Effects of the small forest carnivores on the recruitment and survival of Liaodong oak ( Quercus wutaishanica) seedlings

Abstract

Small forest carnivores of weasel family (Mustelidae) such as Sibirican weasel ( Mustela sibirica), the Eurasian badger ( Meles meles) and the hog badger ( Arctonyx collaris) have a habit of digging for soil animals as their food. To offset the food shortage, the carnivores add insects and amphibians hibernating underground in falls to their diet so as to help themselves get through the adverse seasons in the temperate zones. Each time after getting their prey, the carnivores would dig a funnel-like pit on the forest floor. In Dongling mountainous area, about 110 km west to Beijing, where forests are usually dominated by Liaodong oak ( Quercus wutaishanica Mayr.), seed rains of the oak almost concur with carnivores-digging pits in falls. Since they caught and then buried acorns, the pits help the acorns escape predation to a certain extent and thereby benefit the seedling recruitment and establishment by enhancing rates of the acorn and seedling survivals. To verify the effects of the pits on Liaodong oak regeneration, first we investigated the fate of acorns of the oak in its mast year (the year 2000) by surveying pits left by the carnivores in different habitats, then artificially dug pits on the oak forest floor and checked the fate of the trapped acorns, and last examined the seedling recruitment and establishment in the artificial pits in 2000, 2001 and 2002, respectively. The results showed that each of the artificial pit caught an average of 2.0 ± 1.6 acorns ( n = 300), about 1/3 of which remained and got buried; but the circles, which were marked beside each artificial pit on the floor as comparison, caught much fewer acorns at first and none remained a few weeks later after the seed rain. Seedlings of the oak were found emerging from more than 32% of these artificial pits, and about 90% of them survived in 2002. The small carnivores are therefore assumed to facilitate acorn survival and seedling establishment for the oak species in the study area.