DOI: 10.5061/dryad.6m905qg4v
title: Plant trait responses to variation in N and P availability

description: Global change drivers such as eutrophication and plant invasions will
 create novel environments for many plant species. Through adaptive trait
 plasticity plants may maintain their performance under these novel
 conditions and may outcompete those showing low adaptive trait plasticity.
 In a greenhouse study, we determined if plasticity in traits is adaptive
 or maladaptive in endangered, non-endangered and invasive plant species in
 response to variation of nitrogen (N) and phosphorus (P) availability (N:P
 ratios 1.7, 15 and 135) and whether plastic trait responses are adaptive
 and/or costly for fitness (i.e. biomass). Species choice comprised 17
 species from three functional groups (legumes, non-legume forbs and
 grasses), either classified as endangered, non-endangered or invasive.
 After two months plants were harvested and nine traits related to carbon
 assimilation and nutrient uptake were measured (leaf area, SLA, LDMC,
 SPAD, RMR, root length, SRL, root surface area and PME activity). We found
 more traits responding plastically to variation in P than in N. Plasticity
 only created costs when P was varied. Plasticity in traits was mostly
 adaptively neutral towards fitness, with plasticity in three traits being
 similarly adaptive across all species groups: SPAD (as a measure of
 chlorophyll content, adaptive to N and P limitation), leaf area and root
 surface area (adaptive to P limitation). We found little differences in
 trait plasticity between endangered, non-endangered and invasive species.
 Synthesis. Along a gradient from N limitation, balanced N:P supply and P
 limitation we found that the type of fluctuating nutrient (i.e. if N or P
 is varied) is decisive for the adaptive value of a trait. Variation in P
 availability (from balanced supply to P limitation) created both a
 stronger reduction in fitness as well as created plasticity costs in more
 traits than variation in N availability (from balanced supply to N
 limitation). However, the patterns observed in our study may change if
 nutrient availability is altered, either by nutrient inputs or by a shift
 in nutrient availabilities, e.g. by decreasing N input as foreseen by
 European Legislation, but without simultaneously decreasing P input.
description: The dataset contains plant trait information of 17 annual species
 (grasses, non-legume forbs, legumes). Plants were raised in a greenhouse
 and exposed to N (nitrogen) limitation, P (phosphorus) limitation, and a
 balanced supply of both N and P. After eight weeks, plants were harvested
 and traits were measured.  General information: Family
 (Poaceae, Onagraceae, Fabaceae), Maturity (all plants mature at time of
 harvest), Status (plant species considered either invasive, endangered or
 non-endangered in central Europe), Plant Growth Form (grass, non-legume
 forb, forb), Life Span (annual), Start experiment (start date for each
 individual), End experiment (date of harvest for each individual),
 Treatment (N limitation, balanced nutrient supply, P limitation),
 total.supply.rate.N.mg (total amount of N supplied to each individual in
 the course of the experiment, i.e. 121.5mg, 40.5mg, 13.5mg)
 total.supply.rate.P.mg (total amount of P supplied to each individual in
 the course of the experiment, i.e. 0.9mg, 2.7mg, 8.1mg), repeats.per.trt
 (number of repetitions per trt and species, 1–10).
 Plant species: <em>Avena sterilis, Bromus hordeaceus,
 Bromus japonicus, Bromus secalinus, Bromus squarrosus, Epilobium
 anagallidifolium, Epilobium ciliatum, Epilobium fleischeri, Hordeum
 jubatum, Hordeum murinum, Lolium remotum, Lolium temulentum, Lupinus
 angustifolius, Medicago lupulina, Trifolium arvense, Trifolium dubium,
 Trifolium subterraneum</em> Plant traits include:
 Total Biomass (mg), Total leaf area (mm²), Specific leaf area (SLA,
 mm<sup>2</sup>/mg), Leaf dry matter content (LDMC, mg/g), SPAD
 (measure of chlorophyll content, dimensionless), Root mass ratio (RMR,
 mg/mg), Total root length (m), Specific root length (SRL, m/mg), Root
 surface area (cm<sup>2</sup>), root phosphomonoesterase
 activity (PME, µmol pNPP /g*h). Measurement for most
 traits followed Pérez-Harguindeguy, N., et al. (2013). "New handbook
 for standardised measurement of plant functional traits worldwide."
 Australian Journal of Botany 61: 167-234.