Setting Priorities among Indigenous Fruit Tree Species in Africa: Examples from Southern, Eastern and Western Africa Regions - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 10

genetic variability. G. kola and R. heudelotii ranked ninth and tenth,
respectively. They received low to medium ratings on the above three criteria,
and have medium to long reproduction cycles. The range in ratings was
considered to be narrow enough so that priority was still given to the five
farmer-preferred species.

Valuation and ranking of five priority species

In the humid lowlands of Nigeria, I. gabonensis was grown or collected by the
greatest percentage of households (75%) and had the highest value of
production per grower/collector per year, US$124 (US$ = Naira 40, June
1994) (Table 1.4). However, values were extremely variable and coefficients of
variation for the value of production were more than 70%. Nationwide, D.
edulis ranked second and C. albidum third in percentage of households and
value per grower/collector (Table 1.4). In Cameroon, D. edulis ranked slightly
higher than I. gabonensis in terms of percentage of farmers growing/collecting
and value per grower/collector. R. heudelotii ranked second in percentages of
households growing or collecting, but values per grower/collector were only
one-fourth those of I. gabonensis and D. edulis . G. kola was grown or collected
by only 37% of the households but had a high value per grower/collector, over
double that of R. heudelotii . Two methods were used to estimate quantities
harvested: farmers' recall, usually expressed in terms of local measures, and
multiplying the numbers of trees by tree yields obtained from secondary data.
The two methods yielded fairly similar estimates; for example, in Cameroon,
mean values for D. edulis quantities differed by 8% between the two methods,
for I. gabonensis by 25%, and for G. kola by 36%.
By extrapolating sample values to the estimated number of agricultural
households of the humid lowlands of Nigeria, I. gabonensis 's farm-gate value
for the humid lowlands is estimated at US$145 million, D. edulis at
US$78 million and C. albidum at US$16 million (Table 1.4). Because of the
high variability in the data, there was no significant difference between the
values for I. gabonensis

and D. edulis , though both were higher than

Table 1.4. Region-wide values of production for main tree products, humid lowlands of
Nigeria and Cameroon.

Central, south and east

Humid lowlands of Nigeria provinces of Cameroon

90% confidence interval 90% confidence interval

Mean Upper Lower Mean Upper Lower

(US$ million) limit limit (US$ million) limit limit

Irvingia gabonensis 145 230 59 17 24 11

Dacryodes edulis 78 101 55 22 28 15

Chrysophyllum albidum 16 21 11 0 0 0

Ricinodendron heudelotii 0 0 0 5 11 1