Seed Dispersal Of Quercus Variabilis Trees Under The Mediation Of Animals:from Seed To Seedling

As the key period of plant regeneration,seed dispersal has very important effects on population dispersal and community structure of plants.Scatter-hoarding animals(e.g.,rodents and jays)have critical effects on seed dispersal and regeneration of plants because they move seeds far away from the mother trees and buried them at safe sites(scatter hoard seeds).Some of these seeds will become to seedlings when they escape from predation by animals.A lot of studies have researched the effects of animals on seed dispersal in many plant species,but few of them have looked at the whole process from seed to seedling in the fragmented forests(e.g.,urban forest patch)where are lacking of animals dispersers.In this study,I tracked seed production,animal-mediated seed dispersal(e.g.,rodent),seedling establishment and seedling growth of Quercus variabilis from 2015 to 2017 in the Jiufeng Hill Ecological Park.Dispersers of animals(e.g.,rodent)have sharply reduced in the forest patches of the park due to forest fragmentation and human being disturbance.I wanted to know the details from seed to seedling of Q.variabilis under the reduction of animals in the fragmented forests.The results showed that:1)The stage of seed production:traits of mother tree affected seed production and seed morphology,in 2016,seed production was negatively correlated with the canopy coverage of mother tree;the percentage of abortive seed was negatively related to the distance from mother tree to highway and the nearest neighbor;the percentage of intact seed was positively correlation with the distance from mother tree to the nearest neighbor.In 2017,seed production was positively correlated with the height of mother tree.In 2015,the ratio of seed length and wide was positively correlated with the canopy coverage of mother tree;in 2016,seed length was positively correlated with the distance from mother tree to the nearest neighbor.2)The stage of seed dispersal:the results of the 2015 and 2016 showed that traits of mother tree affected seed fate.In 2016 we studied the effects of seed morphology on seed fate.The results showed that seed morphology also affected seed fate.We found that Sus scrofa,Arctonyx collaris,Niviventor confucianus and Lepus capensis prefers medium-sized seeds were the main seed predators in the study area.Only N.confucianus have the behavior of scatter hoarding,however,no seeds were found scatter hoarded during the period of observation,suggesting that Q.variabilis seeds were hardly dispersed by animals due to reduction of seed dispersers.3)The stage of seed germination and seedling establishment:seed morphology affected seed germination and the height of seedling,in 2016,there was a positive correlation between seed germination schedule and seed weight,seed length and seed width.In 2017,the germination speed was positively correlated with seed weight,seed length and seed width,and negatively correlated with the ratio of seed length/width.In 2017,height of seedling was positively correlated with seed weight during 11-20 days.During 51-60 days,height of the seedling was positively correlated with the seed weight and seed width.The percentage of germination seeds was significantly higher in 2015.The percentage of seedling establishment was significantly lower in 2017 than the other two years under natural conditions.In terms of artificially buried seeds,the results were the opposite:the percentage of seedling establishment in 2017 was significantly higher than the other two years.These results suggested that traits of mother tree affected seed production and seed morphology;traits of mother tree and seed morphology affected the hoarding behavior of rats;seed morphology affected seed germination and the height of seedling.In other words,the traits of the mother tree affected the whole process from seed production to seedling directly or indirectly.The findings could be used as a reference for exploring the stability and function maintenance mechanism of urban forest patches and urban green space ecological-based management.