Grevillea robusta and Sesbania sesban planted within the Vi tree planting project, Kenya. Growth, farmers attitudes and silviculture. A minor field study

agrosilvopastoral systems bois de chauffage comportamiento humano comportement humain crecimiento croissance developing countries forest plantations fuel crops fuelwood grevillea grevillea robusta growth human behaviour kenia kenya petite exploitation agricole sesbania sesbania sesban silvicultura silviculture small farms sylviculture