EVALUATION OF TIMBER TREES PRODUCING VALUABLE FRUITS AND SEEDS IN CROSS RIVER STATE

The study assessed two rain forest reserves in Cross River State for timber trees producing economically valuable fruits and seeds. The reserves are Afi River and Oban West forest reserves. A total of 18 and 42 tree species were enumerated in Afi River and oban West respectively. In Afi River forest, Brachystegia eurycoma had the highest population of 5 per hectare while Canarium schweinfurtii, Dacroydes edulis, Garcinia kola, Irvingia gabonensis, Parkia bicolor, Pentaclethra macrophylla, Recinodendron heudelotii, Tetrapleura tetraptera and Vitex species had the least of 1 each per hectare. In Oban West forest reserve, Allanblakia floribunda had the highest population of 11 per hectare, while Brachystegia eurycoma, Chrisophyllum albidum, Recinodendron heudelotii, Tetrapleura tetraptera and Xylopia aethiopica had the least of 1 each per hectare. It is observed that most of the timber trees producing valuable fruits and seeds have low frequency of occurrence due to timber exploration thereby calling for their conservation and protection.


INTRODUCTION
The tropical rainforests are the world's most vital vault of biodiversity, and are a natural repository of genetic diversity, which offers a rich wellspring of therapeutic plants, high return foods for daily consumption and a lot of other helpful products (Addai et al., 2016).Forest resources are vital to numerous individuals all through the world.On a global scale, a large number of individuals who live in rural areas depend on the products like, wild fruits, vegetables nuts, edible roots, honey, palm leaves, medicinal plants, and bush meat which are derived from the forest to generate income and also for consumption in their households (Andel, 2006) The need to manage and conserve the tropical high forest sustainably cannot be over emphasized.The tropical high forest is the most biologically diverse ecosystem in the world (Turner, 2001) and has been a great source of livelihood from time immemorial.
There is more to be harvested from the forest than trees.Non wood forest products (NWFPs) are an integral part of the livelihood of the 500 million people who live in or near tropical forests that cover 20 percent of the world's land mass [Canadian International Development Agehcy, (CIDA, 2003) and Udo (2002)] assert that forestry has contributed to the industrial sector of the economy by providing major raw materials (saw logs, veneer logs and plywood) needed by wood based industries.Other areas through which forestry contributes to development are provision of food, health care and energy for domestic use.Examples are Irvingia gabonensis Baill, Chrysophylluim albidum G. Don, Garcinia kola Heckel, Monodora myristica Dunal etc.Many of the timber trees of the tropical rainforest produce a variety of highly valuable non timber forest products (NTFPS) like edible and medicinal fruits, seeds, nuts and oils.A considerable number of the trees also produce industrial raw materials like latex, tannin, gum exudates, dyes and resin.The nontimber forest products of these trees are, in some cases, much more valuable than the timbers.They can be harvested for many years without cutting down the trees as contrasted by timber harvesting.Also, their harvesting activity often has infinitesimal impact on the ecosystem.Ford Foundation (1998) opined that the non timber forest products (NTFPs) are particularly in important part of multiple-use strategies, because they increase the range of income generating options for forest dependent villagers while avoiding some of the ecological costs of timber exploitation.As efforts are being geared to check-mate wanton destruction of the remaining areas of the tropical forest and promote sustainable exploitation of its resources, adequate on tree species producing multiple products is imperative to the actualization of their conservation and protection.This study therefore identified timber trees producing valuable fruits and seeds in Cross River State and their population density with a view to making suggestions for conservation and protection of the endangered species.

MATERIALS AND METHODS Study Areas:
The study was carried out in Afi River Forest Reserve and Oban West Forest Reserve in Cross River State, Nigeria.Afi River Forest Reserve is located between latitudes 6° 08' and 6° 26' North and longitudes 8° 50' and 9° 05' E. It covers a total land area of 383 Km2.Annual rainfall and average temperature in the area are about 3,500 mm and 27°C (Balogun, 2003).The mean annual relative humidity is 78% at 7.00 hrs, while the soils vary from clayey-loam to loamy-clay.Oban West forest Reserve is located between latitudes 4° 44' a d 5° 45' North and Longitudes 8° 18' and 8 50' E. It covers an area of 1,042 Km2 with an annual rainfall of about 4,073mm and an average temperature of 25°C (Balogun, 2003).The average annual relative humidity is 80° at 7.00 hrs.The soils range from loamy sand to clayey-loam.The two forests have been subjected to timber exploitation over the years.Data Collection: Three 500m line transects were laid into the core areas of each forest, with the first transect starting 20m away from the access route.Each transect was separated from the other by a distance of 330m.Timber tree species within 10m on both sides of each transect that produce valuable non timber products (fruits and seeds) were identified and enumerated by numbering them with enamel paint.Thus, the total sample area assessed in each forest equated 3 hectares.All trees known to have timber and fruit/seed value were identified counted and their frequency of occurance recorded.All the trees recorded in this survey were species mentioned by Alexander and Effa (1994) in a participatory rural appraisal (PRA) survey of NTFPs in Cross River State.

