Rare, Threatened and Endangered, Oh my!

Knowing the location of rare, threatened and endangered plant species throughout the state of Vermont helps inform conservation decisions.

Endangered species are considered species that play a vital role in their ecosystem and due to pressures, mostly human such as habitat loss and negative human interaction, are declining in numbers very quickly. To ensure the ecosystems that they reside in remain balanced and healthy action to protect these species must be taken. Currently 164 plants are registered in Vermont as threatened or endangered.

With a spatial analysis lens this exploration can be seen in terms of patterns in locations where these unique plant species are present. Understading this dataset is enhanced by the inclusion of spatial analysis, given that a telling value included in the data is Element Occurance. Element Occurance uses historical data, current data and surrounding area data to map areas of conservation species of interest. While much of the other data within the dataset is important in understanding the health of the plant, understanding where it is growing and the conditions/ecosystems that it grows in is a much more productive conservation strategy then focusing on the health of one plant. When it comes to conserving unique species, protecting the habitat they live in is the most productive approach. This is relevant since ensuring that threatened native species remain in communities is intregral to the ecosystem dynamics of our Vermont Wildlands. Grasping where unique species lie helps scientists and researchers learn more and protect them continuning into the future.

Methods and Data

Using data from the Vermont Natural Heritage Inventory, Wildlife diversity program, I generated a map of the state of Vermont with quantitative representation of where the endangered, rare and threatened species are, and where there are greater populations of these species.

Then using the Vermont Protected lands database from the Vermont Open Geodatabase portal, I was able to determine if endangered, threatened or unique species fell within protected lands. This is a measure of how effective conservation efforts are for protecting these species.

The spatial methods I used in analysis consisted of the Hot Spot Analysis tool, which I used to find groupings of similar EO_ID's, essentially pinpointing the locations where certain species should be found, are found or are historically known to be found there. Then I followed that with a selected by location where I used the hotspots I just calculated and selected them by locations that intersected with protected lands, that way I can see how effective the protected lands are in preserving these species.

Against generic counterparts of just understanding where points of these species intersect with protected lands this is much more telling because by incorporating a hotspot analysis of EO_ID there is more prediction for the future based on history, environment and surrounding species that the analysis can be used preemptively, to protect lands where the species might grow again.

A Moran's I spatial autocorrelation was also ran on the species data to understand if there is a correlation between the data points. This allows for understanding if there is a trend in where these species occur, and it is not random.

Results

The map below clearly shows that the population of these species is scattered throughout the state but routinely is found along or in bodies of water and are in locations that are in close proximity to towns.

Overview of rare, threatened and endangered plants in Vermont by locationality and population.

Element Occurrence is a powerful analysis tool, the higher the number of EO_ID the greater the presence of that species is predicted but is not presenting in the population numbers it should be. The highest number of species occur at relatively high EO_ID values meaning that the variables of the environment and surrounding species strongly suggest that the species could be present in large numbers than it currently is in that area.

The distribution of EO_ID, shows a trend of high values in number of species for higher EO_ID values for three spikes within the graph, besides that the graph remains relatively constant at 250-350 range.

Hot spot tool shows areas where the EO_ID values are grouped and where similar species predictions can be made.

Most of the hot spots showed little significance or are cold spots, there are only a few hotspots on the map suggesting that they are not statistically significant or that the standard deviation is lower than the average mean.

Highlighted points are hotspot areas where species with the same EO_ID classification intersect with protected land.

Based on the selected points it can be observed that there is a strong decrease in the number of species locations that are within or intersecting protected lands, going from a large number of 4,642 species of interest locations to 974 species of interest locations being protected.

Moran's I spatial autocorrelation statistics resulted in a Z score of 22.4 and an index of .15. With a Z score that positive and with such a high value it can be stated that there is not a random pattern and that they are a trend of values occurring in close proximity to each other. This is further supported by the first map of the species data where points can be visually seen as being close to one another, the Moran's I statistic supports this further.

Discussion

One of the major shortcomings of this data is that it was only for the month of September of this year, 2022. While the variable element occurrence accounts for historical presence of the species in an area as well as surrounding species, there is no way to demonstrate historical trends in ArcGIS. This would have been helpful to see which years particular species fell into the classification so that it could possibly be matched up with a human event during that year, or possibly a natural or weather event. With such a demonstration, causes could've been deduced.

With the hotspot analysis tool, while it was helpful to be able to see locations where there were hotspots of one type of EO_ID, given that is not multiple years of data, trends to see if the hotspots are shifting are not able to be seen. I also don't think that there were enough other variables to make hotspot assumptions, since the only other data was other EO_ID values. If the components that contributed to determining the EO_ID were included the hotspot tool would have been much more telling. Furthermore, the protected lands database was updated in 2021 and there could have been an increase in protected lands in the past year.

The analysis of this data could have been improved dramatically by using the data that was used to develop the Vermont Natural Heritage Inventory dataset, so that more analysis could be run.

Conclusions

Based on the observations made from these datasets certain conclusions can be made. It is clear that there are locations in which endangered, threatened, and rare species exist outside of protected lands, and it is actually the more common that they remain outside of these protected lands than when they are within the protected lands. It can also be denoted that there are trends in which these species occur and locations in which they might occur in the future can be predicted based on the hotspots of currently noted locations.

While it is important to note that creating protected land is a difficult and lengthy process, that the creation of more protected land in the future can be directed towards these hotspots of these protected species. Since the protection of their habitat is the most effective conservation strategy.

Overview of rare, threatened and endangered plants in Vermont by locationality and population.

The distribution of EO_ID, shows a trend of high values in number of species for higher EO_ID values for three spikes within the graph, besides that the graph remains relatively constant at 250-350 range.

Hot spot tool shows areas where the EO_ID values are grouped and where similar species predictions can be made.

Highlighted points are hotspot areas where species with the same EO_ID classification intersect with protected land.