POPULATION-STRUCTURE, HABITAT PROFILE AND REGENERATION OF HAWORTHIA-KOELMANIORUM, A VULNERABLE DWARF SUCCULENT, ENDEMIC TO MPUMALANGA, SOUTH-AFRICA

Population size and structure, flowering and foliar damage were quanti fied for the seven known populations of the vulnerable Mpumalanga ende mic Haworthia koelmaniorum Oberm. & Hardy (Asphodelaceae). Differences in sites where H. koelmaniorum was found compared with similar sites where it did not occur were assessed by the quantification of biotic a nd abiotic variables at the plant and community scales. Population siz e varied from 25 to 588, with 1591 plants in total. Size structures (l eaf number per plant or rosette diameter) did not vary between populat ions, but no seedlings were found. Overall, 67% of plants were damaged by fire and herbivory, but ail appeared to survive fire. The percenta ge of plants flowering per population varied from 24-76%. Percentage g ermination was high (78-88%), but seeds apparently have short-term (5- 7 month) persistence and thus no seed bank is formed. Plants grow pref erentially on northern aspects above the mid-slope position of quartzi te ridges and within rock fissures. These were characterized by a high cover of fixed and exposed rock, high overstorey shade, low understor ey shade and live vegetation cover. Reduced competition from herbaceou s plants and reduced probability of fire damage are distinctive featur es of these sites. Population dynamics may be characterized by adult p ersistence as seedling establishment is most likely episodic, linked t o high rainfall periods, and coinciding with dispersal of seeds produc ed in the same year to the few suitable rock fissures (safe sites) ava ilable. Present threats, small population sizes, low rates of seedling establishment and a very restricted distribution, dictate that H. koe lmaniorum remains in the Vulnerable IUCN category.