Global Short Term Trend: Relatively stable to decline of 30%
Comments: Overall, the species is believed to have remained relatively stable over the last half-century, in large part due to large, persistent occurrences in Ontario. However, it should be noted that little quantitative data on population trends exists for the Ontario sites, and Austen (2000) lists six Ontario occurrences known or suspected to have declined as of relatively recent surveys. Austen (2000) also notes two New York occurrences believed to have declined as of recent surveys. Extant occurrences in Alabama and Tennessee appear to have decreased greatly since they were surveyed in the 1970s and 1980s.
Global Long Term Trend: Increase of 10-25% to decline of 50%
Comments: Since their initial discovery, the majority of the southern populations have declined drastically or have been extirpated. Tennessee reports two historic and two extirpated sites, including one that was discovered in 1849 but was extirpated through over-collecting by 1930. The one currently extant site in TN supported 200 plants in 1898, decreased to 6 plants in 1929, had stabilized at roughly 17 to19 individuals in the early 1980s, but at last count (2004), there were only 5 small plants and none were producing spores (D. Lincicome pers. comm. 2008). In Alabama, numbers of plants in both populations have apparently experienced a significant decline since the initial discovery (A. Schotz pers. comm. 2008). One population had 20 plants in 1979, 9 plants in 1981, 4 plants in 1990, and 2 plants in1993; researchers visited the site in 2004, but no individuals of A. scolopendrium var. americanum were observed (D. Lincicome pers. comm. 2008). At the other AL site, 97 plants (26 fertile adults, 13 subadults and 58 juveniles) were found during a 1981 survey; as of 2004, the site contained 25 mature plants that were producing spores (D. Lincicome pers. comm. 2008). The first Alabama site is currently protected, but the second is threatened, as the landowner is unwilling to sell and timber harvesting has occurred in close proximity. The situation in the northern part of the range is not as bleak. Five populations are known to be extirpated in Ontario; reasons for extirpation include alteration and fragmentation of habitat (e.g. by logging and forest clearing) and collection. Ontario also has 20 sites ranked historical, but some of these may turn out to be still extant upon further survey. New York has four extirpated occurrences and Michigan has no extirpated occurrences and one historical one; Austen (2000) notes that (some level of) "declines have occurred in each of the four jurisdictions (New York, Michigan, Alabama, and Tennessee) in the United States."