Chapter 2
Literature Review
2.1. Biodiversity
The variety of life on Earth, its biological diversity is commonly referred to as biodiversity. The number of species of plants, animals, and microorganisms, the enormous diversity of genes in these species, the different ecosystems on the planet, such as deserts, rainforests and coral reefs are all part of a biologically diverse Earth.(Shah.A, 2007) .Biodiversity has been most generally defined as the "full variety of life on Earth" (Takacs,1996). More specifically, biodiversity is the study of the processes that create and maintain variation. It is concerned with the variety of individuals within populations, the diversity of species within communities, and the range of ecological roles within ecosystems (Graham Bell, 2007). Biological diversity is the variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequency. For biological diversity, these items are organized at many levels, ranging from complete ecosystems to the chemical structures that are the molecular basis of heredity. Thus the term encompasses different ecosystem, species, genes, and their relative abundance. (Anon, 1987) “Biodiversity Diversity” means the variability among living organisms from all sources including, inter alias, terrestrial, marine and other aquatic ecosystems, and the ecological complexes of which they are part; it includes diversity within species, between species, and of ecosystems (CBD, 1992).Biodiversity or biological diversity pertains to the diversity of biological organisms, both animals and plants in a region, country, continent of the entire glove (Negi, 1993). Though the concept of biodiversity has been known to man ever since he began minutely observe the living being around him, this word suddenly appeared as the catchword of conservationists and biologists towards the end of the last decade. Forest biological diversity means the variability among forest living organisms and the ecological processes of which they are part; this include diversity in forest within species, between species and of ecosystems (SCBD, 2002). It should be quantified and described for a multiple scales, from large landscapes of several thousands square kilometers, to the genetic level within individual organisms (SCBD, 2002).
Ecologists have developed ways to characterize species diversity in a given area:
Within-habitat diversity or alpha-diversity: refers to a group of organisms interacting and competing for the same resources or sharing the same environment. Measured as of species within a given area. (Fisher et al. 1943)
Between-habitat diversity or beta-diversity: refers to the response of organisms to spatial heterogeneity. High beta-diversity implies low similarity between species composition of different habitats. It is usually expressed in terms of similarity index between communities (or species turnover rate) between different habitats in same geographical area (often expressed as some kind of gradient).(Whittaker,1967)
Geographical diversity or gamma-diversity (Whittaker,1972)
2.2 Types of biodiversity
Biodiversity comprises every form of life from the tiniest microbes to the mightiest beasts and gigantic trees.According to Agarwal et al. (1996) the biodiversity exists at three different levels. These are:
Genetic diversity
Species diversity
Ecosystem diversity
2.2.1 Genetic diversity
Genetic diversity means deviation on gene to gene. Genetic diversity is based on variation between genes, i.e. in the functional units of heredity in organisms. Not all the genetic material has a role in heredity, and in some organisms a large proportion of DNA is highly respective in sequence and has no known function. The feature of an organism are determined by the genes received from the previous generation, by the way these genes are expressed and interact, and to an extent by environmental effects on the organism(cdb,000)] It refers to the variation of genes within species (Alamgir, 2003). Genetic diversity of a given species can be assessed by different techniques, including studies of morphological and metric characters, use of biochemical and molecular markers and observations of ecogeographic variation. A wide range of powerful molecular markers (DNA and isozyme) is now available for assessing genetic diversity in particular organisms (Hamrick and Godt, 1990). Depending on the marker used, the information from such studies may provide different insights and level and structure and variation and the evolutionary processes associated with species development and maintenance. For example, in Acacia mangium, virtually no variation was detected using allozymes (Moran et al., 1989); however an RFLP study revealed considerable within and between population variations with greater variation being correlated with better field performance (Butcher et al., 1996). More recently, microsatelite markers have demonstrated much higher variability than RFLP markers in the same species, permitting greater genetic discrimination between individuals. Microsatelite markers will be of great utility in matting system studies (Butcher et al. 2000). Increasingly, attention is being given to ensure that the limited resource for genetic research in rare species are used for studies which will provide information of direct use in developing conservation management plans for the species (Hogbin et al. 2000). Quantitative and adaptive traits, e.g. physiological tolerances to various abiotic stresses and disease resistance, can be assessed through a variety of field and laboratory techniques. Genetic diversity is important as it provides the raw material of evolution and because it ables adaptation and change in orgasioms.high levels of genetic diversity shoud allows species to be flexible in the face of environmental change, wherease low geneticdiversity ,for example in a small isolation population, tends to increase the risk of extinction.( CBD)]
