黄泛沙地不同林龄杨树人工林土壤团聚体及有机碳特征

为明确黄泛沙地不同林龄杨树人工林对土壤团聚体及有机碳的影响,以山东省国有东明林场3 a,5 a,8 a,10 a生杨树人工林土壤为研究对象,采用野外取样、室内试验与湿筛法分析了土壤团聚体组成与稳定性,并分析土壤有机碳含量与储量的变化特征。结果表明:(1)不同林龄杨树人工林团聚体分布均以大团聚体(>0.25 mm)为主,在表层土层(0—20 cm)中,随林龄的增加,大团聚体含量呈先显著降低后增加再略减的趋势; 而在20—40 cm土层中,土壤大团聚体含量为5 a>8 a>3 a>10 a; 在40—60 cm土层无显著差异;(2)在0—20 cm土层中,有机碳含量表现为3 a>5 a>10 a>8 a; 在20—60 cm土层,呈先增后减的趋势,且无显著差异。土壤稳定性与团聚体的形成和有机碳密切相关,有机碳含量与GMD值呈极显著正相关关系;(3)不同林龄杨树人工林有机碳储量均呈现一定程度表聚性,在0—20 cm各林龄碳储量占总碳储量的59.17%～74.26%。在3 a到5 a阶段由于土壤淋溶作用,可能导致有机碳储量发生转移,从表层土层(0—20 cm)向底层土层(20—60 cm)转移,而在8 a到10 a阶段,有机碳储量从底层土层向表层土层发生转移。研究结果为揭示黄泛沙地杨树人工林土壤团聚结构形成与有机碳提升提供了参考。

Distribution Characteristics of Soil Aggregates and Soil Organic Carbon in Populus Artificial Forest with Different Forest Ages in Yellow River Flood Plain

In order to understand different forest age poplar plantation in Yellow River Flood Plain on soil aggregate and organic carbon, 3-year, 5-year, 8-year, 10-year poplar plantations in Dongming state-owned forest farm in Shandong Province were selected as the research objects, field sampling, laboratory test and wet screening method were used to analyze the soil aggregate composition and stability, and analyze the variation characteristics of soil organic carbon content and reserves. The results showed as follows.(1)Soil macroaggregates(> 0.25 mm)were the main aggregates in poplar plantations of different ages. In the topsoil layer(0—20 cm), the content of macroaggregates was firstly significantly decreased, then increased and then slightly decreased with the increase of stand age. However, in the 20—40 cm soil layer, the content of large aggregates was 5-year>8-year>3-year>10-year. There was no significant difference in the 40—60 cm soil layer.(2)In the 0—20 cm soil layer, the organic carbon content was 3-year>5-year>10-year>8-year. In the 20—60 cm soil layer, it showed a trend of increasing first and then decreasing, and there was no significant difference. Soil stability is closely related to the formation of aggregates and organic carbon, and the content of organic carbon is positively correlated with GMD value.(3)The organic carbon storage of poplar plantations in different ages showed a certain degree of surface aggregation, and the carbon storage in 0—20 cm layer accounted for 59.17%～74.26% of the total carbon storage. From 3-year to 5-year, soil leaching may lead to the transfer of organic carbon storage from the topsoil layer(0—20 cm)to the bottom soil layer(20—60 cm), while from 8-year to 10-year, the transfer of organic carbon storage from the bottom soil layer to the surface soil layer. The results can provided a reference for revealing the formation of soil aggregate structure and the improvement of organic carbon in poplar plantation in Yellow River Flood Plain.