Litterfall Dynamic Characteristics And Its Affecting Factors In Natural Secondary Forest Of Pinus Tabulaeformis In Lingkong Mountain,Shanxi

Lingkong Mountain in Shanxi Province is a typical warm coniferous forest in China,which is a natural secondary forest distribution area of Pinus tabulaeformis.The dynamic monitoring research platforms of the 4 hm² of P.tabulaeformis-Quercus wutaishanica mixed forest constructed in 2011 and the forest of 1 hm² of P.tabulaeformis planted in 2013.The data of litterfalls monitored from 2015 to 2016 are taken as the research object.Based on the survey data of ecological communities of the plots,the litter composition,interannual dynamics,and monthly dynamic characteristics of the two community types are analyzed using Excel.And using the pearson correlation analysis method to analyze the correlation between the quantity of litterfall and topographical factors,the defoliation amount of the main tree species and the characteristics of the tree within different radius of the collector,the main results are as follows:?1?Composition and dynamics of litter:In 2015,20 and 10 species of litter were collected from P.tabulaeformis and Q.wutaishanica mixed forests and Pinus tabulaeformis forest,while in 2016,15 and 10 species of litter were collected respectively.There were 10species and 6 species common speciece in the both forest during two years,respectively.In general,the highest number of litter species was collected in October in both communities.Litter composition and dynamics:The litter mass of mixed forests in 2015 and 2016were 9267.956 kg·hm^-2 and 5650.262 kg·hm^-2.The litter mass of pure forests were 9349.466.kg·hm^-2 and 575.131 kg·hm^-2.In 2016,the litter mass and the litterfall of each component of the two community types decreased from the previous year,and there is no significant difference for the amount of litter of the two community types in the same year.The amount of fallen leaves accounts for the largest proportion in litterfall,reaching 45-70%.The proportion of offshoots is relatively stable?10%-14%?.The amount of flower falling changed differently between the two communities,the amount of flower falling and the amount of fallen seed in the mixed forest were reduced,but the reduction range was different.The monthly dynamics of litterfall in different litters of the two communities were compared.It was found that the monthly dynamic patterns of litter mass in mixed forests and the pure forest were both single-peak,with high peak concentrations appearing in October and November.The time at which the min of the litter mass occurs is not stable.The monthly dynamic patterns of litter components were different.The amount of fallen and fallen branches was single-peak,and the peak was consistent with the annual litterfall.The monthly dynamics of the amount of fallen flowers of mixed forests was bimodal,and the peak of two years are in June and July and September and October,respectively,while the monthly dynamics of the pure forests were single-peak,whose the peak in two years appeared in June and July,respectively.In 2015,the monthly dynamics of seed litters of the two communities were both single-peak,with peaks in September and October,but irregular in 2016.The spatial distribution pattern of litter:The number of litter species and weight of litter collected by each collector are quite different,and the quantity of litter and species collected by each collector during the interannual period are also different,indicating that litter is in the horizontal space.There are differences in the distribution pattern,and the horizontal spatial pattern of litter also varies between years.?2?By analyzing the correlation between litterfall and topographic factors?elevation,slope,aspect,and asperity?,the correlation between the two is not significant,indicating that the topographic factors of natural secondary forest of Pinus tabulaeformis in Lingkong Mountain have an less effect on litterfall.?3?11 and 5 litterfall of tree species were collected respectivily in mixed forests and pure forest for two years.The amount of fallen leaves of Pinus tabulaeformis decreased by16%and 32%in 2016,respectively.,while the leaf weight of Q.wutaishanica increased by4%and 59%respectivily.By analyzing the correlation between the weight of leaf of main tree species and the characteristics of their mother trees in the two communities,it was found that the main tree species of mixed forest and the pure forest were extremely significantly related to the characteristics of their mother trees.The correlation between the amount of defoliation in the main tree species and the characteristics of the mother trees with radius of10m,20m,and 30m from the collectors was found.The results showed that the relationship between the defoliation weight and the different radii distance of the mother tree was not significant in pure forest,while the relationship between the leaf weight of Pinus tabulaeformis and the tree?s characteristics at different distances in the mixed forest was inverse proportion,and the correlation of other species is not obvious.