DYNAMICS AND STRATIFICATION OF PROTOZOA IN THE ORGANIC LAYER OF A SCOTS PINE FOREST

Fluctuations in soil biota abundance in different organic layers of a Scots pine forest in The Netherlands were studied by bimonthly counts during 2.5 years. The counts were made using litterbags which were pla ced in the litter (L), fragmentation (F) and humus (H) layers at the s tart of the experiment. Results from the L layer were also compared wi th results from litter which was renewed every 2 months (L') to study colonisation. In this study the results for amoebae, flagellates and c iliates are presented. The highest numbers of soil protozoa were found in the L layer during most sampling occasions. The H layer contained the lowest numbers. The L layer also showed higher numbers than the L' litterbags which were renewed every 2 months. Fluctuations in abundan ce could partly be explained by fluctuations in moisture content. Mois ture content in the litterbags was rather constant throughout the expe riment, although occasionally moisture contents of 10% and 80% were ob served. Fluctuations in moisture content in the L layer were often lar ger than in the F and H layers. Flagellates were the most abundant gro up, reaching numbers of several hundred thousands to several millions per gram fresh weight on various occasions. Amoebae often reached numb ers of between tens of thousands and several hundred thousands. Ciliat es only reached numbers of up to several thousands.