2.2.2 Species diversity
Within-habitat diversity or alpha-diversity: refers to a group of organisms interacting and competing for the same resources or sharing the same environment. Measured as # of species within a given area. ( Fisher et al, 1943) .Species, or alpha diversity, is a measure of number of species of all or various taxa per unit area, more properly referred to as species richness. Another diversity measure is gamma diversity, which in effect reports the sum of alpha diversities across a broader region. Knowledge of diversity of plant and animal species found in forests and their distribution is incomplete. While some groups, such as mammals and birds are often documented reasonably fully, other taxa such as invertebrates and microbes remain virtually unknown (FAO, 1999). The UNEP Global Biodiversity Assessment (UNEP, 1995) suggested that of estimated 13.6 million species of organisms worldwide (including aquatic and oceanic species), less than 1.8 million have been described. The majority of species are insects (8 million), fungi (1.5 million) and bacteria (1 million) and the vast majority of these are undecided. Even among terrestrial plants, many species are incompletely known in some regions. For example, 30-40% of 15,000 botanical specimens held in the Royal Forest Herbarium could be identified during the flora of Thailand Project (OEPP, 1997). For the poorly known groups of organisms, the estimated number of total species often entails considerable, rather tenuous extrapolation. For example, the commonly quoted estimate of global fungus diversity of 1.5 million species (Hawksworth, 1991) has relied on extrapolation from studies in temperate zones. However a recent study of fungi growing on the tropical palm, Licula, suggests that even 1.5 million may be a conservative estimate (Frohlich and Hyde, 1999). Further, even when a species is identified, considerable work remains to determine its range, habitat requirements and relative priority for conservation.
2.2.3 Ecosystem diversity
Ecosystem diversity is reflected in our diverse biogeographic zones such as lakes, deserts, coasts and estuaries. Some of these ecosystems are fragile – wetlands, mangroves and coral reefs. Mangroves or mangals are truly hybrid terrestrial marine ecosystem. They are a diverse collection of shrubs and trees which live in or adjacent to the intertidal zone and are thus unusual amongst vascular plants in that they are adapted to having their roots at least periodically submerged in see water. (CBD). One type of ecosystem that perhaps is neglected more than any other is perhaps also the richest in biodiversity - the Coral Reefs. Reefs are useful to the environment and to people in a number of ways. However, all around the world, much of the world's marine biodiversity face threats from human and activities as well as natural. It is feared that very soon, many reefs could die off. Last updated Tuesday, December 28, 2004. Coral reefs are calcium carbonate stecture developed very largely by stony corals in the order Scleractinia of the phylum Cnidaria. They are essentially tropical, shallow water ecosystems largely restricted to the area between latitudes 30˚N and 30˚S and most abundant in shallow, well flushed marine environments characterized by clear, warm, low nutrient waters that are of average oceanic salinity. They are under constant pressure the conservations of these ecosystems are major challenges (Agarwal et al., 1996). In an ecosystem there may exist different landforms, each of which supports different and specific vegetation. Ecosystem diversity could best be understood if one study the communities in various ecological niches within the given ecosystem, each community are associated with definite species complexes. These complexes are related to composition and structure of biodiversity (Kumar and Asija, 2000).
2.3 Value of biodiversity
There are economic, scientific, aesthetic and ethical values of biodiversity.
Economic: The economic importance of biological diversities are undiscovered future economic potential plants and animals, diverse and wide wild genetic base for crop improvement and breeding programmed, Important sources for modern medicine, raw materials for finish products, life support and non timber plant animal resources for livelihood of many people. Wild biological resources and sites are also important from ecotourism development point of view.
Scientific: Understand the interactions of life forms and their environment and different life processes. Direct economic application of research on poorly known species.
Aesthetic: Wild plants and animals are an irreplaceable source of wonder, inspiration and joy to human beings.
Ethical: The ethical and moral justification is to keep the resource for the use of our next generations. And also to keep the heritage for their inheritance.
In order to highlight the importance of biodiversity conservation to the present consumers, as well as producers it is essential to estimate the worth of species concerned. But valuing biodiversity is a Herculean task. It is difficult to estimate the total value of biodiversity firstly, due to lack of information and uncertainty and secondly, due to variation to location to location, country to country, region to region. Furthermore, the economic value of each species depends upon society’s willingness to pay and willingness to accept which in turn will depend upon the economic, ethical, cultural, aesthetic, and social values (Java and Sristav, 2002).
