Taxus floridana Nutt. ex Chapm.

Taxaceae

Endemic to a very small area in northern Florida, USA where historically the population was much depleted due to selective logging which has led to fragmentation and poor regeneration

Associated Names:

Florida yew

Distribution

Taxus floridana is restricted to a 24km section of ravines and bluffs along the Apalachicola River in Liberty and Gadsden counties in northern Florida. Its current extent of occurrence (EOO) is estimated to be less than 100km². Its area of occupancy (AOO) is estimated to be 24km²

Almost all subpopulations of T. floridana are comprised mainly of large multi-stemmed individuals. Although seed is produced, virtually no new recruitment has occurred during the past two decades. A study of four subpopulations over the last 27 years indicates that adult mortality is greater than recruitment (Redmond & Winn, 2010). Individuals only persist through layering and sprouting. Stem densities may range from several hundred to several thousand per hectare. Small stems are particularly vulnerable to browsing and rubbing by deer.

Habitat and Ecology

Almost entirely restricted to the mid and lower slopes within a few ravines along the the Apalachicola River Bluffs area. Soils are generally moist and acidic. It occurs with a rich assemblage of evergreen and deciduous species including another threatened endemic conifer, Torreya taxifolia. Florida yew is generally shade tolerant and very fire sensitive.

Conservation Status

Global status and rationale

Critically Endangered B1ab(iii,v)

Taxus floridana has a restricted extent of occurrence (EOO) of less than 100km². It occurs at a single location as the principal threats, a lack of regeneration and the impact of an increasing deer population, affect all known subpopulations and localities. There is a continued decline in the quality of habitat in some parts of its range. Adult mortality is greater than recruitment leading to an overall decline in the number of mature individuals. It is therefore listed as Critically Endangered.

Global threats

Clear felling of Pinus palustris forests during the 19th century along with selective logging of the slope forests in the early 1900s may have resulted in range reduction and habitat fragmentation during the 19th and 20th centuries (Reinsmith & Foreman, 1934; Kwit 1998). The most immediate threat facing Florida yew is the lack of regeneration; a causal agent for this has not yet been identified. Rubbing and browsing by white tailed deer is also a problem as it may lead to the death of individual stems. As hunting within protected areas is prohibited, deer numbers within these areas increase during the hunting season (winter), resulting in increased pressure on the yew trees. An additional threat comes from the increasing dominance of fire tolerant species within the ravines and a potential increase in frequency and severity of fires (Mola et al. 2014).

Conservation Actions

The state of Florida lists Florida yew as endangered while at a national level, The Nature Conservancy lists it as as imperiled. Florida yew occurs in several protected areas such as the Nature Conservancy's Apalachicola Bluffs and Ravines Preserve and the Torreya State Park. Several populations are on private land without specific protection.