REPORT ON A VISIT TO THE BRANDBERG HERITAGE SITE TO VISIT A LITHOPS GRACILIDELINEATA SUBSP. BRANDBER

Three members and two associate members of the Lithops Research & Conservation Foundation visited one of the Lithops gracilidelineata subsp. brandbergensis colonies on the Brandberg Heritage site on 29th April 2019 together with the local guide Alphons. The aim of the visit was to determine the size and health of the colony of this unique Brandberg endemic plant.

This subspecies was first discovered on the Brandberg in June 1955 when Jalmar Rudner collected two specimens on the mountain. One of these specimens found its way to Dr de Boer in The Netherlands who described it as a variety of Lithops pseudotruncatella in 1963. After further study of the plants, seeds and seedlings it was concluded that these unique plants are a subspecies of Lithops gracilidelineata and they were reclassified as such by Professor Cole in 1986. Subsp. brandbergensis is one of the seven taxa of plants that has a restricted distribution and only occurs on the Brandberg.

A helicopter trip up the mountain was organised after the appropriate permit was obtained from the Namibian Heritage Council to visit this Heritage site. The members of the LR&CF and the local guide was ferried from the airport in Uis to an area near one of the Lithops localities close to the highest point on the mountain. This colony was last visited in 2003 and 2012 by botanists and hikers on their way to the summit of the Brandberg.

There are at least five subsp. brandbergensis colonies on the Brandberg with the one visited near Aigub (the second highest peak on the mountain) being the highest at an altitude of 2330 m.a.s.l. During the visit a total of 37 plants were found in the 72.3 m2 area of the colony indicating a plant density of 1 plant for every 1.9 m2. Most of the adult plants were single headed (27/37, 73 %) with only one each of the adults being double headed and three headed. A surprisingly high number of plants were young plants (8/37, 21 %). These young plants were of two different age groups and estimated to be two and four years old. Only two plants in the colony showed minor damage to the leaves after being preyed on presumably by herbivorous insects while one plant was moderately damaged by a pressing rock on the face of the plant. The damage to all three of these plants is not serious enough to cause permanent harm to the individuals. In all, 33 % (9/27) of the adult plants were either in flower or had recently flowered.

The only earlier information available on the population size of any of the subsp. brandbergensis colonies on the Brandberg is from the 1986 visit by Professor Cole when he mentioned that they found 40 plants in a colony which is presumably the same colony reported on here. This number is remarkably like the 37 plants found in 2019, 33 years later. Judging by the high number of young plants (8 individuals) in the colony found in 2019, the population has recently increased from about 30 individuals to the current 37. The expansion and retraction of Lithops colonies of all species throughout their distribution range is a natural occurrence in reaction to environmental conditions.

The Lithops gracilidelineata subsp. brandbergensis colony near Aigub is in good health and the current population seems to be stable. Although there is at present no need for any special management or conservation effort to safeguard the plants, the small size of the colony means that it is vulnerable. Monitoring the population at least every few years is recommended to detect any negative trends that might need further management in the future in order to protect these unique Brandberg plants.

We are grateful thanks to the Heritage Council for allowing us access to this unique colony of Lithops on the Brandberg.

A typical Lithops gracilidelineata subsp. brandbergensis single-headed plant. (5557)

A grouping of adult and young Lithops gracilidelineata subsp. brandbergensis plants. Note the plant on the right bottom with one severely damaged leaf.

An unusually large Lithops gracilidelineata subsp. brandbergensis plant and four young plants found growing in the shade of a grass tuft. The white measure is 10 mm x 30 mm. Notice the very young one-year-old plant at the top of the picture above the large plant.

The helicopter on top of the Brandberg Mountain.

A flowering Lithops gracilidelineata subsp. brandbergensis plant on 29th April 2019.