ALBERT

Description: This dataset provides information about the fine root biomass inventory conducted in April 2018 in plots of the interdisciplinary research training group 'RTG2300: Enrichment of European beech forests with conifers. The aim of this study was to examine how enrichment of beech forests with conifer species impacts fine root biomass and other root traits across variable site conditions. The study was carried out in Northern Germany (federal state of Lower Saxony, Germany) and comprised four stand clusters so-called 'quintets'. Each quintet contained five neighboring forest stands: three monospecific stands of European beech (Fagus sylvatica; Be), Norway spruce (Picea abies; Sp), or Douglas- fir (Pseudotsuga menziesii, Dg), and two mixed stands, one composed of European beech and Norway spruce, and one composed of European beech and Douglas-fir. In each of twenty stands, plots of 0.25 ha in size were established. The quintets were clustered according to their geographical location into two regions, "south" and "north", with two quintets in each region. The southern plots are located in higher altitudes with lower mean annual temperatures and a higher annual precipitation. Growing conditions on the northern plots are less favorable than on the southern sites, in particular with respect to precipitation. For fine root sampling, we used a systematic regular sampling grid design with a 10x10m grid established across each study plot. A total of ten grid cells were systematically selected from total 25 grid cells. At each selected cell, one root core was taken. Sampling was carried out from the end of March to mid-April 2018. We used a soil corer of 8 cm diameter to extract soil from the organic layer and mineral soil (0-60 cm). The organic layer which varied by depth was sampled as a whole, while the mineral soil was divided into twelve subsamples, each of 5 cm depth. In total, 200 soil cores with 2147 samples were collected and stored in plastic bags at 4 °C until further processing in the laboratory (maximum storage time four months). Living fine roots and dead roots (necromass) were expressed as fine root dry mass per soil volume (g m-3) and as dry matter per square meter of ground area (g m-2) per soil depth. Specific fine root surface area (SRA, cm2 g-1), and specific fine root length (SRL, m g-1) were calculated from fine root area and fine root length divided by dry fine root biomass. Root area index (RAI, root surface area per ground area, m2 m-2) was estimated by multiplying specific fine root surface area by the fine root biomass in a horizon