Variation in plant functional traits is best explained by the species identity: Stability of trait‐based species ranking across meadow management regimes

Abstract

It is commonly assumed in trait‐based studies that plant functional traits are species‐specific, being more variable among species than among different environmental conditions. If the environment affects traits, it is assumed that species react in a similar direction and conserve the functional distances. The rank of species based on the trait values is then unchanged, which justifies the use of species trait averages from database values. Such assumptions of species specificity are, however, increasingly disputed by studies showing overall high intraspecific trait variability. To test the species specificity and ranking stability of functional traits, we sampled plant individuals of almost all species (66 in total) within each plot of a long‐term (19 years) land use management experiment, which comprised a factorial combination of fertilization, mowing and removal of the dominant species Molinia caerulea in an oligotrophic wet meadow in the Czech Republic. Plant individuals were measured for eight commonly used traits: height, leaf dry matter content (LDMC), specific leaf area (SLA), leaf δ13C content, leaf carbon content, leaf δ15N content and leaf nitrogen content. Height, LDMC and SLA were also extracted from the LEDA trait database for comparison. Species identity consistently explained the largest portion of trait variability (40%‐68%). Land use managements had a considerably lower effect (0.4%–9% of explained trait variability for individual traits). The species trait averages computed for each land use management regime separately were mutually correlated, showing the stable trait‐based species ranking. Ranking stability of species trait averages was observed despite land use management changing absolute trait values and despite the tremendous intraspecific trait variability (causing substantial overlap of trait values for different species). For all treatments, our measured species averages for LDMC and SLA were also stably ranked with species averages from the LEDA database. Synthesis. Our results showed that species conserve the functional distances in different environmental conditions from where they were measured. Species trait averages can describe general trends in functional composition, although averaging reduces the ecologically interesting information of the intraspecific trait variability. A plain language summary is available for this article.

Mammalian herbivory shapes intraspecific trait responses to warmer climate and nutrient enrichment

“…Anthropogenic nutrient enrichment, either via airborne deposition or climate warming inducing the release of nutrients from soil organic matter, is a major cause of biodiversity loss and shifts in plant community composition worldwide (Boutin et al., 2017; Stevens, 2019; Tilman et al., 2001). In experimental studies, nutrient addition has also been shown to modify intraspecific traits, for example, to enhance plant height, SLA, foliar N content and leaf greenness (Mudrák et al., 2019; Tatarko & Knops, 2018). These are traits related to rapid growth in resource‐rich conditions (Reich, 2014; Wright et al., 2004) and they are therefore likely to confer greater performance and competitive ability under nutrient‐rich conditions (Carmona et al., 2019; Suding et al., 2005).…”

Species traits are better determinants of mobility than management in a species‐rich meadow

“…Data on functional traits of our study species were compiled from various sources (listed in Table 1). Clonal and architectural traits were extracted from the CLOPLA database (Clonal plants Database; Klimešová et al , 2017), leaf traits are from on‐site, using mostly a single measurement campaign in 2013 (for detail see Mudrák et al , 2019), and seed and dispersal traits are older measurements from the site (Stachová, 2005). For the analyses, species trait values were averaged over all the treatments and a single value per species was used.…”

“…We are grateful to the authors of Mudrák et al (2019) (Ondřej Mudrák, Jiří Doležal, Alena Vítová) and many students participating in the 2013 trait measuring campaign, and all the students assisting with vegetation recording and experiment maintenance during the years. We thank Francesco de Bello for his feedback on previous versions of the paper and Nichola Plowman for revision of our English.…”

Niche differentiation, competition or habitat filtering? Mechanisms explaining co‐occurrence of plant species on wet meadows of high conservation value

“…Köhler et al, 2005;Doležal et al, 2018;Tonn et al, 2019). Recently, a great emphasis is placed on the examination of ecological mechanisms shaping the community composition (see review in Mudrák et al, 2019), and thus on the exploration of the community assembly rules (Maire et al, 2012;Hedberg et al, 2014).…”

“…Řezníčková, 2007;Kącki and Michalska-Hejduk, 2010) and to more general management issues (e.g. Schaffers, 2002), while studies examining the functional diversity of Molinia meadows are sparse (but see Mudrák et al, 2019).…”