Data: Measuring plant attractiveness to pollinators: methods and considerations

Global pollinator declines have fostered increased public interest in creating pollinator-friendly gardens in human-managed landscapes. Indeed, studies on urban pollinator communities suggest that flower-rich greenspaces can serve as promising sites for conservation. Ornamental flowers, which are readily available at most commercial garden centers, are ubiquitous in these landscapes. These varieties are often non-native and highly bred, and their utility to pollinators is complex. In this study, we used observational data and citizen science to develop a methods framework that will assist stakeholders in the floriculture industry to incorporate metrics of pollinator health into existing breeding and evaluation protocols. The results of this study support how plant attractiveness to pollinators is often dependent on variables such as climate and plant phenology, which should be considered when developing an assessment tool. Furthermore, we found that some cultivars were consistently attractive across all observations while for other cultivars, pollinator visitation was apparently conditional. We determine using multiple statistical tests that 10 min is a sufficient length of time for observation of most plant types to broadly estimate three measures of plant attractiveness: visitor abundance, primary visitors attracted, and cultivar rank attractiveness, without sacrificing efficiency or accuracy. Additionally, we demonstrate that properly trained non-expert observers can collect accurate observational data, and our results suggest that protocols may be designed to maximize consistency across diverse data collectors.Floral_area_MG_B A_P indicates whether the cultivar was a container annual (A) or an in-ground perennial (P) Area_inch2 is the calculated area of the floral display for each replicate. This value was converted to cm2 for the manuscript. This measurement is based on floral area images taken on the data of data collection for dataset B. MG_data_descriptive_B The observer field indicates which unique observer conducted the observation. We used letters in place of names to preserve observer privacy. All observers given the descriptive data sheets were novice observers. Replicate indicates which of the three replicates/cultivar that data corresponds to. Replicate identity was unique to the study and indicated using field flags for each data collection event. MG_data_simple_B The observer field indicates which unique observer conducted the observation. We used letters in place of names to preserve observer privacy. Observer experience is indicated in the 'ExperienceLevel" column Replicate indicates which of the three replicates/cultivar that data corresponds to. Replicate identity was unique to the study and indicated using field flags for each data collection event. MDO_data_A Floral_Area_inch2 is the calculated area of the floral display for each replicate. This value was converted to cm2 for the manuscript. This value is based on images taken on the date of observation. InfloresenceNum is the estimated number of infloresences or compound flowers on a single plant at the time of observation and is another proxy for floral area. This value was ultimately not used in the final analysis. Replicate indicates which of the six replicates/cultivar that data corresponds to. StartTime is the time at which the observation commenced Time indicates when, in minutes:seconds from the start time, each insect visitor was observed in the 30 minute observation period Climate_dataA_B This is the hourly climate data for the dates of the experiment, extracted from the Pennsylvania State Climatologist database (https://climate.met.psu.edu/).Funding provided by: The Hoticultural Research Institute*Crossref Funder Registry ID: Award Number:This study includes two different datasets. The first is the dataset (A) was used to determine the minimum amount of time needed to observe a single plant to obtain accurate metrics of pollinator visitation. This data was collected by a single individual (E. Erickson), who observed a plant in the field for 30 minute increments and recorded the time the each individual visitor arrived at that plant and the taxonomic order of that visitor. The second dataset (B) was used to quantify how unique observers differed in the flower visitors they recorded on plants. Novice and experienced observers were each given unique data sheets that were either descriptive (insect morphotaxa) or simple (insect orders). Each observer watches a single plant replicate for 10 minutes and all observers observed a representative replicate of each cultivar in the study. Separate observers were used for the container annual and the in-ground perennial trials. Floral area measures were calculated by first photographing each cultivar in birds-eye-view with a meter stick held at the crown of the plant and calculating the area in bloom based on user defined pixel measurements in Adobe Photoshop All data analyses were conducted in R, and the code is included in this data archive