Biomass in different biotopes – an extensive resource - Biomass as Energy Source: Resources, Systems and Applications - page 102

Figure 5.18. Tropical crops in Ghana (photo E. Dahlquist). Papaya originates from central and South
America, but is now common in all tropical areas.
5.3 BIOMASS IN THE TROPICS
The focus of this chapter has been on biomass in Europe. In Europe, we have all the biotopes
accept for real tropical areas, although some areas are almost tropical. As a complement, this
section 6.3 will cover at least some aspects of tropical climate and biotopes as well. Cassava
( Manihot esculenta ) is an important crop in many tropical countries. Tweneboah (2000) states
that cassava is the staple food for more than 200 million people in sub-SaharanAfrica. The reason
is that it can grow in marginal land areas where the soil is poor. It also has high calorific value
and is relatively easy to store. It is also resistant to drought. Another important crop is yam, which
is very important in West Africa, and especially in Nigeria, the most populous country in Africa.
For yam, there is a high demand on enough moisture during the full growth period, but especially
during the 14-20 weeks of growth. 1000-1500mm rain per year and a dry season of 2-4 months
gives optimum yield conditions. Still 20-25 million tonnes/year is produced, which is 90% of
the world production. Sweet potato ( Ipomoea batatas ) and aoids (cocoyams) are other important
food crops in sub-Saharan Africa, even if they are not as important as staple food as cassava and
yam. Cocoyam ( Xantosoma sp.) is normally cultivated in the tropical forest areas where is used
to give shade to other crops. Sweet potato on the other hand is cultivated more in the savannah
areas closer to the Sahara region, where it often grown on relatively poor sandy soils. Due to this,
the productivity is relatively low. Information about both the crops and how to cultivate them is
given in Opeke (1997). In Figure 5.18, we see a typical view of crops cultivated in gardens in
Accra, Ghana. Also exclusive trees like jacaranda, hickory and others are species of importance
for furniture and similar products.
Banana and plantain (musa) are other important crops. Plantain is a staple food crop in the
central African low land forests. It is especially popular in Cameroon, Gabon, Republic of Congo