Study On Gap Regeneration Dynamics In Aleurites Montana Plantation Forest

The forest gap is an indispensible driver in forest ecologieal variation.The gap provides adaptive habitat for species and maintains the biodiversity.It is an important factor instructure population and dynamic fluctuation.Thus,the gap was considered as an important condition for forest succession and regeneration.With the concept of energy-saving,low-carbon,green environment,sustainable development have rooted deeply in people's mind,Aleurites Montana Loury world-famous and endemic to China,attracts more and more attention as a tree spices in producing industrial o1l.It 1s treated as one kind of tree species for biomass energy,with the priority to develop and utilize.Based on time background,the paper takes Aleurites montana plantation forest as the research object and 1s supported by much of the initial groundwork in own group.In order to explore gap regeneration in plantation and understand the rules of forest succession,we conducted Aleurites montana plantation forest in Jianyang city of Fujian Province in this paper.We studied gap characteristics,the tmpact of the environment in gap on species and regeneration difference in gaps and forest was compared.This study is helpful to provide the theoretical foundation to the sustainable management in plantation.The main conclusions were as follows:1.Gap characteristics can render important reference for the regeneration response of the major tree species in gaps and influence microenvironment in gap and community.Because of the big difference in the manner and intensity of interference,gap characteristics in plantation and natural forest 1s different.Through field investigation of gaps in Aleurites montana plantation forest in Jianyang city of Fujian Province,this paper analyzed gap characteristics in relation to sizes,shapes,ages,ratio of diameter to height and so on.The results indicated that,in Aleurites montana plantation forest,the size of canopy gap varied from 6.56?45.24 m2,of which the number of 10 to 20 m2 was the largest;the size of extended gaps ranged from 23.11?167.48 m2,and a large proportion of extended gaps were in the size of ?50 m2.From the ratio of canopy gap to expanded gap,canopy gap was significantly greater than the fluctuation range of expanded gap.Expanded gap was also smaller than canopy gap in shape index.Most gaps were formed 2 years ago.The most important manner of gap formation was the Artificial Felling,shareing 53.85%of the total gap makers,and the second important manner of gap formation was Standing die(16.92%).The ratio of diameter to height of expanded gap and canopy gap was also summarized as the single peakcurve.The later was relatively concentrated.The principle component analysis was adopted with 10 common quantifiable indicators of gap characteristics and showed that the gap could be characterized by the following indicators:the gap area index,shape index gaps,age gaps indicators,the gap height indicator.2.Based on investigation of gaps and non-gaps in Aleurites montana plantation forest,the quantitative characteristics of tree species,the difference in interspecific relation and species diversity in gaps and non-gaps stands were investigated.The results showed that,in the quantitative characteristics of tree species,there were significantly different in gaps and non-gap stands.The relative density,relative frequency and relative cover,the treelayer,shrub layer and the herb layer had a little difference and the important value were also different.In the interspecific relation,the proportion of species-pairs in gaps and non-gaps as a whole which had significant or highly significant correlation was less and the connection degree of most species-pairs has not been balked of the level of significance,which suggested that the interspecific relationships between forest tree species are not most closely.The number of species-pairs in non-gaps is less than gaps,but the positive association of Ppedes-pairs was tend to increase.As to species diversity,non-gaps was lower inspecies diversity index than gaps but gained ascendancy over ecological dominance indicesand evenness index.3.By using redundancy analysis,we researched the relation between the impact of the environment in gap on species.The results indicated that:The environnental factors in different layers of communities were different.Altitude and the ages of gaps played the most important role in the forming of community distribution pattern in treelayer;the gap area and slope played the most important role in the forming of community distribution pattern in shrub layer;aspect and gap border trees played the most important role in the forming of comnunity distribution pattern in herb layer.