Seed dispersal of three sympatric oak species by forest rodents in the south slope of Qinling Mountains, China

Forest rodents,as seed predators and dispersers,play important roles in the regeneration of plants. Seed characteristics and food abundance influence the eating and hoarding strategies of rodents. In order to understand the seed selection differences by rodents,in 2011 and 2012 three sympatric Fagaceae plants( Quercus aliena var. acuteserrata,Q. variabilis and Q. serrata var. brevipetiolata) were used to study seed dispersal in Foping National Nature Reserve,located in the Qinling Mountains,China. Prior to the experiment,rodent density was surveyed from August to October of each year.Cage traps( 27.0 cmx14.0 cmx14.0 cm),baited with peanuts,were set 10 m apart along two transects in each plot and were deployed from 17: 00 to 17: 30 daily. Traps were checked after 14 hours and all captured rodents were processed and immediately released. The seed mast was also surveyed from mid-August to late November of each year. 36 collection boxes were set up under 36 trees( 12 trees of each species). The collection boxes were approximately 1 m2 and were monitored every 7 days. Physical properties of the collected seeds were measured by technicians in the lab and chemical propertieswere determined by the Center of Grain Quality at the Ministry of Agriculture,China. Seed dispersal was surveyed in a deciduous broadleaved forest each year. Ten sites( 1 mx1 m) were established as seed stations with a minimum distance of15 m from one another. 20 tagged seeds of each of each of the three tree species( n = 60) were placed at each station. Seed counts at each box occurred on days 1,3,5,10,17,27 and 50 following presentation. Missing seeds were located by visual search and their fates followed. The results showed that:( 1) rodents preferred to cache Q. variabilis seeds( with higher energy) at a greater distance,and eat Q. serrata var. brevipetiolata( with lower energy) in situ. Q. variabilis were cached farther than Q. variabilis( 2011: 1.52 m,2012: 4.03 m). All three seed types were cached further when food was scarce.( 2) In a mast seeding year( 2011),rodents consumed seeds slowly and cached more seeds. 67. 33% seeds remained at each station on the 10 th day,and 29. 67% seeds remained in caches on the 50 th day. In the year that food resources were relatively poor,rodents tended to eat more seeds. All seeds were removed by the 10 th day and only 3.83%seeds remained in the caches on the 50 th day. When food was most scarce,all three kinds of seeds were cached less.( 3)Although m