University of Florida

Tim Johnson: Research

Research Justification

North America possesses approximately 250 species of orchids, 118 of which are found in Florida (56 state endangered, 17 state threatened). Florida native orchids populations are declining due to habitat loss from land conversion for agricultural and residential uses, exotic plant invasions, poaching, and habitat mismanagement. While no Florida native orchid is federally-listed as endangered or threatened, many of the state’s orchid species could become extinct if conservation and recovery plans are not investigated and instituted.

In 2005, the Plant Restoration, Conservation, and Propagation Biotechnology Program in the Environmental Horticulture Department at the University of Florida partnered with the US Fish and Wildlife Service to study the biology and restoration of orchid taxa in the Florida Panther National Wildlife Refuge. This refuge has provided us with a unique opportunity to study orchids in a natural and secure environment. The Florida Panther Refuge Orchid Project has two key objectives: 1) to protect south Florida’s unique orchid flora by developing proactive management solutions and 2) to lead the way in North American orchid conservation through the generation and application of scientifically sound orchid management practices.

I am fortunate to be part of a chain of people that have made the Florida Panther Refuge Orchid Restoration Project possible. My research focus is on the seed physiology, seed ecology, and reintroduction biology of the grass-pink (Bletia purpurea; state threatened). I use a combination of laboratory experiments and field experiments to better understand the biotic and abiotic factors that influence germination and population establishment of orchid populations in situ. I am especially interested in using what I learn to develop management plans that enhance the establishment of self-sustaining orchid populations.

Research Project

Study Species

Bletia purpurea (pine-pink; Orchidaceae) is found in south Florida, the West Indies and Central America. It can be found growing terrestrially in disturbed pinelands, or semi-epiphytically on floating logs. This species is known for producing cleistogamous and open flowers, sometimes on the same plant. It is a showy species that produces 0.5-1.0m tall inflorescences of light pink flowers. Clusters of a dozen or more plants are not uncommon.

Seed physiology and seed ecology of Bletia purpurea (pine pink)

Very little is known about orchid seeds or how environmental cues effect germination and stand establishment. For this project, I am using incubators to examine how temperature and chemical signals effect germination.

The effect of local adaptation on introduction success of Bletia purpurea

For orchids, which are often rare, patchily distributed, and often selectively removed from intact ecosystems via poaching, studying reintroduction methods is vital. By culturing seedlings from different populations within the Florida Panther National Wildlife Refuge and conducting mutual planting experiments at different locations, I am assessing how local adaptation affects establishment and fitness proxies.

Pollination biology of Bletia purpurea

Understanding the pollination mechanism (i.e. selfing, obligate outcrossing, mixed) and breeding barriers allows for a clearer picture of a species' ecology. Additionally, identifying an orchid's pollinators may be crucial to the preservation, management and continued success of that species. Artificial pollination will be used to test the pollination mechanism of B. purpurea.

Population genetics of Bletia purpurea

The population genetics of this threatened species have not been explored. Understanding the genetic diversity within and between populations will allow conservation practitioners at the FPNWR to safeguard the historic processes that have shaped each population. AFLPs will be used to determine the population diversity and structure of B. purpurea populations in the study area. These results will be discussed in the context of what is learned from the pollination biology study.