石漠化区林草恢复与传统农耕对土壤团聚体和有机碳含量的影响

Effect of Forest and Grass Restoration and Traditional Farming on Soil Aggregates and Organic Carbon Content in Rocky Desertification Area

为探明石漠化治理区林草植被恢复后土壤团聚体的粒径分布、结构稳定性、有机碳的分布特征,以关岭-贞丰花江石漠化治理示范区4种林草植被(金银花、火龙果、花椒和草地)与传统种植方式玉米地进行对比研究,采用湿筛法进行团聚体分离和测定,对比分析了石漠化治理方式与传统农耕方式下土壤团聚体稳定性和团聚体有机碳分布规律。结果表明:(1)5种样地水稳性团聚体均以大团聚体(>0.25 mm)粒级含量为主,大团聚体(>0.25 mm)含量表现出草地>金银花地>火龙果地>玉米地>花椒地,团聚体含量总体上随粒级的减小而降低;(2)团聚体的平均质量直径和几何平均直径均为草地>金银花地>火龙果地>玉米地>花椒地;(3)土壤团聚体有机碳含量表现为金银花地>草地>火龙果地>花椒地>玉米地,说明从传统种植方式转变为林草植被后,土壤有机碳含量得到提高。除花椒地外,其他样地土壤团聚体稳定性均优于玉米地,土壤有机碳含量都高于玉米地。综上所述,石漠化治理区退耕还林和植被恢复有利于土壤结构改善和碳库容量提升,促进喀斯特石漠化生态环境的改善。

In order to find out the particle size distribution, structural stability and organic carbon distribution characteristics of soil aggregates after restoration of forest and grass vegetation in rocky desertification control area, this paper compared four species of forest and grass vegetation(honeysuckle, pitaya, pepper and grassland) in Guanling-Zhenfeng Huajiang rocky desertification control demonstration area with traditional planting corn field. The wet screening separate method was used and the agglomerate was measured to compare and analyze the stability of soil aggregates and the distribution of organic carbon in aggregates under the control of rocky desertification and traditional farming modes. The results showed that:(1) The water-stable aggregates of the five plots were mainly composed of large aggregates(>0.25 mm), and the content of large aggregates(>0.25 mm) showed grassland > honeysuckle ground > pitaya ground > corn field > pepper field, the aggregate content decreased with the decrease of the particle size.(2) The mean weight diameter(MWD) and geometric mean diameter(GMD) of the aggregates were grassland > honeysuckle ground > pitaya ground > corn field> pepper field.(3) The organic carbon content of soil aggregates was: honeysuckle ground > grassland > pitaya ground > pepper field >corn field, indicating that the soil organic carbon content was improved after changing from traditional planting mode to forest grass vegetation. Except for the pepper field, the stability of soil aggregates and the soil organic carbon content in other plots were higher than that in the corn field. In conclusion, in the rocky desertification control area, returning farmland to forest and vegetation restoration was favor to improve soil structure and increase carbon storage capacity, and promote the improvement of karst rocky desertification ecological environment.