Unit 5
Threats to Biodiversity

Learning Outcomes

Prerequisites

Key words

Habitat, Wildlife, Rare, Extinct, Endemic, Vulnerable, IUCN

Discussion

Do you know what the threats to Biodiversity are? Which plants and animals from our region are included in the IUCN list?

At present biodiversity on the Earth is facing various threats. One of the major threats is habitat destruction which occurs due to deforestation and human interference. Indiscriminate devastation of rich biodiversity on our planet is posing a threat not just to plants and animals but to the entire humanity. Although, species may become extinct due to natural selection and other natural causes, a number of species are fast disappearing from the face of the earth due to man’s intervention. We could cause many more to become extinct even before we know them. Global climate change has significantly altered hydrological pattern and other ecological functions triggering or aggravating biodiversity loss.

The main causes of threat to biodiversity are habitat loss, degradation and fragmentation of habitat, introduction of invasive alien species, climate change, habitat change, nutrient pollution and loading and overexploitation. Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby reducing biodiversity and species abundance. Man has begun to overuse or misuse most of these natural ecosystems. Due to this ‘unsustainable’ resource-use, once productive forests and grasslands have been turned into deserts and wastelands have in-creased all over the world.

2.5.1 Habitat loss

The primary effect of habitat destruction is a reduction in biodiversity, which refers to the variety and abundance of different species of animals and plants in a particular setting. When an animal loses the natural home or habitat that it needs to survive, its numbers decline rapidly, and it moves toward extinction. Humans rely on technology to modify their environment and replace certain functions that were once performed by the natural ecosystem. Other species cannot do this. Elimination of their ecosystem whether it is a forest, a desert, a grassland, a freshwater estuarine, or a marine environment will kill the individuals in the species. Human destruction of habitats accelerated in the latter half of the twentieth century.

In the tropics, these losses also represent the extinction of species because of high levels of endemism. Tropical forests are under threat largely from conversion to other land-uses, while coral reefs are experiencing increasing levels of over exploitation and pollution. If current rate of loss of tropical forests continues for the next 30 years (about 1 percent per year), the projected number of species that the remaining forests could support would be reduced by 5 to 10 percent relative to the forest in the absence of human disturbance.

2.5.2 Poaching of Wildlife

The illegal hunting as well as harvesting of animals is the second biggest direct threat to species after habitat destruction. Poaching poses a growing threat to animals such as elephants and rhinos, as well as to smaller creatures, including certain lizards and monkeys. Poaching of wildlife for trade and commercial purposes has been on the rise for the last many decades. It has been a significant cause of the extinction of hundreds of species and the endangerment of many more, such as whales and many African large mammals, Asian tigers, etc. Most extinction over the past several hundred years is mainly due to overharvesting for food, fashion, and profit.

In 2015, the United Nations General Assembly unanimously adopted a resolution for tackling illicit trafficking in wildlife. The Sustainable Development Goals have laid down specific targets to combat poaching and trafficking of protected species. Specific threats to certain animals are related to large economic benefits. Skin and bones from tigers, ivory from elephants, horns from rhinos and the perfume from the musk deer are extensively used abroad. Bears are killed for their gall bladders. Variety of wild plants with real, or at times dubious, medicinal value are being over harvest-ed. The commonly collected plants include Rauvolfia, Datura, etc. Collection of garden plants includes orchids, ferns and moss.

2.5.3 Man-Wildlife Conflicts

Man-wildlife conflict refers to the interaction between wild animals and people and the con-sequential negative impact on both of them. Worldwide Fund for Nature (WWF) defines this conflict as “any interaction between hu-mans and wildlife that results in a negative impact on human social, economic, or cultural life, on the conservation of wildlife population, or on the environment.” Although man-wildlife conflict is as old as human civilization, in modern times the degree of conflict has been on the rise due to high rise in human population in the past several centuries.

There are many consequences of man versus wildlife conflicts. The major consequences are:

• Destruction of wildlife habitats
• Injury and loss of life of both humans and wildlife
• Crop damage and livestock depredation
• Damage to human property
• Decrease in wildlife population and reduction in geographic rang-es
• Trophic cascades

Wildlife faces numerous threats. The effects of climate change, loss of habitat from deforestation, illegal wildlife trade, infrastructure and conflict with humans are factors that led to a significant decline of wildlife species and to the possible extinction of species whose numbers were really low already. Mangroves have been cleared for fuel wood and prawn farming, which has led to a decrease in the habitat essential for breeding of marine fish. Wetlands have been drained to increase agricultural land. The current destruction of the remaining large areas of wilderness habitats, especially in the super diverse tropical forests and coral reefs, is the most important threat worldwide to biodiversity. Scientists have estimated that human activities are likely to eliminate approximately 10 million species by the year 2050. At the present rate of extinction, about 25% of the world’s species will undergo extinction fairly rapidly. Human actions could well exterminate 25% of the world’s species within the next twenty or thirty years. Much of this mega extinction spasm is related to human population growth, industrialization and changes in land-use patterns. A major part of these extinctions will occur in ‘biorich’ areas such as tropical forests, wetlands, and coral reefs. The loss of wild habitats due to rapid human population growth and short term economic development are major contributors to the rapid global destruction of biodiversity.

