The research aim was to assess the vegetation and soils of the Rora
/’ Habab plateau, Eritrea and to develop methods of propagating the native tree
species, juniper and olive. The research consisted of vegetation and soil
surveys, interviews with local people, archival research, and experiments on
propagation of olive and juniper. Junipers are now confined to the north of
the plateau. Olives are more abundant in the north but have very few
individuals in the centre, where there are many dead trees, or south. Soil
erosion was ubiquitous and often severe. Soil morphology and nutrient status
were related to vegetation, topography, land use, and erosion status, and
varied greatly over short distances. Soil texture was coarser and most chemical
factors (except total Ca and exchangeable Na) were lower in the south.
Organic C, total N, exchangeable Ca, percent day, CEC and the sum of bases
were higher in soils from grazed land than in cultivated fields. Germination of
olive seeds was 92% when the endocarp was removed; stratification had little
effect. Rooting of olive stem cuttings attained 76% under mist when parent
plants were fertilised and cuttings were treated with rooting hormone.
Germination for juniper was 56% after stratification at 5°C for 30 to 60 days.
Juniper stem cuttings rooted in only one of three experiments, where rooting
was 78% in a well ventilated, cool, low-mist environment. Olive seedlings
which were fertilised and watered every 7, 14, or 21 days for two months,
were taller, had lower root:shoot ratios and soil moisture than unfertilised
plants. Fertilised seedlings watered every 28 days died. Root volume was less
for plants watered every 21 days but watering interval had little effect on
other variables in unfertilised seedlings. Ecological restoration is urgently
required to rehabilitate the Rora plateau, which has Africa’s most northerly
remnant juniper / olive woodlands.