DOI: 10.71615/bexis.31543-11
title: Age and stem anatomical traits of Galium mollugo (collected between 2017-2019 in three regions of Germany)

description: Life span of plants is a key demographic trait important for the life history of plant species, the persistence and stability of plant populations and plant species` responses to environmental changes. However, information on the longevity of plant individuals (or ramets) and specifically its variation dependent on environmental conditions such as land use or regional differences in climatic conditions is not available for a large number of grassland species. Stem anatomical traits related to functions such as transport, storage and mechanical support are largely ignored in ecological studies of herbaceous species and therefore it is not known how sensitively these traits respond to variation in environmental conditions.<br>The data contain the age and stem anatomical traits of Galium mollugo, which was sampled with 20 individuals in 64 populations (in four cases with less individuals) located on grassland experimental plots (EP) in the three German regions (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin) chosen to represent different land-use intensities in each region to get an estimate of age distribution within populations. The age was determined by counting growth rings at the oldest part of plant samples (root crown, or distal part of rhizoms) in thin cross sections made with a microtome; the width of the stem anatomical tissues (diameter of the pith, and width of phellem, cortex, phloem, xylem and individual growth rings) was also measured at the cross sections. The data collection was part of the project ForbAge within the framework of the DFG-funded joint project Biodiversity Exploratories (https://www.biodiversity-exploratories.de).
description: Study design: The study populations of Galium mollugo were chosen using the vegetation records of the Core Botany Project for the years 2012-2016 (i.e. 5 years before starting the sampling in 2017; dataset ID 27386). For sampling a transect of 50 m length x 2 m width on the eastern side of each experimental plots was available. Sampling was conducted in the years 2017 to 2019 in summer and autumn, when the growth ring of the current year is already well developed. In each year, plots in all regions and with different land-use intensity were sampled to avoid bias in sampling, but each plot was sampled only once. Several samples overlap with the dataset (ID 31542) on the anatomy for multiple plant species for all grassland EP`s, which contains data for species, which reached an average cover of at least 1% in the species inventories; they can be identified with the Sample ID which are identical in both datasets. |Sampling design: Sampling was done along a transect of 50 m x 2 m on the eastern side of the EP. Each population of Galium mollugo (see above) was sampled with 20 individuals with at least 1 m distance between the individuals of the same species. The plants were carefully excavated to get the oldest plant part (the root crown in species with a long-lived primary root, or the most distal part of the belowground stolons). |Sample preparation: Samples were washed to remove adherent soil. Afterwards the samples were trimmed to a piece of appr. five cm including the oldest part, which was preserved in 70 % ethanol until further processing. |Sample analysis: Thin cross sections (5- max. 40 µm) were made with a microtome (GSL-1). If possible, the section was placed at the stem part of the root crown, where all tissue types are visible. The cuts were transferred from the microtome blade to a drop of glycerin-water mixture (1:1) on a slide and covered with a cover glass. Using a Axio-Scope A1 Microscope (Zeiss, Jena, Germany) with the inbuilt filters for polarized light, the cuts were studied to count annual growth rings and to measure the width of stem anatomical traits. |Equipment: microtome (GSL-1), Axio-Scope A1 Microscope (Zeiss) |Data preparation: The dataset does contain the values of all analyzed samples after checking the raw data for plausibility. In several cases, it was not possible to determine the age when growth rings where not clearly developed. Moreover, we excluded few samples from analyses due to labelling mistakes during field work.