Changes of the oribatid community after a windthrow event

Abstract

In December 1999 the winter storm ‘Anatol’ hit the southern coast of the Baltic Sea and caused damage toforest areas along the coast. On the Darss peninsula in north-eastern Germany the storm destroyed one relatively large forest area and several small ones. Interestingly, mainly spruce trees were affected. The large windthrow area measured about 2.5 ha. This area was chosen to investigate the long-term effects of a windthrow event on the fauna. Repetitive sampling was carried out in the first 4 years after the storm (2000-2003) and in the 6th year (2005), and additional samplings are planned for the 10th and the 15th year. To investigate the soil micro-arthropods, in 2000-2003 samples were taken three times a year, in spring, summer, and autumn, directly under root plates of two fallen spruce trees, in the windthrow area, and in adjacent pine and spruce stands. Altogether 81,023 specimens of oribatid mites had been found in all 4 years. Results show that the overall abundance of oribatid mites decreased from 2000 to 2002 on almost all plot – including the control plot in the fir forest –, before their numbers started to increase again in 2003. On the plots underneath the root plates the abundance of oribatid mites increased continuously over the years as the plots were recolonised. The oribatid mite community on the windthrow area changed over the years, but these were quantitative rather than qualitative changes.