Seed Abundance Dynamics Of Corylus Mandshurica And Quercus Mongolica And Their Effects On The Population Fluctuations Of Small Rodents

Rodent population dynamics can be regulated by various external environmental factors. The effects of food availability on rodent population have been the focus of ecological research. Here, we conducted field investigations combined with the experiments in the lab and semi-natural enclosures, in an attempt to analyze annual seed abundances of Corylus mandshurica and Quercus mongolica and their influences on population fluctuations of small rodents Tamias sibiricus and Apodemus peninsulae in Xiaoxing’anling Mountain areas. To understand the regulating mechanism of seed abundance, we also studied the influence of different seeds on food hoarding behaviors, survival, growth and physiology of the two rodent species. The main results included:(1) The seed abundances of C. mandshurica and Q. mongolica fluctuated among the eight years. The seed crops of C. mandshurica were significantly positively correlated with the mean temperature of in April in the current year, while no significant correlation was found between precipitation. The seed crops of Q. mongolica were significantly and positively correlated with the mean temperature in May; however, there were no significant correlation with precipitation.(2) Our enclosure experiments showed that both T. sibiricus and A. peninsulae consumed seeds of C. mandshurica and Q. mongolica. Despite differences in food hoarding patterns, the two rodent species hoarded seeds of the two local tree species for food supply. Therefore, seeds of C. mandshurica and Q. mongolica appeared to be the main food resource of T. sibiricus and A. peninsulae for winter survival.(3) The populations of both T. sibiricus and A. peninsulae fluctuated significantly among the studied years as indicated by trap success. Trap success of A. peninsulae was consistently higher than that of T. sibiricus. Further analyses indicated that trap success of T. sibiricus in the current year was significantly and positively correlated with seed crops of C. mandshurica in previous year, but negatively correlated with acorn crops of Q. mongolica. Differently, trap success of A. peninsulae was unable to be explained by seed crop of either C. mandshurica or Q. mongolica. However, it was found to be positively correlated with the sum of seed crops of C. mandshurica and Q. mongolica in previous year. These results indicate that seed abundances of C. mandshurica and Q. mongolica show different effects on the population fluctuations of the two small rodent species.(4) Feeding with seeds of C. mandshurica showed no significant effects on survival rates of both T. sibiricus and A. peninsulae. Moreover, the mean body masses of T. sibiricus and A. peninsulae tended to increase when fed with seeds of C. mandshurica. However, feeding acorns of Q. mongolica reduced survival rates of T. sibiricus but not A. peninsulae. Although survival rate was not significantly affected, the body masses of A. peninsulae and T. sibiricus decreased significantly. We propose that different physiological responses to seeds of C. mandshurica and Q. mongolica may be the main reason to explain the different effects of seed abundance on the population fluctuations of the two small rodent species.