In September 2003, we informed about an exotic pest which had attacked eucalyptus trees in Western Kenya (see WRM Bulletin Nº 74), and reflected on the inherent risk of the monoculture pattern.
Now, the harm has reached neighboring Uganda, with Mpigi, Luweero, Masaka, Kasese, Mbarara, Bushenyi, Mbale, Kapchwora, Tororo, Lira and Apac being the worst hit districts.
The gall-forming wasp, Blue Gum Chalcid (Ophelimus eucalypti), becomes a pest for the exotic eucalyptus (kalitunsi) trees growing in large scale monoculture plantations. The wasp lays eggs in the tender parts of the plant, which react by forming galls (swellings). The attacked leaves fold and remain tiny leading to stunting of the whole plant, says Peter Kiwuso of the Forestry Resources Research Institute.
Eucalyptus, originating from Australia, has been planted in Uganda for about a century now. A study by Philip Karugaba, from The Environmental Action Network (TEAN), identifies the introduction of this exotic tree as one of two major factors (the other being grasses) that have replaced virtually to disappearance the indigenous species of trees --including the shea butter tree, whose seeds produce cooking oil used locally throughout Northern Uganda.
In Uganda, environmental conditions allows the eucalyptus to mature in just four years. This circumstance has fostered the large scale commercial plantation of this tree, which has been reported to be “spreading in the countryside like wild bush fire”. And like a wild fire, it is becoming destructive. Indeed, this is what typically has been going on all over the planet.
“The eucalyptus tree is thirsty and anti-social. Its fast growth rate places great demand on soil water and nutrients while its shed leaves do not permit growth of any other vegetation around the tree”, reads the paper. Anyway, maybe the same could be said about any other fast growth species. The ultimate problem is the model, the large scale monoculture pattern which worsens any effect, transforms insects into plagues, goes against the diversity of nature, and eventually proves expensive and weak. For tree farmers who have invested heavily in the fast growing trees, an event like this means a disaster.
For the approach that sees the forest ecosystem exclusively from its wood component, equating monoculture tree plantations with forests, we think the phrasing may be reformulated to say: “Can’t see the plantations for the trees”.
Article based on information from: “Ugandan Eucalyptus trees have an uninvited guest”, Gerald Tenywa, New Vision (Kampala), March 9, 2004; Paper prepared by Philip Karugaba, The Environmental Action Network (TEAN), Uganda, for the San Francisco Tobacco Free Project, http://tobaccofreekids.org/campaign/global/casestudies/uganda.pdf