DOI: 10.5061/dryad.hm6nr2c
title: Data from: Seasonality promotes grassland diversity: interactions with mowing, fertilization and removal of dominant species

description: 1. Current biodiversity declines in species-rich grasslands are connected
 with the cessation of management, eutrophication and the expansion of
 dominant grass species. One of the theoretical mechanisms limiting
 biodiversity loss is the ability of subordinate species to avoid
 competitive exclusion by seasonal niche separation from dominant species.
 Here we explore how seasonality underpins the maintenance of diversity in
 temperate meadows under different management regimes and competition
 intensities in relation to species functional traits. 2. We studied eight
 different communities in a long-term meadow experiment that manipulated
 mowing, fertilization and dominant species (Molinia caerulea) removal. In
 each community, species-specific trait and biomass data were taken five
 times during the year to test whether seasonal variation in species
 composition and functional strategies enable species to coexist. 3. Mown
 unfertlized meadows exhibited pronounced seasonal variations in community
 composition and structure, linked to differences in resource-use
 strategies between mid-summer dominants and the spring and autumn
 subordinates. Higher specific leaf area and foliar nitrogen concentration
 in the fast-growing dominants, and increased water use (δ13C) and nutrient
 acquisition (δ15N) efficiency in resource-retentive subordinates, best
 predicted their temporal niche separation. Seasonal segregation of species
 with contrasting strategies increased after mowing cessation, and the
 resulting summer dominance of Molinia. Conversely, the seasonal dynamics
 were markedly reduced by fertilization, promoting tall grasses over sedges
 and forbs throughout the entire year, thereby decreasing the overall
 taxonomic and functional diversity. When Molinia was removed the
 compositional changes during the season became less pronounced, being
 significant only in mown unfertilized plots. 4. Seasonal shifts in
 community composition reduced the competitive interactions and promoted
 the coexistence of dominant and subordinate species. Seasonality reversed
 the negative mid-summer diversity-productivity relationship to a positive
 one during the spring and autumn, and seasonality only prevented diversity
 loss in unfertilized conditions possibly because competition is most
 intense in summer. In fertilized meadows, subordinate species are not able
 to escape competitive exclusion by shifting their phenological peaks to
 the spring or autumn periods because asymmetric competition is intense
 over the entire growing season. Studying seasonal dynamics is key to
 understanding the maintenance of grassland diversity under ongoing land
 use change.
description: Dolezal_JEcol-2018
 SeasonalityData were collected in
 the field in eight different communities in a long-term meadow
 fully-factorial experiment that manipulated mowing, fertilization and
 dominant species (Molinia caerulea) removal. In each community,
 species-specific trait and biomass data were taken five times during the
 year. We collected vegetation data in each permanent plot (24 in total) by
 clipping the aboveground biomass in April 2004, June 2004, August 2004,
 October 2004 and March 2005. We measured several plant traits relevant to
 competitive ability (plant height), nutrient acquisition (δ15N), water use
 efficiency (δ13C) and allocation (SLA - specific leaf area, LNC - leaf
 nitrogen concentration, LDMC and StDMC - leaf and stem dry matter content,
 respectively).Dolezal_JEcol-2018.xlsx