| The Korean pine(Korean pine)broad-leaved mixed forest is the climax community type of the northeast forest area.The community is not only with high species diversity and large biomass,but also the structure of the community is more stable and complex.However,due to historical reasons and unreasonable operation in modern times,its forest structure has been severely damaged and its stand quality has been reduced.Since the implementation of the"Natural Forest Protection Project"in China,many measures have been taken to protect and restore the Korean pine broad-leaved mixed forest.Therefore,the research on it is of great significance.A 1.44-hm~2 Korean pine broad-leaved mixed forest plot was established in the Hongshi National Forest Park in Huadian City,Jilin Province,northeast China in 2016to analysis the spatial patterns and associations of the 8 major species in order to gain insights into the ecological process of population formation and mechanism of species coexistence.All trees at least 3.1cm in diameter at breast height(DBH)were mapped and investigated,recorded the species name,number,DBH and relative coordinates.The spatial distribution patterns and spatial associations of 8 main tree species at two different life-history stages at different scales were analyzed by using the point pattern method which univariable and bivariate pair correlation function.We found that:(1)1135 individuals were recorded in the plot that belonging to 12 families,14genera and 22 species.The diameter class structure of all individuals in the plots showed an obvious"L"type,indicating that the regeneration of the community was good and belonged to the growth type stand.The 8 main tree species had more small diameter trees,and the number decreased with the increase of diameter class except Abies holophylla and Tilia amurensis.(2)The spatial distribution of main tree species in the plot varied with spatial scales and tree size,and was affected by habitat heterogeneity.Generally speaking,they were aggregated at small scales,and appeared random distribution with the increase of scales;moreover,with the increase of diameter class,the degree of aggregation generally decreased.When habitat heterogeneity existed,the distribution of aggregation was mainly at the scales of 0-30m;after removing habitat heterogeneity,the scales of aggregation decreased significantly,mainly in the range of0-5m or 0-10m.It showed that the distribution of tree species in the plot was affected by habitat heterogeneity,and habitat heterogeneity was mainly played at large scales.(3)Spatial correlations were mainly based on uncorrelated and negative correlation.There were only 10 of 56 pairs showed significant associations among the8 populations including 7 pairs of positive associations and 3 negative associations.There were only 2 of 20 pairs showed significant associations among 5 young tree species,and they were positive associations.There had 15 of 56 pairs showed significant associations among adult species,and included 13 pairs of negative associations and 2 positive associations.There were only 6 of 40 pairs among saplings and adults were significant associated,and included 4 pairs of positive associations and 2 negative associations.On the whole,the intra-and interspecific associations of the 8 main species at two different life-history stages in the plot were mainly unrelated and negative related.We infer that seed dispersal limitation,competition ability,and the requirement for topography and light may affect spatial distributions and associations of species,maintaining the coexistence of these species and species diversity of Korean pine broad-leaved mixed forest.Selection of plant species,tree age or DBH size,their horizontal spatial configuration and the effect of habitat heterogeneity are essential in the restoration and management of natural forest and construction of plantation,and our results may provide a scientific theoretical basis. |
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