Tree Species for Commercial Tree Planting in Uganda
There are many trees - both indigenous (i.e. native) and exotic - that grow in Uganda but when the objective is to grow commercial timber plantations, the choice is limited. In fact, two species dominate the plantation areas established to date in Uganda - namely, Pinus caribaea var. hondurensis and Eucalyptus grandis. In specific areas other species have been (or are being) planted - such as Musizi ( Maesopsis eminii), Pinus patula, P. oocarpa, Cupressus lusitanica, Auraucaria spp., Terminalia spp. and Teak ( Tectona grandis) but the total area of these species is relatively small at present. There are also other species that have shown promise in trials in the region that could become important in the future - species such as Eucalyptus hybrid clones, Cedrela odorata and Pinus tecunumanii. A brief description of the main species is given below:
Pinus caribaea var. hondurensis (PCH):
PCH is a fast growing tropical species that is well suited to conditions throughout many parts of Uganda. It copes well with shallower soils on lower elevation sites and has proved to be very adaptable - performing well on fairly dry sites in Nakasongola, Masindi and Mayuge as well as cooler, wetter sites in Kyenjojo, Bushenyi and Mubende. PCH is easy to raise from seed though only improved seed should be used for commercial planting: such seed is available from breeding programmes in Australia, South African and Brazil and has been imported into Uganda since 2002.
PCH must be heavily thinned to produce large diameter sawlogs quickly. High pruning (to 7-10m) is also being recommended to produce high quality sawlogs. Growth rates of 15-25m3/ha/yr and rotations of 18-25 years are anticipated with good management practices and using improved seed.
Eucalyptus grandis:E. grandis is well known in Uganda, being first introduced around 1912. It is commonly planted for fuelwood and poles and is an important source of income for small farmers. As other sources dwindle, E. grandis is increasingly being recognised as a valuable source of timber too. It is easy to raise from seed and coppices vigorously when cut. Many of the E. grandis trees in Uganda have hybridised, however, and thus it is important to use only improved seed from tree breeding programmes (mainly in Southern Africa) for commercial plantations here.
In Uganda, E. grandis is best suited to deep soils in the cooler, moist areas - particularly in the west - around Kabarole and Bushenyi, in the West Nile region and in the south-west (Kabale). On suitable sites and with good management, E. grandis can grow extremely quickly: Mean Annual Increments of over 50 m3/ha/yr can be achieved in such areas, though an average of 25-35 m3/ha/yr is more likely. Rotations of 8-15 years are expected for the production of sawlogs and large poles. E. grandis must be intensively managed (very well weeded and heavily thinned) to produce high yields otherwise plantations can fail completely.
Maesopsis eminii (Musizi):
Musizi is a fast growing indigenous species of considerable promise for timber production in Uganda. It produces a general purpose hardwood timber. Its main drawback is that it is not easy to grow in plantations as say E. grandis, and on an equivalent site will yield significantly less than E. grandis at final harvest. Musizi must be thinned on time to produce straight stems - otherwise they bend towards the light.
Musizi prefers moderately fertile, deep and well drained soils.It is a natural pioneer species in the Tropical High Forest - around Lake Victoria's shore (from Mayuge/Jinja to Rakai); across towards Fort Portal and down the Albertine Rift (Masindi to Kabale). It is not suited to high and/or dry (<1200mm) areas.
Hybrid Eucalyptus clones:
Hybrid clones of E.grandis crossed with E.camuldulensis (GC) and E.grandis crossed with E. urophylla (GU) were imported from South Africa in 2002 and 2003 and provenance trial plots were established in many different parts of the country. The clones have shown tremendous potential to expand the plantable area for eucalypts in Uganda. GCs are suited to drier sites and GUs are suited to hotter more tropical sites. Following assessment results from these trials by NaFORRI (with some showing very impressive growth rates) , SPGS in partnership with Uganda Gatsby Trust is promoting the multiplication and limited field planting of over 100,000 clones by commercial growers since early 2008. Basing on performance assessments of these field plantings, further multiplication of the clones will be done for the subsequent planting seasons and larger scale planting recommended.
For more details on these clones please see SPGS Tree Planting Guideline Chapter 21: Planting Hybrid Eucalyptus Clones
Araucaria ( A. cunninghamii & A. hunsteinii) and Terminalia spp. ( T. superba & T. ivorensis) have shown promise on very good sites, with high rainfall and deep soils. Seed supply, however, will restrict these species planting for the near future. Pinus patula and Cupressus lusitanica perform well only in the cool, high altitude sites of south-western Uganda. Teak is likely to only do well in the low altitude sites in northern Uganda.
For a more detailed description of each of the main plantation species, refer to SPGS Tree Planting Guideline Chapter 5 - Tree Species for Commercial Planting. Further details on what species will grow where in Uganda can be found in Guideline Chapter 6 - Site-Species Matching.One of the primary objectives of the Sawlog Production Grant Scheme is to develop Uganda's commercial plantation forestry sector in order to fulfill Uganda's timber requirements is a sustainable and environmentally sensitive manner. When this is achieved then hopefully the pressure will be taken off the remaining natural and Tropical High Forests. Tragically this is currently from where most of the timber is cut