil organic carbon, fulvic acid, humic acid, polysaccharide, total glomalin-related soil protein and the easily extractable glomalin-related soil protein. The response relationship between the distribution ratio and stability of aggregates and aggregate cemented substances was explored through redundancy analysis. The results showed that: 1) Compared with CK, ecological transition increased the content of >2 mm and 0.25~2 mm agglomerates, with increments of 1.61% to 5.29% and 1.59% to 5.45%, In addition, the mean weight diameter and geometric mean diameter of the agglomerates also increased, with increments of 0.05 to 0.16 mm and 0.02 to 0.08 mm, respectively, and the CP mode performed best; the rate of agglomerate destruction decreased, ranging from 24.85% to 66.15%. 2) Compared with CK, the contents of six organic cementing substances were increased by the four ecological transition modes, and the content of calcium carbonate in inorganic cementing substances was reduced. 3) The explanation rates of humic acid and easily extractable glomalin-related soil protein for the distribution proportion and stability of aggregates were 59.0% and 14.8%, respectively, reaching a significant level (P<0.05), and the contribution rate of humic acid was the highest, which was 71.0%. In summary, different modes of ecological transformation improved the stability of soil aggregates and the content of organic cementing materials, among which the CP mode had the best effect, and humic acid was the most significant cementing material affecting the distribution ratio and stability of soil aggregates. The results of the study are important for guiding the ecological transformation of abandoned jujube forests and promoting ecological restoration in the Loess Plateau region.

     

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