兴安落叶松人工林土壤碳密度分布特征研究

Distribution of plantation soil carbon density in Larix gmelinii forest

【目的】分析不同人工更新造林方式下兴安落叶松林土壤碳密度分布特征,为研究地区人工林生态系统碳汇管理及造林实践提供理论依据。【方法】2015年7-8月,以内蒙古大兴安岭林区不同人工更新造林方式(荒山荒地、水湿地、火烧迹地)和林龄(幼龄林、中龄林)的兴安落叶松林人工林为研究对象,通过野外调查与室内分析相结合的方法,对兴安落叶松幼龄林和中龄林0~40cm土层土壤有机碳、碳密度以及分布特征进行比较研究。【结果】不同人工更新造林方式下,幼龄林和中龄林落叶松各土层土壤有机碳含量分别为26.84~105.42,30.26~101.81g/kg,土壤有机碳主要集中在0~20cm土层,其所占比例在63%以上,均随着土层的加深而降低;幼龄林和中龄林落叶松各土层土壤碳密度分别为23.80~106.98,34.84~89.48t/hm^2,也随着土层的加深而降低,0~20cm土层碳密度占土壤总碳密度的60%以上,呈现表层聚集现象。幼龄林不同人工更新造林方式土壤总碳密度(0~40cm土层)分别为火烧迹地(258.98t/hm^2)>荒山荒地(249.24t/hm^2)>水湿地(238.12t/hm^2),中龄林不同人工更新造林方式土壤总碳密度分别为荒山荒地(263.92t/hm^2)>火烧迹地(253.83t/hm^2)>水湿地(249.44t/hm^2),且不同更新造林方式之间差异均显著。【结论】不同人工更新造林方式下,兴安落叶松人工林土壤有机碳含量及碳密度存在明显差异,在未来研究区造林实践中,建议选择火烧迹地、荒山荒地造林,对于水湿地应以保护和保护性利用为主,并且减少人类活动对森林表层土壤的干扰和破环。

[Objective] This paper analyzed soil carbon density and distribution under different artificial reforestation methods in Larix gmelinii forests to provide theoretical basis for regional ecosystem carbon sink management and cultural practices of plantation forest. [Method] During July to August , 2015 , soil organic carbon,carbon density and distribution in depth of 0--40 cm in Larix gmelinii forests that were planted under different artificial reforestation ways （barren wasteland, wet ground and burned forest sites） with different ages （young growth and middle-aged） were determined based on combination of field investi-gation and lab analysis at Daxingan Mountains in Inner Mongolia. [Result] The organic carbon contents in young and middle-aged Larix gmelinii forests were 26.84-- 105.42 and 30.26-- 101.81 g/kg. The 0-- 20 cm soil layer contributed to more than 63 ~, and they decreased with soil depth. The layer carbon densities were 23.80--106.98 and 34.84--89.48 t/hm2. They also decreased with soil depth and the ratio of surface 0--20 cm layer was more than 60% ,indicating surface aggregation. The averages of total soil carbon densi- ty in young forests were in a decreasing order of burned forest sites（258.98 t/hm2）〉barren wasteland （249.24 t/hm2）〉 wet ground （238.12 t/hm2） ,while the order for middle-aged forests was barren waste- land （263.92 t/hm2） 〉 burned forest sites（253.83 t/hm2）〉wet ground （249.44 t/hm2）. There were sig- nificant differences among different artificial reforestation methods. [Conclusion] There were significant differences in soil organic carbon and carbon density of Larix gmelinii plantations among different refores- tation ways. Burned forest sites, barren hills, and wasteland afforestation are suggested. Wet ground should be protected and protectively used and the interference of human activities should be reduced.