Spatial Patterns And Interspecific Spatial Associations Of Tree Seedlings In A Secondary Forest In Montane Region Of Eastern Liaoning Province,China

Secondary forest has become the main part resource of montane region of eastern Liaoning province,China.With quadrat and quantity ecology methods,combining two null models,this paper studied the species composition,spatial pattern and interspecific spatial associations of tree seedlings of secondary forest in the montane region of eastern Liaoning province,to provide scientific basis for secondary forest management and the restoration and protection of vegetation,etc.The main results are as follows:1.Based on the analysis of 4-ha survey data of woody seedlings,There were 22 species of tree seedlings,belonging to 11 families in secondary forest in the montane region of eastern Liaoning province.The main tree species were Fraxinus rhynchophylla,Acer mono,Juglans mandshurica,Syringa reticulata,Acer pseudo-sieboldianum,Fraxinus,et al;15760 tree seedlings were recorded,Fraxinus rhynchophylla had the largest number of individuals,accounting for 32.93% of the total number of individuals;The numbers of tree seedlings showed great variations among different quadrats,Juglans mandshurica had the largest numbers of quadrats at two scales of 5m×5m and 10 m×10 m,while Acer mono and Juglans mandshurica had the largest numbers of quadrats at two scales of 20 m×20 m;The height structure of all individuals showed reversed "J" shape,and there were differences in the height structure of tree seedlings with abundance above 100;The dominant species(Fraxinus rhynchophylla,Acer mono)showed significant aggregation pattern,Juglans mandshurica,Acer tegmentosum,etc.showed obvious difference.2.This study analyzed spatial patterns of tree seedlings in a secondary forest at scales of 0-50 m.The results showed that: under complete spatial randomness null models,94% of the species at the scale of 0-20 m showed significant aggregation pattern,and all of the species at the scale of 0-4 m showed significant aggregation pattern;the proportion of species exhibiting aggregated patterns decreased with spatial scale,at the scale of 50 m,the random distribution pattern became the main form of tree species distribution;under heterogeneous Poisson process null model,about 6% of the species at the scale of 0-24 m showed significant aggregation pattern,48% and 52% of the species at the scale of 26-50 m showed random distribution and regularity pattern respectively;species attributes had no significant influence on tree seedling aggregation,which indicated that the spatial pattern was mainly influenced by seed dispersal limitation and habitat heterogeneity.3.This study analyzed interspecific spatial associations of trees and tree seedlings in a secondary forest at scales of 0-50 m.The results showed that: Under complete spatial randomness null models,the proportion of species pairs of positive correlation was highest,at the scale of 50 m,the proportion of species pairs showed positive correlation,uncorrelated and negative correlation tended to be equal;under heterogeneous Poisson process null model,species pairs mainly showed negative correlation,and the proportion of species pairs exhibiting negative correlation increased with spatial scale;Under two null models,the proportion of species pairs exhibiting uncorrelated of trees was higher than which of tree seedlings,under complete spatial randomness null models,the proportion of tree species pairs exhibiting uncorrelated correlation at scales of 0-50 m was higher than negative correlation.Under heterogeneous Poisson process null model,only 2% of trees species pairs showed positive correlation,the proportion of species pairs exhibiting negative correlation increased with spatial scale,at the scale of 50 m,64% of the trees species pairs showed negative correlation,under complete spatial randomness null models,only 18% of the trees species pairs showed negative correlation,which indicated that the interspecific spatial associations of trees and tree seedlings closely,which mainly influenced by habitat heterogeneity in the montane region of eastern Liaoning province.