AGR 203 Forest Management PDF

AGR 203 (FWM 201): INTRODUCTION TO FOREST RESOURCES AND WILDLIFE MANAGEMENT WEEK 6 A. Concept of Normal Forest Normal Forest is an ideal state of forest condition which serves as standard for comparison of an actual forest estate, so that the deficiencies of the latter are...

AGR 203 (FWM 201): INTRODUCTION TO FOREST RESOURCES AND WILDLIFE MANAGEMENT WEEK 6 A. Concept of Normal Forest Normal Forest is an ideal state of forest condition which serves as standard for comparison of an actual forest estate, so that the deficiencies of the latter are brought out for purposes of sustained yield management. Normal Forest envisages an ideal state of perfection, serving the purpose of good scientific management. Normality is that practically attainable degree of perfection in a forest which we strive to secure in all parts of the forest and to maintain it in perpetuity. A forest which contains a regular and complete succession of age-gradations or classes in correct proportion so that an annual or periodic felling of the mature woods results in an equalization of the annual or periodic yield. Normal forest is one in which growing stock is so distributed by size and age classes as to provide a sustained yield of nearly equal annual volumes through growth. A forest which, for a given site and given objects of management, is ideally constituted as regards growing stock, age class distribution and increment, and from which the annual or periodic removal of produce equal to the increment can be continued indefinitely without endangering future yield. In other words, a normal forest is an ideally constituted forest with such volumes of trees of various ages so distributed and growing in such a way that they produce equal annual volumes of the produce which can be removed continuously without detriment to future production. It serves as a standard of comparison for sustained yield management. The concept of sustained yield management involves the management of trees in the forest such that trees are harvested at maturity (rotation age) and replaced by new trees, naturally or artificially, so that year after year, there are mature trees available at all times. Normal forest is that forest which has reached and maintained a practically attainable degree of perfection in all its parts for the full satisfaction of management. Under a given method of treatment and rotation, a forest is termed a normal forest when it has the following attributes: (a) a normal series of age-gradations or age-classes; (b) a normal increment, and consequently; (c) a normal growing stock. Forest formation A typical forest has 4 layers, namely; forest floor, under-storey, canopy and emergent layers Forest floor-the layer of the undergrowth where RH is high (95%) and the temperature is fairly stable (25 to 30⁰C). Receives little light penetration. Rainwater reaches this level by flowing down the trunk of the trees. Has many seeds lying dormant for years waiting to receive sufficient sunlight, heat, water and space for growth following a gap created after a fallen tree. Understorey - layer between the canopy and the forest floor. It is made up of shrubs and smaller trees growing to 12 ft in height. The amount of sunlight to this layer is limited, as is the rainfall. The Understorey layer provides a very sheltered environment for its inhabitants. 1 Canopy layer – This is the layer beneath the emergent layer and it comprises of smaller trees between 75 to 90 ft high. These trees form a living umbrella sheltering the flora and the fauna below from extreme heat, wind and rain. As there is little wind below the canopy most of the trees rely on insect, birds and bats to pollinate the flowers. Few plants rely on wind to disperse their seeds. This layer is the home to thousands of animal species such as primates and birds. Emergent layer - consists of the tallest and usually oldest trees which are about 40m (120 ft) high and spread out over the tops of other trees. These trees take the brunt of climatic changes e.g. they receive the highest sunlight, hottest temperatures, wind and rain B. Nigeria Vegetation Zones Vegetation is an assemblage of plant cover on the earth. Vegetation of a geographical area is the response to the climatic condition in the area. Nigeria vegetation reflects similarity in west-east zonation of vegetation and climate and a progressive decline in rainfall and length of wet season in south-to-north direction characterized by transitional zones from one belt to another. Nigeria has 2 broad belts of vegetation types-forest and savanna. There are also the mountain vegetation on the isolated plateau of the central and the far eastern part of the country. Forest zone is composed of vegetation or plant formation in which trees are the dominant species. Nigeria has heavily forested coastal south where humid tropical conditions favour tree growth. The forest zone is subdivided as follows: Saline water swamp; Freshwater swamp and Tropical evergreen rainforest Saline water swamp comprises of vegetation on the coastal strip of varying width from