Md. Arafat Rahman
Biological diversity is the variety of life forms at all levels of biological systems. Rapid environmental changes typically cause mass extinctions. Most of the species that ever lived on Earth, amounting to over five billion species, are estimated to be extinct. Estimates on the number of Earth’s current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described.
Biodiversity is a measure of variation at the genetic, species, and ecosystem level. Biodiversity is not evenly distributed; rather it varies greatly across the globe as well as within regions. Among other factors, the diversity of all living things depends on temperature, solids, geography and the presence of other species. The study of the spatial distribution of organisms, species and ecosystems, is the science of biogeography. Diversity consistently measures higher in the tropics and in other localized regions such as the Cape Floristic Region and lower in Polar Regions generally. Rain forests that have had wet climates for a long time, such as Yasuní National Park in Ecuador, have particularly high biodiversity.
Marine biodiversity is usually higher along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future as a primary result of deforestation. It encompasses the evolutionary, ecological, and cultural processes that sustain life.
Forest biological diversity is a broad term that refers to all life forms found within forested areas and the ecological roles they perform. As such, forest biological diversity encompasses not just trees, but the multitude of plants, animals and microorganisms that inhabit forest areas and their associated genetic diversity. Forest biological diversity can be considered at different levels, including ecosystem, landscape, species, population and genetic. Complex interactions can occur within and between these levels. In biologically diverse forests, this complexity allows organisms to adapt to continually changing environmental conditions and to maintain ecosystem functions. Forests provide habitats for 80 percent of amphibian species, 75 percent of bird species and 68 percent of mammal species. About 60 percent of all vascular plants are found in tropical forests. The biodiversity of forests varies considerably according to factors such as forest type, geography, climate and soils in addition to human use.
Terrestrial biodiversity is thought to be up to 25 times greater than ocean biodiversity. Forests harbour most of Earth’s terrestrial biodiversity. The conservation of the world’s biodiversity is thus utterly dependent on the way in which we interact with and use the world’s forests. A new method used in 2011, put the total number of species on Earth at 8.7 million, of which 2.1 million were estimated to live in the ocean. However, this estimate seems to under-represent the diversity of microorganisms.
Agricultural diversity can be divided by whether it is ‘planned’ diversity or ‘associated’ diversity. This is a functional classification that we impose and not an intrinsic feature of life or diversity. Planned diversity includes the crops which a farmer has encouraged, planted or raised e.g. crops, covers, symbionts, and livestock, among others, which can be contrasted with the associated diversity that arrives among the crops, uninvited e.g. herbivores, weed species and pathogens, among others.
Associated biodiversity can be damaging or beneficial. The beneficial associated biodiversity include for instance wild pollinators such as wild bees and syrphid flies that pollinate crops and natural enemies and antagonists to pests and pathogens. Beneficial associated biodiversity occurs abundantly in crop fields and provide multiple ecosystem services such as pest control, nutrient cycling and pollination that support crop production.
The control of damaging associated biodiversity is one of the great agricultural challenges that farmers face. On monoculture farms, the approach is generally to suppress damaging associated diversity using a suite of biologically destructive pesticides, mechanized tools and transgenic engineering techniques, then to rotate crops. Although some polyculture farmers use the same techniques, they also employ integrated pest management strategies as well as more labor-intensive strategies, but generally less dependent on capital, biotechnology, and energy.
Biodiversity’s relevance to human health is becoming an international political issue, as scientific evidence builds on the global health implications of biodiversity loss. This issue is closely linked with the issue of climate change, as many of the anticipated health risks of climate change are associated with changes in biodiversity. This is because the species most likely to disappear are those that buffer against infectious disease transmission, while surviving species tend to be the ones that increase disease transmission, such as that of West Nile Virus, Lyme disease and Hantavirus.
The growing demand and lack of drinkable water on the planet presents an additional challenge to the future of human health. Partly, the problem lies in the success of water suppliers to increase supplies and failure of groups promoting the preservation of water resources. According to the World Health Organisation, only 71% of the global population used a safely managed drinking-water service.
Some of the health issues influenced by biodiversity include dietary health and nutrition security, infectious disease, medical science and medicinal resources, social and psychological health. Biodiversity is also known to have an important role in reducing disaster risk and in post-disaster relief and recovery efforts. According to the United Nations Environment Programme a pathogen like a virus have more chances to meet resistance in a diverse population. Therefore, in a population genetically similar it expands more easily. For example, the COVID-19 pandemic had fewer chances to occur in a world with higher biodiversity.
Evidence from market analysis and biodiversity science indicates that the decline in output from the pharmaceutical sector since the mid-1980s can be attributed to a move away from natural product exploratio in favour of genomics and synthetic chemistry, indeed claims about the value of undiscovered pharmaceuticals may not provide enough incentive for companies in free markets to search for them because of the high cost of development; meanwhile, natural products have a long history of supporting significant economic and health innovation.
Marine ecosystems are particularly important, although inappropriate bioprospecting can increase biodiversity loss, as well as violating the laws of the communities and states from which the resources are taken. Many industrial materials derive directly from biological sources. These include building materials, fibers, dyes, rubber, and oil. Biodiversity is also important to the security of resources such as water, timber, paper, fiber, and food. As a result, biodiversity loss is a significant risk factor in business development and a threat to long-term economic sustainability.
There is now unequivocal evidence that biodiversity loss reduces the efficiency by which ecological communities capture biologically essential resources, produce biomass, decompose and recycle biologically essential nutrients. There is mounting evidence that biodiversity increases the stability of ecosystem functions through time. The impacts of diversity loss on ecological processes might be sufficiently large to rival the impacts of many other global drivers of environmental change.
It plays a part in regulating the chemistry of our atmosphere and water supply. Biodiversity is directly involved in water purification, recycling nutrients and providing fertile soils. Experiments with controlled environments have shown that humans cannot easily build ecosystems to support human needs; for example insect pollination cannot be mimicked, though there have been attempts to create artificial pollinators using unmanned aerial vehicles. The economic activity of pollination alone represented between $2.1–14.6 billion in 2003.
In absolute terms, the planet has lost 58% of its biodiversity since 1970 according to a 2016 study by the World Wildlife Fund. The Living Planet Report 2014 claims that “the number of mammals, birds, reptiles, amphibians, and fish across the globe is, on average, about half the size it was 40 years ago”. Of that number, 39% accounts for the terrestrial wildlife gone, 39% for the marine wildlife gone and 76% for the freshwater wildlife gone. Biodiversity took the biggest hit in Latin America, plummeting 83 percent. High-income countries showed a 10% increase in biodiversity, which was canceled out by a loss in low-income countries.
Global agreements such as the Convention on Biological Diversity, give “sovereign national rights over biological resources”. The agreements commit countries to “conserve biodiversity”, “develop resources for sustainability” and “share the benefits” resulting from their use. Biodiverse countries that allow bioprospecting or collection of natural products, expect a share of the benefits rather than allowing the individual or institution that discovers/exploits the resource to capture them privately. Bioprospecting can become a type of biopiracy when such principles are not respected.
Focusing on limited areas of higher potential biodiversity promises greater immediate return on investment than spreading resources evenly or focusing on areas of little diversity but greater interest in biodiversity. A second strategy focuses on areas that retain most of their original diversity, which typically require little or no restoration. These are typically non-urbanized, non-agricultural areas. Tropical areas often fit both criteria, given their natively high diversity and relative lack of development.
Author is Columnist & Asst. Officer Career & Professional Development Services
Department, Southeast University