Declining floral color diversity shifts bee color preferences in fragmented habitats
Data files
Nov 07, 2025 version files 856.85 KB
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bee_visitation_frequency_to_each_floral_color_within_each_island.xlsx
11.68 KB
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flower_color_reflectance_spectra.xlsx
554.54 KB
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plant_bee_interactions_on_islands.zip
286.90 KB
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README.md
3.73 KB
Abstract
Habitat fragmentation reduces floral color diversity in plant communities, shifting in color preferences of bee pollinators as shown by altered visitation frequency. We conducted a two-year survey of plant-bee interactions on 41 islands and the adjacent mainland habitats in a reservoir island system of eastern China. Reflectance spectra of the flower samples were measured using a portable spectrometer. Results showed that floral color composition was predominantly blue-green and blue, and a reduction in island area significantly decreased floral color diversity. Visitation frequencies to blue-green, ultraviolet-blue, and ultraviolet-green floral colors declined significantly with decreasing island area. Changes in floral color diversity altered bees’ color preferences, significantly impacting total floral visitation frequency. Bees’ color preference for blue-green flowers increased with island area, and floral resources showed no significant effect on visitation frequencies.
Dataset DOI: 10.5061/dryad.612jm64gq
Description of the data and file structure
We selected 41 islands (seven large islands (>20 ha) and 34 small islands) and 16 mainland sampling sites for field surveys in Thousand Island Lake. We conducted biweekly surveys covering all islands from March 22 to July 15, 2023, and from March 26 to July 23, 2024. For each year, we had seven replicated surveys. Each survey was carried out on days without rain or strong winds during two time slots: 8:30-12:00 and 13:00-17:00. At each site, we established fixed transects (100-m long × 4-m wide) in edge habitats with high flowering herb richness and another in interior habitats extending inward from the edge. Edge transects were surveyed for 15 minutes, and interior transects for 10 minutes per visit. We recorded bee visits, defined as contact with anthers or stigmas on flowers of herbs, shrubs, and trees within a vertical layer of 3.5 m above ground. We identified bee species and estimated their abundance, recording the visiting behavior through photographs or videos. We defined the visitation frequencies as the number of bees observed visiting flowers per unit area of each floral color.
Reflectance spectra of the samples were measured using an Ocean Insight portable spectrometer (model SR-6UVV400-25; wavelength range: 180–850 nm) with Ocean View software. The spectrometer system consists of a deuterium-halogen light source (AvaLight-DHc: 200–2,500 nm), a fiber optic probe, and a standardized white panel for calibration. Reflectance spectra were recorded over the 300–700 nm wavelength range. Software parameters were set to automatically save measurements every 100 ms, with six consecutive scans collected and stored for each sample to obtain six technical replicates. Reflectance values from multiple points were averaged to generate composite spectral data for each flower.
Files and variables
File: plant_bee_interactions_on_islands.zip
Description: The dataset comprises plant-bee interaction records from 41 islands and adjacent mainland areas in Thousand Island Lake. This dataset is provided as a compressed archive comprising 42 Excel files, each named according to its island and mainland. Every file is structured with the following column headers: island, which corresponds to the island number; number, which indicates the count of interactions; plants, which identifies the plant species code; and bees, which identifies the bee species code.
File: flower_color_reflectance_spectra.xlsx
Description: Reflectance value of flower color of each plant species at specific wavelengths.
Variables
- The first column ("wavelength") specifies light wavelength (nm), the header row ("PL1-PL98") denotes 98 distinct plant species, and the numerical values represent floral color reflectance measured at specific wavelengths across the spectrum.
File: bee_visitation_frequency_to_each_floral_color_within_each_island.xlsx
Description: The visitation frequencies of bees to each floral color type across the island and the adjacent mainland habitats.
Variables
- The first column designates sampling locations (islands and mainland), the first row identifies floral color types. The color codes B, BG, G, UB, and UG correspond to blue, blue-green, green, ultraviolet-blue, and ultraviolet-green floral colors, respectively, which represent bee-perceptible chromatic signals. And numerical values correspond to bee visitation frequencies (number per unit area) for each color type. Missing data are represented by blank cells.