The Unique Purdiaea nutans Forest of Southern Ecuador — Abiotic Characteristics and Cryptogamic Diversity

The genus Purdiaea is a Neotropical genus of bushes and small trees belonging to the Ericales or heath alliance (Anderberg and Zhang 2002; Ståhl 2004). Purdiaea nutans Planch, is the only species of the genus in continental South America, occurring sporadically on nutrient-poor ridges or highly exposed areas in the Venezuelan Guyana Highlands and in the northern Andes from Colombia to northern Peru (Homeier 2005b; Figs. 19.1, 19.2). In all known localities it appears as isolated tree or shrub within mixed forest stands, except in the Rio San Francisco valley, southern Ecuador (Prov. Zamora-Chinchipe), where the only known forests dominated by P. nutans occur (Bussmann 2001, 2002; Paulsch 2002; Chapter 10.1 in this volume). These Purdiaea forests (Purdiaeaetum nutantis Bussmann 2002) cover about 200ha of upper mountain forest, more than half of which are located within the RBSF (Mandl et al., unpublished data).