Welwitschia is one of the world鈥檚 strangest and most resilient plants, living in the exceptionally dry Namib desert, which stretches along the coasts of Angola, Namibia and South Africa. But climate change may push these hardy plants past their limits, suggesting that they should be placed on the IUCN Red List of Threatened Species.
Vaguely reminiscent of a pile of kelp nowhere near the ocean, welwitschia (Welwitschia mirabilis) is unlike anything else on Earth. The plant consists of just two ever-growing leaves. These can grow to more than 4 metres long erupting out of a subterranean stem. These tough leaves split and coil, turning into a dishevelled, sun-baked heap over the plant鈥檚 roughly 1000-year-long lifespan.
Welwitschia鈥檚 botanical weirdness, iconic status in the Namib, and dearth of conservation evaluation caught the attention of Pierluigi Bombi at the Institute of Research on Terrestrial Ecosystems in Italy.
Advertisement
Using modelling and plant distribution data, Bombi had previously calculated that climate change could have a serious effect on one of the four remaining subpopulations of welwitschia. This group of plants, located in northern Namibia, is the furthest north 鈥� the others are found over larger ranges in western Namibia and southwestern Angola.
To help verify this prediction, Bombi and his colleagues conducted a field expedition last year in Namibia. They recorded the location of 1330 plants and gauged their health using a scale based on leaf colour 鈥� greener leaves were considered healthy, while reddish or brown leaves were a sign of stress.
鈥淯nfortunately, the field evidence confirmed completely our negative expectations,鈥� says Bombi.
Gloomy climate outlook
Based on climate modelling, the team also predicted that the northern Namib desert of 2050 will be as much as 2.5掳C hotter than it is today, but with no appreciable change in precipitation, dramatically reducing habitat quality. Given the poor health of the plants growing there today, and the deterioration of their habitat expected in the decades ahead, Bombi and his colleagues argue that welwitschia should be placed on the IUCN Red List.
Wendy Foden of the Cape Research Centre in South Africa says the team 鈥渞ightly point out that the lack of Red List assessment for Welwitschia mirabilis is concerning and represents an important priority.鈥�
But she says the study has limitations, because it only evaluated one of the four subpopulations.
Bombi counters that each welwitschia subpopulation should be considered separately, as they appear to occupy slightly different roles within their ecosystems, and grow in different locations and conditions.
Judith Arnolds at the South African National Biodiversity Institute commends the research, but says longer-term data is needed to determine whether the poor health of the plants may have been due to an anomalously stressful year, or longer-term effects.
Bombi says a key next step is a species-wide assessment of welwitschia鈥檚 vulnerability to climate change and the implementation of a long-term monitoring program for the plants in Namibia.
搁别蹿别谤别苍肠别:听bioRxiv, DOI: ;
