Rangeland recovery not guaranteed
With erratic rainfall and continued pressure on rangelands, human intervention is needed to facilitate recovery.
08 April 2020 | Agriculture
The productive potential of Namibian rangelands has been compromised, especially in communal areas, due to degradation.
According to Erastus Ngaruka, technical officer for livestock within Agribank's agri advisory services division, the main forms of rangeland degradation are bush encroachment and soil erosion. These two forms of degradation result from improper rangeland utilisation practices such as overgrazing, land clearing and soil mining practices, amongst others.
Ngaruka said rangeland productivity is influenced by a combination of factors such as rainfall, soil condition, seed availability and utilisation.
He said a rangeland refers to a land area inhabited by native plants such as grass, forbs, shrubs and trees that is utilised by domestic and wild animals.
Current rainfall activities seem to be favourable as many farmers are observing an abundance of grasses in grazing areas and areas that had bare patches in previous seasons, Ngaruka said.
However, “this is not optimal rangeland recovery yet”.
“Rangeland recovery occurs in three basic succession stages, namely pioneer, sub-climax and climax, and are distinguished by the type and species of grasses observed.”
According to Ngaruka, the pioneer stage is the lowest ranked stage, with grasses having little grazing value compared to the climax stage that recruits the most valuable grass species. The grazing value entails palatability (acceptance or taste), nutritional composition and quantity (amount of leaves and stems produced).
Ngaruka added that currently Namibian rangelands are in their pioneer stage of recovery.
“The grasses in abundance are the annual type of grasses with a short lifecycle, which are only available during the rainy season.”
He said these grasses have taken over some grazing areas in the central, eastern and northern regions, and will disappear in July/August, leaving most grazing areas bare.
Human intervention needed
Ngaruka added that given the recurrent erratic rainfall and the continued pressure on rangelands, the shifts in plant/grass succession stages will take longer than wished for, unless there are human interventions to facilitate the natural processes of rangeland revegetation.
Ngaruka said one such practice is to reintroduce valuable grasses by reseeding (planting grass).
“The practice can be done at various scales in backyard gardens, planting fields, in camps or grazing areas. The native valuable grasses that are commonly cultivated in the country include Cenchrus ciliaris (blue buffalo), Anthephora pubescens (wool grass) and Smitdia pappophoroides (Kalahari sand quick), amongst others.”
Apart from grazing value, grasses also protect the soil.
“They stabilise and shield the soil from adverse impacts of rainfall, wind and temperatures.
“Optimal rangeland recovery assessments should be based on species composition, grass density and soil organic matter and stability. Any rangeland rehabilitation intervention should be supported with a sustainable utilisation regime,” Ngaruka added.