Data from: To provide pollinator nesting habitat, cut dead perennial stems in their first winter
Data files
Mar 27, 2026 version files 54.09 KB
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all_samples.csv
35.81 KB
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occupants.csv
5.56 KB
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README.md
10.43 KB
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vol_survey.csv
2.29 KB
Abstract
Pollinator habitat management has traditionally focused on floral resources, but the stems of flowering perennial plants could also provide nesting and overwintering resources for solitary bees and wasps. Seasonal vegetation management therefore risks destroying nesting or overwintering insects. In residential pollinator gardens, gardeners receive conflicting advice—with little evidence base—about when dead plant stems can be removed without disrupting nesting or overwintering pollinators. To address this knowledge gap in a mesic temperate climate, we conducted participatory research in which volunteers provided stem samples from their gardens, sampling cohorts of dead stems through winter, spring, summer, and fall. We received a total of 2,879 stems, representing 75 samples from 20 gardens in four ecoregions. This dataset documents the sampled stems and their insect residents, and includes results of a volunteer experience survey conducted at the end of the project. Overall, 37 stems were occupied by living insects, and eight contained evidence of recent occupants, representing at least 12 species of solitary bees and wasps dominated by the genus Ceratina. Winter stems—those that had been alive and uncut in the previous growing season—were not occupied. Although the overall occupancy rate was low, our results verify that stems of perennial plants in residential gardens provide nesting and overwintering resources. Trimming (but not removing) stems in their first winter is the management practice that would maximize this resource for pollinators without disturbing its occupants.
Dataset DOI: 10.5061/dryad.n02v6wx86
Description of the data and file structure
Data from stems of perennial plants, collected from residential gardens and demonstration gardens, and examined for solitary bees and wasps nesting or overwintering inside. Data from a volunteer experience survey conducted to evaluate the participatory research approach.
Files and variables
File: all_samples.csv
Description: This dataset is used to analyze the seasonal occurrence of solitary bees and wasps in stems (Fig. 4 in main manuscript). Each row represents one site/ date/ stem-species combination; for analysis, rows are further pooled so that one 'sample' includes all stems from a site/ date combination, regardless of species. Some rows are excluded from analysis (see 'exclude' and 'exclude_reason' columns). This dataset also provides the distribution of all stem diameters (whether occupied or not) shown in gray in Fig. 3.
Variables
- row: unique identifier for each row of the dataset
- project_year: 2022 (volunteers enrolled in 2021, submitted stems in 2022) or 2023 (volunteers enrolled in 2022, data collected in 2023
- sample_date: data stems were collected from garden, in mm/dd/yyyy format (na if a specific date was not provided)
- sample_season: factor describing season when stem was collected (winter=about 1 month before last frost; spring=May; summer=August; fall=one month after first frost; fall_uncut = after first frost, but stems intact with no distal portions removed; the fall_uncut sample was analyzed separately from the main seasonal analysis
- county: North Carolina county where garden was located
- address: unique identifier for each garden
- stem_latin: full name of stem to finest taxonomic identification provided by the volunteer; could include genus, species, and cultivar (na if a stem was unidentified)
- genus: stem genus (na if a stem was unidentified)
- no_stems: total number of stems of the given taxon in the sample
- no_occupied_bees_wasps: number of stems occupied by living bees or solitary wasps of any developmental stage
- number_with_evidence_of_bees_wasps: number of stems that contained no living bees or solitary wasps, but did contain identifiable evidence of having been recently occupied by solitary bees or wasps (based on nest architecture or physical remains)
- d1_mm: interior diamater of the hollow or pithy portion of the stem in mm; up to five stems measured per sample, represented in columsn d1_mm through d5_mm; na if no measurement taken
- d2_mm: see d1_mm
- d3_mm: see d1_mm
- d4_mm: see d1_mm
- d5_mm: see d1_mm
- exclude: if 'yes', sample was excluded from the analysis of seasonal stem occupancy. Note that these samples were still included on other parts of the results
- exclude_reason: if 'exclude' = 'yes', this column gives the reason for exclusion (the way in which the sample departed from the seasonal protocol)
File: occupants.csv
Description: This dataset is used to generate Figure 2a, as well as the distribution of occupied stems (colored stacked bars) in Fig. 3. It also provides additional information about the developmental stage of stem occupants.
