Functional distance mediates plant interactions
Creators: name: Jimeno-Alda, Julia
Publisher: name: Zenodo
Year: 2025
Subjects: plant interaction
plant traits
manipulative experiment

description: data set from FUNCTIONAL DISTANCE MEDIATES PLANT INTERACTIONS

http://sci-hub.tw/10.5061/dryad.0zpc8674x

Dataset from experimets developed in the article "FUNCTIONAL DISTANCE MEDIATES PLANT INTERACTIONS"

Julia Jimeno-Alda1*, Jose A. Navarro-Cano2, Marta Goberna2, Miguel Verdú11 Department of Ecology and Global Change; Centro de Investigaciones Sobre Desertificación (CIDE, CSIC-UV-GV), Carretera Moncada - Náquera, Km. 4,5. 46113 Moncada, Valencia Spain.2 Department of Environment and Agronomy; Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), Ctra. de La Coruña, km 7, 5, 28040 Madrid, Spain





Corresponding author: jimeno.a.julia@gmail.com



 

The outcome of plant interactions is strongly dependent on the set of physiological, morphological, and reproductive traits harboured by the interacting species. Two trait-based mechanisms are behind these plant interactions: a) trait dissimilarities, when species with similar traits compete more due to niche overlap, and b) trait hierarchies, when species with more efficient traits outcompete species with inefficient traits. Trait dissimilarities present a negative relationship between plant functional distance and interaction strength, and a positive relationship for trait hierarchies. We hypothesised that functional distance between species affect the outcome of plant interactions through both mechanisms. We established a manipulative experiment with ten species growing in hetero- and conspecific pairwise combinations and evaluated thirteen above- and belowground traits. We estimated neighbour effect by measuring the relative change (RC) in trait values of a focal species (RCfocal) caused by the presence of a heterospecific neighbour (RCneighbour), contrasted with the changes induced by a conspecific neighbour. We explored i) which traits were more affected by neighbours, ii) which species were more affected as focal or neighbour, and iii) how the neighbour effect varied with the functional distance between pairs. Neighbour effects on focal traits showed a variable intensity, contingent upon the specific identities of both plant species within the pair. Despite the high variability in neighbour effects, species that grew with a functionally similar neighbour exhibited larger traits than those growing with a dissimilar one due to the prevalence of trait hierarchies over trait dissimilarities. The heterogeneity found on the neighbour effects responded mainly to differences between above- and belowground traits, reinforcing the need to consider them both for a mechanistic comprehension of community dynamics. Trait hierarchies prevailed but trait dissimilarities were also detected on specific root traits, indicating that both mechanisms simultaneously determine the outcome of plant interactions.

 

A greenhouse experiment was established to measure neighbour effects in ten short life span species. To select the species, we first collected forty-two Mediterranean herbs and shrubs species from May to September 2020 in two different natural locations: Torrelodones, Madrid, Spain (40.59, -3.93), and Sierra Ministra, Castilla la Mancha, Spain (41.02, -2.37). These areas are characterized by granite lithologies and limestones of cold semi-arid steppes (Bsk, Köppen climate classification).

We selected 10 species from distinct evolutionary clades trying to capture a wide range of functional dissimilarities: Trifolium angustifolium (Fabaceae), Vicia villosa (Fabaceae), Bromus tectorum (Poaceae), Hordeum murinum (Poaceae), Andryala integrifolia (Asteraceae), Helichrysum stoechas (Asteraceae), Thymus mastichina (Lamiaceae), Micropus erectus (Asteraceae), Hirschfeldia incana (Brassicaceae) and Plantago coronopus (Plantaginaceae). Seeds from the selected species were sown in 300 pots covering all possible pairwise combinations. With 10 different focal species, we could obtain 45 heterospecific pairs and 10 conspecific pairs that were replicated 6 and 3 times respectively, accounting thus for the intraspecific variability in the response to the neighbour.  Then, we finally seeded two hundred seventy pots (540 individuals) in heterospecific pairs and thirty pots (60 individuals) in conspecific combinations. Fifty pots (100 individuals) were not measured due to death of the individuals. See Appendix S1: Table S1 and Table S2 for further description.

Soil used as substrate for the experiment was collected in La Canaleja Agricultural Research Field Station, located in Alcalá de Henares, central Spain (40.51, -3.31). The area is semi-arid, with low and irregularly distributed rainfall (annual average of 353 mm). Soils are Calcic Haploxeralfs, with a sandy-loam texture, neutral (pH of 7.9), non-saline (0.123 dS/m) and with low contents of total organic carbon (7.5 g kg -1) in the topsoil layer (Martín-Lammerding et al., 2015). Soils were collected in February 2021 at depth of 5 to 20 cm (to avoid seed bank in the topsoil centimetres) and sieved through a 5 mm mesh. Soil was heated at 120 °C for 1 h to reduce the microbial load and mixed with silica sand at 9:1 vol/vol. Pots (12 × 25 × 18 cm) were filled with this mix (5.7 l) and let stabilize until seeding on 10th of February. We selected 2-5 seeds per species at 1 cm depth to ensure the germination of at least one individual per species and pot. When more than one individual per species emerged, the surplus seedlings were removed, remaining only one individual. Watering lasted from March 2021 to July 2021 and added 1.8 ± 0.2 L/m2 per day distributed in 3 pulses of 5 minutes five days a week. Radiation was homogenous due to shade cloths placed on top of the greenhouse. The temperature of the greenhouse was set to 22∘C degrees using a heating/cooling system. More details of the experiment can be found in Appendix S1:Table S1 and S2, and Appendix S1 and Figure S1

 

TRAIT MEASUREMENT

Individuals from the greenhouse experiment were harvested and measured from 22th June to 30th July 2021 when most of the individuals were full-grown adults. We measured 13 above- and belowground morphological, physiological and reproductive traits: plant height, plant weight, aboveground plant weight, specific leaf area (leaf area/leaf dry weight from 3 leaves per individual), total photosynthetic area (mean leaf area × number of leaves), number of flowers, root length, root weight, number of root nodules (only present in T. angustifolium and V. villosa), leaf C, leaf N, root C and root N. A total of 244 leaves and root samples (for which we had enough material) were dried at 60 °C and ground. C and N contents were measured with an ELEMENTAL LECO TruSpec CN elemental analyser (LECO, Michigan). All these traits are ecologically relevant as they are related to plant fitness (growth, survival, and reproduction) as well as to different ecosystem functions (see Appendix S1: Table S3 and S4).