7. Inventory of the High Forests and Plantations in Nigeria

7.1. Overview

In March 1993, the African Development Bank (ADB), Abidjan, approved a grant of UA 1.72 million for the implementation of a study tagged "The Forest Resources Study of Nigeria". The overall objective of the study is to enhance industrial forestry development in the country and to facilitate management of its remaining forest resources in all efficient and environmentally adequate way. Essentially, the study consists of three major components namely: -

A. Inventory of the high forest areas in the southern one quarter of the country i.e. about 20,000 km2. The following States constitute the study area concerning high forest: Lagos, Oyo, Ogun, Osun, Ondo/Ekiti, Edo, Anambra, Delta, Rivers/Bayelsa, Imo, Akwa-Ibom, Abia, Cross River and Enugu/Ebonyi.

B. Inventory of forest plantations throughout the country, except those in the arid north. Specifically, the States involved include all states inventoried for the high forest and the following States: Kwara, Niger, Kogi, Benue, Taraba, Adamawa, Plateau/Nasarawa, Kaduna, Kano and Kebbi.

C. Sub-studies, which include private sector involvement and socio-economic assessment, wood-based industrial sector review, market and pricing policy assessment, review of forest legislation, survey of indigenous fruit trees (IFTs), and silvicultural investigation of selected IFTs.

The following States in the arid north are not covered by the study: Sokoto/Zamfara, Katsina, Jigawa, Yobe, Bauchi/Gombe and Borno).

The FRS was implemented as a consultancy assignment by Beak Consultants of Canada with the support of the Federal Government of Nigeria (FGN). Some of the specific obligations of FGN include provision of relevant documents to facilitate the study, establishment of a study implementation unit (SIU), secondment of appropriate staff (mainly inventory officers) and financial resources to pay staff emoluments. The FRS was expected to be completed in 24 months with effect from December 1995. The results of this study is urgently needed for providing adequate and up-to-date information on the forest resource situation in the country and for defining the future role of the forestry sub-sector in the social and economic development of Nigeria. It may be recalled that the last inventory exercise in Nigeria was conducted about 20 years ago by the Food and Agricultural Organisation (FAO) and the UNDP. Draft reports of the FRS are now being assessed. It is hoped that a Final Project Completion W rkshop will be held by May 1999.

7.2. Inventory of the High Forests

Prior to the inventory of the high forests and plantations, a Preliminary Information Gathering (PIG) exercise was conducted to facilitate stratification of forest types, densities and site characteristics. Geographic Information System (GIS) technology was also used to isolate specific forest strata. Stratified Random Sampling (SRS) was used for the high forest inventory. The only limitation imposed for this inventory approach was the requirement to distribute inventory plots across the 14 High Forest States. In other to perform the exercise efficiently, sampling units were taken as point clusters. Each cluster of size 1km by 200 m in area, was composed of two tracts (each of 200 m by 200 m) located 600 m apart at either end of the 1 km line. Within each tract, four plots of 50 m x 50 m were established at the corners to serve as recording unit for the enumeration.

Beak Consultants (1998) noted that each cluster, therefore, consisted of 8 plots or enumerating units. Because of the difficult terrain in the Mangrove, Forested Fresh Water swamp and Riparian Forests the size of the cluster was reduced by half i.e. the size of the cluster reduced to 500m x 100m while those of the tract and plot were 100 m x 100 m and 25 m x 25m respectively. The sampling intensity used for inventory of the high Forest was estimated at 0.01% (Beak Consultants 1998).

7.3. Inventory of Forest Plantations

Beak Consultants (1998) used stratified random sampling to undertake the inventory of forest plantations in the study area. The PIG exercise also facilitated the stratification of plantations according to ecological zones, species, density, soil type and age. In order to satisfy the objectives of this inventory, more plots were established within a plantation to capture variability within than to establish fewer but larger plots. Plots of 0.01 ha were therefore randomly established in selected plantations proportional to the plantation size as shown in Table 5.

Table 5: Number of plots established according to plantation size.

According to Beak Consultants (1998), a total of 958 plots were enumerated each measuring 0.01 ha in size. A total area of 9.58 ha was enumerated thus giving a sampling intensity of approximately 0.01%.