Materials and methods
Study site description
The study was conducted in a species-rich deciduous forest in the Hainich National Park, Thuringia, Germany. This national park is one of the largest unfragmented broad- leaved forests in Europe. It contains areas of diVerent levels of tree species diversity due to diVerences in forest manage- ment strategies in past centuries. For selecting the study plots, the whole area of the national park was screened for possible study plots that met the following criteria: (1) the stands should be dominated by either one, three, or Wve tree species (with European beech being present at variable den- sities in all stands), (2) all plots being mature stands with the trees of the diVerent species in the age of maximum pro- ductivity (80–150 years), (3) comparable above-ground stand structure in terms of basal area and dbh, (4) similar climate conditions, and (5) comparable soil conditions in terms of geological substrate (Triassic limestone covered by Pleistocene loess), similar soil texture, and comparable thickness of the mineral soil proWle depth above the bed- rock. The selection procedure resulted in about 20 possible sites that met these criteria suYciently. In this sample, the 12 study plots (50 m £ 50 m) which fulWlled these criteria best were selected representing three diversity levels (DL 1, DL 2, DL 3) with each four plot replicates. Maximum
Materials and methodsStudy site descriptionThe study was conducted in a species-rich deciduous forest in the Hainich National Park, Thuringia, Germany. This national park is one of the largest unfragmented broad- leaved forests in Europe. It contains areas of diVerent levels of tree species diversity due to diVerences in forest manage- ment strategies in past centuries. For selecting the study plots, the whole area of the national park was screened for possible study plots that met the following criteria: (1) the stands should be dominated by either one, three, or Wve tree species (with European beech being present at variable den- sities in all stands), (2) all plots being mature stands with the trees of the diVerent species in the age of maximum pro- ductivity (80–150 years), (3) comparable above-ground stand structure in terms of basal area and dbh, (4) similar climate conditions, and (5) comparable soil conditions in terms of geological substrate (Triassic limestone covered by Pleistocene loess), similar soil texture, and comparable thickness of the mineral soil proWle depth above the bed- rock. The selection procedure resulted in about 20 possible sites that met these criteria suYciently. In this sample, the 12 study plots (50 m £ 50 m) which fulWlled these criteria best were selected representing three diversity levels (DL 1, DL 2, DL 3) with each four plot replicates. Maximum
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