| Ecological public welfare forest is an important product of forestry classification management in our country,and is great significance for promoting the construction of ecological civilization and the modern forestry,which concerns the regional eco-environmental quality.The ecological forest of Chenda state-owned forest farm was studied,where were in Sanming City of Fujian Province.The goal of stand structure optimization and adjustment was extracted by analyzing stand species composition,diameter distribution,height structure and the law of the spatial structure on the basis of stand survey in the wild and data collection using theories of forest mensuration,forest management and structure of forest management.Then the optimization and adjustment technology of ecological public welfare forest was constructed by the two angles of selective cutting and replanting,that was desirable to provide theoretical reference for management,construction and optimization of ecological public welfare forest.The main contents were as follows:(1)In the study area,there were 9 tree species in ecological public welfare forest,of which the dominant species is Castanopsis carlesii.The diameter distribution features of Castanopsis carlesii ecological forest were that the number of tree gradually reduced as diameter increasing in the study area,and 2cm diameter stem number was significantly inverted-J distributed.The diameter class value of q was 1.38 using negative exponential fitting,and the distribution of stand diameter class was reasonable,which corresponded to typical inverted-J distributed of uneven-aged forest.The ecological public welfare forest's stand tree height increased with DBH mounting.Curve slope was larger in diameter 0?30cm and tree height increased quickly;tree height grew slowly when diameter was more than 30cm.Stand volume generally lied between 175.42 m3/hm2 and 312.61 m3/hm2.Accumulation rate of small,medium,large and extra large diameter class was 1:3:4:2,while large and extra large diameter classes(diameter class>26cm)were the main of accumulation,the rate of which was from 52%to 72%.(2)The characteristic of stand spatial distribution pattern,size differentiation,species isolation and competition was analyzed by using uniform angle index,mingling degree,neighborhood comparison,competition index and open comparison.Stand spatial distribution pattern belonged to aggregation distribution.Stand species isolation was low and each species isolation varied greatly.Stand average neighborhood comparison of DBH was 0.52,distribution ratio was more balanced in each class and size differentiation was not low.Forest average competitive index was 4.38,and rank of the,nain competitive index was Schimia superba>Cunninghamia lanceolata>Castanopsis sclerophylla>Castanopsis carlesii>Pinus massoniana,with Castanopsis carlesii as the most obvious advantage in the competition.The average open comparison was 0.31,while the mount that trees' growth space was not enough was 66%.(3)Based on multiplication-division method,composite index of stand spatial structure(Z)was constructed by analysing uniform angle index,mingling degree,neighborhood comparison,competition index and open comparison.Composite index of stand spatial structure was between 0.343 and 0.413,while the average was only 0.379,and the whole spatial structure quality trended to be low in the study area.(4)The correlation degree was respectively 0.841,0.852,0.791,0.782 and 0.842 among mingling degree,uniform angle index,neighborhood comparison,competition index,open comparison with composite index of stand spatial structure by gray correlation method in the study area.The rank was uniform angle index>open comparison ratio>mingling degree>neighborhood comparison>competition index,according to the correlation degree.(5)The goal of stand structure optimization and adjustment was extracted by analyzing stand structure characteristics using sustainable forest management theory in the study area.Then the optimization and adjustment technology of ecological forest was constructed around managing target from the two angles of selective cutting and replanting.Selection cutting adjustment technology was illustrated from selective cutting method,which mainly could adopt ecological thinning.The selective cutting intensity should be controlled in 10%to 15%.Based on the method of forest structure management,the elective logging needed to meet the following conditions:When distribution pattern of forestry was aggregated distribution,selective cutting tree was chosen form the forestry in the spatial structure unit which uniform angle index more than 0.5;When distribution pattern of forestry was uniform distribution,elective cutting tree was chosen form the forestry in the spatial structure unit which uniform angle index less than 0.5,so that the forestry which open comparison ratio and mingling degree was less than or equal to 0.5,neighborhood comparison was more than 0.5and row spacing of the reserve was less than 0.5 was chosen as selective cutting objects.Uniform or local replanting technology about ecological public welfare forest was proposed according to low stand density and canopy of forest,replanting trees could be determined from the seasonal aspect and the replanting way was mixed mode.replanting suitability rating and suitable replanting region map were determined by respectively using K-means clustering method and spatial interpolation technology,replanting trees spacing was more than 3m and 72 0 between replanting tree and the last four trees was better.(6)Stand structure management was optimized after adjusted by modeling selective cutting case and replanting case.After adjusting stand forest structure,the distribution pattern was random distribution,and the uniform angle index was from 0.50 to 0.52,and mingling degree and open comparison increased by more than 10%.It demonstrated that structured forest management provided theoretical basis and practical guidance for the management and transformation of ecological forest,thus improving functional effects of region ecological forest. |
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