Population Structure And Community Characteristics Of Vatica Mangachapoi In Ganshiling,Hainan Island

Vatica mangachapoi is a key species,constructive species and dominant species in tropical lowland rainforest of Hainan Island,which plays an important role in protecting biodiversity and maintaining ecosystem stability.Vatica mangachapoi is plant of the second-class protection in China,which has the ability of rapid recovery and strong environmental adaptability,and it plays an important role in the restoration of lowland rainforest ecosystem in Hainan Island.Based on the principles and methods of quantitative ecology,this paper studied the growth pattern,population structure and dynamics,niche and interspecific association of main tree species,community classification and ordination of Vatica mangachapoi community in Ganshiling,Hainan Island.It was expected to reveal the restoration condition of Vatica mangachapoi community,predict the direction of community succession,and provide reference for the protection,restoration and rational utilization of lowland rainforest.The main results were as follows:1.The mixed-effect model of height and DBH（diameter at breast height）of Vatica mangachapoi was constructed.The mixed-effect model of height and DBH was more reliable and stable.Compared with the basic model,the determination coefficient of the mixed effect model increased by 0.10,and the mean absolute error and root mean square error decreased by0.12 and 0.58 respectively.The DBH data of Vatica mangachapoi was discontinuous,showing that the population was in recovery,and its growth and development were easily affected by environmental factors.2.The population structure and dynamics of Vatica mangachapoi were studied.The diameter,height and canopy structure of the population of Vatica mangachapoi were of"L"type,that is,the number of individuals with low grade was large,and it belongs to the growth population.The static life table analysis showed that the environmental resistance and competition pressure of the middle age tree individuals were the biggest and the mortality rate was the highest（87%）.The survival curve analysis showed that the survival of the population tended to be subtype B₁ in deevey-Ⅱ.The survival analysis showed that the population had the characteristics of rapid decay and high competition pressure in the middle term.In the low age stage,the number of seedlings in the population of Vatica mangachapoi was large,which could cope with environmental resistance and competition pressure;when the individuals were in the middle age stage,the environmental resistance and competition pressure faced by the growth and development increased greatly;in the later stage,the individuals gradually declined with the population entering the physiological death.The time sequence prediction analysis showed that the population of Vatica mangachapoi could recover rapidly and have good potential for renewal and development.3.Niche and interspecific association of main tree species in Vatica mangachapoi community were studied.In general,there was niche overlap among the main species in the community,but was no significant correlation between them.There were abundant environmental resources in the community,the competition among the main species tended to be gentle,and the community structure and function were in a state of rapid recovery.Vatica mangachapoi had the best utilization of environmental resources and the best growth and development condition.With the passage of time,it showed a trend to replace the Hopea reticulate in the community.4.The classification and ordination of Vatica mangachapoi community were studied.The12 plots and 20 main tree species were divided into 6 community types and 6 ecological species groups by two-way cluster analysis and redundancy analysis.Altitude,soil bulk density and slope have great influence on the growth and development of main tree species.Vatica mangachapoi and Garcinia oblongifolia were environmental generalized species,which could adapt to various habitats;Antirhea chinensis,Cyclobalanopsis blakei,Heritiera parvifolia,Engelhardia fenzelii and Croton laevigatus were environmental specialized species,whose distributions were seriously restricted by environmental factors.