Abstract
The data collection contains 171 root samples, where the root mass, the root length and the root depth are given. Furthermore, the database contains the main environmental parameters that influence rooting (climate, land use, soil, vegetation composition). The rooting data are provided separately for three root categories: (1) very fine roots (diameter between 0 - 1 mm), (2) fine roots (diameter between 1 - 5 mm), and (3) coarse roots (diameter between 5 - 20 mm). Roots of woody species with a diameter larger than 20 mm were not considered, as the distribution and diameter of coarse roots (especially trees) in the soil vary greatly spatially. The rooting samples were taken between 1994 and 2017 in the most widespread vegetation communities and land-use types in 13 Alpine study sites along a north-south transect from Tyrol (Austria) via South Tyrol to Trentino (both in Italy). 15 samples were taken from arable land, 56 samples from intensively used hay meadows, 15 samples from extensively managed hay meadows, 16 samples from lightly stocked pastures, 32 samples from agriculturally unused grasslands, and 37 samples from forests. The roots were collected with core samplers of 6.8–7.7 cm diameter and a maximum core depth of 70 cm. In the laboratory, the soil cores were split into the O-horizon (if present) and mineral soil layers of various thicknesses (0–3 cm, 3–8 cm, 8–13 cm, 13–23 cm, 23–38 cm, 38–53 cm, and >53 cm). Root extraction was performed manually with the roots cleared of soil in sieving cascades under running water. The root mass was weighed and based on the mass, the root length and root depth distribution were determined according to the method of Tasser et al. (2005). As environmental parameters 79 potential impact variables on rooting, including 19 site variables, six land-use variables and 53 vegetation variables, are present in the database. The vegetation variables are based on vegetation relevées after Braun-Blanquet, in whose center the root samples were taken. Meteorological parameters were measured in the most study sites at a distance of < 150 m from the rooting samples using different microclimate stations. For detailed soil characterization, soil profiles were investigated directly at the sample site or at a representative site with the same land-use type and identical plant communities in the immediate vicinity (<50 m distance). For all soil samples, we analyzed pore size distribution, soil bulk density, soil particle density, total soil porosity, soil texture, and soil organic C and pH. Furthermore, we calculated mean Ellenberg's indicator values (EIV) for temperature (T), moisture (F), soil reaction (R) and soil productivity or fertility (N) for all study sites. Past and present management practices at the study sites were recorded by interviewing landowners.