Research On The Community Characteristics Of Natural Cryptomeria Fortunei In Tianbaoyan National Nature Reserve

Based on the methods of community Mathematics &Applied Statistics,the natural Cryptomeria fortunei community characteristics was researched in Yong'an Tian baoyan national nature reserve,including the species composition and the characters of flora,the quantity characteristics of dominant species,species diversity features,the spatial distribution patterns of the main species,the distribution of the high scales and diameter scales and various kinds of model fittings, main species'niche characteristics and inter-specific association in tree layer,intra- and inter- specific competition comparison,and static life table research.The main results were as following:(1)Analyzed from the quantity characteristics of the main species in tree layer,the results showed that the main species with a relatively larger importance value in the tree layer were Cryptomeria fortunei , Pinus massoniana Lamb , Eurya japonica Thunb ,Tsuga longibracteata W.C.Cheng,Quercus palustris,etc.The species with the largest importance value was Cryptomeria fortunei which reached 97.087 percent and much more than other plants.The main species with a larger importance value in the shrub layer were Eurya japonica Thunb , Ilex crenata Thunb , Bredia sinensis ( Diels ) ,Rhododendron moulmainense Hook,Cryptomeria fortunei,etc and the dominant species were not obviously;the most dominant species in herb layer were Dicranopteris linearis, Dryopteris podophylla and Miscanthus sinensis while the rest of all distributed relatively evenly.(2)Analyzed the different species compositions of the studied community,the results showed that the natural Cryptomeria fortunei community had 112 kinds of species in all,which belonging to 53 families and 88 genus,including 58 kinds of woody plants and 54 kinds of herbaceous plants.There were 33 kinds of species(82.5%)which belong to 15 families and 27 genus in the tree layer were evergreen trees;7 species(17.5%) were deciduous trees belonging to 6 families and 6 genus;44 species(77.8%)belonging to 26 families and 34 genus in the shrub layer were evergreen plants while 14 kinds(22.2%) were deciduous plants belonging to 10 families and 12 genus.The analysis of the flora features showed that there were 11 kinds geographical distribution patterns of the families in natural Cryptomeria fortunei community,The distribution types which took up the most families were pan-tropical distribution,and world distribution was in the second place.According to the geographical distribution types of genus,the community had 17 tpyes, the most dominant type of which was world distribution and pan-tropical distribution closely followed.(3)6 species diversity indexes were used to estimate Cryptomeria fortunei community species diversity in different elevation,and the results showed that the order of diversity value in high elevation was shrub layer>herb layer>tree layer,and herb layer>tree layer>shrub layer in mid- and low-elevation.With the change of the elevation,the diversity order in tree layer was:high-elevation>mid elevation>low-elevation,in shrub layer was:high-elevation > low-elevation > mid elevation,and there was no significant difference in herb layer.It concluded that at high-elevation there were better thermal and humidity condition , while the conspicuous decline of species richness at mid-elevation and low-elevation due to serious human disturbance.(4)The research of DBH and high scale distribution showed that the DBH distribution was a classic pyramidal shapes which had a great potential in communities development.The curves of the mid- and low- elevation increased first and then decreased immediately.The share rate of every DBH scale in high- and mid- elevation was very similar which decreased first and then increased and last decreased closely to zero.The high scale distribution shaps in mid- and low elevation were very similar,and the share rate curves of high scales in tree layer were very similar with the quantity distribution of high scales in the three elevation.(5)The research of main species spatial distribution patterns in tree layer of the community showed that It would have a little affection to the distribution patterns if different indexes and scales were chosed to be used.The comparison of the spatial distribution patterns of the main species between the natural Cryptomeria fortunei community and planted Cryptomeria fortunei community showed that,in general, Cryptomeria fortunei, Pinus massoniana,and Eurya japonica Thunb all followed aggregated distribution pattern under different analysis methods,which was very consistent with the research formerly.From the comparison of the spatial distribution patterns of Cryptomeria fortunei population in different elevation,the results showed that it was aggregated distribution pattern in high and mid- elevation,while even distribution pattern in low elevation.The function mode M*=0.660+0.972 x(R=0.962)was found using the Iwao equation which also indicated that the population followed the aggregated distribution pattern.(6)The Hegyi's signal trees competition index model was used to research the changes of the competition index of Cryptromeria fortunei populations under disturbance of different intensities,and the relationship between competition index and DBH has been studied,and the relationship model was established.The results showed that with the increase of the disturbance intensities,the general and the intra-specific competition intensities of the investigated three sample plots decreased obviously.The order of the general and intra-pecific competition intensity was CI(1)> CI(2)> CI(3) and CIintra(1)> CIintra(2)> CIintra(3),although the inter-pecific competition intensity didn't increase obviously.The relationship between competition intensity and DBH closely follow the power function model: CI = 161.1639 ?D1.1126,and the model can be well used to predict the competition intensity of Cryptromeria fortunei populations in this area.(7)Niche characteristics of 12 major populations of natural Cryptromeria fortunei forest in Tianbaoyan National Nature Reserve were analyzed by quantitative method. The niche characteristics include niche breadth , niche similarity proportion and niche overlap. The results showed that most of the populations investigated in the natural Cryptromeria fortunei forest had wide niche, and the populations with narrow niche relatively less.The first four populations with the widest niche were Cryptromeria fortunei,>Castanopsis fargesii Franch>Cyclobalanopsis gracilis>Castanopsis eyrei . The niche overlap and similarity proportion of the 12 dominant species were comparably big,which indicated that the intra species competition was very serious in the community investigated.From the niche characteristics of Cryptromeria fortunei population,we can see that Cryptromeria fortunei had the widest niche breadth,and also had the biggest niche overlap and niche similarity proportion with Schima superba Gardn et Champ.(8)A series of methods including the analysis of variance,chi-square test,W test,association coefficient(AC)and Jaccard coefficient and so on were calculated based upon a 2×2 contingency table to determine the overall association,the statistical significance and the association coefficient of the each species pair of 15 main species in arborous layer of Cryptromeria fortunei communities in Yong'an Tianbaoyan national nature reserve,Fujian province.The results showed that the overall association was significantly positive correlation among fifteen main populations and the inter-specific association was not obviously correlated among most of species pairs except only a few of them.6 Species pairs like 11-12( Cyclobalanopsis gracilis-Castanopsis eyrei ) and 10-14 ( Machilus velutina- Cyclobalanopsis glauca)were significantly positive correlation.2 Species pairs like 2-4( Pinus massoniana- Tsuga longibracteata ) and 7-9 ( Pinus taiwanensis Hayata- Ternstroemia gymnanthera )were significantly negative correlation.But most of them didn't reach a significant level,and furthermore the mutual independence of them was very strong between each species pair.(9)An ecological investigation was made on the natural Cryptromeria fortunei population in Tianbaoyan national nature reserve of Fujian Province by using checkerboard frame method and based on the theory of population life table and survival analysis,the life table of the population was established by the method of spatial series substituting for time series.The population dynamic variation was analyzed on survival rate,accumulated mortality rate and mortality density curves.The results showed that in general,the survival curve was DeeveyⅡpattern,and the population grew weakly in earlier period and stably in middle age period but declined in old age period.The survival rate of the population decreased monotonically,whereas the accumulative mortality rate was in adverse.The mortality rate curve and the survival rate curve had the similar variation rate both of which was bigger in the earlier period than that in the later period.The variation trend between mortality rate and loss rate was basically similar both of which existed 2 peaks which was NO.3 and NO.5.Several functions of life table were used well in survival analysis to explain clearly the structure and dynamic variation of Cryptromeria fortunei population.