| In the worldwild scalse ecological enviroment is worsening constantly and the forest system,as the largest ecological mainland ecosystem resisting ecological enviromental problems,was confronting the dilemma of continuous destruction and management asthenia,which made the decline of natural forest area,reduction of the planted forest quality and gradual degradation of forest function. The forest structure was the intrinsic nature, while its function was the external manifestation, thus structure determined function. How to clear forest structure? How to understand coupling relations between the structure and the function? It was the most essential question that realized the problems such as function optimization, and so on, by adjusting forest structure. This article's content is a part of the public welfare industry of the state forestry administration research projects:"Southern collective secondary forest tending and thinning and efficient use of technology research (The Item Number:201004032)".With the study of stand structure(such as diameter structure, tree height structure, crown width structure, horizontal distribution patterns of forest, space isolation degree of forest and size differentiation of forested.),the whole stand models based on the parameters of diameters structure shape and forest mean age were constructed in this article, by classifying individual tree growth models through neighbourhood comparison on the basis of the space analysis methods of non-fixing subject tree, simulating stand growth and changes of diameter structure through individual tree growth models. Finally, the transformation which was from adjustment of stand density to adjustment of diameter class, could be realized by using the whole stand models.Diameter structure aspect was as followed:among3kinds of stand types (Choerospondias axillaris forest, Castanopsis sclerophylla forest and Sassafras tzumu forest),the specific gravity of small diameter class was generally lower than45%in mixed forest, while it was normally below20%in pure forest; and it was under15%in Castanopsis sclerophylla forest. Stand natural renewal capacity and stability of community succession appeared normal, especially there being adverse trend in pure forest. Shape parameters were between1.01and3.13, diameter distribution shape was basically leftist unimodal montiform after fitting. Tree height structure aspect was as followed:the tree height span and standard deviation of mixed forest were both higher than those of pure forest, so as the number of forest stories, the vertical structure of mixed forest was more complicated, and its utilization ratio to vertical space was higher than pure forest. Shape parameters were between1.49and3.99, the image of mixed forest was basically leftist unimodal montiform, whereas that of pure forest was basically rightist unimodal montiform.The crown width structure aspect was as followed:the shape parameters were between1.28and2.43. and distribution shape was basically leftist unimodal montiform.The crown width span and standard deviation structure of mixed forest was more complex, the utilization ratio to level space was higher than pure forest.Forest level distribution pattern aspect was as followed:the mean uniform angle index of the3kinds sand types was respectively0.61,0.62,0.55,all for aggregation distribution. The proportion under random distribution of forest was generally below20%,the development trend was the transformation from even distribution and random. distribution to clustered distribution. The isolation degree of forest space aspect was as followed:the average mingling degree of3kinds stand types was respectively0.47,0.25,0.51,except for light degree group mixture of Castanopsis sclerophylla forest, the other two types both belonged to moderate group mixture, There was a positive correlation between average mingling degree and proportion of species configuration. The same kind of species almost appeared clustered distribution in pure forest, of which the species configuration had obvious unreasonable phenomenon. Forest competition situation aspect was as followed: Choerospondias axillaris and Liquidambar formosana in Choerospondias axillaris forest were both in competitive advantage position, whereas Cunninghamia lanceolata and Sassafras tzumu were in competitive disadvantage in whole appearance; and in the whole, the Liquidambar formosana in Castanopsis sclerophylla forest was in weak competitive supriority,while Castanopsis sclerophylla was in partial inferior position. In Sassafras tzumu forest, Sassafras tzumu, Choerospondias axillaris, Liriodendron chinensis,Pinus massoniana and Castanopsis sclerophylla were all in competitive superiority, while Cunninghamia lanceolata showed a competitive inferior.In the respect of3kinds space distribution structure, the results of non-fixing subject tree space analysis methods had significant or extremely significant, and in which there was a significant or extremely significant correlation between the numbers of subject tree and dianmeter,tree height, crown width and heighbourhood comparison. It was found that the space analysis methods based respectively on non-fixing subject tree and fixing4strains subject trees were muturally independent, and the former had convincingness to the latter.With forest competitive situation, individual tree growth models were classified and fitted, then the single tree models were divided into2communities, respectively competition advantage forest(neighbourhood comparison>0.5)and competition disadvantage forest(neighbourhood comparison<0.5),thus growth situation of actual crop was expressed more precisely.In the terms of single tree models,comphrehensively considering fitting of the available data,complexiy of models and prediction effects about future.the single tree model, Gompertz model is the best in Choerospondias axillaris, Gauss model and Logistic model are the best in Castanopsis sclerophylla, Logistic model and Schumacher model are the best in Sassafras tzumu, Schumacher model and Logistic model are the best in Pinus massoniana, Gauss model and Gompertz model are the best in Cunninghamia lanceolata, Gompertz model is the best in Liquidambar formosana.In the terms of stand growth simulating aspect,with continuous growth of stand mean age from overall perspective of procession.avaerage of current annual growth was basically first increased and then decreased,the inflection point basically occurred in about50years. Among middle-age forest(Choerospondias axillaris forest and Sassafras tzumu forest), excluding the effection of stand mean age,there was a extremely significant negative correlation between shape parameters and average of current annual growth.Among matural forest(Castanopsis sclerophylla forest),there appeared a extremely positive correlation between shape parameters and average of current annual growth.On the constructure of whole stand models,the growth model of2parameters(stand mean age and shape parameters)had superior to that of1parameter(stand mean age).Although there was a positive correlation between stand mean age and stand current annual growth in moddle-age forest,contribution weight was smaller,whereas there appeared a negative correlation in the whole shape parameters,contribution weight was larger.There was a ngative correlation between stand mean age and stand current annual growth among mature forest,but contribution weight was smaller,while it appeared a negative correlation in the whole shape parameters,contribution weight was larger;the manifestation was more obvious in mixed forest.The main innovations of this study had following3aspects:1.The space structure of3kinds typical stand types of southern collective forest zone were researched by using influence circle,defining subject tree and constructing space analysis methods on the basis of non-fixing subject tree.2.The single tree growth models were classified by using competition situation,which accorded with standing growth of forest.Meanwhile.on the basis of fitting effects of existing data,models would be the optimal selection combined with future prediction results.3. The whole stand growth models of6seed types of3kinds typical stand types in southern collective forest zone were consturcted on the basis of shape parameters and stand mean age of stand diameter structure,what realized the goals that stand density of stand production practice was adjusted forward step by step and develped to the adjustment of stand diameter grade. |