According to Java and Sristav (2002), the present valuation of biodiversity is based on the premise that it is a biological resource meant to provide:
The maternal basis for human life;
For agricultural and other utilitarian needs.
Nutritionally significant edible plants and animal species.
Medicinal drugs for human and animal health care.
Coastal zone stabilization through mangrove ecosystems.
Support to fisheries through coral reefs.
Place for religious practices.
Aesthetic value.
Values of biodiversity can be justified on ecological, social, economic, cultural and moral grounds, but our self-interest is obvious. Biodiversity is important to us for two primary reasons. Diversity within species, between species and among ecosystems enhances the possibilities available to them in evolutionary process, increasing their resilience to changing environmental conditions. An example of the importance of this to humans is the use of genetic resources from wild relatives of domesticated species to develop hardier varieties of crops. Secondly, diversity of species and ecosystems contributes to the life sustaining mechanisms of the planet (Alamgir, 2003). A loss of biodiversity may impair important ecological functions and result in a degradation of the environment that may ultimately affect human welfare. Impoverished soils, for example, may jeopardize the generation of a forest following logging (Anon, 2001). Diversity manifested by the countless kinds of genetic materials, varied species and ecosystem has enormous values. The variety of distinct microorganisms, plants, animals and habitats can influence the productivity and services derived from the ecosystems (Smitinand, 1995). Plants are fundamental to earth’s life support system and central to human survival. Vegetation derives many of the processes of the biosphere and plants provide humankind with timber, food, fuel, medicine and shelter. Virgin natural forest with diversified tree species with pre-requisite for conservation of wildlife resources as it provides food, shelter, safe breeding ground and water to them. As a result, stability of the ecosystem can be ensured. Floral diversity also have a potential impact on conservation of watersheds which reduce soil erosion and landslides, conserves soil moisture, yields good quality water, regulates stream flow and ensure regularity in hydrologic cycle (Khan, 1991).
Forests world-wide generate a wide range of goods and services that benefits from human kind. According to(SCBD, 2002), from an economic perspective these values can be conveniently classified as:
Direct use values: values arising from consumptive and non-consumptive uses of the forest, e.g. timber, fuel, bush meat, food and medicinal plants, extraction of genetic material and tourism.
Indirect use values: values arising from various forest services such as protection of watersheds and the storage of carbon.
Option values: values reflecting a willingness to pay to conserve the option of making use of the forest even though no current use is made of it.
Non-use values (also known as existence or passive-use values): these values reflect a willingness to pay for the forest in a conserved or sustainable use state, but the willingness to pay is unrelated to current or planned use of forest.There are other notions of value, for example, moral or ethical value, spiritual and religious value and cultural value (SCBD, 2002).
2.4 Threats to Forest Biodiversity
It is important to distinguish between underlying or ultimate causes for loss of biodiversity from the direct causes. The underlying (or ultimate) causes of forest destruction are the factors that motivate humans to degrade or destroy forests; complex causal chains are usually involved. The underlying causes originate in some of the basic social, economic, political, cultural and historical features of society. They can be local, national, regional or global, transmitting their effects through economic and political actions such as trade or incentive measure (WWF, 1998). The direct (or proximate) causes of biodiversity loss in forests are human induced actions that directly destroy the forests (such as conversion of forest land, continuous overexploitation or large scale logging) or reduce their quality (by, for instance, unsustainable forest management or pollution). Direct causes of lost are dealt with following a discussion of the underlying causes.
The driving forces behind direct human impact on forest degradation and deforestation and, consequently, on biodiversity loss are both numerous and interdependent (McNeely et al., 1995;). Forest biodiversity is directly linked to the existence of forest and to the way of forests are managed, and that deforestation and forest degradation including unsustainable logging, slash and burn agriculture, the building of infrastructure such as dams and roads, pollution, fires, infestation and effects of invasive species are themselves the main proximate causes for loss of forest biodiversity loss. Some of these proximate causes, such as climate change or agricultural development, can also act as underlying causes. It is often more immediately profitable to deforest areas or to logs forest in an unsustainable way, than to sustainably manage them, and this has been identified by the AHTEG (Ad hoc Technical Expert Group) as one of the primary causes for the high rate of deforestation and forest degradation and, therefore for the current loss of forest biodiversity. Among underlying causes are broader macroeconomic, political and social causes such as population growth and density, globalization, poverty and unsustainable production and consumption patterns, structural adjustment, political unrest and war; institutional and social weakness such as lack of good governance, illegal logging, lack of secure land tenure and uneven distribution of ownership, loss of cultural identity and spiritual values, lack of institutional, technical and scientific capacity, lack of information, insufficient scientific knowledge and inadequate use of local knowledge; market and economic failures such as under-valuation of forest biological diversity goods and service; policy failures such as wrong incentives and subsidies and ill-defined development programmes, ill-defined or unenforced regulatory mechanisms and lack of environmental impact assessments (WRI et al., 1992; M).
