| Evergreen broad-leaved forest plays an important role in global carbon cycle and forest resources.The distribution area of evergreen broad-leaved forest in China is the largest in the world.However,due to the destruction and felling of human activities,the original evergreen broad-leaved forest is less preserved and gradually replaced by artificial or semi natural coniferous forest.Therefore,the restoration and protection of evergreen broad-leaved forest is very important.Based on the survey data of 1 hm2(100 m × 100 m)evergreen broad-leaved forest in Tianmu Mountain,Zhejiang Province,four dominant tree species with more than 100 individuals were selected as the main tree species: Phoebe sheareri,Cunninghamia lanceolata,Torreya grandis and Cyclobalanopsis gracilis.By analyzing the age structure,survival curve,competition index,spatial distribution pattern and correlation of the four main tree species,the relationship and spatial distribution of the main tree species were discussed It is expected to provide a reference for the protection of evergreen broad-leaved forest in Tianmu Mountain.The main results are as follows:(1)There are 2,282 woody plants with DBH ≥ 1cm in evergreen broad-leaved forest community,belonging to 90 species,65 genera and 39 families.According to DBH size,the measured plants were divided into small diameter(1cm < DBH ≤ 10cm),medium diameter(10cm < DBH ≤ 20cm)and large diameter(20cm < DBH).According to the number and species richness of individual trees and plant species,small diameter level > medium diameter level > large diameter level;according to dominance index and diversity index,small diameter level > large diameter level According to the evenness index,large diameter level > medium diameter level > small diameter level.Through the calculation of the important value,it is concluded that the dominant species in the sample plot are Phoebe sheareri,Cunninghamia lanceolata,Torreya grandis,Cyclocarya paliurus,Cyclobalanopsis gracilis,Camellia pubescens,etc.(2)There are 599 Phoebe sheareri trees,whose age structure is dominated by diameter class 1young individuals,and the survival curve is deevey Ⅲ;there are 134 Cunninghamia lanceolata trees,whose age structure is dominated by diameter class 3 old individuals,and the survival curve is deevey Ⅰ;there are 120 Torreya grandis trees,whose age structure is dominated by diameter class 1 young individuals,and the survival curve is between deevey Ⅰ;There are 176 Cyclobalanopsis gracilis plants in total,and the age structure is dominated by diameter class 1 young individuals,which is an increasing population,and the survival curve is deevey Ⅲ.(3)In intraspecific competition,the competition intensity was as follows: Phoebe sheareri >Cyclobalanopsis gracilis > Cunninghamia lanceolata > Torreya grandis.When Phoebe sheareri was taken as the object,the competition intensity was Cunninghamia lanceolata >Torreya grandis>Cyclobalanopsis gracilis;when Cunninghamia lanceolata was taken as the object,the competition intensity was Phoebe sheareri>Cyclobalanopsis gracilis>Torreya grandis;when Torreya grandis was taken as the object,the competition intensity was Cunninghamia lanceolata> Phoebe sheareri > Cyclobalanopsis gracilis;when Cyclobalanopsis gracilis was taken as the object,the competition intensity was Cunninghamia lanceolata> Torreya grandis> Phoebe sheareri.The intraspecific competition between Phoebe sheareri and Cunninghamia lanceolata was stronger than that between species.(4)The population of Phoebe sheareri and individuals of different diameter classes are mainly distributed in clusters,covering a wide range in the evergreen broad-leaved forest,with the highest density in the northwest corner.The population spatial distribution is good,and the relationship between the diameter classes is close and positive correlation.The population of Cunninghamia lanceolata was mainly concentrated in the southeast corner of evergreen broad-leaved forest,and mainly distributed in clusters.Only diameter class 1 and diameter class 2 individuals were randomly distributed in a small spatial scale.The spatial distribution of the population was uneven,and there was a positive correlation between the diameter classes.The population of Torreya grandis distributed in clusters in a small spatial scale and randomly in a large spatial scale,covering a wide range of evergreen broad-leaved forest.The individuals in diameter class 1 were mainly distributed in clusters,while the individuals in diameter class 2 and 3 were mainly distributed randomly.There was a positive correlation between diameter class 1 and diameter class 2 in small spatial scale,but no significant correlation in large spatial scale.There was a negative correlation between diameter class 1 and diameter class 3 in small spatial scale,but no significant correlation in large spatial scale.Diameter class 2 and diameter class 3 are positively correlated in the range of 13 ~ 28 m,while they are not correlated or negatively correlated in other spatial scales,and are mainly negatively correlated in large spatial scales.The population of Cyclobalanopsis gracilis was mainly distributed in clusters,mainly concentrated in the southeast corner of evergreen broad-leaved forest,with uneven spatial distribution.The individuals of diameter class 1and 2 were mainly distributed in clusters,while the individuals of diameter class 3 were mainly distributed in random.There was a positive correlation between diameter class 1 and diameter class 2,but there was no significant correlation between diameter class 1 and diameter class 3,and between diameter class 2 and diameter class 3.(5)In spatial distribution,Phoebe sheareri was negatively correlated with three populations of Cunninghamia lanceolata,Torreya grandis and Cyclobalanopsis gracilis;Cunninghamia lanceolata was positively correlated with two populations of Torreya grandis and Cyclobalanopsis gracilis;Torreya grandis was positively correlated with Cyclobalanopsis gracilis,and with the increase of spatial scale,it first increased and then decreased.Conclusion: the evergreen broad-leaved species in Tianmu Mountain are rich and the diversity is high,especially the richness and diversity of young individuals,the community development is good and the structure is stable.The dominant species are Phoebe sheareri,Cunninghamia lanceolata,Torreya grandis,Cyclocarya paliurus,Cyclobalanopsis gracilis,Camellia pubescens,etc.The dominant species,such as Phoebe sheareri,Torreya grandis and Cyclobalanopsis gracilis,were growth type populations,while Cunninghamia lanceolata was decline type populations.The intraspecific competition between Phoebe sheareri and Cunninghamia lanceolata was stronger than that between species.Phoebe sheareri was in the dominant position in interspecific competition,and negatively correlated with Cunninghamia lanceolata,Torreya grandis and Cyclobalanopsis gracilis in spatial distribution.Cunninghamia lanceolata,Torreya grandis and Cyclobalanopsis gracilis tend to separate from Phoebe sheareri in spatial distribution in order to slow down the competition and exclusion effect of Phoebe sheareri,and achieve coexistence.In terms of spatial distribution,there is a positive correlation between Cunninghamia lanceolata,Torreya grandis and Cyclobalanopsis gracilis. |
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