Data Paper |
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Corresponding author: Eugenia Siccardi ( eugenia.siccardi@unifi.it ) Academic editor: Stefano Chelli
© 2026 Eugenia Siccardi, Virginia Amanda Volanti, Andrea Coppi, Andrea Scartazza, Eleonora Peruzzi, Valerio Lazzeri, Serena Doni, Leonardo Latilla, Federica D’Alò, Carlotta Volterrani, Olga Gavrichkova, Lorenzo Lazzaro.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Siccardi E, Volanti VA, Coppi A, Scartazza A, Peruzzi E, Lazzeri V, Doni S, Latilla L, D’Alò F, Volterrani C, Gavrichkova O, Lazzaro L (2026) A multi-proxy dataset of plant functional traits in Italian semi-natural grasslands under grazing exclusion and simulated drought. Vegetation Ecology and Diversity 63: e191956. https://doi.org/10.3897/ved.191956
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Semi-natural grasslands are high-value biodiversity hotspots that provide critical ecosystem services, yet land-use changes and shifting precipitation patterns increasingly threaten them. Understanding the ecological stability of these habitats requires high-resolution data integrating taxonomic and functional perspectives. This paper presents a multi-proxy dataset (https://doi.org/10.5281/zenodo.19052795) collected within the “CAROLINA: Impact of land-use change on climate resilience of semi-natural grasslands” project, focusing on the short-term impacts of grazing exclusion and simulated drought across three distinct Italian climatic zones: Mediterranean plains (San Rossore), Central Apennine hills (San Venanzo), and Alpine mountains (Tesino). The experimental design employs a manipulative approach using three treatment levels: grazed, as a control, grazing exclusion, and grazing exclusion + drought, with the latter simulated via rain-out shelters following the International Drought-Net protocol. The dataset integrates taxonomic diversity from floristic-vegetational surveys (88 plot × 164 species), leaf morphological functional traits for 39 species (leaf area, LA, specific leaf area, SLA, leaf dry matter content, LDMC, and plant height, H), and ecophysiological functional traits based on carbon and nitrogen elemental and stable isotope composition (δ13C, δ15N) from 37 surveyed species across the three sites. This comprehensive repository provides a foundational resource for long-term monitoring and ecological modelling of grassland responses to global change, supporting the development of effective conservation practices.
Climate resilience, ecophysiological diversity, functional traits, semi-natural grassland
Semi-natural grasslands are environments with a long history of traditional, low-intensity pastoral and agricultural activities (
The dataset aims to take an important step towards understanding the dynamics linking the two diversity layers and identifying the best management and conservation practices for these valuable grassland habitats and their characteristic plant communities. By providing a comprehensive multidimensional framework of plant structural and performance-based differences, these data offer a foundational resource for long-term monitoring and ecological modelling of Mediterranean and temperate grassland responses to global change.
The experimental phase of the project was designed to study the short-term effects of grazing suppression through fencing, as well as the impact of reduced precipitation, which was simulated using rain shelters. The experiment was conducted across three sites. San Rossore (43°44'06.5"N, 10°19'31.9"E, 5 m a.s.l.), located in the Migliarino, San Rossore, Massaciuccoli Regional Park extending along the coast of the Tuscany region (Northwestern Italy), is characterised by a mild and dry climate (mean annual temperature of 16.2 °C and approximately 540 mm of rainfall, Csa climate zone of the Köppen-Geiger climate classification), and lays on a recent alluvial geological substrate composed of sandy and silty deposits from the Serchio and Arno rivers. Within this setting, the alternation of wetlands and sandy ridges supports hygrophilous and mesophilous herbaceous vegetation, maintained through extensive rotational cattle grazing. San Venanzo (42°49'38.6"N, 12°15'52.6"E, 500 m a.s.l.), which is found on private pastures in the Umbrian Apennines (Central Italy), is characterised by a temperate continental climate (mean annual temperature of 12.9 °C and 801 mm of rainfall) as it is situated in a transition zone between hot-summer Mediterranean (Csa) and more temperate climates (Cwa), and it rests on a unique Pleistocene volcanic substrate known for the presence of rare rocks like Venanzite. This geological setting, shaped by the San Venanzo volcanic complex, supports a landscape mosaic where Turkey oak (Quercus cerris) forests alternate with open pastures, which were restored in the 1980s for extensive cattle grazing. Tesino (46°06'51.7"N, 11°42'11.7"E, 1667 m a.s.l.) is located in the Passo Brocon area (Cinte Tesino), within the Lagorai mountain range of the Eastern Alps in the Trentino-Alto Adige region at an elevation of 1667 m a.s.l. The site features a harsh subalpine climate spanning the humid continental (Dfb) and subarctic (Dfc) zones (mean annual temperature of 5.5 °C and 1866 mm of rainfall), and sits upon a geological substrate of metamorphic rocks, specifically the quartz phyllites of the Lagorai chain. These acidic, nutrient-poor soils support subalpine grasslands dominated by Nardus stricta and Norway spruce (Picea abies) forests, maintained through seasonal cattle grazing managed under local municipal leases. Climate data are provided by the Euro-Mediterranean Centre on Climate Change (CMCC) (