Causal factors are likely varied over time, sometimes drastically. At certain stage of development, rapid income growth could promote forest decline by, for example, increasing demand for forest products and by enhancing human capacity to alter forests. When economics reach a certain threshold, the process is reversed. At this point, increases level of income per capita begin to associated with factors such as technological improvements, better functioning of government institutions, urbanization and less relative dependence on agricultural and forest production. That leads also a change in the composition of demand for goods and services with greater demand for environmental services of forests and for uses, such as recreation, that do not necessarily lead to the forest cover (Contreras-Hermosilla, 2000).
Source: SCBD, 2002.
Figure 2.1 Main causes of forest biological diversity loss
2.5 Conservation of biological diversity
Man has been directly or indirectly dependent on biodiversity for sustenance to a considerable extent. Increasing population, pressure, urbanization and industrialization, however led depletion of the natural resources. The immediate task before the country is not only to manage and to conserve the existing the natural resources and ecosystems but also the restoration of degraded ecosystem through cooperation and support of people. Conservation of biowealth and natural resources is essential for providing security to the nation. The best way is to concentrate on conservation of phytodiversity which will automatically take care of animal and microbial diversity because most of the plants provide food, shelter and congenial habitat to a large number of animals and microbes (Shukla and Chandel, 2000).
Taxonomic study of the components of any ecosystem is essential not only for understanding and assessing the richness of biodiversity but also for the conservation of biodiversity. Biological diversity is to be preserved to achieve sustainable development.
According to Shukla and Chandel (2000), conservation of biodiversity is of two types:
In-situ conservation
Ex-situ conservation
2.5.1 In-situ conservation
In-situ conservation measures are related to the biodiversity of the ecosystems of the original habitats and natural environment. According to Shukla and Chandel (2000), it is the best, easiest, most advantageous and most feasible method to conserve natural biodiversity which aims at:
Consolidating the network for the protected areas for wildlife to ensure the conservation of ecosystems and biogeographic units.
Establishing new protected areas based on utility, distinctiveness and endangerment of species.
Coordinating new and existing protected areas to facilitate gene flow and migration among populations and to ensure proper representation of species and habitat.
Ensuring conservation of biodiversity and rich ecosystems outside the network of protected areas.
Minimizing or banning the activities like over-exploitation, pollution, poisoning and introduction of exotic species leading to loss of biodiversity including habitat destruction.
Encouraging continuous and traditional agricultural practices.
Encouraging public participation in planning and management of protected areas.
Enhancing the ecological and social value of protected areas and providing incentives for biodiversity conservation on adjacent private lands.
Initiating regional cooperation for conservation of ecosystem species.
Conducting periodical reviews of protected areas and plan for assessing present and future needs
2.5.2 Ex-situ conservation
Sometime the populations of species may decline or may become extinct due to genetic or environmental factors such as genetic drift, inbreeding, demographic and environmental variations, habitat loss, deteriorating habitat quality, competition with exotic species, disease and over-exploitation. In such cases In-situ conservation may not proves to be effective and a species can be protected from becoming extinct only through maintaining individuals in artificial conditions and human care and protection. Such measures are included under Ex-situ conservation. Examples of Ex-situ conservation are zoos, sports forms, aquaria, botanical gardens, arboreta, genes, gametes, embryo, seed banks, captive breeding programme, etc (Shukla and Chandel, 2000).
According to Shukla and Chandel (2000), the following Ex-situ steps have been suggested to restore and conserve biodiversity: Strengthing the capacity of Ex-situ conservation to facilitate biodiversity conservation, public education and sustainable development. Encouraging the establishment of seed or gene bank of endangered species. Strengthing the facilities for conservation of crop and livestock genetic resources. Collection and maintenance of microbial cultures. Developing cooperation between In-situ and Ex-situ conservation, habitat restoration and habitat rehabilitation.
