Soil sampling was carried out on a subset of 100 plots of two overlapping extinction scenarios on Site A (Extinction scenario A and B). The samples were collected from young forest communities composed of 1 - 24 species (see general plot information concerning community compositions of the BEF-China experiment: http://china.befdata.biow.uni-leipzig.de/datasets/71; Species nomenclature following the Flora of China). The species composition covers two overlapping species pools and also includes two commercially relevant tree species monocultures (Extinction scenario E, Pinus massoniana and Cunninghamia lanceolata). Moreover, we also sampled plots without trees. Sampling was carried out in July 2015.

Within the plots, we collected soil samples from 12 random positions which followed a frame around the central 8 x 8 trees of every plot. Soil cores with a diameter of 13 mm were taken from the first ten centimeters of the top layer. These subsamples were pooled plotwise, freshly sieved in 2 mm fraction, homogenized and stored in the fridge for analyses.

Plots of Exctinction scenario A and B (http://china.befdata.biow.uni-leipzig.de/datasets/71). 100 plots were sampled, including non-tree community plots and monocultures of Pinus massoniana and Cunninghammi lanceolata (Extinction Scenario E).

Sampling was carried out throughout July 2015.

No tree species were included in the analyses. However, soil cores were taken from communities comprising the following species (and their mixtures according to (http://china.befdata.biow.uni-leipzig.de/datasets/71): Nyssa sinensis Castanea henryi Quercus fabri Lithocarpus glaber Quercus serrata Koelreuteria bipinnata Choerospondias axillaris Castanopsis sclerophylla Triadica sebifera Liquidambar formosana Sapindus saponaria Schima superba Castanopsis eyrei Cyclobalanopsis myrsinifolia Rhus chinensis Cyclobalanopsis glauca Castanopsis carlesii Melia azedarach Triadica cochinchinensis Diospyros japonica Acer davidii Cinnamomum camphora Daphniphyllum oldhamii Quercus acutissima Pinus massoniana Cunninghamia lanceolata

hot and wet

Samples were oven dried, extracted with 1M KCl, shaken for 1 hour and vacuum filtered. Extracts were measured at 540 nm with a microplate reader.