| This paper make two plots located in secondary forest of Tilia amurensis as research object(one is natural restoration and the other was selective cutting)which in Xiaojiu forest farm of Shangzhi city,Heilongjiang province.By means of spatial and non-spatial structure analysis,the vertical structure,dominant population,dead standing tree and regeneration characteristics of stands were analyzed.To explore the influence of disturbance types on quality of natural secondary forest of Tilia amurensis.and provide theoretical basis for restoration and management of natural secondary forest of Tilia amurensis in the future.The results showed that:For the two stands,the diameter-order distribution of trees was inverted J-type,which was consistent with the distribution law of diameter-order of trees in natural uneven-aged forests.For the upper forest layer,the diameter distribution of trees in the two stands tend to be normal distribution,and the trees of the upper forest layer in the selective cutting stand were more in line with the normal distribution,while the young trees in the lower forest layer are more,so the diameter distribution of trees in the selective cutting was closer to the original forest.The FSSI and FSSD indexes of the natural recovery stand were 0.66 and 0.63,respectively,and the two indexes of the selective cutting stand were 0.71 and 0.59,respectively.It could be seen that the spatial structure of trees was better in the selective cutting stand.From the trivariate distribution of spatial structure parameters,it could be seen that the trees in the two stands were random,complete mixture and predominant,accounting for 3.89%and 5.62%respectively.From the vertical structure of trees,the trees of upper forest layer with random distribution and advantaged status,and was surrounded by 4 other species in two stands,accounting for 10.1%and17.5%respectively.The trees of middle forest layer with random distribution and advantaged status,and was surrounded by 3-4 other species,accounting for 4.2%and 6.7%respectively.The trees of middle forest layer with random distribution and disadvantaged status,and was surrounded by 3-4 other species,accounting for 11.7%and 12.1%respectively.It showed that selective cutting management promoted the restoration of stands and upper and middle forest layers.There were a certain difference in the composition of dominant tree species in the two stands,the important values on the top three in natural restoration stand were Tilia amurensis,Acer mono and Quercus mongolica,respectively,in the selective cutting stand were Tilia amurensis,Acer mono and Tilia mandshurica.Through the trivariate distribution of spatial structure,it could be seen that most of Tilia amurensis were random distribution and disadvantaged state in the natural recovery stand,which were more than one other tree species around,and the proportion of trees with the "optimal" spatial structure unit was 1.61%.In the selective cutting stand,the random distribution and disadvantaged state of Tilia amurensis was surrounded by 3-4 other tree species,and the "optimal" spatial structure unit ratio was 11.26%.In the natural recovery stand,9.6%of Acer mono with random distribution and absolutely disadvantaged status,and was surrounded by 2 other species.The proportion of Acer mono was 14.2%with the same state in selective cutting stand.In the natural recovery stand,more Quercus mongolica in random distribution and absolutely disadvantaged state which were surrounded by 4 other species.Tilia mandshurica was evenly distributed(surrounded by 1 other tree species)and was random distribution(surrounded by 4 other tree species)of more trees in selective cutting stand,and these conditions of Tilia mandshurica with equal quality status.The spatial structure of Tilia amurensis in the selective cutting stand was significantly superior to the stand of natural recovery.The spatial structure of Acer mono more reasonable in the natural recovery,Quercus mongolica and Tilia mandshurica in the forest stand was not stable.In the selective cutting stand,Tilia amurensis and Acer mono in the predominant position among dead standing trees.In the natural recovery stand,only Tilia amurensis among dead standing trees were dominant.According to the diameter distribution and height distribution of dead standing trees,the proportion of small individuals of dead standing trees in two stands were more than 50%,so it could be analyzed that the main reason for the formation of dead standing trees in two stands was inter-specific competition,and the small individual trees were suppressed.In the natural recovery stand,13.6%of the dead standing trees with random distributed and absolute disadvantage,which all the surrounding trees were of other species.In the selective cutting stand,17.5%of the dead standing trees with random distributed and absolute disadvantage,and the dead standing trees surrounding dead standing trees trees were all other species.The results showed that the dead standing trees in the two stands were randomly formed,the spatial structure of the dead standing trees in the selective cutting stands was poor,and the degree of inter-specific mixture in the natural restoration stands was greater.According to the quadrivariate distribution of spatial structure parameters of dead standing trees,which in two stands was random,with strong inter-specific mixture and obvious size differentiation.The quadrivariate distribution can reflect the existence of 3-4 live standing trees around the dead standing trees in this state.The above information further indicates that inter-species competition was the main reason for the formation of dead standing trees in two stands.To the important value of the seedlings,it was 7.92 in natural recovery stand and 3.88 in selective cutting stand to the soft broad-leaved tree species(heliophile),while,it was 64.46 in the natural recovery stand and 68.86 in the selective cutting stand to tolerant tree species.the seedlings showed clumped distribution at the scale of 0-18m in natural recovery stand,while at the scale of 0-15m in selective cutting stand.The seedling clumped intensity in the natural recovery stand was large,while it showed random distribution on a large scale in both two stands.more than 40%tree species pairs were negative correlated at the large scale from 14 to 45m in the natural restoration stand,and about 60%of species pairs at all the scales did not have correlation in the selective cutting stand.In summary,this paper based on the trivariate and quadrivariate distribution of structural parameters to analyze the information of vertical structure,dominant tree species,dead standing trees in the secondary forest of Tilia amurense.And the complex stand space structure was visually displayed in the form of 3D.These information provide the basis for accurate adjustment of stand structure.The study showed that the overall horizontal distribution pattern of the two stands tends to be reasonable.In the management of stands,the dominant degree of tree species,the competitive relationship between trees should be adjusted and the establishment of top-level communities.Through trivariate distribution of spatial structure to select the cutting wood in the stand precisely.When two stands was managed,firstly,the inferior trees with clumped distribution which were surrounded by four trees of the same species were firstly selected as the cutting target.Secondly,the inferior trees with clumped distribution which were surrounded by three trees of the same species were selected as the secondary cutting objects.In addition,the inferior trees with clumped distribution which were surrounded by two trees of the same species as the alternative cutting object.The stand structure was gradually improved by cutting several times in a small amount.The climax community of the forest was established by replanting the dominant tree species and the climax tree species(Korean pine).To promote the succession process of stands and truly realized the restoration and management objectives of the secondary forest of Tilia amurensis. |
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