Evaluating Forest Naturalness Based On Stand State Characteristics

Sustainable forest management is the topic of modern forestry development, the major issue of an international forestry academic circle facing is how to scientific management, protection and cultivation multi-functional forest resources. The existing forest communities are comprehensived the results of long-term interference in humans and adaptation of site environment; it has been marked brand of human impact in history and more or less forced to leave their natural state. In order to evaluating and descripting extend of human impact on forest communities in history and explore the sustainable forest management measures scientifically, the concept of the naturalness was proposed. This study put forward a new evaluating method of forest naturalness based on stand state and taken 15 typical stands in different climatic zones as example, analyzed the stand state characters that including the tree species composition, structure characters, tree species diversity, vigor feature and disturbance intensity, and so on, and evaluated the stands forest naturalness, the main conclusions are as follows:1.This paper proposed an new concept of forest naturalness based on stand state that is similarity degree of the existing forest with zonal virgin or climax communities in tree species composition, structure characters, tree species diversity, vigor feature and the extend of the human disturbance, it not only including the forest tree species composition, spatial structure characteristics, non-spatial structure characteristics but also the forest regeneration ability, production capacity and human disturbance extend.2. Fourteen indictors have been selected from forest tree species composition, structure character, tree species diversity, vigor feature and disturbance extend and two methods have been proposed included reference system existing and not existing to evaluate the forest naturalness, and these made forest naturalness quantitative analysis realized. Using the qualitative and quantitative methods divided forest naturalness into seven different grades.3. The broad-leaved Korean pine natural forest in temperate continental climate zone has abundance tree species composition and high tree species diversity. The tree species distribution is evenly and dominant species concentration is high in plot of the 54th compartment, however, in plot B of the 52th compartment is the poorest. The diameter distribution of three stands is unreasonable uneven-aged forest diameter distribution and the undergrowth regeneration of plot A of the 52th compartment is bad, the plot B of the 52th compartment and plot of the 54th compartment are faverable. There have certein amount coarse woody debris in three plots and main composition is companion tree species and pioneer tree species.4. Trees in the broad-leaved Korean pine natural forest distribute in random pattern, the average mingling status of stands lies between intensity mingling and very intensity mingling. In plot A of 52th compartment, Populus davidiana, Juglans mandshurica, Betula costata and Pinus koraiensis are predominate tree species and Syringa reticulate, Quercus mongolica, Acer tegmentosum and Sorbus alnifolia are disadvantages in spatial structure units; in plot B of 52th compartment, Populus davidiana, Padus racemosa, Phellodendron amurense, Betula costata, Acer tegmentosum, Quercus mongolica and Fraxinus mandshurica are predominate in spatial structure units, however, Acer mandshuricum, Carpinus cordata, Ulmus laciniata and Syringa reticulate are disadvantages; in plot of 54th compartment, Pinus koraiensis, Abies nephrolepis, Ulmus davidiana,Tilia amurensis, Acer mono and Quercus mongolica are intermediate status and Carpinus cordata, Acer mandshuricum, Acer tegmentosum and Syringa reticulate are between intermediate status to disadvantages status in spatial structure , there have no absolute disadvantages tree species in stands. The canopy structure of three broad-leaved Korean pine natural forest stands is typical multi layer structure.5. Quercus aliena natural forest on Xiaolongshan in warm temperate and north subtropical transitional zone tree species composition is very complex and tree species richness and diversity is high relatively. There has plenty of coarse woody debris in Wangangou stand, however, there have no coarse woody debris in Xiangtangou and Baiyingou stands. The diameter distribution of Wanangou stand and Xiangtangou stand is reasonable uneven-aged forest diameter distribution; the Baiyinxigou stand diameter distribution is multi-peak mountain shape distribution. Trees in Wangangou and Baiyinxigou Quercus aliena natural forest distribute in random pattern and Xiangtangou in Quercus aliena natural forest distribute in slight cluster pattern. The average mingling of Wangangou stand lies between intensity mingling and very intebsity mingling and the individual size differentiation of Quercus aliena population is significant, Xiangtangou stand average mingling status is intensity mingling and the tree species individual size differentation is complex, the average mingling of Baiyinxigou stand