Study On The Quantitative Analysis Of The Oak Natural Secondary Forest In Baotianman Nature Reserve

The indicator of structure which is one of the main characters of the forest is the basis researching of forest which includes forest protection,forest management,and forest health assessment. The indicator of forest spacing structure is the important aspect of forest structure and is also the significant supplement of the traditional forest structure which is lack of spacing distribution information. This thesis choose the Oak Natural Secondary Forest in BaoTianMan National Nature Reserve as the study object, states forest basis structure like tree species, diameter, height and analysis forest spacing structure distribution on 32 temporary sample plots, then gets spacing information from another 10 settled sample plots in Arcview and with the help of el and the method of distribution type index and method of distance then describe the forest spacing structure to supply the evidence which is used for protection forest with indicator of mixture degree, big-small comparable data and angle.Research the forest basis structure: a) tree species: the result of the basis character of each tree species and the main value is that this resign has ample tree species in which the dominant one is Q.aliena Bl and the second ones are var.btecipetiolata Nakai, Quercus variabilis. The result of three different biodiversity index are a little bit different but shows the same tendency like: the biodiversity index of Q.aliena Bl plus var.btecipetiolata Nakai and biodiversity index of Q.aliena Bl plus Quercus variabilis are in higher level but the forest of net Q.aliena Bl is in low level. b) diameter: the fitting results of 7 main tree species with 5 probability distribution functions show that neither of the 5 functions can fit the Q.aliena Bl but fit the rest ones after inspected byχ2 and in which the function Weibull is the best and followed by the function Bata. From three characteristics of diameter distribution, we can see that the trees of the middle and little diameter is in the most in the oak natural secondary forest; the diameter distribution curves of var.btecipetiolata Nakai, P.strobilacea Sieb.et, L.obtusiloba Bl. are relatively flat, they show that the separated degree of the diameter bands are very big. The diameter distribution curves of the other four trees are sharp, and their separated degree of diameter bands is small and concentrated. c) height distribution: the analysis result of height indicator shows the difference of average height between sample plots is large and the standard deviation is not too evidence but the standard deviation in sample plot is very large. For tree species, the main ones shows that the largest quantity of trees distributes at the average height location which is a un-symmetrical and mountain area cave. The trees in middle clay are largest and higher clay which lays in the right of apex is small. The Quercus variabilis lays in the higher clay and the Q.aliena Bl lays in the higher-middle clay and the Tilia europaea and L.obtusiloba Bl are in the low clay. The result of fitting by Weibull with 2 parameters to the main tree species and the inspected result byχ2 show that the regulation of height is same with diameter.The result of integrated analysis with different indicators of method distribution index in sample plots and method assemble index which related with distance shows that the investigated age degreeⅡ,Ⅲ,Ⅳof Oak Natural Secondary Forest are randomized distribution but, for each indicator, the value shows the randomized degree which increase with the rank of age degree is different and the age degreeⅡis lowest which means it has assemble character.For the spacing structure parameter analysis, a) the result of the mixture degree analysis of Oak Natural Secondary Forest is that it is commonly low and the value increases with the rank of age grade, the different tree species has obviously deviation like the mixture degree of Q.aliena Bl is low and other tree species are strong or huge strong. b) the result of the big-small compared value shows that the average diameter of each age grade is not too different for the diameter but the distribution frequency of each tree species are obviously different, the dominant tree species lower than others. The P.strobilacea Sieb.et,L.obtusiloba Bl,var.btecipetiolata Nakai are strongly restrained so in the negative location and the Q.aliena Bl is in positive location which is restrained with age grade increasing. For height indicator the tendency is same as the rule in diameter and the result of relationship analysis of this two indicators show that they are strongly coincident when they are used on the forest with different age grade and the growth of different tree species. c) the result of angle analysis shows that it is not too different within age grade in which gradeⅡis largest, 0.511, and the three age grades are randomized distribution according to the standard. For the value of angle, age gradeⅡis obviously larger than gradeⅢ,Ⅳthat shows it has assemble distribution character, namely the forest changes its former assemble distribution type to randomized one and stable gradually from lower age grade to high age grade. For tree species, 4 around trees are randomized distribution to most of them and less of them show average distribution.