Study On The Stand Spatial Structure And Species Competition Relationship Of Natural Machilus Versicolora Community In MangdangShan Nature Reserve

In natural Machilus versicolora community of MangdangShan Nature Reserve,adjacent lattice method was used to set up two experimental research plots,and the community forest was taken for kotoki location investigation.In this community,Machilus versicolora,Choerospondias axillaris,Liquidambar formos,Paulownia,Castanopsis fordii Hanc,Alniphyllum fortunei,,ect.were advantage species.Meanwhile,in the community species composition,Machilus versicolora accounted for leading status,and forest environment was decided by this species.The diameter distribution of the Machilus versicolora and its community showed an inverse J-shape as a whole,which obsevered the regularity of the diameter distribution of the natural uneven-aged forest.It meaned that the tree quantity decreased along the increasement of the diameter size,and finally became stable.Analysed via the highness class structure,the population lost stable rate in this community was 1.52%,while the intex value for Machilus versicolora is 29.50%.From the 2nd highness class,the community species diversity index and highness class had a negative correlation.The uptrend of Whittaker index(i.e.used to reflect the community regeneration rate)with the raising highness class gradient was obvious.The whole community was at stable development state and these tree species were still active.Mixed degrees,neighborhood comparison,corner scale was used to analyze community forest space structure.Average mixed degree was 0.829,so it was in between strength and intensity mixture,which indicated that the spatial segregation degree of each tree was high in this stand.The size differentiation distribution frequency of advantage,subdominant,doctrine,disadvantage,absolute disadvantage in forest were uniform.The value of neighborhood comparison was 0.528.that was to say the overall was in doctrine level.Average corner scale for the community was 0.448,and the horizontal distribution pattern of the forest stands was even distribution.The Machilus versicolora community have been a complex community of different species mix in high degree,and the competition relationships between trees were intensive.It won’t become a climax community in short term.Hegyi competition index was adopted to analyze community species competition,but only Machilus versicolora,Castanopsis fordii,etc.had species competition,the competition value maximum was Machilus versicolora and it had a fierce competition with its common associated species.Species competition index had an obviously negative related relationship with object wood DBH size.Competition index gradually decreased with increment of object wood DBH size,thus power function could be a great way on relationship of competition index and object wood DBH size for return analysis.Analysis on spatial structure of Machilus versicolora and relationship between species provided references and supports for using natural forest and resources reasonably and efficiently,as well as realizing sustainable development of forest.