DOI: 10.5061/dryad.w0vt4b95p
title: Unveiling the role of foliar fungi in mediating leaf photosynthesis under global change

description: Global nitrogen (N) deposition and changes in precipitation patterns
 profoundly influence leaf photosynthesis and carbon sequestration in
 terrestrial ecosystems. Foliar fungi, a critical microbial community on
 leaf surfaces, could simultaneously impact several leaf functions.
 However, the regulated effects of foliar fungi on leaf photosynthesis in
 response to nitrogen and water additions remain unclear.  Here,
 using a long-term field and a complementary pot fungicide experiment in an
 alpine meadow, we quantified the effects of nitrogen and water addition on
 leaf photosynthesis and foliar fungal communities in two dominant species.
description: <strong>Site description</strong>
 The experiment was conducted at Haiyan County (36.92° N, 100.94°
 E, 3090 m a.s.l), located on the northeastern Qinghai-Tibetan Plateau.
 This region has a mean annual temperature of 0.94°C and mean annual
 precipitation of 404.66 mm, with approximately 80% of precipitation
 occurring during the growing season (June to August). The vegetation at
 this site is dominated by <em>Carex alatauensis</em> and
 <em>Leymus secalinus</em>. The soil at the study site is
 classified as Mat-Gryic Cambisol with a clay-loam texture. Additionally,
 the soil pH is approximately 8.09, soil total carbon concentration is
 21.28 g kg<sup>-1</sup>, and soil total nitrogen concentration
 is 3.33 g kg<sup>-1</sup>.
 <strong>Experimental design</strong>
 Our study conducted both a long-term field experiment and a
 complementary pot experiment. The field experiment was separated from the
 adjacent pot experiment by 5 m buffer zone.
 <strong>Field experiment</strong>
 The nitrogen (N) and precipitation addition experiment has been
 established since 2017. Nitrogen was applied as urea at a rate of 10 g N
 m<sup>-2</sup> year<sup>-1</sup>, manually
 distributed before the onset of the annual growing season (late April).
 Increased precipitation treatment was simulated by adding water equivalent
 to 10% of the mean annual precipitation (approximately 40 mm), distributed
 across eight events: twice in June, and three times each in July and
 August. Therefore, the experiment included four treatments: control, (CK),
 no nitrogen or water addition; nitrogen addition, (N, 10 g N
 m<sup>-2</sup> year<sup>-1</sup>); water addition
 (W); nitrogen and water addition, (NW, 10 g N m<sup>-2</sup>
 year<sup>-1</sup> with water addition). Each treatment was
 conducted with 5 replicates. Plots were 3 × 3 m in size, which were
 randomly distributed with a 1 m buffer zone separating adjacent
 plots. Within each plot, species composition and height
 were recorded in a 0.5 × 0.5 m quadrat throughout the study period.
 Above-ground net primary productivity was measured annually at its peak
 (early August) by clipping all above-ground biomass at ground level. The
 samples were sorted by species, oven-dried at 70 °C for 48 hours to a
 constant weight, and above-ground net primary productivity was calculated.
 Dominant species were identified based on their contribution to total
 above-ground net primary productivity, with <em>Carex
 alatauensis</em> and <em>Leymus secalinus</em> selected
 as the focus species for further analysis.
 <strong>Pot experiment</strong>
 For further verify the role of foliar fungi community, a pot
 experiment was conducted in 2023 nearby the experimental field, following
 the same treatment design as the field experiment. Polyvinyl chloride
 pipes with a diameter of 16 cm were cut into 20 cm height pots. Each pot
 was filled with 6 kg of air-dried, sieved (0.2 mm) clay-loam soil
 collected from the experimental field. Dominant plant species,
 <em>C. alatauensis</em> and <em>L. secalinus</em>,
 were transplanted into the pots from experimental field in mid-August
 2023. To ensure sufficient plant survival after the winter and spring,
 five individuals of <em>C. alatauensis</em> and three
 individuals of <em>L. secalinus</em> were maintained in each
 pot. Each treatment was conducted with 5 replicates.
 Before foliar fungicide treatment, we ensured that the plants
 were mature. Foliar fungicide treatments were applied after the first
 water addition in July 2024, using "Score Profi" (25.0%
 Difenoconazole) and "Ortiva" (10% Azoxystrobin) to investigate
 the role of foliar fungi on leaf photosynthetic properties.
description: # Unveiling the role of foliar fungi in mediating leaf photosynthesis
 under global change Dataset DOI:
 [10.5061/dryad.w0vt4b95p](https://doi.org/10.5061/dryad.w0vt4b95p) ###
 Description of the data and file structure **Overview** 1. This study
 includes four data files (CSV format) and one analysis file (R). All data
 and code referenced in the main text have been uploaded. 2. Some data
 mentioned in the Supplementary Information (SI) relate to other, currently
 unpublished manuscripts. If needed, please contact:
 [heychhh@163.com](mailto:heychhh@163.com)**.**Notes added for clarity: The
 four CSV files and the single R script are **sufficient to reproduce all
 analyses and figures reported in the main text**. Additional SI-related
 datasets are **not required** to reproduce the main results described in
 the article. ### Files and variables #### Files at a glance * `data/` —
 four CSV files (file names listed below) * `Photo_upload.csv` —
 [Experimental Plot Leaf Photosynthetic Measurement Data] *
 `phyllosphere_upload.csv` — [Field-Measured Data on Phyllosphsere Fungal
 Diversity in Experimental Plots] * `Correlation_upload.csv` — [Data
 compilation on the mean values of leaf photosynthetic traits at the plot
 scale and Phyllosphsere fungal diversity] * `Pot_experiment_upload.csv` —
 [Potted Plant Experiment: Leaf Photosynthetic Capacity Response Data
 Table] * Phyllosphere_Photosythesis_code.R — the complete R workflow used
 for data cleaning, statistics, and figure generation for the **main
 text**. Please replace `XXXX*.csv` with your actual file names and a
 one-line description each. Variables * Year: Experimental year * Seq:
 Measurement sequence * Block: Experiment block * Treatment: Experimental
 treatment setup * groupW/W.add/W.add1: Whether to water addition *
 groupN/N.add/N.add1: Whether to nitrogen addition * Species/Species1:
 Experimental subjects * A: Light-saturated CO2 assimilation capacity *
 gsw: Stomatal conductance * Fungi_Chao1: Phyllosphere fungal Chao1 index *
 Fungi_Shannon: Phyllosphere fungal Shannon index * N: Leaf nitrogen
 content * Fungicide: The fungicide treatment * lnRR.A: The
 logarithm-transformed response ratio of A (Light-saturated CO2
 assimilation capacity) ## Code/software The code
 (Phyllosphere_Photosythesis_code.R) was also uploaded. All meta-analyses
 were conducted in *R* software (version 4.3.3; R Core Team) and figures
 were generated using the ‘*ggplot2*’ package. ## Access information Other
 publicly accessible locations of the data: * NA Data was derived from the
 following sources: * NA