DOI: 10.25829/bexis.31348-12
title: Plant species richness and biomass, and soil microbial properties data used in "Microbial drivers of plant richness and productivity in a grassland restoration experiment along a gradient of land-use intensity"

description: Plant-soil feedbacks (PSFs) underlying grassland plant richness and productivity are typically coupled with nutrient availability; however, we lack understanding of how restoration measures to increase plant diversity might affect PSFs. We examined the roles of sward disturbance, seed addition and land-use intensity (LUI) on PSFs. We conducted a seed addition and disturbance experiment (SADE) in ten grasslands along a LUI gradient and characterized plant above- and belowground biomass and richness, soil microbial biomass carbon and nitrogen (Cmic and Nmic); microbial community composition in terms of microbial groups determined from phospholipid fatty acid biomarkers (PLFAs); enzyme activities (Beta-D-Glucosidase, Xylosidase, N-Acetylglucosaminidase and Acid phosphatase); soil properties (pH, Olsen P, bulk density, extractable carbon and nitrogen, mineral nitrogen = nitrate + ammonium and the proportion of fungal OTUs assigned to saprotrophs, pathotrophs (putative plant pathogens) and symbiotrophs (mycorrhizal symbionts). This dataset contains the data that was analysed on soil samples and plant species richness and biomass of the years 2015, 2016, 2017 and 2018 on 10 selected SADE plots in the Schwäbische Alb, southwestern Germany.
description: Detailed description of study design: In each of 10 grasslands we set-up a full-factorial experiment consisting of disturbance and seed addition treatments. This resulted in four 7 m × 7 m subplots per grassland, which contained one of four combinations: control, disturbed, seeds added and both disturbed and seeds added. In most cases the four subplots were grouped together with a 2 m margin between the subplots. In few cases, subplots were more scattered because of site heterogeneity or requirements by farmers owning the grasslands. For the disturbance treatment, the top 10 cm of the grassland sward was destroyed using a rotary harrow. Thereby, the sward was broken up and turned over, creating open patches with bare soil while fragments of the former sward, were left on the disturbed subplots. Disturbance was applied once in October 2014. The seed addition treatment consisted of adding a highly diverse, region-specific seed mixture of plant species to each subplot. While the same seed mixture was added to each plot within a region, different species pools were used for different regions. Seeds were purchased from commercial seed suppliers which guaranteed regional origin from geographically defined zones. The mixture consisted of 66 species and in the Schwäbische Alb. The number of seeds added depended on seed mass and was targeted to 100 seeds × m−2 (for seeds &lt; 1 mg), 34 (for seeds 1mg − 10 mg) and 17 (for seeds &gt; 10 mg). In few cases, the final number was slightly lower due to limited seed availability. Seeds were added twice, with two thirds of the mixtures added in November 2014 and one third in March 2015. For an even distribution of the seeds, they were mixed with sand or crushed soybean, which was also added to the control plots. We recorded the species and their cover to analyse different stability measures, community assembly with disturbance and/or seed addition effect depending on the land-use intensity and initial species richness. Details on how collection of different data sets was designed is provided in the underlying BExIS data sets.&lt;br/&gt;Sampling design: We surveyed the vegetation each year in early summer from 2015 to 2018. For each subplot, plant species richness, belowground and aboveground biomass as well as soil and microbial properties are provided. Vegetation surveys were done on 2 m x 2 m subplots. biomass was cut on 4 50 cm x 50 cm subplots (at the height of 2cm). The dried biomass was weighed to the nearest gram. We collected soil samples each year in early summer from 2015 to 2018 on each treatment plot with a soil auger of 5.4 cm diameter, 10 cm depth. We recorded the precise core depth to calculate soil bulk density. Four soil cores per plot in the first year and two cores per plot in the following years were mixed and a subsample was frozen in dry ice for molecular analyses (DNA isolation and amplicon sequencing) and transported to a -80°C freezer. Soil samples were sieved (5 mm) and plant roots were washed, dried and their mass recorded (belowground biomass). Soil pH was measured only once per plot in soils from the soil sampling campaign in 2014. Soil phosphorus was measured in all selected plots and subplots in 2015 only. Please refer to BExIS dataset 25986 for a more detailed description of the experiment.&lt;br/&gt;Sample preparation: Soil samples were frozen, thawed, sieved with a 5 mm sieve, and frozen again at -20°C until analysis. Plant aboveground biomass was dried for 48 h at 80°C and weighed to the nearest gram. Plant belowground biomass was obtained by sieving the soil cores at 5 mm, washing, drying at 60°C for 72 h and weighing.&lt;br/&gt;Sample analysis: Details on sample analysis are provided in the underlying BExIS data sets.&lt;br/&gt;Equipment: Details on Equipment are provided in the underlying BExIS data sets.&lt;br/&gt;Data preparation: Data from the selected datasets was subsetted with data from AEG2, AEG6, AEG7, AEG9, AEG10, AEG15, AEG18, AEG21, AEG33, AEG49. The contact persons of the original datasets are in the document attached.&lt;br/&gt;Literature references: Abrahão A., Marhan S., Boeddinghaus R. S., Nawaz A., Wubet T., Hölzel N., Klaus V. H., Kleinebecker T., Freitag M., Hamer U., Oliveira R. S., Lambers H., Kandeler E. (2022): Microbial drivers of plant richness and productivity in a grassland restoration experiment along a gradient of land use intensity. New Phytologist.&lt;br/&gt;Data references: BExIS datasets 24006, 19812, 20646, 23506, 24066, 25546, 27646, 19566,19067, 31352 and 31353.