宁南县城后山泥石流生物治理

后山属泥石流活跃区,需加以治理。治理区面积8.39平方公里,县城面积2.00平方公里。1985—1989年开展治理。后山泥石流生物治理总投资10.09万元。其完成的工程有:造林面积2077亩,栽桑面积50亩,栽油桐面积450亩。生物治理后,创产值48.74万元。因而投入与产出比1.0∶4.8。森林覆盖率从1985年的27.3％增加到1989年的43.8％。生物治理在后山泥石流综合治理中起着举足轻重的作用。

A PLANT CONTROL PROJECT OF THE HOUSHAN DEBRIS FLOW BY NINGNAN COUNTY TOWN

The planting project had been carried out at Houshan by Ningnan County Town during 1985-1989. The forests for conserving water and soil were built at the middle and upper reaches;the protection forest belt for fixation canal was built at the lower reaches. According to the climatic characters and varied stand conditions in local county, the afforested area has been more than 133ha in the trial region and 960,000 trees have been planted by the field,roads, houses and along canals for five years based on trial plantation and screcling various sorts of trees,selecting the best seasons for planting,breeding in the mutritions bags and cultivating in the strange soil ,and strengthening the protection and management. Up to new,the forest cover rate has increased form 27. 3% to 43. 8%;the uncovered land has decreased from 8. 4% to 2. 3%.Due to the plant control measures of the Houshan debris flow by Ningnan County Town,the wood storage increased 1,600m3. The economic effects of woods, tung oil and silkworm are 5 times for the investment of the project. In the forest land,the thickness of the dead soil covering is up to 6-7cm.In comparison with the uncovered land,the organic matter of forest land is 16. 4 times,the effective P content is 6. 1 times and the effective K content is 2. 4 times. Owing to improving the vegetation condition, the erosion lighlened and the runoff weakened, the soil is consolidated and the collapse and landslide lessened. Thus the loose soild materials and hydraulic condition for debris flow lessened.