Current Status, Threats and Conservation Needs of The Endemic Cycas wadei Merrill

Abstract

The population size and structure of Cycas wadei were assessed along with habitat traits to update the current level of knowledge for conserving this Critically Endangered endemic species. Direct measurements of plant density and size, chemical analyses of soil and leaf tissue samples, and surveys of sympatric plants were conducted. The adult population was calculated at 5,051, indicating historical population size estimates were inaccurately low. Highest densities in forested fragments were 800 plants per hectare, with adults comprising 34% of the population. Density in grasslands was as high as 1,100 plants per hectare, with adults comprising 31% of the population. The dominant grass was Themeda gigantea (Cav.) Hackel, not Imperata as previously reported. The prediction that the soils were ultramafic was rejected but opinions that the soils were extremely infertile were confirmed by soil analyses. Leaf stoichiometry revealed the cycad plants were primarily limited by potassium availability and secondarily limited by phosphorus availability. Habitat conversion is the acute threat that must be monitored in the near future, and an attempt to moderate or halt this conversion is the greatest conservation need. Poaching is a second threat that has not been acute to date, but has the potential to become a greater threat if the remote habitat becomes more connected to national trade routes. Fire damage is the third major threat, and has the potential to become a greater threat if historical fire frequency is altered