Checking the Consistency of Volunteered Phenological Observations While Analysing Their Synchrony

Abstract

The increasing availability of volunteered geographic information (VGI) enables novel studies in many scientific domains. However, inconsistent VGI can negatively affect these studies. This paper describes a workflow that checks the consistency of Volunteered Phenological Observations (VPOs) while considering the synchrony of observations (i.e., the temporal dispersion of a phenological event). The geographic coordinates, day of the year (DOY) of the observed event, and the accumulation of daily temperature until that DOY were used to: (1) spatially group VPOs by connecting observations that are near to each other, (2) define consistency constraints, (3) check the consistency of VPOs by evaluating the defined constraints, and (4) optimize the constraints by analysing the effect of inconsistent VPOs on the synchrony models derived from the observations. This workflow was tested using VPOs collected in the Netherlands during the period 2003–2015. We found that the average percentage of inconsistent observations was low to moderate (ranging from 1% for wood anemone and pedunculate oak to 15% for cow parsley species). This indicates that volunteers provide reliable phenological information. We also found a significant correlation between the standard deviation of DOY of the observed events and the accumulation of daily temperature (with correlation coefficients ranging from 0.78 for lesser celandine, and 0.60 for pedunculate oak). This confirmed that colder days in late winter and early spring lead to synchronous flowering and leafing onsets. Our results highlighted the potential of synchrony information and geographical context for checking the consistency of phenological VGI. Other domains using VGI can adapt this geocomputational workflow to check the consistency of their data, and hence the robustness of their analyses.

25-year retrospective longitudinal study on seasonal allergic rhinitis associations with air temperature in general practice

“…Climate change introduces new plant species in regions that are able to survive in higher temperatures, including allergenic species 14 . In addition, warmer temperatures in winter or early spring lead to less changes in flowering and leafing onsets of plants, and consequently to an earlier start of the pollen season 15 . A warm end of the year causes plants to flower longer or to flower again 14 .…”

Exploring Spring Onset at Continental Scales: Mapping Phenoregions and Correlating Temperature and Satellite-Based Phenometrics

“…These networks not only educate the general public but also have lowered the barriers for volunteers to collect and share geo-referenced phenological observations. Although ground phenological observations continue to directly support a variety of ecological studies [8], [10], [11], they are not ideal for continental scale studies because they tend to be sparse and discontinuous (i.e., they do not have the required temporal and spatial coverage). This is recognized by phenologists who often combine ground observations with weather data to create phenological models [8].…”

Modelling tick bite risk by combining random forests and count data regression models

“…This unique dataset enables new approaches to monitor and model elusive public health threats, such as tick bites. However, volunteered data is often unstructured, contains positional inaccuracies and reporting bias, and observations have a variable quality [25,26], conditions that might cause difficulties when including volunteered data in a scientific workflow.…”