3.1. FOREST MANAGEMENT INTERVENTION
3.2. IMPROVEMENT OF FOREST QUALITY
3.3. CONSERVATION OF FOREST GENETIC RESOURCES
Formal forest management and conservation in Tanzania dates back to the German period, following the realization of unsustainable and destructive forest degradation through uncontrolled harvesting and encroachment for agriculture. A move was followed by the gazettement of the first forest reserve in 1906 (Ahlback, 1986).
The objectives of forest management are diverse following the varied nature of the ecosystem itself. These are classified based on protection as well as production. Protection enhanced forest management is aimed at managing catchment areas and biological diversity conservation. This is facilitated by restricting human activities in forest reserves and national parks. On the other hand, production forest management is mainly for round wood production and involves forest development and harvesting.
Various methods have been developed and used to facilitate natural forest management. These methods include inducement of natural regeneration, enrichment planting, protection of regeneration against weeds, fires and grazing/browsing. Inventories and surveys were conducted some years ago to obtain the actual status of the forest and for planning management interventions.
3.2.1. Demand and supply of seeds
3.2.2. Tree improvement
Afforestation programs in Tanzania for industrial purposes started in the early 1950s in a number of places, by introducing fast growing exotic timber species (Borota and Procter, 1967). This necessitated the establishment of the seed section at the silvicultural research station in Lushoto to deal with matters such as collection, processing, storage, testing, distribution and certification (Shehaghilo, 1984). Seed procurement was through local collections within the established seed orchards, seed stands and selected plantations.
Due to increased rates of environmental degradation caused by deforestation as well as growing awareness on environmental conservation among communities, there has been an increase in tree planting activities to meet a variety of objectives such as firewood, building poles, timber and raw material for wood based industries. Consequently, the demand for tree seed increased significantly, necessitating the establishment of the National Tree Seed programme to deal with all matters related to seed procurement (Shehaghilo, 1991). Some seed handling activities are however still going on at the Lushoto Silvicultural Research Centre.
The NTSP harvests an annual average of 8.5 tons of clean seed from more than 130 species and sells them to more than 500 customers inside and outside the country. Customers include governmental departments, research organizations, private companies, non-governmental organizations (NGOs), aid organizations and farmers.
In Tanzania, tree improvement activities started during the German colonial period in 1891 following the introduction of exotic tree species (Schabel, 1990). Species trials were established in the arboreta at Kigogo, Sao Hill (1935) and Lushoto (1952). Eucalyptus and Pinus species were the most widely planted tree genera, followed by cypress, Cedrela, Gmelina, Azadirachta indica, Senna siamea, Acacia spp. and Tectona grandis (TAFORI, 1999).
From the 1950s, the emphasis was on provenance testing, progeny testing, seed orchard and seed stand establishments, selection of plus trees and establishment of clonal banks for Cupressus lusitanica, Pinus patula, P. radiata, P. caribaea, P. elliottii, Tectona grandis by the Tanzania Forestry Research Institute (TAFORI). The results from established experiments have been used in the establishment of plantation forestry in the country. Currently, efforts are being made to broaden the genetic base and species range for the Casuarina spp., Grevillea robusta and Azadirachta indica (TAFORI, 1999). Further, a plan has been proposed aimed at breeding for resistance against aphid attacks on cypress. In addition, the NTSP is managing improved seed stands for Acacia mangium, Azadirachta indica, Bixa orellana Casuarina equisetifolia, Eucalyptus tereticornis, E. camaldulensis, Gliricidia sepium and Pithecelobium dulce.
Conserving diversity between and within plant species stems from a wide array of economic, social, biological, ecological, scientific and aesthetic values that plant genetic resources provide to humanity. Maintaining diversity within plant species allows plants in the wild to evolve and thus to maintain or enhance their adaptation to the changing environment. It also provides people with the opportunity to select and breed to improve desirable plant characteristics such as disease resistance, environment adaptation and end uses.
Growing population, especially in developing countries, has increased the world demand for food and agricultural products. As a result, human activities have accelerated the rate of species disappearance and loss of races and varieties within species. As a result, many plant species are rapidly losing genetically distinct populations of special value for genetic improvement and breeding. In this situation, conservation of genetic diversity within plant species becomes a prerequisite to enhance tree species perpetuation.
The heritable variations found between and within species can be conserved through a network of managed areas called in situ conservation and/or through ex situ conservation in seed banks, plantations, arboreta, etc.
In situ conservation of genetic resources is conducted in the original habitat of the plant. It is complementary to ecosystem conservation which focuses on variation between different species and on their interrelationships. In Tanzania, in situ conservation of forest genetic resources is enhanced through established forest reserves (12 517 000 ha) and in national parks (2 000 000 ha). Regardless of its role as a reserve for genetic resources, the governmental forest reserves are constantly threatened by encroachment and wild fires. Lack of systematic management, unclear boundaries and inadequate resources for controlling these forest reserves have led to illicit felling of trees to the extent of threatening some important tree species found in them (MNRT, 1998).
Ex situ conservation of genetic resources is a practical method to conserve species and genes that are endangered or vulnerable in their natural habitat for maximum security. In Tanzania, ex situ conservation of forest genetic resources dates back to 1935 when the first arboretum was established at Kigogo. This was followed by six other arboreta making up a total of seven, comprised of different exotic and indigenous tree species. Further, the Silvicultural Research Centre owns one botanical garden in the East Usambara containing some threatened and endemic tree species. In 1980, the silvicultural research station, in collaboration with DANIDA/FAO (Danish Agency for Development Assistance/Food and Agriculture Organization of the United Nations), established four ex situ gene conservation seed stands in Ruvu, Kwamarukanga, Urumwa and Buhindi. This trial consisted of Pinus caribaea, P. oocarpa, Eucalyptus tereticornis and E. camaldulensis from different provenances.
