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Ecological impacts of Prosopis invasion in riverine forests of Kenya

Published on
September 18, 2012

On September 6th, Gabriel Muturi defended his PhD thesis on the ecological impacts of Prosopis invasion in riverine forests of Kenya. Prosopis trees have been introduced to restore the degraded drylands in Kenya, but it turned out that they they invaded other areas, with negative consequences.

Promotor is Frits Mohren, copromotor is Lourens Poorter, and the other promotor is dr. Bernhard Kigomo of the Kenyan Forestry Research Institute.

Drylands occupy large parts of the world, and as much as 87% of Kenya. They are important for the livelihoods of local people that depend on livestock. At the same time these drylands have been degraded through a combination of droughts and overexploitation. Prosopis trees have been introduced from Latin America to restore the degraded drylands in Kenya. These species seemed to be ideal because they resist drought and provide fodder and fire wood, but it turned out that they were so successful that they invaded other areas, especially the productive, riverine forests, with negative consequences for the local vegetation and people.

“Gabriels PhD thesis has provided important insights in the invasiveness of riverine forests and dry woodlands in Kenya, and the mechanisms involved in this,” says copromotor Lourens Poorter. “Gabriel used a range of techniques, working with remote observations from space, down to the level of the genes, to unravel what was going on. He found that Prosopis has increased strongly during the past decades, and is invading and replacing the native Acacia tree stands. Prosopis also suppresses the density and diversity of understory herbs, which provide an important source of fodder for livestock. He showed in a nice, experimental setup that the negative effects of Prosopis on Acacia can be attributed to chemical compounds in its leaf litter. And with a detailed genetic analysis he showed that it is a complex of various Prosopis species that is invading in Kenya. Gabriels results contribute, therefore, to a better understanding of the drylands of Eastern Africa, and can be used in the further development of sustainable woodland management and use.”

Ecological impacts of Prosopis invasion in Riverine forests of Kenya
Muturi, G.M. (2012) PhD thesis Wageningen University, Wageningen, NL.
with references, with summaries in English and Dutch; 162 pp.
ISBN: 9789461734020