河北坝上地区植被恢复的土壤碳水效应

The Coupling Interaction of Soil Organic Carbon and Soil Water of Vegetation Restoration in Bashang Area of Hebei

坝上地区植被恢复影响土壤水分和土壤有机碳含量,从而影响区域水源涵养和土壤固碳能力。为了保证植被恢复的可持续性,确定该地区土壤水分和有机碳对植被的响应对于维护生态系统的稳定具有重要意义。以林地、灌木、农地、草地为研究对象,研究0—200 cm土壤水分和有机碳的垂直分布特征,并确定影响其变化的驱动因素。结果表明:(1)与草地相比,植被恢复导致深层土壤水分亏缺,林地和灌木深层(120—200 cm)土壤水分亏缺效应分别为-0.23±0.08和-0.16±0.05;(2)与草地相比,植被恢复增加固碳效应,且随着土层深度的增加而增加;(3)对照草地的碳水耦合协调度始终显著高于其他植被类型(p<0.05),且始终属于碳水平衡状态;而林地和灌木浅层土壤(0—60 cm)属于碳水协调状态,但深层(120—200 cm)碳水耦合协调度仅分别为0.54±0.03和0.57±0.04,处于失调状态。(4)土地利用对深层(120—200 cm)土壤有机碳和土壤水分的变化更加重要,而土壤质地是影响整个土壤剖面变化的稳定因素。研究认为该区域植被恢复固碳效应的增加是以深层土壤水分亏缺为代价,碳水失调影响区域生态恢复的可持续性。

Vegetation restoration affects soil water content and organic carbon,as well as water conservation and soil carbon sequestration capacity in Bashang region.To ensure the sustainability of vegetation restoration,it is critical to determine the response of soil water content and organic carbon to vegetation restoration for maintaining the ecosystem stability.In this study,the vertical distribution characteristics of soil water and organic carbon in 0—200 cm depths were studied in different vegetation types,including forestland,shrub,farmland and grassland,and the driving factors affecting their variations were also studied.The results showed that:(1)Compared with grassland,vegetation restoration resulted in deep layer soil water deficit,and the deep layer soil water deficit of forestland and shrub was-0.23±0.08 and-0.16±0.05,respectively.(2)Compared with grassland,vegetation restoration increased the soil carbon sequestration,and the soil carbon sequestration effect increased with depth.(3)The carbon-water coupling coordination degree of control grassland was significantly higher than that of other vegetation types(p<0.05),and was always in carbon-water coordination state.The shallow layer(0—60 cm)of forestland and shrub was in a carbon-water coordination state,while the deep layer(120—200 cm)soil carbon-water coordination degree was only 0.54±0.03 and 0.57±0.04,respectively.(4)Land use was more important for deep layer(120—200 cm)soil organic carbon and soil water variations,while soil texture was a stable factor affecting their variations in the whole soil profile(0—200 cm).It is concluded that the improvement of carbon sequestration effect of vegetation restoration was at the cost of deep soil water deficit,the imbalance of carbon and water could affect the sustainability of regional ecological restoration.