At each location, an area of 135 m2 was fenced off to prevent cattle from grazing. Specifically, at the San Rossore site, grazing management involves 15 head of cattle occupying an area of 3.4 hectares. The San Venanzo pasture covers 60 hectares and supports a herd of 25 cattle, while in the Tesino subalpine pastures, a herd of 51 cattle grazes an area of 15 hectares. Three treatment levels were established, each with three replicate blocks (2 × 3 m): Control (G as per ‘grazed’), which was located outside the fence and exposed to ambient precipitation and extensive grazing; Grazing Exclusion (GE), which was located inside the fence and exposed to ambient precipitation; and Grazing Exclusion + Drought (GED). A schematic figure of the experimental design is available in the Suppl. material
Geographic location and environmental characteristics of the three study sites in Italy. The map indicates the positions of San Rossore (coastal), San Venanzo (hilly), and Tesino (alpine). The table summarises the elevation (m a.s.l.) and the Köppen-Geiger climate classification for each site, highlighting the environmental gradient across the study areas.
Climatic characteristics, specific rainfall reduction, soil properties, and stocking density across the three study sites (San Rossore, San Venanzo, and Tesino). MAT: Mean Annual Temperature; MAP: Mean Annual Precipitation. Specific rain reduction under the shelter in mm and in %.
| Site | MAT, °C | MAP, mm | Expected rain reduction, mm | Expected rain reduction, % | Soil texture | Stocking density, head/ha |
|---|---|---|---|---|---|---|
| San Rossore | 16.2 | 540 | 308 | 57 | Sandy loam | 4.4 |
| San Venanzo | 12.9 | 801 | 400 | 50 | Loam | 0.4 |
| Tesino | 5.5 | 1866 | 616 | 33 | Sandy loam | 3.4 |
Vegetation surveys were conducted at San Rossore in late April 2024, San Venanzo in mid-May 2024, and Tesino in early July 2025. These dates were specifically selected to align with the peak vegetative season of each site, accounting for regional climatic variations to ensure optimal sampling results. Vegetation surveys were conducted in two 1 × 1 m subplots, one at each of the opposite corners of the main plot. Within the GED plots, the subplot was delineated 50 cm towards the centre of the plot to avoid the margin effect and ensure the entire subplot was covered by the rain shelter. Due to unexpected mowing at San Rossore shortly before sampling took place, the number of control replicates for that site was reduced to two. For each subplot, the present species were recorded and assigned a relative abundance with a percentage scale. Total cover could exceed 100% to allow for overlap. Most species were identified in situ; however, those that were difficult to identify were collected and determined in the laboratory. Taxonomic nomenclature follows the Portal to the Flora of Italy, version 2024.3 (http://dryades.units.it/floritaly/), derived from Checklists of the native floras of Italy (
To assess functional diversity, we targeted the most abundant species in each plot following the 80% cumulative cover criterion (
The isotope ratios of C (R = 13C/12C) and N (R = 15N/14N) were measured to calculate δ13C and δ15N (‰) referring to the Vienna Pee Dee Belemnite (VPDB) and atmospheric N2 standards, respectively, as:
Where Rsample is the isotope ratio of the sample, and Rstd is the isotope ratio of the international standard. For δ13C calibration, IAEA-CH-7 Polyethylene Foil (δ13C = −32.15‰), IAEA-CH6 sucrose (δ13C = −10.43‰), and IAEA-600 caffeine (δ13C = −27.5‰) were used to scale the measurements to the Vienna Pee Dee Belemnite (VPDB) international standard. For δ15N calibration, IAEA-600 caffeine (δ15N = +1‰), USGS40 L-Glutamic Acid (δ15N = −4.5‰), and IAEA-NO-3 potassium nitrate (δ15N = +4.7‰) were used to normalise results to the atmospheric N2 standard (
The dataset presented has been deposited in the open-access Zenodo repository, which was selected for its long-term preservation policy, Digital Object Identifier (DOI) assignment, and compliance with the FAIR principles (Findable, Accessible, Interoperable, Reusable). It contains seven separate tabs, which are described below. Overall, the database includes data sampled in 88 treatment plots: 18 at San Venanzo and a further 18 plots at San Rossore, where surveys were repeated for two years (2024 and 2025). However, two plots could not be surveyed in 2024 due to unexpected mowing at San Rossore. Finally, there are 18 plots at Tesino, which were surveyed just once in 2025 due to the inability to construct the experimental design during the first year. There are three types of treatment plots (G, GE, and GED) at each site. Each type