Effect of tree seed crop on small mammal populations and communities in oak and beech forests in the Drahany Upland (Czech Republic)

In 2002 (year with poor seed crop) and 2003 (year with good seed crop), the trapping of small mammals was carried out into standard snap-traps on transects situated in the area of the Křtiny Training Forest Enterprise, U buku locality (the Drahany Upland). The trapping was carried out in both years once a month in the period of September-November, in two types of forest of the community Querci-fageta: in a stand dominated by oak and in a stand dominated by beech. In total, 146 individuals were recorded, out of them 142 rodents - Apodemus flavicollis (81 individuals), Apodemus sylvaticus (32), Clethrionomys glareolus (29) and 4 individuals of insectivores - Sorex araneus. Apodemus flavicollis dominated in both types of stands. In the most numerous Apodemus flavicollis, body dimensions were compared between oak and beech stands; the differences were not significant. Species diversity (owing to the presence of Sorex araneus) is slightly higher in oak stands (diversity index H' = 1.60) as compared with beech stands (H' = 1.43). From the aspect of faunistic similarity, it is the case of very similar communities (Re = 97.3; IBC = 0.79). In all trapped individuals, basic body parameters were measured. In the oak forest, a higher total abundance was determined in all species as compared with the beech forest. Rodent populations responded to the poor crop of beechnuts and acorns in 2002 by a decline in numbers and to the good seed crop in 2003 by an increase in numbers (Apodemus spp.). Another response was the prolongation of reproduction period. In stomachs of the rodents caught in 2003 the percentage of starch granules of consumed food was superior to 2003.