Ken-ichi, I can affirm that Chuck’s addition of the observation to iNaturalist has alerted at least some of us in the vicinity to be alert for an infestation we might not have thought was a concern. I am just a volunteer, and I am not plugged in to EDDMapS, but I have come to trust the information found in iNaturalist more than I trust any database I have found that is purported to document observations of invasive species.
I know, for example, that at least 243 of the 584 observations of Ligustrum japonicum in EDDMapS are of no value. Yesterday, I reviewed the database that is the source of those observations. I found that 90 percent are not L. japonicum at all:
- The lion’s share are other Ligustrum species—186 L. lucidum, 16 L. sinense, and 8 L. quihoui.
- Five cannot be identified to species.
- Two are in some other genus.
- Two show no evidence of the organism.
Based on the locations of the observations that either are L. japonicum or cannot be identified to genus, none of those plants are wild. In other words, these 243 observations document not even one L. japonicum that has escaped cultivation, let alone invaded anything, but they are used to establish the notion that it is highly invasive. (The other databases behind EDDMapS aren’t necessarily better. Some document only that a plant is known to exist in a county—without indicating whether it’s someone’s hedge or a 20-acre monoculture infesting a preserve. Others document the size and location of an infestation, but lack any photos of the invasive species. It’s the classic case of having lots of data, but little information.)
So far as I can tell, the databases that feed into EDDMapS are based on an expert verification model. Many people may submit observations, but the observations are not added to the database until a designated expert verifies them. There is no built-in mechanism to flag errors or question decisions made by the designated expert. Consequently, the designated experts have no opportunity to learn of, let alone from, their errors. That sets us up for many systematic errors, leading to a situation in which 90 percent of the reported observations of a species thought to be invasive aren’t that species and the other 10 percent aren’t outside of cultivation.
By contrast, iNaturalist allows for immediate publication of the observation. Review and verification starts right away, too—and continues until the community settles on the best identification. In this crowdsourced peer review, mistakes get fixed. Recently volunteers cleaned up data on L. japonicum and L. lucidum in North America.
If you refer to sources that use these expert verification databases, you will learn that L. japonicum is spread by birds, outcompetes other plants, and forms monocultures in fields and forests throughout the South and at least in riparian areas farther west.
If you refer to iNaturalist, you will learn that L. japonicum has hardly ever escaped cultivation—but that infestations of L. lucidum, which is known to establish monocultures, have often been misidentified as L. japonicum. (From this information, a graduate student might be inspired to look for reasons that L. japonicum seems to be well behaved while other members of its genus are so highly invasive.)
iNaturalist is correct. But the databases built by expert verification are the ones that are used to develop policies—policies that determine what plants can be sold in nurseries, as well as policies that determine what tips homeowners are given about the plants they could choose for their own landscapes.
It sure would be nice for the policies to be developed from data that has been demonstrated to be correct. Or would that make too much sense? :-)