Study On The Effect Of Mixed Ratio On The Interspecific Relationship Of Bamboo And Broad-leaved Tree Mixed Forest

Phyllostachys edulis is one kind of bamboo species,which has widely uses and high economic value,Bamboo and Broad-leaved Tree Mixed Forest is an excellent mix of bamboo and wood mixed business model.This research is based on the study of Bamboo and Broadleaved Tree Mixed Forest in the nature reserve of Yongan City,Fujian Province,the broadleaf crowns vertical projection area occupies the percentage of the sample area was taken up as the mixing ratio,and 10 different mixing ratios were set up: 5%~10%,10%~15%,15%~20%,20%~25%,25%~30%,30%~35%,35%~40%,40%~45%,45%~50% and more than 50%.Based on the theory of species competition,combined with the aboveground biomass index of Phyllostachys edulis,from the ecological relationship among the trees,the biodiversity and stability of the forest,the spatial distribution pattern and the correlation,the spatial homogeneity evaluation and the species competition effect,which five aspects to comprehensive analysis and comparison the differences of different mixed proportions of Bamboo and Broad-leaved Tree Mixed Forest,revealing the effect of mixed ratio on the interspecific relationship of Bamboo and Broad-leaved Tree Mixed Forest.Finally,from the perspective of bamboo management,according to different business purposes,recommend suitable mixed proportion and better symbiotic relationship with the bamboo tree species,and visualization through the SVS software presented for the management of Bamboo and Broad-leaved Tree Mixed Forest to lay a good theoretical and practical basis.The main results are as follows:(1)In the study of niche,Castanopsis chinensis,Castanopsis fargesii and Alniphyllum fortunei were the dominant species of Phyllostachys edulis,and have wide distribution and a high proportion of the total resources,their importantces and niche breadth were strong,what's more,their ecological adaptability was strong,they play an important role in the change of community structure.When the resources used by Phyllostachys edulis are insufficient,it is also more likely to cause potential competition.(2)The case of biodiversity and stability indexes: the higher the proportion of crown,the mixed degree is higher,the lower the density of bamboo forest biodiversity is higher;the slope is high,diversity of the regeneration layer is high;the biological diversity of uphill is higher than that of downhill;When the spatial distribution tends to be randomly distributed,the biodiversity is higher and the biodiversity is lower when it is clustered.The density of broadleaf trees has a significant position in all the factors that affect biodiversity.In the forest stability factor,the higher the weight are the density of broad~leaved trees,the average DBH and average height of broad~leaved trees,slope,elevation,followed by the average DBH of Phyllostachys edulis and the average Phyllostachys edulis height.With the increase of biodiversity,the stability of the forest was improved to some extent,and the stability was stronger in the stand with mixed ratio of 20% to 30% and above 40%.(3)In the study of spatial distribution and association,the effection of variation of mixed ratio on the structure of bamboo high were larger than diameter grade,the spatial distribution pattern of Bamboo and Broad-leaved Tree Mixed Forest with mixed ratio increases,aggregate distribution range gradually reduced,the mixed ratio is greater than 45%,the spatial distribution pattern tends to be randomly distributed.The spatial correlation between Phyllostachys edulis and broad~leaved tree was not strong.When the ratio of mixed was too large,both of them had positive correlation.At the aggregation scale,the positive effects of the emergence of broad~leaved trees on the DBH of Phyllostachys edulis occurred in the mixed stand,when the mixed ratio was too large,the emergence of broad~leaved trees had no effect on the DBH of Phyllostachys edulis.(4)In the study of spatial homogeneity,the spatial homogeneity evaluation system of Bamboo and Broad-leaved Tree Mixed Forest was constructed for the first time,the relationship and priority order between influencing factors and homogeneity index are: competition index > mingling > open comparison index > neighborhood pattern > spatial density index > neighborhood comparison.The spatial structure of the stand of the mixed ratio of 25%~30%(No.5 plot)was better,and the ecological system was more uniform,and the evaluation grade was the highest.The evaluation grade of number three plot and number four plot is lower than that,but the aboveground biomass of Phyllostachys edulis number five plot(45.057kg103/hm2)was less than number three plot(69.594kg103/hm2),the forest comprehensive benefits of the number three plot(mixed ratio = 15%~20%)and number three plot(mixed ratio = 20%~25%)was the best from the perspective of bamboo mixed forest management point of view.(5)In the study of competitive effect,the intrinsic competition of Phyllostachys edulis stands in a significant position in the competition of the whole forest,and the maximum is reached when the mixture ratio is 15%~20%,and then the trend of decline is lower.When the mixing ratio is more than 40%,the interspecific competition effect is stronger than intrinsic competition of Phyllostachys edulis.The effective radius of single tree competition effect is 3m,and the maximum influence range is 6m.The effect of broad-leaved trees on average DBH of Phyllostachys edulis was the least affected by Choerospondias axillaris,followed by Alniphyllum fortunei and Cinnamomum camphora.The most affected was Sassafras tzumu,Phoebe zhennan;and the effect of Castanopsis chinensis on average competition index of Phyllostachys edulis was largest,and then was Choerospondias axillaris,Castanopsis fargesii.The least affected is Alniphyllum fortunei.The effect of broad-leaved trees on the number of trees per unit area of Phyllostachys edulis was the smallest,and the number of bamboo trees was 0.32 plants/m2,followed by carnation 0.29 plants/m2 and 0.224 plants/m2.(6)In path analysis,the aboveground biomass of Phyllostachys eduliswas closely related to the density of bamboo,and the strongest total effect factors were the other.The crown ratio was both negatively correlated with the aboveground biomass of Phyllostachys edulis and the density of bamboo,with the largest negative total effect;the average height and the average DBH of Phyllostachys edulis which is closely related to each other and the strongest total acting factors of each other.Effect of spatial homogeneity index is achieved mainly by the indirect effect,while the direct effect is small,the positive direct effect on average height,and direct effect on the average DBH of Phyllostachys edulis.The crown ratio is more directly affected by intrinsic competition and interspecific competition which has positive effect on the bamboo,intrinsic competition plays a negative direct effect.(7)Management Strategy of Bamboo and Broad-leaved Tree Mixed Forest,according to the different operating purposes,the ecological benefits of Bamboo and Broad-leaved Tree Mixed Forest management,it is recommended that the proportion of mixed should not be less than 25%,which have the best spatial homogeneity(Level 4)and the forest stability was strong,what?s more,the aboveground biomass of Phyllostachys edulis is 45057kg/hm2.The economic benefit of Bamboo and Broad-leaved Tree Mixed Forest management,it is recommended that the proportion of mixed should not be more than 20%,the spatial heterogeneity was better(Level 3),the aboveground biomass of Phyllostachys edulis is 69594kg/hm2;taking into account the ecological and economic benefits of the mixed forest of bamboo and broad-leaved forest,the proposed mixing ratio of 20% to 25% is more appropriate,because of the spatial heterogeneity was better too(Level 3)and the stability of the forest was strong,and the aboveground biomass of Phyllostachys edulis reached 60378kg/hm2,which was 13% lower than that of the mixed ratio of 15%~20% and was 34% higher than that of the mixed 25%~30%.With regard to the selection of the related species of Phyllostachys edulis associated tree species,it is suggested that the first choice of Choerospondias axillaris and camphor,followed by Castanopsis chinensis and Cinnamomum camphora.Under the proposed mixed ratio,they all can form a good symbiotic relationship with Phyllostachys edulis,but that should be controlled crown by pruning,scientific adjustment of the proportion of mixing.