has three repetition plots, with two subplots placed at opposite corners of each plot (tab ENV in the database). A total of 164 plant species were recorded during the two-year floristic survey (tab SURVEY), while 358 individuals belonging to 39 species were measured for leaf functional traits (tab LEAF TRAITS PER LEAF). Average leaf traits measurements were then calculated at the species level (tab LEAF TRAITS PER SPECIES). Some species were measured at more than one site depending on their abundance. Ecophysiological analyses of carbon and nitrogen elemental and stable isotope composition were conducted on 283 individuals from 37 species at the individual level. Of these, 75 individuals from 9 species were measured at San Rossore, 141 individuals from 21 species at San Venanzo, and 67 individuals from seven species at Tesino (tab ISOTOPES PER INDIVIDUAL). Average isotope measurements were then calculated at the species level (tab ISOTOPES MEAN PER SPECIES). The metadata were carefully structured, with a description of the data contained in each column of each tab provided in the first tab (tab METADATA).
All trait measurements were collected by trained botanists following standardised protocols (see the ‘Morphological and physiological functional traits’ section), and taxonomic identification was harmonised according to national floristic references. Data quality control (QC) was primarily based on expert visual inspection. All records were screened to identify evident transcription or digitalisation errors (e.g., inconsistent units, misplaced decimal points, or clearly implausible values). When such errors were detected, they were corrected by referring to the original field records, when available, or in few cases, measurements were repeated, when possible, to verify and correct the original values. No formal statistical outlier detection procedure was applied, and no observations were removed based on predefined outlier criteria. The dataset is structured in long format, where each row represents a single trait measurement. The absence of records for a given species–trait–replicate combination reflects that no measurement is available. No imputation of missing observations was performed. Metadata were carefully structured to facilitate integration with other vegetation databases and to ensure reusability for ecological analyses and conservation planning at different spatial scales.
This multi-proxy dataset provides robust data with which to investigate the interactions between land-use abandonment and climate stressors in semi-natural grasslands. By integrating taxonomic and functional layers, the dataset serves as a foundational resource for ecological modelling and predicting the climate resilience of plant communities in Mediterranean and temperate regions. While this dataset offers a multidimensional perspective on grassland resilience (Figures
The histograms show the dominant plant families across the three study sites (San Rossore, San Venanzo, and Tesino), based on their frequency of occurrence in the sampling plots. For clarity, only the five most frequent families at each site are displayed. The y-axis represents the total occurrences, defined as the cumulative number of individual species records per family across all sampling plots within each site. The taxonomic structure reveals a clear dominance of Poaceae and Asteraceae across all locations, which is characteristic of Mediterranean and temperate herbaceous communities. However, the internal ranking varies, reflecting different climatic and soil conditions.
The boxplots illustrate the distribution of species richness (number of species per plot), with the horizontal line representing the median. Individual data points (plots) are overlaid and distinguished by treatment: G = grazing, GE = grazing exclusion, and GED = grazing exclusion and drought. Colours and shapes of the points correspond to the different experimental treatments, while the box colours represent the sites. Median richness was similar between San Rossore and Tesino, while the highest values were observed at San Venanzo. The spread of the boxplots and the position of the whiskers further indicate the degree of vegetation homogeneity. A compact boxplot suggests a more uniform plant community, whereas a wider spread reflects greater environmental heterogeneity within the site. Accordingly, Tesino exhibited the most homogeneous vegetation.
The density plots for leaf traits show how values for four key functional traits are distributed, considering the means calculated for each measured species. These are Specific Leaf Area (SLA), Leaf Dry Matter Content (LDMC), Leaf Area (LA), and Plant Height (H). These plots show how often values occur for species in the database. The distributions of SLA and LDMC are crucial indicators of the leaf economics spectrum. A peak in high SLA values suggests dominance by ‘acquisitive’ (fast-growing) species, while a wide LDMC distribution indicates a variety of strategies for nutrient retention and leaf toughness. Most species have relatively small leaves and are low-growing, with a few ‘functional outliers’ (large-leaved or tall species).
