Spatial Distribution Pattern And Interspecific Competition Of Cyclobalanopsis Gilva To The Different Interference Intensities

As a precious timber specie,Cyclobalanopsis gilvahas limited natural resources and no large area of artificial afforestation.In order to study the ecological characteristics of Cyclobalanopsis gilva population of different disturbance intensities,the community of three populations with different disturbance intensities was investigated.Refer to the strength of various disturbance traces(the number of trails,the size and quantity of cutting piles,the number of branches)and interviewed nearby villagers,the disturbances of the three populations were as follows:community A-no disturbance,community B-mild disturbance,community C-severe interference,so as to study the spatial distribution pattern and interspecific competition of Cyclobalanopsis gilva of different disturbance intensities,and provide scientific basis for rational and efficient management of Cyclobalanopsis gilva plantation.1.In the undisturbed community A and the mildly disturbed community B,the important values of Cyclobalanopsis gilva were ranked first.In community A the important value of Cyclobalanopsis gilva is 131.174,accounting for 43.72%of the tree layer;The important value in community B is 50.671,accounting for 16.89%of the tree layer;The important value of Cyclobalanopsis gilva in community C was 77.645,which was lower than 78.010 of Cunninghamia lanceolata.With the increase of the degree of disturbance,the important value of Cyclobalanopsis gilva in the communities were gradually decreased.There are 44 species in community A and 54 species in community B and 88 species in community C.The Margalef index in community decreased in order A>C>B,Shannon-Wiener index ranked as A>C>B,the Simpson index in three communities is close,the Pielou index ranked as B>C>A.2.Congregating distribution is the basic attribute of the spatial distribution pattern of Cyclobalanopsis gilva,in both community A and community C showed such characteristics,and the congregating degree of community A is higher than that of community C.The distribution pattern of Cyclobalanopsis gilva population was different at different development stages.With the population age increased,the distribution pattern had a trend from congregating to homogenous,the congregating intensity decreased some what.In the small populations of Cyclobalanopsis gilva in community C,the age of Cyclobalanopsis gilva was roughly equal,and the distribution type was homogenous.As a result of the reduction of the regeneration of Cyclobalanopsis gilva seedlings,the degree of aggregation was reduced.3.Cyclobalanopsis gilva population has a larger niche breadth in the three community.The niche breadth of the Cyclobalanopsis gilva in community A,B and C was 0.726,0.813 and 0.701,respectively,and was the highest in the mildly disturbed community B.With the increase of the disturbing intensities,the mean of the niche overlap index increased,and there were 39%of the pairs of the population over average in community A,43%in community B and 61%in community C.4.In the competition of Cyclobalanopsis gilva population with other dominant species in community A and B,Cyclobalanopsis gilva population always won.The dominant status of Cyclobalanopsis gilva was significant in the two communities,but the competitive advantage was affected by the interference.In the community C,the competitive ability of Cyclobalanopsis gilva is not as good as that of Cunninghamia lanceolata,Castanopsis fargesii and Schima superba.With the increase of the degree of disturbance,some of the competitive ability is inferior to the tree species of Cyclobalanopsis gilva,such as Cunninghamia lanceolata,gradually gain an advantage in community succession.