1)The purpose of planting: Species selected must be able to fulfill the objective for planting them – e.g. soil and water conservation – in catchment areas, improvement of soil fertility (supply of mulching material, green manure), animal fodder, shade, and saleable products such as fruits, fire wood and charcoal, timber for construction, craft materials, etc.
2) The environment e.g. climatic conditions, soil type and altitude
3) The ability of the species to establish and provide a wide range of utility, preferable for more than one purpose and a high degree of profitability.
Availability of good quality seed on time is a pre-requisite for all tree planting activities. The Kenya Tree Seed Centre, a programme within KEFRI, supplies good quality seed. The centre also provides technical advice on selection of good seed sources. The work of the centre is supported by sub-centres ar Nyeri, Londiani, Kakamega, Kitale, Kibwezi, Gede and Turkana. Quality seed can also be obtained from any sub-centre, field officers of the Kenya Forestry Department or from the Tree Seed Centre at Muguga. It would be important for farmers to be able to obtain tree/shrub seeds from the open market and raise their own seedlings as they do with other farm crops, such as maize, cabbages, etc. The most important species for five of the seven of Kenya’s ecological zones have been listed in an alphabetical order under each ecozone (AEZ). Ecological zones I and VII have been excluded because currently there is hardly any tree planting taking place in these zones. The remaining five ecozones are deemed as receiving annual rainfall as follows:
Ecozone II (over 1400 mm)
Ecozone III (800 to 1400 mm)
Ecozone IV (400 to 800 mm) and
Ecozone V and VI (less than 400 mm)