Very high extinction risk for Welwitschia mirabilis in the northern Namib Desert

Abstract

One of the most recognizable icons of the Namib Desert is the endemic gymnosperm Welwitschia mirabilis. Recent studies indicated that climate change may seriously affect populations in the northern Namibia subrange (Kunene region), but their extinction risk has not yet been assessed. In this study, we apply IUCN criteria to define the extinction risk of welwitschia populations in northern Namibia and assign them to a red list category. We collected field data to estimate relevant parameters for this assessment. We observed 1330 plants clustered in 12 small and isolated stands. The extent of occurrence has a surface area of 214.2 km2 (i.e., <5000 km2) and the area of occupancy a surface area of 56.0 km2 (i.e. < 500 km2). The quality of habitat is expected to face a reduction of 69.47% (i.e., >50%) as a consequence of climate change predicted in the area. These data indicate a very high extinction risk for welwitschia in northern Kunene, hence, we classify these populations as endangered (EN) according to IUCN criteria. Similar assessments for other subranges are prevented by the lack of relevant data, an issue that deserves further research attention. Our results advocate the necessity of a management plan for the species, including measures for mitigating the impact of climate change on isolated populations across its fragmented range.