Comments: The major identifiable threats to this species are water regime perturbations (such as flooding), ATV traffic, heavy grazing and succession. Many of the sites are remote wetlands, so development is not considered a major threat to the species at this time.
One of Maryland's populations as well as one of Pennsylvania's were flooded by a recreational lakes. In West Virginia some occurrences are becoming shaded by succession and the lack of grazing (pers. comm. P. Harmon).
ATV use has been documented at very few sites, but many of the sites are vulnerable to such use, as well as to alteration by logging equipment.
Sites located in agricultural areas may be vulnerable to grazing, although occasional light grazing may benefit the species rather than harm it. It is unclear whether grazing animals (cattle or deer) eat Polemonium vanbruntiae; biologists have differing observations. One report suggests that grazing in one population has limited flowering (Harmon 1990); other biologists (Bartgis 1990 and Ed Thompson 1990) report seeing no evidence of grazing even in areas of heavy deer use.
There seems to be consensus among biologists familiar with this species that open wetlands are more suitable habitat than closed canopy wetlands. Therefore, succession may be a threat to some populations. Bartgis (1990) indicates that several West Virginia populations occur in areas which were grazed in the past, and he suggests that the plant may be in those areas as a consequence of openings created by grazing. Some of these areas may be threatened by succession. Many of the wetlands in which this species is found, however, are probably naturally open because of their water regime. In closed wetlands, natural perturbations such as windthrow provide openings in the canopy where the plant may colonize. While a subpopulation in one of these openings may become threatened by succession, other openings may appear and the plant presumably "moves around" within the wetland. None of this has been documented, however, so we can only cautiously assume that the plant does better in openings than in shade, and manage accordingly.
Populations in New Jersey and Pennsylvania have disappeared for unknown reasons. More information on these populations may help in determining threats to the species.
Some sites may face immediate danger due to development pressure and natural succession. At one site in New York, it was noted that few plants flower under heavy canopy but these plants produce many flowers where sunlight reaches the forest floor. More research is needed to determine how long these plants might survive under heavy canopy without any successful reproduction.