Data Processing and Analysis:
The frequency of occurrence of a tree species in each forest was determined in order to estimate its population per hectare by dividing the total population in the sampled area by 3.
To be able to explore the heterogeneity of the species, diversity index was calculated for the two forest locations (Afi and Oban-in the north and south) using Simpson's diversity index.This is expressed as follows:-DI = N(N-1) q ∑ ni (ni -1) i -1 Where Di = Simpson's diversity index N = Total number of individual trees counted Ni = Number of individuals of each species enumerated for i = 1 ------q q = Number of different species enumerated

DISCUSSION
The presence and population density of a tree species in a tract of rainforest is greatly influenced by the microclimate within the forest and the quantity of viable seeds produced by the tree concerned (Olajide, 2004).For instance a shade intolerant species will find it difficult to regenerate in a rainforest with closed canopy.Thus, the population density of such a species would be low in that forest while adult trees will hardly survive.The low population of tree species in, the study area may be due to unfavorable microclimate and the absence of viable seeds on the forest floor.Low population densities of a number of economics species due to dearth of viable seeds and poor microclimate was reported by Christie and Armesto (2003).Also, abundance or rarity of timber trees of economic value in an area of rainforest is a function of the intensity and pattern of its exploitation (Olajide, 2004).Therefore, the fewer population of individual tree species observed in the study area can be linked to ove'r exploitation of the trees for timber.Olajide ( 2004) established a positive relationship between poor population densities of some tree species and the mortality of their old mother trees.Parthasarathy and Karthikeyan (1997) (2006) has shown that the aqueous extract of G. kola may have biochemical significance in the treatment of some liver disease.

CONCLUSION
From oral interactions with some community members, the timber trees producing valuable fruits and seeds found in the study area are important especially to the immediate communities as they sustain the economic well-being of the people.The value of these trees in terms of their NTFPs may outweigh the value of the trees during their life span in comparison with the sawn timber value (Alexander & Effa, 1994).In order to prevent their extinction, government should out-law their exploitation for timber from the forest estates.The people living close to these forest should be incorporated into a conservation program to prevent their timber exploitation and ensure conservation and sustainable production of valuable NTFPS.Clusters of these trees could be preserved through establishment of Strict Natural Reserves (SNR).Conservation and management of these species can also maintain the forest diversity act as a gene pool and improve stocking.

Table 1 :
Timber trees producing valuable NTFPS in Afi River Forest Reserve, Cross River State

Table 2 :
Timber trees producing valuable NTFPS in Oban West Forest Reserve, Cross River State.

Table 3 :
Diversity index of Timber trees producing valuable NTFPS in Afi River and Oban west forest reserves, Baillonella toxisperma, Canarium schweinfurthii, Dacryodes edulis and Garcinia kola.The diversity of the species in Oban is denoted by the presence of Chrysophyllum albidum, Coula edulis and Xylopia tree per hectare (Table1).As shown in Table 1, 11 out of 12 timber trees in Afi river forest reserve produce edible fruits except for Ricinodendron heudelotii, in which leaves and seeds are edible.A. floribunda and B. toxisperma produce seeds from which edible oil is extracted.On the other hand, Garcinia kola produces seeds that are eaten as B. eurycoma, Chrysophyllum albidum, R. heudelotii, Tetrapleura tetraptera and Xylopia aethiopica (Table 11).A Simpson's diversity index of 12.75 was calculated for Afi River Forest Reserve while 6.11 was obtained for Oban West Forest Reserve.The diversity exhibited in Afi is denoted by the presence of four species that are not recorded in Oban.These are -