The Mechanisms Of Quercus Acorns To Counter Predation By Rodents And Insects

In2009,2010, and2011, seed rain and insect infestation of two oak species(Quercus aliena and Quercus variabilis) were investigated in the National Forest Parkof Tianchi Mountain, Luoyang, Henan province. At the same time, acorn germinationexperiments were conducted in the lab to explore the mechanisms of several Quercusacorns to counter seed predation by rodents and insects in Henan University of Scienceand Technology. The results showed that:1. In the three years of2009to2011, the crop sizes of Quercus aliena andQuercus variabilis changed significantly. There were very few seeds trapped in theyear of2010. The overall infestation rates of Quercus aliena and Quercus variabilis ofthe three years are36.18%and13.68%.2. The germination rates of the infestation acorns were significantly lower thanthose of the healthy ones; the large acorns showed higher germination potential thansmall ones. The upper part removal of cotyledons exhibited significant impact onacorn germination, indicating its importance in supporting acorn germination andseedling growth.3. However, the number of leaves of seedlings developed from uninfested acornswas significant lower than those from insect damaged acorns, possibly reflecting theinduction effect of insect damage on ramet tillering of infested acorns. The feedingactivity of larvae in acorns did not necessarily result insignificant negative effect onseedling growth, but the apical cotyledon loss by artificial excision would causenegative effects.4. Simulated radicle removal by rodents, in one hand, affected germination ratesof the pruned acorns. In another hand, radicle removal promoted the accumulation ofabove-ground biomass of seedlings. Simulated radicle removal induced the prunedacorns to produce multiple adventitious roots; however, reduced root length, and the below-ground biomass.5. When the radicle reached10cm in length, the pruned radicles showed greatpotential to regenerate into normal seedlings even if the cotyledons were removed.Regeneration from the pruned radicles may serve an alternative way to cope withpredation by rodents and other animals in the field..6. Simulated removal cotyledons by rodents had no significant effect on thegrowth of several oak seedlings. A variety of oak seedlings can survive even withoutthe nutritional support of cotyledons when the epicotyl was more than4cm in height.