Study site
Field sampling was carried out in the Central and Southern Black Forest
in southwest Germany. The 135 research plots each measured 100 x 100 m
in size with a minimum distance of 750 m between plots. These plots
belong to the ‘Conservation of forest biodiversity in multiple-use
landscapes of Central Europe’ research project (Storch et al. 2020, Fig.
2), and are all located in temperate mountainous forests between 434 m
and 1334 m above sea level. The annual average temperature is about 6.9
°C with a yearly average precipitation of 1205 mm (climate station of
the city of Titisee-Neustadt, www.climate-data.org , accessed
2020/2/16).
Forests are dominated by Abies alba, Fagus sylvativa andPicea abies growing on cambisol, umbrisol and podzoles. The
forest stands are managed with continuous cover forestry (Gustaffson et
al. 2019). The bedrock consists of gneiss and granite in the west, with
lower Triassic sandstone and middle and upper Triassic limestones
towards the east.
We selected the plots to cover a large landscape and forest structure
gradient. For the landscape gradient, we set three categories of forest
cover within a 25 km radius from the centre of each plot: <
50%, 50–75% and > 75% forest coverage estimated by
raster data (state agency of spatial information and rural development
of Baden-Württemberg, accessed 2016). Additionally, we obtained the
forest structure gradient based on the number of standing dead trees
assessed from aerial images ((state agency of spatial information and
rural development of Baden-Württemberg, accessed 2016): 0, 1-9,
>10. Detailed information can be found in Storch et
al.
(2020).