Citizen science data can complement collections well for some applications

Natural history collections such as herbaria are crucial to our understanding of where and in what quantities various plant species – and the diseases that affect them – occur, and how those populations are changing over time. Unfortunately, new specimen collection has fallen over the last several decades, making it difficult for researchers to keep up with changes in distribution and abundance at a time of massive environmental change. However, citizen science platforms such as iNaturalist, Zooniverse, and others have exploded in popularity over the past decade, with iNaturalist alone boasting over 10 million plant records. Can the data amassed using these platforms be used alongside traditional natural history collections to help make up for the shortfall in new accessions?

In a new commentary published in the American Journal of Botany, authors Allyson Kido and Michael E. Hood have studied the incidence of anther smut to investigate whether iNaturalist data can be used to assess disease occurrence and whether that data reflects the distribution and frequency of the disease seen in herbarium specimens. Anther smut served as a useful subject for the comparison because it is common, affects only the anthers, and is easily recognized, yet is often overlooked by casual observers as well as botanical collectors, avoiding bias in those wanting to avoid diseased specimens. Kido and Hood compared data on anther smut distribution in the Caryophyllaceae from fungarium collections, surveys of plant collections in herbaria, and surveys of floral observations gleaned from iNaturalist.

The researchers found that the iNaturalist anther smut data was comparable in quantity to that of the fungarium and herbarium collections surveyed. Notably, though, the iNaturalist data was collected in the space of a decade, while the specimen collections ran over two centuries. The citizen data also covered a time period in which collections were declining, helping fill in “holes” in the collector-generated data. “Particularly for the disease we were studying, the herbarium and iNaturalist data showed extremely similar patterns of where the disease occurs and which types of plants are most affected,” says Hood. “There were some noticeable differences, however, that likely reflect the activities of botanists and citizen scientists. The herbaria tended to have more material from hard-to-reach places, like alpine species, while iNaturalist had more observations in cities and towns or the types of local paths and roadways that people tend to walk along.”

The fact that collections aren’t keeping pace with changing distributions as collecting declines and the climate shifts makes citizen data useful in pinpointing where targeted collecting can be most valuable, as well as how conservation efforts can be tailored for threatened species. “Data in natural history collections are excellent for determining where the species have been, as the material goes back many decades,” Hood explains. “The combination of these sources of information can help determine where declining species are hanging on and perhaps the types of habitat that would most help in their conservation. The comparisons across decades can further reveal shifts in species distributions or timing of their development. For species that are rare and understudied, the access to recent location data saves tremendous time and effort in searching for them, making studies of their abundance and diversity more feasible.”

Asked if there’s a danger that increased use of citizen science data will be used to justify further decreases in funding for collections, Hood says it’s something he worries about a lot. “We tried to stress the value of both the data in natural history collections and the specimens themselves, and also pointed to the complementary possibilities,” he explains. “We also need to recognize the limitation to online observations. While many citizen scientists make truly remarkable observations, with multiple clear photos of the key plant structures and the environment, for most the main information is the plant’s occurrence, location and date, and [species identification]. The specimens in natural history collections are used to study a much broader range of details, including the variation among individual plants in terms of their size, structures, and recently their genetics. The environment is changing rapidly, and being able to study the effects on wildlife requires much more than the snapshot of their current distributions.”