缙云山典型植物群落次生演替中土壤抗冲性研究

Study on Soil Anti-Scourability in Secondary Succession of Typical Plant Communities in Jinyun Mountain

通过原状土冲刷试验,研究了缙云山10种存在次生演替序列的典型植物群落坡面薄层水流的水力学参数特征及侵蚀产沙量的变化。研究结果表明:(1)在1,1.5,2 L/min放水流量下,植物群落间坡面薄层水流的侵蚀产沙量大多存在极显著的差异;(2)坡面薄层水流的雷诺数和弗汝德数有随放水流量增大而增大的趋势,但其流型和流态保持不变;(3)由坡面产沙量与径流切应力的概念模型并结合产沙量和径流切应力的试验数据,确定10种植物群落土壤的临界切应力以评价植物群落土壤的抗冲性强弱(抗冲性由强到弱的顺序为:白茅>栲树>四川大头茶>香樟>润楠>慈竹>杉木+香樟>毛竹>马尾松+香樟>马尾松);随着植物群落由低级向高级的演替进程.土壤抗冲性总体呈增强趋势;(4)通过土壤抗剪强度预测临界切应力的模型,在野外可快速、较准确地判断土壤抗冲性的强弱。

The chracteritics of hydraulic parameters and erosion and sediment yield variation of slope sheet flows of ten typical plant communities with secondary succession in Jinyun Mountain are studied by means of the scouring experiment with the original soil. The results of this study indicate that （1） under the discharge flows of 1,1.5,2 L/min,there exist distinct differences mostly in the erosion and sediment yields of slope sheet flows of plant communities. （2） With the increase of the discharge flows,the Reynolds number and Froude number of sheet flows increase,but their flow pattern and state remain unchanged. （3） By analyzing the conceptual model of the sediment yield and flow shear stress and combining it with the relative experimental data,the soil critical shear stresses of ten plant communities are determined to evaluate the soil anti-scourabilities of plant communities （the order of the anti-scourabilities from strong to weak is that Imperata cylindrica 〉 Castanopsis fargesii 〉 Gordonia acuminata 〉 Cinnamomun camphora 〉 Machilus pingii 〉 Neosinocalamu.s a f finis 〉 Cunninghamia lanceolata Cinnamomun camphora 〉 Phyllostachys pubescens 〉 Pinus massoniana 〉 Cinnamomun camphora 〉 Pinus massoniana ）. With the succession of plant communities from the low stage to high stage,the soil anti-scourability tends to increase generally. （4） Through the soil anti-shear strength,the model of the critical shear stress is predicted that r=0. 716 5k＋0. 209 5 ,and this model can determine the soil anti-scourability quickly and relatively exactly in the field.