| Traditional forestry mainly diversity index,evenness index and other parameters for non-spatial stand structure research,the lack of spatial distribution of trees and their properties,and with the rise of research in recent natural forests,stand spatial structure increasingly Vietnam has become a hot research.Taking Tianma Nature Reserve in natural deciduous broad-leaved mixed as the research object.Through a overall survey,according to the terrain conditions,community physiognomy and species composition,the ten sample areas were selected from the deciduous broadleaved mixed forest,the total area of ??7209 m2.Detailed records of species name,DBH,and factors like higher forest land elevation,slope,aspect and other factors woodland for sample areas which are eligible.Meanwhile,using the Total Station(South NTS-320)for gauging the trees coordinates(x,y,z)positioning.In each area,using diagonal method in each area’s four corners and the two diagonals to set up five shrub plots,whose area is 4 m2 and the specifications is 2m × 2m,the total shrub plots are fifty and the total area is 200m2;there are the area of 1m2 and the specification of 1m×1m about each herbal plot,the total number is fifty and the total area is 50m2.The survey plots of shrubs and herbaceous are main content: botanical name,strain(Cong)number,cover,height and so on.Using the Total Station measured the geographical coordinates for tree plots,then using the software of winkelmass1.0 to calculate the mingling stands,the number and size than the three spatial angle scale structural parameters and determine the degree of open and competitive index..Using five various parameters of forest spatial structure,the ecological dominance index including Simpson index(D),species diversity index Shannon-wiener index(H ’),the evenness index of Pielou index(J’)and importance value(IV),and the index of mingling,the size ratio of the number,angle scale,open and competitive,to analysis Pegasus protected areas of natural deciduous broad-leaved mixed type of plant diversity and spatial structure characteristics.(1)The research record the plant of 94 families,144 genus and 202 species,the three biotype,the tree including 27 families,37 genus and 48 species,the shrub including 34 families,56 genus and 88 species,and the herbal including 33 families,51 genus and 66 species,these are 23.8%,43.6% and 32.7% of the total number of species.(2)The whole stand diameter structure was positive too left distribution,showing astructure of the same age of the forest and more forest trails.For the main tree species,Castanea seguinii of mainly in both diameter classes,in line with normal distribution;the Platycarya of most in both diameter classes,in line with normal distribution;the Bothrocaryum controversum whose diameter structure presents obvious normal distribution,Quercus glandulifera which distribute more over eight diameter class,ten diameter class and other small diameter class,in line with the anti-type "J" distribution.(3)The species of the Important value of forest communities in tree layer >5,including Castanea seguinii,Platycarya,Bothrocaryum controversum,and Quercus glandulifera.Castanea seguinii is the dominant Species for that type of tree lager,Platycarya,Bothrocaryum controversum and Quercus glandulifera is the subdominant species for its type of tree lager;in the shrub layer,Lindera reflexa is the only one of important value greater than five,so the Lindera reflexa is the main constructive species of shrub layer;in herbaceous layer(including vines)species whose important values greater than 2 are Hispid Arthraxon,Ferns,Festuca Arioides Lam,Paederia Scandens,Longhairy Antenoron Herb,Keiskea,Viola chaerophylloides and Qi Hao,the important value of Hispid Arthraxon,the main constructive species in herb layer,is the biggest one.(4)The rank of Shannon-wiener index(H ’): shrub layer(3.967),herb layer(3.384),tree layer(2.671);Pielou index(J ’)performance: shrub layer(0.880),herb layer(0.781),tree layer(0.664);Simpson index(D’)as follows: shrub layer(0.972),herb layer(0.920),tree layer(0.857).the species richness,Shannon-wiener index(H ’),Pielou evenness index(J’)and Simpson dominance index(D ’)of Shrub layer showed the highest values,which means the richest species and equally distributed.(5)The average full-mingling of the forest land is 0.677,which is between intensivemingling and moderate intensive-mingling,forest stand more complex,stable state,the same situation species aggregation little,high degree between species.The average full-mingling of Castanea Seguinii is the least,0.531,Castanea Seguinii and Platycarya is the moderate intensity mixed,the average full-mingling of Cornus Controversa is 0.743,which is in the intensive-mingling.the average full-mingling of Quercus Glandulifera is0.865,which is in the extremely intensive intensive-mingling.The whole angle index of the stand is 0.516,individual in a random distribution as a whole.The average angle scale of each main tree species of Castanea is 0.551,the average angle of Platycarya is 0.523,the average angle of Cornus Controversa is 0.522,and these three species are generally clustered distribution.the average angle of Quercus Glandulifera is 0.469,the spatial distribution pattern from uniformly distributed to random distribution.The average size ofthe whole forest odds is 0.485,the entire stand of trees diameter ratio of the number is equally distribute.and the growth do not show a clear differentiation.The diameter ratio of the number of Castanea Seguinii is only 0.259,which distributed at the edge to the doctrine of the state,and in a state of absolute advantage position;the odds of diameter size of Platycarya is 0.415,growth between subdominant to moderation status;the odds of diameter size of Cornus Controversa is 0.525,in moderation status;the odds of diameter size of Quercus Glandulifera is 0.729,in bad state in its structural units.(6)The average open degree of forest of woodland is 0.355,forest growth space is almost fully state.The average open degree of Castanea Seguinii is 0.377,distribution frequency of plenty of growing space is 0.307;The average open degree of Platycarya is 0.312,the frequency of the lack of growing space is the highest.The average open degree of Cornus Controversa is 0.342,about 40% of basic adequate space for individual growth state;The average open degree of Quercus Glandulifera is 0.369,the number of plenty of growing space is the biggest.(7)Comparing the intra species competition index between the main tree species and adjacent competition wood,The average index of competition of Quercus Glandulifera is the highest,located in the most suitable niche,then the average index of competition of Cornus Controversa is 2.87;the average index of competition of Castanea and Platycarya is 1.88 and 1.81,the lowest intensity of the interference suffered competition is Platycarya. |
