封育年限对干旱河谷灌丛土壤理化性质的影响

目的]探讨不同封育年限对干旱河谷灌丛土壤理化性质的影响,为该地区的天然植被恢复与管理提供理论依据。方法]采用野外调查和实验室分析相结合的方法开展研究。结果](1)封育后灌木层的盖度、密度、平均冠幅、高度明显升高,而草本层则相反。(2)随着封育年限的增加,土壤容重呈V形变化,封育13a达到最小值,而群落植被特征、土壤孔隙度、土壤持水量、土壤养分,呈倒V形变化,封育13a达到最大值。0—40cm,封育13a的土壤平均速效N,P,K较未封育草地分别增加26.42%,107.35%,33.92%;全量N,P,K含量分别增加了168.42%,47.62%和31.12%。(3)封育后,土壤理化性质有所改善,具有明显的表聚现象,土壤固碳能力有所提高,土壤有机碳密度表现为:F_(13)F_(22)F_(30)F_5CK;土壤有机碳储量表现为:F_5F_(13)F_(22)F_(30)CK,说明在狼牙刺群落封育恢复过程中,土壤环境有较为明显的改善。(4)采取封育措施后,外界干扰减少,狼牙刺灌丛覆盖度增加,从而增加地上生物量,使生产力得到提升,生物量与封育年限存在线型关系。结论]采取封育措施后,干旱河谷地带的狼牙刺群落植被特征和土壤理化性质及有机碳密度和储量均优于未封育,植被自然恢复状态良好。

Effects of Fencing Time on Soil Physicochemical Properties of Sophora Viciifolia in Semi-arid Valley

Objective] The effects of different fencing time on physical-chemical property of soil in arid valley shrub were studied to provide theoretical basis for the restoration and management of natural vegetation in this region. Methods] Field investigation and laboratory analysis were used. Results] (1) Coverage, density, average canopy and height of the shrub layer were significantly increased after hillsides closing, but it is opposite for the herb layer. (2) With the increase of closing age, soil bulk density showed a V-shaped change and reached the minimum value in 13 a. However, vegetation community characteristics, soil porosity, soil water retention capability and soil nutrient all showed an inverted V-shaped curve, they reached the maximum values around 13 a after the hillsides was closed. As compared with the no closing hillsides, the average soil available N, P, K in 0-40 cm layer increased by 26.42%, 26.42%, 107.35%, respectively; total amount of N, P, K content increased by 168.42%, 47.62% and 31.12%. (3) After closing hillsides to facilitate afforestation was conducted, obvious surface convergence phenomenon was observed. Soil physio-chemical properties and carbon sequestration capacity increased. Soil organic carbon densities of plots(F) with different closing ages(n) showed as the following rank: F₁₃ > F₂₂ > F₃₀ > F₅ > CK. Soil organic carbon reserves was showed as: F₅ > F₁₃ > F₂₂ > F₃₀ > CK. It is showed that soil environment had more obvious improvement in Sophora viciifolia community along restoration process. (4) After close hillsides to facilitate afforestation was carried out, interference was decreased, the coverage of Sophora viciifolia bushes got increased, aboveground biomass and productivity also got increased. There was a positively linear relationship between biomass and closing hillsides to facilitate afforestation age. Conclusion] After close hillsides to facilitate afforestation was carried out, Sophora viciifolia community vegetation characteristics, soil physio-chemical properties, soil organic carbon density and reserves were all better than the corresponding ones of no closing hillsides.