At present, humans have intensified use and production of some so-called economically valuable species ignoring others' contribution. Lately, humans have started to understand significance of ecosystem services generated by different species and estimated that 60% of the ecosystem services, accessed, are in decline due to unsustainable human actions (MA, 2005).
Millennium Ecosystem Assessment warned that the cost of failure to halt biodiversity loss on land alone in last 10 years is estimated to be $ 500 billion and if the current trend of biodiversity loss continues then in near future the humanity itself will face extinction.
Therefore, the realisation of a balanced world with all living beings' respective role has come to the forefront of the recent scientific researches. The UN has supported the awareness by declaring 2010 as International Year of Biodiversity. The United Nations Environment Programme (UNEP) has further added value to the recent worldwide movement of conserving biodiversity by setting this year's World Environment Day theme as “ Many species. One planet. One future”.
Bangladesh is endowed with very rich biodiversity resources and it is evident from its species diversity profile, particularly for angiosperms and avi-fauna. Recently published 4th National Biodiversity Report estimates that the country possesses 3,611 species of angiosperm, 2,623 belonging to 158 families of dicotyledons and, 988 to 41 families of monocotyledons. Since the country's economy is largely natural resources based, the sheer majority of the human population directly depend on its biological resources to sustain their lives and livelihoods.
However, country's overwhelming population and their demand for development often compel them to pay little or no heed to biodiversity. Industrial development, expansion of agriculture, human settlements, unplanned urbanisation and rural infrastructure development all have exerted negative pressure on our environment, particularly resulting in the destruction of habitats of valuable biodiversity resources.
Climatic change, not completely a new phenomenon but recently soared up in policy arena, is another strong factor apprehended responsible for biodiversity loss. Climate change and biodiversity exhibits an inverse relationship. Loss of biodiversity causes climate change; on the other hand, climate change induced natural calamities contribute to biodiversity loss. Bangladesh, supposedly a darling child of nature, is affected from both climate change and poverty. Consequently, its biological resources experience immense pressure; rather than being considered as natural capital, the resources are always regarded as raw materials.
Agriculture is the world's oldest occupation and constitutes the biggest employment sector. Both basic sustenance (nutrients and calories) for people and raw materials for industries have been coming from agriculture since inception of civilization. Yet, agriculture is fundamentally dependent on biodiversity and eco-system services. Species of crops and livestock and their genetic diversity are the basis of agriculture. Even the insects contribute a lot to the agro-production. Species of earthworms, fungi, soil-micro organisms, as well as flora and fauna surrounding agricultural areas underpin ecosystem services that sustain agriculture, such as pollination and nutrient cycling.
Being an agrarian country, life and economy of Bangladesh are largely dependent on agriculture. In spite of introduction of mechanical agriculture, still larger farmer community practices nature dependent agriculture where they use bull to cultivate their land, earthworm as their plough, cow dung, small trees and leaves as their manure, insects as their agent of pollination and so forth. Every component of the natural environment works as their helping agent in agricultural production. Even if so-called green revolution has been given credit for alleviating poverty and providing food to the country's large population , but recent food crisis has depicted an opposing scenario where mechanised agriculture, which pay little attention to biodiversity, has been blamed for degrading environmental quality and consequently the production decline.
Intensified production system using only few varities, dominates the current agriculture production system. Even though presence of more than 10,000 rice varieties in the country is a clear example of our vast wealth of genetic resources, but now there are only ten types of local rice in production practice and this sector has been dominated by High Yielding Varieties (HYV) which need an intensive use of fertilizers, insecticides and so on resulting in an adverse impact on the surrounding environment. Once abundant, fish resources might be the most affected by synthetic agri input.
Together with the staple rice small amounts of vegetable and fish constitute the everyday diet of overwhelming majority population of Bangladesh. Moreover, fisheries are important occupation of many of the rural poor, constituting main income source for near about 2 million households. Flood plains, rivers, streams, canals, beels and ponds in Bangladesh are equipped with 260 species of fresh water fish resources. Among them, 140 species are classified as small indigenous fish species. Moreover, a considerable number of estuarine and marine fish species have enriched country's fish resource stocks. However, overcatch, destruction of habitat, pollution, conversion of wetlands to alternative uses have resulted in extinction of many fish species and subsequent wild catch has declined sharply in recent years.
The extinction of local fish species and associated decreased production has affected poor people's diet mostly. Millions of poor rural people are now suffering from malnutrition, who once were dependent on fish to meet their protein demand. Interestingly, official statistics estimate that total fish production has been increasing; this is due to aquaculture practice with some fast growing hybrid and exotic fish species. Regrettably, many of the widely cultivated exotic fish species have been identified as invasive and they exert negative externalities to our local ecosystem. Moreover, poor people have limited or no access to such commercial fish culture. And they cannot afford fish from the market due to high prices. Many of the rural poor cannot even remember now when they had fish last time.
Forests provide food and vast array of materials for medicinal, cultural and spiritual purposes as well as building materials and firewood, more specifically the poor is the primary beneficiary from the forest. It is estimated that one billion people worldwide depend on drugs derived from forest plants. Moreover, by providing home to a large number of birds and wildlife forests play an important role to conserve valuable biodiversity resources. Forests' ecological, social and economic functions are also praiseworthy. Forests store and purify drinking water, protect watershed, mitigate natural disasters, and control erosion, cycle nutrients, help to store carbon and to regulate climate and contribute to the regional and national economies both directly through revenues, value adding and employment.
Even if Bangladesh is a forest poor country, only 6% of country's total land is forest covered, yet it is very rich in species diversity. The hill forest alone supports 2,259 species of angiosperm. Sundarbans, world's largest single mangrove block and a world heritage site, is a unique habitat of spectacular Royal Bengal Tiger. Being the most bio-diverse forest in Bangladesh, Sundarbans alone supports 53% of birds, 43% of animals, 42% of reptiles, 36% of amphibians, 29% of plants and 17% of fish species of the country's total biodiversity resources.
However, Bangladesh's forests have decreased significantly in terms of both area and quality over the last few decades. The annual deforestation rate is estimated to be around 3.3% (Khan et al. 2004). Number of factors are responsible for forest degradation. The increasing population and associated increased demand for timber, shelter, food continues to put pressure on existing forest resources resulting in over exploitations. Moreover, introduction of some exotic species such as Eucalyptus, Acacia etc. and their wide plantation is another important cause of some native species' extinction. These exotic species neither fitted with local environment nor support birds or any wildlife. Additionally, these have introduced some pests, which incur a huge loss every year.
Every year about 20% new settlements are being added at the expense of productive homestead agriculture and forest lands, which basically used to provide food and livelihood to the rural poor. Homestead ecosystem is also very important for providing shelter to wildlife. With dwindling forest cover, this importance is becoming far more significant. Most of the small mammals and birds still existing in the country are completely dependent on this ecosystem, including agricultural land for their survival.
Again, culture and biological diversity are closely intertwined. Biodiversity remains at the centre of many religions and culture. The close association between biodiversity and culture is particularly apparent at sacred sites -- areas which are held to be of importance because of their religious and spiritual significance. In Bangladesh, there is a significant diversity in ecosystem, culture, especially rural and indigenous culture, which is the centre of attraction to many tourists.
We do not have another planet to depend on, except this mother earth. The earth is still livable and beautiful because it has many species, who perform different functions to keep the earth functioning. All the species have been created for serving and supporting human beings as argued by many religions. Biodiversity loss, therefore, will eventually lead to human extinction. We have to protect all the species for our own sake, for keeping the world colourful and, above all, surviving.
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