Seed Predation And Seed Dispersal Of Common Lithocarpus Species By Insects And Rodents In The Ailao Mountain

Many animals predated and dispersed plants’ fruits and seeds in the forest ecosystem, such as birds and rodents. In general, the propagules of plants were exposed to high risk of attacking by natural predators, such as insects, vertebrates and fungi. Most rodents consumed large quantities of plants’ seeds and fruits. On the other hand, they disperse their seeds and fruits away from parent trees or other seed sources via their hoarding behavior and scattering them under the litters or in the shallow layers of the surface oil, which may influence spatio-temporal distribution of the seeds and fruits, and consequently provided advantageous conditions for seed germination and seedling establishment. Pre-dispersal seed predation suggested that seed damage through feeding and consumption of many animals such as insects and boreal mammals before seeds depart from the mother tree. In general, pre-dispersal seed predation is affected not only by seed crops and seed traits, but also by predator species such as insects and rodents. The time and intensity of seed predation can be a major selective force in the evolution of life-history traits in plants, such as germination rates and production of a soil seed bank. Predator satiation is a highly coevolved behavior interaction of plant with seed predator, and it has been proposed as a selective factor limiting the destructive abilities of animals and promoting the survival of dispersed seeds. A large number of animals hoard plant seeds. This behavior not only adjusts spatio-temporal distribution of food and enhances animal survival in times of food shortage, but also promotes seeds dispersal.The Ailao Mountains is one of the biggest subtropical forests existed in the world. Fagaceae are dominant or common species in this region. To reveal the relationships between these Fagaceae species and related seed-eating animals are important to better understand the mechanisms of species diversity. From September to December of 2013 and 2014 in Ailao Mountain, we studied the dynamics of weevil-infested acorns and soil seed bank, and seed predation and dispersal of common Lithocarpus species by rodents. This study included three parts:(1)the spatial patterns of insect seed predation on Lithocarpus seeds;(2)seasonal dynamics of the scatter-hoarding behavior of seed-dispersing animals of three common Lithocarpus species;(3)annual soil seed bank of three common Lithocarpus species.The results showed:(1)Our results showed that Dremomys rufigenis, Niviventer coxingi, Apodemus draco and R.f.fvlrescens were main seed dispersers and predators.(2)In the present study, insects are important seed predators for the three common Lithocarpus species. Insects included Curculio spp. and Hylobius Germar and Cynipid(gall wasps). Among these insects, Curculio spp. was the main insect seed predators, but the damage caused by the other two insect groups was relatively small.( 3) In 2013, there was no significant difference between intact and weevil-infested seeds of 3 kinds of Lithocarpus species in their different dynamic. As time goes by, forest rodents have the ability to detect weevil-infested seeds of Lithocarpus pachyphyllus var. Fruticosus and Lithocarpus xylocarpus. Predicted that when food resources were relatively poor, rodents weakened their selecting strategy and tended to eat both kinds of acorns simultaneously.(4)Based on investigation data from 100 quadrates in 4 typical sample plots, seed loss occurred mainly in ways of germination, vermiculating, physiological death, predation and removal by animals and mildewing, among which predation and dispersal were not the most primary factors, and the insect-infestation rate was higher in low-yield year than that in high-yield year. Above all,Variation of seeding-mast may be a defensive strategy that plants response to seed predators: mast year rate of insect-infestation was lower, and much more intact seeds in soil seed bank, as well as rodents can identify intact and infested seeds of Lithocarpus pachyphyllus var. Fruticosus and Lithocarpus xylocarpus, but was not sensitive to Lithocarpus chintungensis; whereas rate of insect-infestation was higher, and higher percentage of infested seeds in soil seed bank, rodents tended to feed intact and infested seeds of Lithocarpus species at the same time in non-mast year. The results indicated that during the year of mast seeding, a large number of seeds might have more chances to escape animals’ predating, thereby increasing the opportunities of germination and seedling building, which promoted the regeneration of plant finally. In all, it is supporting the hypothesis of predator satiation.