Agroforestry: growing with the population
The population density in the highlands of rural Kenya and Rwanda is increasing and the average farm size is declining. With an average rainfall of 1,000 mm, permanent agriculture remains the most important economic sector and source of export and agroforestry is common. Yet, surveys and photographs show that tree cover is increasing along with the population. How? Was it like this all along? Actually, no. By 1948, the average population density had risen to about 100 persons per sq km and these districts became food exporters. Intensive cultivation of maize, unaccompanied by any erosion control measures, led to rapid soil degradation. Yields plummeted by the 1970s and the 1980s. Migration became had become common, along with malnutrition and poverty. This led to a demand for agroforestry.
Apart from the few sacred and high-value protected species, trees were rarely planted. Live hedges became important for demarcation of boundaries, and fencing, for protection from invading livestock. Indigenous fruit tree species like mango ( Mangifera indica ) and guava ( Psidium guajava ) were introduced and protected. In the last decade of the 20th century, transplantation of wildlings and protecting tree species became important.
To acquaint the African farmers with valuable trees and agroforestry, the Kenyan government's agricultural extension project conducted a study in 1987. The study showed significant changes: free-standing trees had increased in number by 125-513 per cent and the length of dense hedges increased by 29 per cent. Sara J Scherr, US-based natural resource economist who has worked in Kenya, points out that this was to obtain critical consumption goods and to diversify income sources. While the potential of agroforestry is significant in the tropics, Scherr emphasises the need for "institutional and policy support.' She points out that farmers face strong disincentives to practice agroforestry in many countries where land-use regulations. Scherr says Kenya has a history stemming from the colonial period prohibiting growing trees in cropland implemented through fines and restrictions. In Ethiopia, the government claims