The Distribution, Density, and Estimates of Carbon and Inorganic Nutrients in some Lesser-Used Species

Timber is the third foreign exchange earner for Ghana and timber exports had for some time now been based on the so-called prime timber species (Table l) with little attention being paid to other species called secondary species or Lesser-Used species (LUS). This is with the result that prime species have been exploited, most of them are currently threatened, and their harvesting either reduced or banned. To sustain the timber industry therefore attention has been focused on the promotion of the Lesser-Used species. Currently however, many international initiatives have focused on sustainable management of forests, and this has resulted in the establishment of Forest Stewardship Council (FSC) which has the ambition of setting world-wide standards for good forest management (FSC, 1992). The FSC is currently drawing up the principles and criteria for forest management which they hope will be used by organisations for forest monitoring and certification, consumers of forest products and policy makers. The FSC is also proposing to become an independent non-governmental international organisation, which will evaluate, accredit and monitor forest certification programmes. Certification of forest products will be one way to promote sustainable forest management practices. They propose that this should be market driven. Certification initiative that will provide economic rewards to forestry operations which will ascribe to management practices that are ecologically sustainable, socially beneficial and economically viable. By complying with certifying standards, the forest products will be granted access to the burgeoning worldwide 'green' market. The implications are that unless forestry activities are sustainable and environmentally acceptable, access to market will be difficult. Thus, sustainable forest management is necessary if the marketing of LUS is to succeed. Sustainable forestry as recently defined means "the stewardship and use of forests and forest land in such a way and at a rate, that maintains their biodiversity, productivity, regeneration capacity, vitality and their potential to fulfil now and in the future, relevant ecological, economic and social functions at local, national and global levels, and that does not cause damage to other ecosystems" (Helsinki Ministerial Conference, 1994).

Maintenance of productivity is an essential factor for sustainable forest management. However, one of the most important factors for productivity is nutrient availability. Thus in assessing the ecological sustainability of forest activities, the impact on nutrient availability should be determined. Many studies have however shown that in tropical forests between 60-90% of nutrients are stored in the above-ground biomass (Jordan 1985, Ruhiyat 1989). Thus, estimation of nutrients in the above-ground biomass of any species is a good indicator of the contribution of the species to nutrient availability in the ecosystem. Also among current global environmental problem that is of most concern is the accumulation of green house gases in the atmosphere which has begun to change the global climate (IPCC 1990). Reports suggest that managed forests and agroforestry systems have the potential to sequester and conserve about 10GT of carbon annually. Thus one of ecologically functions of the forest that is of global interest and which should be part of sustainable forest management practices is the sequestration and conservation of carbon.

However, the contribution of LUS in Ghana to nutrient availability and sequestration of carbon is not known. However, these contributions to ecological sustainability cannot be discussed without reference to the resource base. This paper therefore provides estimates nutrient and carbon storage of some Lesser-Used species as well as distribution and density.