人工樟子松林对毛乌素沙地土壤颗粒组成和固碳效果的长期影响

目的]探讨人工樟子松林对毛乌素沙地土壤颗粒组成和固碳的长期影响,为综合评价沙地植被恢复的生态环境效应提供科学依据。方法]选择毛乌素沙地东南缘人工栽植21,36和56 a的樟子松林和流沙地为采样地,对0—30 cm的土壤进行了分层取样分析,以探讨人工林建设对半干旱荒漠区土壤颗粒组成及不同粒级含碳量的长期影响。结果]随着栽植年限的增加,土壤颗粒呈逐渐细化的趋势,且表层(0—5 cm)细颗粒含量均高于下层(5—30 cm)。造林后土壤有机碳(SOC)和无机碳(SIC)含量均显著增加,最高值分别是流沙地的4.90倍和4.32倍;栽植年限对SOC含量和土壤有机碳密度(SOCD)的影响大于SIC含量和土壤无机碳密度(SICD)。相对于流沙地,各粒级SOC,SIC含量均在栽植56 a样地增幅最大,且均在细砂粒组分中增幅最大。团聚体和粉黏粒有机碳含量与土壤总有机碳含量之间存在显著的线性相关关系(p0.01),粗砂粒和粉黏粒有机碳对总有机碳的贡献率和粉黏粒无机碳对总无机碳的贡献率较为显著(p0.05)。结论]随着樟子松栽植年限的增加,土壤团聚体、粉黏粒含量和土壤固碳能力均显著提高。

Long-term Effects of Pinus Sylvestris Afforestation on Soil Particle Composition and Carbon Sequestration in Mu Us Sandy Land

Objective] The long-term effects of Pinus sylvestris var. mongolica afforestation on soil particle composition and carbon sequestration in Mu Us Sandy Land were studied in order to provide a scientific basis for comprehensive evaluation of ecological environment effects of vegetation restoration.Methods] Artificial Pinus sylvestris with different shelterbelt planted years(21 years, 36 years, 56 years) and shifting sandy land were selected as sampling sites on the southeastern margin of the Mu Us sandy land, and 0-30 cm soils were collected and analyzed layer by layer to explore the long-term effects of plantation construction on soil particle composition and carbon conteunder different particles grades in semi-arid desert areas.Results] With the increase of planting years, the soil particles became finer gradually, and content of fine particles in the surface layer(0-5 cm) were higher than beneath layers(5-30 cm). The contents of soil organic carbon(SOC) and inorganic carbon(SIC) increased significantly after shelterbelt construction, and the highest values were 4.90 times and 4.32 times of the shifting sandy land, respectively. The effect of shelterbelt age on SOC content and SOC density(SOCD) was more significant than SIC content and SIC density(SICD). Compared with the shifting sandy land, SOC and SIC contents of each particle size increased most obvious in the shelterbelt planted for 56 years, and the increase of amplitude was largest in fine sand. There were significant linear correlations between organic carbon content of aggregate and silt-clay and total soil organic carbon content, respectively(p<0.01). The contribution rates of organic carbon in coarse sand and silt-clay to total organic carbon, inorganic carbon in silt-clay to total inorganic carbon were significant, respectively(p<0.05).Conclusion] The contents of soil aggregates and silt-clay particles and soil carbon sequestration capacity were significantly improved with the increase of Pinus sylvestris shelterbelt age.