This pilot tool provides users with a rapid assessment of whether the trend shown in observations shared through GBIF for a given species is likely to be useful to researchers exploring species population trends.
The tool allows a user to navigate to a location and timespan of interest and generate an analysis showing whether the number of annual observations for the target species is increasing or declining as a proportion of overall observations of the selected higher taxon. This analysis involves normalizing observation trends for the species against all data collected for a higher taxonomic group. By normalizing against the group, the analysis attempts to compensate for biases in observation effort.
The algorithm
To explain the algorithm, please consider the following example taken from the early thorn moth (Selenia dentaria), normalized against its order (Lepidoptera). All data that is used for this application is available for download through GBIF.org.
- In 1968, there were four occurrences (of a total of 12 lepidopterans) = 33.33%
- In 2002, there were three occurrences (of a total of 6 lepidopterans) = 50%
- The proportion of observations of the target species within the total number of observations of the selected higher taxon has increased from 33% to 50% and the relative observation trend is thus positive.
We welcome all feedback and feature requests for this tool, as we strive towards a better understanding of what analyses are possible with the data that is openly available.
This project has received funding from the European Union’s Seventh Programme for research, technological development and demonstration under grant agreement No 308454.