Ecological factors determining the distribution patterns of Cyrtanthus nutans in North -Western KwaZulu-Natal

Abstract

Background: Cyrtanthus nutans R.A.Dyer is a range-restricted species occurring in northwestern KwaZulu-Natal, South Africa and in Eswatini, and is currently classified as Vulnerable in accordance with the IUCN criteria. Land transformation and disturbance of natural habitats have resulted in an ever-increasing fragmentation of the species’ range.Objectives: This manuscript provides a description of some of the abiotic and biotic factors associated with the remaining natural populations of C. nutans in the Sour Sandveld and Moist Tall Grassland Bioresource Groups of northwestern KwaZulu-Natal.Methods: An investigation was conducted in the northwestern KwaZulu-Natal region to determine the effect that key ecological and anthropological determinants have in influencing the distribution and survival of the species. Data collected included sites of occurrence, estimated population numbers, elevation, ecological factors (soils/geology, climate, veld composition), and human/animal activities.Results: The northwestern KwaZulu-Natal C. nutans populations were found to occur primarily in untransformed veld within the Moist Tall Grassveld, Dry Highland Sourveld and Sour Sandveld Bioresource Groups. It occurs largely on gradients of < 10% on mid- to lower terrain slopes and predominantly within an altitude range of between 1 100 and 1 300 m a.m.s.l.Conclusion: C. nutans occurs in a narrow altitudinal range and has a preference for soils with high nitrogen and organic carbon and low phosphorus and acidity levels.