While the high plain has been converted into farmland over the past 50 years, the slopes of the mountain ranges are still covered by natural forest, changing composition with altitude. The unique Afromontane vegetation formations are the main attraction of the area.
Montane dry forest (Lluis Dantart, CRBA)
The Abune Yoseph area is made up of a diversity of vegetation types including bushlands, woodlands, montane dry forests, and Afroalpine grasslands. The massif is made up of three main ecosystems: the montane dry forest, montane grassland and the Afroalpine ecosystem, which exist in altitudinal belts from 2,000 to 4,284m. All of these ecosystems suffer as a result of human intervention by means of agriculture and livestock grazing, although the higher altitudes suffer to a lesser extent.
The montane dry forest exists between 2,950 and 3,300m. The dominant species are Erica arborea, Hypericum revolutum (St. John's wort), African juniper (Juniperus procera) and Rosa abyssinica (the only wild rose in Africa). The densely vegetated forest, placed on the northwestern slope, sustains a large diversity of mammals and birds.
Between 3,300 and 3,600m, tall grasses, giant lobelias and different thistles become more frequent. This area is the montane grasslands.
Moving upwards from 3,600 to 4,285m, the vegetation changes rather abruptly into moorlands covered with the shrubby vegetation of Euryops pinifolius (charenfe).
Afroalpine (Lluis Dantart, CRBA)
This is the magnificent Afroalpine. Here, the most striking species of plant are the giant lobelia and the red-hot poker.
Giant Lobelia (Lobelia rynchopatelum)
Lobelia (Lluis Dantart, CRBA)
These large plants grow 2 to 3m high before sending up a single cluster of dark bluepurple flowers. The total height of the plant can be a maximum of12m.
Every few years, the lobelias have what is known as a ‘mast’ year, when – for unknown reasons – a greater proportion of the plants flower. The cluster is hollow and has several thousand flowers, each of which produces several thousand tiny seeds. One inflorescence can, therefore, produce over seven million seeds. Once the plants have flowered, they die– although the dead plant ‘skeletons’ last for several years.
Plants growing at high altitudes (3,000 to 4,000m) face two main challenges from the environmental conditions: the high levels of solar irradiation, and the extremes in temperature and wind. To deal with these conditions, the young, sensitive leaves of giant lobelias are protected from the strong sunlight by always orientating vertically. The older leaves, which have had sufficient time to develop, are filled with NPQ (a bio-chemical molecule to protect them against UV) and are horizontal.
There is a big advantage to being able to grow above the soil level in climatic conditions of high altitudes. At the soil level, daily temperature variation can be up to 50°C. At 2m above the soil surface, the fluctuation reduces to only about 12°C. But in order to grow to such a height, giant lobelias need to protect their apical meristem – the part of the plant from which it grows and forms their leaf bud – from the extremes in the environment, particularly the face of a cold wind.