Effects of Clear-Cutting on the Enchytraeids in a Scots Pine Forest Soil in Central Sweden

Abstract

The populations of enchytraeids in a Scotch pine forest soil were investigated for 4 yr in a newly-felled area and a control forest, and for 2 yr in a 10 yr old felling. The population of Cognettia sphagnetorum (Vejd.), which comprises 99% of the enchytraeid numbers, increased drastically in abundance a short time after felling. Maximum densities were reached 2.5 yr after felling when plots covered with felling residues had 171,000 individuals m-2 and plots cleaned from slash 129,000 individuals m-2, which was 700 and 500%, respectively, of the population in the control forest. The populations at the clear-cut treatments had returned to the level of the control by 4 yr after felling. In the old clearing, the abundance of C. sphagnetorum decreased to .apprx. 15% of the control. The results are discussed on the basis of changed food availability and changed C. sphagnetorum population qualities. The peak populations in the clear-felled treatments differed widely from the control; gregarinid parasitized worms were more frequent, and sexually mature C. sphagnetorum were found for the 1st time at the site.