Density distributions of elemental and isotopic composition are shown. The distributions of δ13C and δ15N are suitable indicators of intrinsic water-use efficiency and nitrogen source/cycling, respectively. The plots illustrate the frequency distribution of carbon and nitrogen concentrations and their respective stable isotope compositions across the sampled plant individuals (n = 283). The upper panels display (from left to right): C (%), leaf carbon concentration; C/N, carbon-to-nitrogen ratio; and N (%), leaf nitrogen concentration. The lower panels show the isotopic composition: δ13C (‰), relative to the VPDB standard; and δ15N (‰), relative to atmospheric N2.
Researchers would like to thank the local institutions and people who made the establishment and maintenance of the experimental sites possible: Mr. Angelo Gualdana for the San Venanzo site; the Migliarino, San Rossore, Massaciuccoli Regional Park Authority for the San Rossore site; and the Municipality of Cinte Tesino and Mr. Carlo Piazza for the Tesino site. We acknowledge Michele Mattioni, Luca Sessa, and Daniele Piastrelloni for their contribution to the site set-up, and Luciano Spaccino and Irene Tunno for their help with isotopic analyses.
Conflict of interest
The authors declare that they have no conflict of interest. Lorenzo Lazzaro is part of the Editorial Review Board in Vegetation Ecology and Diversity but took no part in the peer review or decision-making process for this manuscript.
Ethical statement
No ethical statement was reported.
Artificial Intelligence (AI) use
The authors accept full responsibility for the content of the manuscript, including the disclosure of any use of AI.
Regarding the use of AI in the preparation of this manuscript, the authors declare the following: Gemini 3 Flash to improve the style and readability of the text. After using the tool, the authors reviewed and corrected the content as necessary.
Funding
This study was funded by the European Union – NextGenerationEU, Mission 4 Component 2, PRIN2022PNRR project P20228JYWN – Impact of land use change on climate resilience of semi-natural grasslands (CAROLINA), CUP B53D23023480001 and B53D23023490001.
Author contributions
Eugenia Siccardi: Conceptualisation; methodology; data curation; formal analysis; visualisation; writing – original draft, review, and editing. Virginia Amanda Volanti: Data curation; writing – review and editing. Andrea Coppi: Data curation; writing – review and editing. Scartazza Andrea: Data curation; writing – review and editing. Peruzzi Eleonora: Data curation; writing – review and editing. Lazzeri Valerio: Data curation; writing – review and editing. Doni Serena: Data curation; writing – review and editing., Latilla Leonardo: Data curation; writing – review and editing. D’Alò Federica: Data curation; writing – review and editing. Volterrani Carlotta: Data curation; writing – review and editing. Gavrichkova Olga: Project administration; Data curation; writing – review and editing. Lorenzo Lazzaro: Project administration; conceptualisation; data curation; writing – review and editing.
Author ORCIDs
Eugenia Siccardi https://orcid.org/0009-0008-4738-0633
Virginia Amanda Volanti https://orcid.org/0009-0004-7851-4607
Andrea Coppi https://orcid.org/0000-0003-4760-8403
Andrea Scartazza https://orcid.org/0000-0001-5048-5112
Eleonora Peruzzi https://orcid.org/0000-0003-2523-6557
Valerio Lazzeri https://orcid.org/0009-0007-1219-0269
Serena Doni https://orcid.org/0000-0002-9428-9778
Federica D’Alò https://orcid.org/0000-0001-9604-9965
Carlotta Volterrani https://orcid.org/0009-0007-5721-3102
Olga Gavrichkova https://orcid.org/0000-0003-1818-4912
Lorenzo Lazzaro https://orcid.org/0000-0003-0514-0793
Data availability
The dataset is available as supplementary material and stored in the Zenodo repository at the following link: https://doi.org/10.5281/zenodo.19052795 (
Schematic representation of the experimental design
Data type: docx
Explanation note: The layout includes three replicated blocks for each treatment: (GED) Grazing exclusion and drought induced by rainout shelters (shaded grey areas); (GE) Grazing exclusion under ambient precipitation; (G) Grazed control plots. Blue squares represent the subplots (A and B) designated for floristic surveys within each experimental unit.