| As an important forest resource with high economic and ecological values,the bamboo industry is becoming China’s forestry sunrise industry.At present,bamboo forest management is generally faced with the double pressures,such as falling prices of bamboo raw materials and rising labor costs in rural areas,which are important issues that need to be solved urgently to improve bamboo forest management benefits.In view of the low mechanization of traditional selective cutting and high labor costs in bamboo forest harvesting management,we took the typical clump bamboo Bambusa rigida as the research object.We have set up two cutting modes:cluster cutting(1/3 clump,1/2 clump,whole clump)and strip logging(bandwidth:3m,6m,9m,20m)to study the impact of different cutting modes on the restoration and renewal of clumped bamboo,by taking the traditional selective cutting as a control.In addition,a model of B.rigida aboveground biomass before and after harvesting was created to explore the changes of its stand biomass.With comprehensive evaluations of the characteristics of bamboo shoots and new bamboos,stand biomass and soil physical and chemical properties after cutting,a mechanized cutting mode of B.rigida was proposed creatively,which provides scientific bases for the future development and application of the mechanized and labor-saving cutting management model.The main conclusions are as follows:(1)The recovery characteristics of different clump cutting intensity were proposed through clump cutting researches which also indicated the feasibility of clump cutting.Compared with the traditional selective cutting,there was no significant difference in the number of bamboos in1/3 clump and 1/2 clump in the first year after cutting.The average DBH was significantly lower than that in traditional selective cutting,while it can be restored to the pre-cutting level in the second year.After the whole clump felled,the number of shoots and new bamboos increased significantly,while the DBH of bamboos decreased significantly.The numbers of new bamboos were 6713,4338 and 3394 per·hm~2 after cutting for three consecutive years,which were equivalent to 2.20,1.21 and 1.02 times compared with traditional selective cutting,respectively.The mean DBH were 1.42,2.55 and 3.42cm,which corresponded to 28.80%,52.47%and 69.80%when comparing with the traditional selective cutting.The mean DBH increased with time after cutting,and there was no significant difference among the number of adult bamboos in the third year in contrast to the traditional selective harvesting.According to the growth and recovery of B.rigida for 3 consecutive years after harvesting,it is estimated that it can recover to the pre-cutting level in 4-5 years.(2)The mean DBH in the first year after different strip cutting(3m,6m,9m,20m)were 1.31,1.28,1.29 and 1.42cm,and in the second year,they were 2.26,2.67,2.66 and 2.70 cm,respectively.Compared with the mean DBH in the first year,it significantly increased with the increase of bandwidth,the DBH under 20m bandwidth cutting was significantly higher than that in the other bandwidths.The number of new bamboos and the mean DBH were significantly higher than those in traditional selective cutting reserved strip,which increased with the increase of cutting bandwidth.The number of bamboos under 9-20m strip cuttings was 6120per·hm~2,and the mean DBH was 5.10cm.In addition,these two indices under 9m and 20m bandwidth cutting after shooting were better than those before shooting,and there was no significant difference among bandwidths.(3)Twenty-eight aboveground biomass models of B.rigida before and after harvesting were selected to compare the allocation characteristics of individual bamboo and stand biomass before and after cutting.The biomass of each organ of B.rigida was bamboo stalks>bamboo branches>bamboo leaves,bamboo stalks accounted for 84.82%before harvesting,then changed into58.50%,69.13%and 83.68%after 3-year cutting respectively.The proportion of bamboo stalks returned to normal level in the third year after cutting.The traditional bamboo cutting method has greatly restricted the application of clump bamboo,while the different intensities clump and strip cutting are innovations and attempts for the cutting method of clump bamboo.With the deep research,it is expected to break through the traditional bamboo forest selective cutting operation mode and establish a mechanized cutting technical model for clump bamboo to provide an important scientific basis for the development,promotion and application of modern forestry cutting tools such as electric cutting bamboo shears and cutting chainsaws in bamboo cutting. |
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