Variables
- row: unique identifier for each row of the dataset (does not correspond to all_samples.csv)
- project_year: 2022 (volunteers enrolled in 2021, submitted stems in 2022) or 2023 (volunteers enrolled in 2022, data collected in 2023)
- county: North Carolina county where garden was located
- address: unique identifier for each garden (same as in all_samples.csv)
- sample_season: factor describing season when stem was collected (winter=about 1 month before last frost; spring=May; summer=August; fall=one month after first frost; fall_uncut = after first frost, but stems intact with no distal portions removed; the fall_uncut sample was analyzed separately from the main seasonal analysis
- stem_latin: full name of stem to finest taxonomic identification provided by the volunteer; could include genus, species, and cultivar (na if a stem was unidentified)
- stem_genus: stem genus (na if a stem was unidentified)
- occupant: scientific name of occupant to finest taxonomic identification accomplished; could include genus or genus + species, or descriptor for morphospecies
- occupant_genus: bee or wasp genus (na if unidentified)
- occupant_figure: some taxa were pooled for Fig. 3 (e.g., 'Hylaeus modestus' and 'Hylaeus sp' were pooled into 'Hylaeus'; this column contains the taxonomic groupings used in the figure
- stem_diam: interior diamater of the hollow or pithy portion of the stem in mm (na if unmeasured)
- excluded from season analysis: although this dataset is not used directly in the seasonal analysis (Fig. 4), this recordkeeping column reiterates whether a stem was excluded from that analysis by stating the reason for exclusion; if not excluded, the entry is 'no'
- excluded from network: if a stem was excluded from Fig. 2a, this column states the reason for exclusion; if not excluded, the entry is 'no'
- excluded from stem diameter figure: if an occupied stem was excluded from Fig. 3, this column states the reason for exclusion; if not excluded, the entry is 'no'
- n_adult: number of adult bees or wasps in stem when split
- n_pupa: number of pupae in stem when split
- n_larva: number of larvae in stem when split
File: vol_survey.csv
Description: This dataset contains results of the volunteer experience survey. Each row represents one survey response, and each column represents one question, and each cell value represents the ordinal values selected in response to the question.
Variables
- row: unique identifier per row; each row represents one individual survey response
All columns that begin with 'x01' respond to the question "How important was each of the following factors in your decision to join this project? I wanted to:". Each item was ranked 0 (not important), 1 (somewhat important), or 2 (very important).
- x01.1_research: Be a part of a research project
- x01.2_garden_pollinators: Learn more about managing the garden for pollinators
- x01.3_stem-nesting_insects: Learn more about stem-nesting insects
- x01.4_other_volunteers: Meet and work with other volunteers who have similar interests
- x01.5_statewide_project: Be part of a multi-county/statewide project
- x01.6_new_volunteer_opp: Find a new or different type of volunteer opportunity
All columns that begin with 'x03' respond to the question "How satisfied were you with the following aspects of this project?". Each item was ranked 0 (not satisfied), 1 (somewhat satisfied), or 2 (very satisfied).
- x03.1_training: Training provided
- x03.2_support: Support provided
- x03.3_reporting: Stem collection and information reporting procedures
- x03.4_communication: Communication from agent and state team
- x03.5_experience: Your volunteer experience
- x03.6_overall: Overall project
All columns that begin with 'x04' respond to the question "How satisfied were you with the following resources provided for this project?". Each item was ranked 0 (not satisfied), 1 (somewhat satisfied), or 2 (very satisfied).
- x04.1_protocol: Instructions (research protocols document)
- x04.2_info_on_pollinators: Information on stem nesting pollinators
- x04.3_sample_form_shipping: Materials supplied: sample information form (year 2 only); shipping/mailing supplies
- x04.4_training_webinar: Initial training webinar
- x04.5_reminders: Reminders and update emails
All columns that begin with 'x06' respond to the question "How much did your knowledge of the following subjects increase as a result of participating in this project?". Each item was ranked 0 (no increase), 1 (moderate increase), or 2 (substantial increase).
- x06.1_manage_overwintering: How to manage the garden to support overwintering pollinators
- x06.2_stem_nesters: Stem-nesting insects
- x06.3_research: Conducting horticultural research
All columns that begin with 'x07' respond to the question "In the future, how likely are you to:". Each item was ranked 0 (not at all likely), 1 (somewhat likely), or 2 (very likely).
- x07.1_consider_winter
- x07.2_participate_research
- x07.3_statewide
All columns that begin with 'x08' respond to the question "How rewarding did you find the following aspects of participating in this project?". Each item was ranked 0 (not rewarding), 1 (somewhat rewarding), or 2 (very rewarding).
- x08.1_learning_management
- x08.2_stem_nesters
- x08.3_conducting_research
- x08.4_contributing_research
- x08.5_volunteer_collab
The remaining columns are ungrouped and respond to individual questions described for each column.
- x10_use_of_time: Response to the question "Do you agree this type of project is a good use of Master Gardener volunteer time?". Each item was ranked on a scale from 1 (strongly disagree) to 5 (stronly agree).
- vol_years: Response to the question "How many years have you volunteered with the Extension Master Gardener program?" Options were: 2 years or less; 3 - 5 years; 6 - 8 years; 9 - 11 years; 12 - 15 years; More than 15 years
- sex: Response to the question "What is your sex?" Options were: Male; Female; Prefer not to respond
- race: Response to the question "What is your race?" Options were: White; Black/African American; Asian; American Indian; Native Hawaiian/Pacific Islander; Two or more races; Other race; Prefer not to respond
- ethnicity: Response to the question "What is your ethnicity?" Options were: Latino/Hispanic; Not Latino/Hispanic; na=Prefer not to respond
- age: Response to the question "What is your age?" Options were (in years): 18-30; 31-40; 41-50; 51-60; 61-70; 71-80; 81-90; 91-100
- education: Response to the question "What is the highest level of education you have completed?" Options were: High school/General Education Degree; Associate Degree; Bachelor's Degree; Master's Degree; Doctoral Degree
Human subjects data
The volunteer experience survey included informed consent. This research was exempt from full IRB review, as determined by administrative review of NCSU eIRB protocol #26858. The multiple-choice responses included in this dataset include no individually identifiable information. Open-ended responses are excluded from the dataset (instead they are summarized in aggregate in Appendix S2 of the associated manuscript).