lies between moderate and intensity mingling status and the individual size differentiation of Quercus aliena population lies between advantage and moderate in spatial structure units. The canopy structure of three Quercus aliena natural forest stands is typical multi layer structure.6. Tree species composition is simple and tree species diversity is low in the stand which is the natural shrub transfrom plantation on Xiaolongshan, there has little coarse woody debris in stands, however, the undergrowth regeneration is favorable in all of the stands. Natural shrub transfrom plantation stands diameter distribution is complex and not all the stands diameter distribution is typical plantation diameter distribute character. Trees'distribution in uniform pattern of the most transfrom plantations except the zone transform plantation Pinus armandii which trees distribution is random pattern. The mean mingling of the five transform plantation stands is low relatively and lies between weakly mingling and moderate mingling; the trees individual size differentation of different transformation models in spatial structure is significant and the conifer species lies in sub-dominant and the broadleaved tree species lies between weakness status and absolute weakness status. The canopy structure of the five natural shrub transfrom plantation is simple and lies between single layer and multi layer status.7. Tree species composition is simple and tree species diversity is low relatively of evergreen broad-leaved mixed forest in subtropical humid climate zone; the diameter distribution of the stands is unreasonable uneven-aged forest diameter distribution and the quantity of coarse woody debris and undergrowth regeneration is relative larger, however, the mixed forest tree species composition is complex and the tree spcies diversity and evenness is high relatively, the diameter distribution is typical uneven-aged forest distribution and the quantity of undergrowth regeneration is large relatively, there has little coarse woody debris in mixed forest. Trees'distribution is random pattern and the tree species segregation is low relatively in evergreen broad-leaved mixed forest, the individual size differentation of Cyclobalanopsis glauca, Liquidambar formosana and Rhus verniciflus is significant and the canopy structure of the evergreen broad-leaved mixed forest is typical multi layer structure status. Trees'distribution is cluster pattern and the tree species segregation is high relatively in mixed forest, the individual size differentation of tree species is complex and the canopy structure lies between single layer and multi layer status.8. Evaluated the stands forest naturalness of the seven stands on Xiaolongshan in Gansu province by two kinds of forest naturalness evaluting methods respectively, the resulted show that the status of clear-cut of natural timber forest-natural regeneration in Xiangtangou and selective cutting as tending of natural timber forest in Baiyingxigou is secondary forest status, their forest naturalness grade is 5; the status of the clear-cut shrub transform Pinus armandii stand and zone transform Pinus armandii stand, Pinus tabulaeformis stand is native tree species mixed status, their forest naturalness grade is 4; the status of the clear-cut shrub transform Pinus tabulaeformis stand is native tree species pure forest status and the status of the clear-cut shrub transform Larix kaempferi stand is native tree species mixed with exotic tree species status, their forest naturalness grade is 3. The forest naturalness evaluating result consistent of the different stand types on Xiaolongshan by two methods.9. Used the analytic hierarchy process based on entropy method evaluted the 7 stands forest naturalness which including the broad-leaved Korean pine natural forest in north-east china, evergreen broad-leaved mixed forest and mixed forest in Guizhou province, the resulted show that the status of evergreen broad-leaved mixed forest and the 54th compartment of broad-leaved Korean pine natural forest is original nature secondary forest status, their forest naturalness grade is 6; the status of mixed forest in Guizhou and the 52th compartment of broad-leaved Korean pine natural forest is secondary forest status, their forest naturalness grade is 5.To sum up, this study put forward a new forest naturalness evaluating method based on stand status from reference system existing and not existing respectively, reallized the forest naturalness quantitative analysis. The first time used the stand spatial structure characters, undergrowth regeneration and coarse woody debris in forest naturalness evaluating; the entropy method and analytic hierarchy process combination in coress of evaluation indictors'weight distribute so that the evaluation of naturalness of forests more in line with objective reality. The evaluating method of forest naturalness has better distinguishing in descripting the near natural extend of the different stands types, it also have other features such as easy operation, well explained, and so on; the study provide a new perspective in evaluating forest naturalness and it has certain practical value.