Encouraging captive farming and breeding facilities for highly exploitated areas of biological resources. Establishment captive farming and breeding facilities, zoo, aquaria, botanical gardens, national parks, biosphere reserves etc. Initiating legal action against damage of biodiversity. Developing long-term and short-term action plans for diversity conservation and sustainable use. Emphasizing the role of woman in the conservation and sustainable utilization of biodiversity. Preparation and enactment of National Biodiversity Acts with provision for biodiversity conservation. Creating an international fund for biodiversity conservation. Development of database on biodiversity.
Action towards Conservation
Government’s policies, legislation and major initiatives for biodiversity conservation:
There are several legislative policies and initiatives that provide provisions for regulating, harvesting and protecting plants and animals in the country. Those are (Haque, 2001):
Bangladesh Wildlife (Preservation) (Amendment) Act, 1974: The law provides for the preservation, conservation and management of wildlife in Bangladesh. According to the Act the term wildlife or ‘wild animals’ means “any vertebrate creature, other than human beings and animals of usually domesticated species or fish, and include the eggs of birds and reptiles” only.
Bangladesh Forest Act, 1927 and subsequent amendments: The law provides protection of and development of forests. The government may assign a reserve forest to any forestland or wasteland, or any land suitable for afforestation, which is the property of the government, over which the government has the property rights, or to the whole or any part of the forest produce of which the government is entitled. Subsequently, the Forest law has been amended and updated for a number of times in response to changing needs.
Forest Policy and Forest Sector Mater Plan: The government of Bangladesh first formulated the National Forest Policy in 1979. But as the situation began to change with increased demand for forestry products and consequent depletion of forest resource and degradation of the overall environment, the government had to update it and formulate a revised policy which is known as the Forest Policy 1994.
The biodiversity issue has been given increased importance in the latest policy. The policy stated that attempts will be made to bring about 20% of the country’s land under the afforestation programmes of the government and the private by 2015. In order to achieve self-reliance in forest products and maintenance of ecological balance, the government will work hand in hand with the NGOs and people’s participation will be encouraged.
The policy further stated that the priority protection areas are the habitats that encompass representative samples of flora and fauna in the core areas of National Parks, Wildlife Sanctuaries and Game Reserves, Attempts will also be made to increase the extent of these protected areas by 10% of the reserve forest area by 2015.
To achieve the objectives and targets as stated in the policy, the government has also formulated The Forestry Sector Master Plan (1995 to 2015). The financial requirements to implement the plan have been estimated to be about Tk. 80,000 million.
Protection and conservation of fish-Fish Act 1950 and Fish Rules: There are many provisions for the protection and conservation of fish in the inland waters of Bangladesh. By the Act ‘fishery’ means any water body, natural or artificial, open or closed, flowing or stagnant (such as river, haor, baor, beel, floodplain, canal, etc.) in which activities for growing fish, or for conservation, development, demonstration, breeding, exploitation or disposal of fish or living organisms related to such activities are undertaken. The protection and conservation provisions of Fish Rules 1985 prohibit the catching/hunting of certain fishes for specified times or places and prohibited use of certain equipment. The Acts and Rules are undoubtedly measures in favour of biodiversity conservation.
Environment Policy, 1992: The Environment Policy adopted in 1992 gives due importance bio-diversity and related issues. The Policy includes, inter alia, the following aspects:
Rivers, canals, ponds, lakes, haors, beels, baors, and all other water bodies and resources should be kept free from pollution;
Wetlands should be conserved for the protection of migratory birds;
Activities which diminish the area of wetlands/natural habitats of fish should be prevented and rehabilitative measures encouraged;
Existing projects on water resources development, flood control and irrigation should be examined to determine their adverse impacts on fisheries;
Environmental impact assessment (EIA) should be conducted before undertaking new projects for water resources development and management, and also for the projects of other sectors that are likely to effect the environment.
Bangladesh Environmental Conservation Act 1995: The Bangladesh Environmental Conservation Act of 1995 was promulgated for environmental conservation, improvement of environmental quality, control and mitigation of environmental pollution in the country.
Declaration of Ecologically Critical Areas (ECA): In April, 1999 the government of Bangladesh officially declared 40,000 ha, within six separate wetland areas. The said ecological critical areas are the Cox’s Bazar-Teknaf sea beach, Sonadia Island, St. Martin’s Island, Hakaluki Haor, Tanguar Haor and Marjat Baor.
