滨海盐渍区不同土地利用方式土壤-植被系统碳储量研究

Carbon storage of soil-vegetation system under different land use patterns in saline coastal regions

  • 摘要: 盐渍区土地利用变化与土壤-植被系统固碳潜力耦合关系的研究对以植被建设、增加碳汇为目的的盐渍区最优土地利用方式的实施具有重要的理论和实际意义。本研究以滨海撂荒盐碱裸地为对照,连续观测和定量描述栽植3年和10年的柽柳林、栽植2年和8年的人工枸杞林及冬季咸水结冰灌溉结合地膜覆盖下的棉田的土壤有机碳和植被生物量的动态变化过程,探讨滨海盐渍区不同土地利用方式下土壤-植被系统固碳能力,为进一步提升区域碳储量提供理论依据。研究表明:1)柽柳、枸杞的栽植及结冰灌溉结合覆膜等土地利用方式在撂荒盐碱地实施后,土壤-植被系统固碳能力明显增强,且土壤容重显著减小;栽植10年的柽柳林和栽植8年的枸杞林土壤-植被系统碳储量最高,分别为118.24 t·hm-2和96.27 t·hm-2,比冬季咸水结冰灌溉结合地膜覆盖棉田增加58.51 t·hm-2和36.54 t·hm-2,比撂荒盐碱裸地增加83.39 t·hm-2和61.42 t·hm-2。2)对不同土地利用方式固碳趋势研究发现,栽植3年的柽柳林和栽植2年的枸杞林土壤-植物系统固碳速率较高,分别为10.08t·hm-2·a-1和2.71 t·hm-2·a-1。冬季咸水结冰灌溉结合地膜覆盖棉田固碳速率较低,仅为0.53 t·hm-2·a-1。栽植10年的柽柳和栽植8年的枸杞样地,植株固碳速率明显减慢,土壤-植被系统表现为一个弱的碳源。春季地表覆膜处理棉花存活率低且植株成熟后秸秆被移除,碳储量每年净减少0.86 t·hm-2。撂荒盐碱裸地在无外源碳补充的条件下表现为碳源,土壤-植被系统碳储量减少速率为1.42 t·hm-2·a-1。综上所述,滨海盐渍区人工栽植柽柳和枸杞是提高区域碳储量的有效途径。

     

    Abstract: Research on the coupling relationship between land use change and carbon sequestration potential in soil-vegetation systems in saline coastal plains has been of great theoretical and practical significance in terms of optimizing the implementation of land use with the purpose of vegetation restoration and enhancing carbon sink. This study used an abandoned bare saline-alkali land as the control to determine the dynamic changes in carbon storage in soil-vegetation systems under 3 years and 10 years old Tamarix chinensis plantations, 2 years and 8 years old Lycium chinense plantations, and frozen saline water irrigated cotton field with plastic mulching, and cotton field only mulched with plastic film. Based on continuous observation and quantitative description, we discussed carbon sequestration potential of soil-vegetation systems under the land use patterns and provided theoretical basis for increased regional carbon storage. The results were as follows:1) T. chinensis and L. chinense plantations and cotton cultivation with frozen saline water irrigation and plastic mulching significantly increased soil organic carbon content and reduced soil bulk density. T. chinensis planted for 10 years and L. chinense planted for 8 years had the highest carbon storage, 118.24 t·hm-2 and 96.27 t·hm-2, which recorded carbon storage increases of 58.51 t·hm-2 and 36.54 t·hm-2 respectively over cotton fields under frozen saline water irrigation with plastic mulching treatment. It also increased by 83.39 t·hm-2 and 61.42 t·hm-2 respectively over abandoned bare saline-alkali lands. 2) T. chinensis planted for 3 years and L. chinense planted for 2 years had the highest carbon sequestration rate, which was respectively 10.08 t·hm-2·a-1 and 2.71 t·hm-2·a-1. The rate of carbon sequestration was lowest (0.53 t·hm-2·a-1) for cotton field under frozen saline water irrigation with plastic mulching. T. chinensis planted for 10 years and L. chinense planted for 8 years had the weakest performance as carbon source and needed increased carbon storage by land use change or vegetation regeneration. The carbon storage of cotton field only with plastic film mulching decreased 0.86 t·hm-2 per year due to remove of cotton straw. The abandoned bare saline-alkali land was a carbon source because not exogenous carbon input, whose carbon storage decreased 1.42 t·hm-2 per year. By comparing the advantages and disadvantage of each land use type, T. chinensis and L. chinense cultivation was the most efficient way of increasing regional carbon storage in saline coastal regions.

     

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