Net production of small rodents in deciduous forest

Abstract

In deciduous stands (Tilio-Carpinetum) of the Niepolomicka Forest (Southern Poland) the numbers of rodents were estimated during four consecutive years by means of prebaiting and intensive removal method. Bank voles (Clethrionomys glareolus) and yellow-necked field mice (Apodemus flavicollis) constituted 92.5°/o of all rodents in this forest. Small rodents went in this period through a population cycle from a high density (32.1 vole and 5.9 mice per ha during the year on the average) to a low density (8.1 and 2.0 individuals, respectively). The mean number for the four year cycle amounts to 19.0 rodents/ha. When young animals staying in the nests are also taken into account the mean numbers should be increased by approximately 20%. The age of mice and voles was determined and then life tables were constructed and curves of individual growth were drawn. At high population density the mean life span of voles amounts to 2.2 and mice to 2.4 months, while at low density the corresponding figures are 2.6 and 3.3 months. The rate of body weight increase was lower in the year of mass occurrence. The turnover of individuals was also related to density and in the population of voles it ranged from 5.5 to 4.6 per year, while in the population of mice -from 5.0 to 4.0 per year. The turnover of biomass amounted on the average to 3.6/year in both populations. The number of rodents born during the year was estimated and the net production was computed from the curves of their growth and survival. In consecutive years the net production ranged from 755 to 2691 g/ha year, out of this 562 to 1977 g/ha year falling for voles and 177-755 g/ha year for mice. The mean year production of all rodents amounted to 1360 g, which corresponds to 1983 kcal/ha year. The net production of rodents was compared in a dozen or so forest and grassland ecosystems. A logarithmic describing the relationship between the production of a population and its mean year density was calculated on the example of voles population.

Changes of body weight and hematological parameters in a fluctuating population of Apodemus flavicollis

“…All this led to earlier occurrence of maximum numbers in the peak year {e.g. Bobek, 1973). Any winter reproduction in A. flavicollis has never been observed in Białowieża Primewal Forest.…”

Senescence in Natural Populations of Mammals: A Reanalysis

“…Although the correct reference for Microtus is lacking, the life table used by Promislow (1991) is very similar to captive populations (e.g., Leslie and Ranson 1940) with much longer life span (about 90 wk) than in natural conditions [about 60 wk (Myllymaki 1977)]. And in Clethrionomys, high within-year variability in density precludes valid use of life tables for estimating survival (Bobek 1973). We must ask, therefore, if the relationship between life span and senescence is just a consequence of poor data for some murids.…”

Gradients in density variations of small rodents: the importance of latitude and snow cover

“…East Europe (only Clethrionomys glareolus): Andrzejewski 1975Bobek 1973;Grodzinski et al 1970 andRyszkowski 1971 for Poland and a compilation of many papers from U.S.S.R. in Bashenina (1981 …”