DOI: 10.5061/dryad.n5tb2rc0p
title: Seed limitation interacts with biotic and abiotic factors to constrain novel species’ impact on community biomass and richness

description: Seed limitation can narrow down the number of coexisting plant species,
 limit plant community productivity, and can also constrain community
 responses to changing environmental and biotic conditions. In a 10-year
 full-factorial experiment of seed addition, fertilisation, warming, and
 herbivore exclusion, we tested how seed addition alters community richness
 and biomass, and how its effects depend on seed origin and biotic and
 abiotic context. We found that seed addition increased species richness in
 all treatments, and increased plant community biomass depending on
 nutrient addition and warming. Novel species, originally absent from the
 communities, increased biomass the most, especially in fertilised plots
 and in the absence of herbivores, while adding seeds of local species did
 not affect biomass. Our results show that seed limitation constrains both
 community richness and biomass, and highlight the importance of
 considering trophic interactions and soil nutrients when assessing novel
 species immigrations and their effects on community biomass.
description: Datasets used in "Seed limitation interacts with biotic and abiotic
 factors to constrain novel species impact on community biomass and
 richness" from Nomie Pichon, Elina Kaarlejrvi and Anu Eskelinen,
 2023, Ecology Letters. Biomass, richness and trait values measured in 2019
 on a seed addition experiment started in 2009, in Kilpisjrvi, Finnish
 Lapland. The experiment manipulates factorially seed addition from local
 and novel species, warming, NPK fertilisation, and mammal herbivore
 exclosure (levels are always untreated/treated). The experiment consists
 in 56 plots. Plots are cut in two subplots, one subplot is unseeded, the
 other subplot is seeded, summing up to 112 subplots. See methods for more
 info on the design. If you have further questions:
 [noemie.pichon@yahoo.fr](mailto:noemie.pichon@yahoo.fr) The models used in
 the analyses are found in "Seed_limitation_code.R" We included
 here three different datasets: 1. **Seed_limitation_dataset_all.txt** This
 dataset contains species richness and biomass in each plot, for the whole
 community, for novel species, for local species, and for resident species.
 Total community richness is the sum of novel, local and resident richness.
 Same goes for biomass. N = 112. Typical model: lme(Richness ~
 Fertilization * Warming * Exclosure * Seeding, random = ~ 1|Plot_Nb,
 subset(ds_all, Species_origin == "Total_community")) Variable
 Description Plot_Nb individual plot number, 1 to 56 Exclosure herbivore
 exclusion treatment, fenced or unfenced Fertilization fertilization
 treatment, fertilized or unfertilized Warming warming treatment, warmed or
 unwarmed Seeding seed addition treatment, seeded or unseeded
 Species_origin category for the origin of the species: novel, local,
 resident, or total. Richness number of vascular plant species Biomass
 vascular plant dry biomass, g per 25 25 cm plot 2.
 **Seed_limitation_dataset_seeded_unseeded.txt** This dataset contains the
 difference in species richness and biomass between seeded and unseeded
 plots, for novel, local and resident species. N = 56. Typical model:
 lm(Richness_seeded_unseeded ~ Species_origin + Fertilization * Warming *
 Exclosure, ds_seeded_unseeded) or lm(Richness_seeded_unseeded ~
 Fertilization * Warming * Exclosure, subset(ds_seeded_unseeded,
 Species_origin == "Novel_seeded")) Variable Description Plot_Nb
 individual plot number, 1 to 56 Exclosure herbivore exclusion treatment,
 fenced or unfenced Fertilization fertilization treatment, fertilized or
 unfertilized Warming warming treatment, warmed or unwarmed Species_origin
 category for the origin of the species: novel, local, or resident.
 Richness_seeded_unseeded difference in number of vascular plant species
 between seeded and unseeded plots Biomass_seeded_unseeded difference in
 vascular plant dry biomass between seeded and unseeded plots, g per 25 25
 cm plot 3. **Seed_limitation_dataset_traits.txt** This datatset contains
 community weighted mean functional trait values (cover x species specific
 trait value) measured on site (or from litterature for four species, see
 methods). Traits: specific leaf area, leaf dry matter content, leaf C:N
 ratio, leaf C:P ratio, height, leaf N:P ratio, tannins content, phenols
 content. N = 112. Typical model: lme(CWM_LDMC ~ Fertilization * Warming *
 Exclosure * Seeding, random = ~ 1|Plot_Nb, ds_traits) Variable Description
 Plot_Nb individual plot number, 1 to 56 Exclosure herbivore exclusion
 treatment, fenced or unfenced Fertilization fertilization treatment,
 fertilized or unfertilized Warming warming treatment, warmed or unwarmed
 Seeding seed addition treatment, seeded or unseeded CWM_Height community
 weighted mean height, cm CWM_SLA community weighted mean specific leaf
 area, m2 kg-1 CWM_CN community weighted mean leaf C:N ratio CWM_CP
 community weighted mean leaf C:P ratio CWM_Tannins community weighted mean
 tannins content, mg g-1 CWM_Phenols community weighted mean phenols
 content, mg g-1 CWM_LDMC community weighted mean leaf dry matter content,
 mg g-1 CWM_C community weighted mean leaf % carbon CWM_N community
 weighted mean leaf % nitrogen CWM_P community weighted mean leaf %
 phosphorus CWM_NP community weighted mean leaf N:P ratio