Rare species: are basically those species that are infrequently encountered. Such a designation can be made by the national or the state governments and also the provinces.

However this designation is different from endangered or threatened species. If a species has a large and dispersed population, that particular species may be considered as endangered or vulnerable but not rare. Still, rare species are usually considered threatened because it is not likely that a small population size can recover from ecological disasters.

For example, if a species is only found as an endangered species, it cannot be termed rare. The International Union for Conservation of Nature (IUCN) uses the term ‘rare’ to designate those species which are found in isolated geographical locations. They are not classified as endangered but are classified as ‘at risk’. The concept of rare species can also be used for those species which have a very narrow endemic range or fragmented habitat.

It is believed that almost 75 percent of the known can be classified under the designation ‘rare species’. Many of the rare species are at risk of being given the designation of endangered or vulnerable if the negative factors affecting them continue to operate. Some of the rarest species in the world are – giant otter, sumatran rhinoceros, vaquita, red wolves, etc. IUCN categorized them and made a list called ‘red list’. Another document which consists of a list of rare and endangered species in an area was established by the Russian federation. This book is known as Red Data Book. These documents consisting of a list of species are used as a guide for researchers to estimate the level of threat. There are separate books for both flora and fauna.

Threatened Species:

Threatened species are any species which are vulnerable to extinction in the near future. International Union for Conservation of Nature treats threatened species not as a single category, but as a group of three categories: vulnerable, endangered, and critically endangered, depending on the degree to which they are threatened.

Critically Endangered Species:

Critically Endangered (Cr) is the highest risk category assigned by the IUCN for wild species. Critically endangered species means the numbers of a species have decreased, or will decrease, by 80% within three generations. It is therefore considered to be facing an extremely high risk of extinction in the wild. Threatened Species are any species, including animals, plants, fungi, etc., that are vulnerable to endangerment shortly.

Extinct Species:

A taxon is extinct when there is no doubt that the last individual has died. It cannot be found in the areas it once inhabited. A species may be extinct from a local area, country, region, or area in the continent or the Earth. Eg: Dodo, Passenger Pigeon. Extinction of a particular animal or plant species occurs when there are no more individuals of that species alive any-where in the world. This is a natural part of evolution. But sometimes extinctions happen at a much faster rate than usual.

Endangered Species:

These are species that are in danger of extinction. The survival of such species is difficult if the negative factors that have led to a de-cline in their population continue to operate. Endangered species are any species that is at risk of extinction because of a sudden rapid decrease in its population or a loss of its critical habitat. One of the principal factors in the endangerment or extinction of a species is the destruction or pollution of its native habitat. Giant panda, Tiger, Whooping crane, Blue whale, Asian elephant, Sea otter, Snow leopard, Gorilla are listed as endangered species. Endangered species can be defined as those species which are under risk or threat of being extinct. Endangered species, sooner or later enter the extinction phase. In order to prevent this, necessary actions have to be taken. If a species which was native to a region and its population strength reduced from 50 percent to 5 percent, such species are known are Endangered species.

Vulnerable (VU) Species:

Vulnerable species is a species which has been categorised by the IUCN as likely to become endangered unless the circumstances threatening its survival and reproduction improve. It is therefore considered to be facing a high risk of extinction in the wild.

Endemic Species:

These are species found only in some particular areas, usually isolated by natural or geo-graphical barriers. Endemic species are those plants and animals that exist only in one geographical region. Species can be endemic to large or small areas of the world. Some may be endemic to the particular continent; some are endemic to a part of a continent, and others to a single island. Endemic species are important because they are in the habitats restricted to a particular area due to climate change, urban development or other occurrences. Endemic species are often endangered, so it is important to save the species. Usually, an area that contains the endemic species is isolated in some way so that species have difficulty spreading to other areas. A native species is one that is found in certain ecology due to natural processes, such as natural distribution and development.

Native species are also called indigenous species. The key aspect of the species being native is that it occurs in an area without human influence. When a species is indigenous, it is found in a particular location or surrounding areas. An endemic species, however is a native species found only in a picky area, large or small. Often an endemic species is confined to a certain area because they are highly adapted to the particular niche. They may eat only a certain type of plant that is found nowhere else, or a plant is perfectly adapted to flourish in a very particular climate and soil type. Because of the area of expertise and inability to move into new habitats, some endemic species are at particular risk of destruction when a new disease hits, when the habitats quality is threatened, or if an invasive species enters its region and becomes a competitor or predator. The extreme opposite of endemism is cosmopolitan distribution.

Keystone Species:

Keystone species is a species whose addition to or loss from an ecosystem leads to major changes in the occurrence of at least one other species. Certain species in an ecosystem are considered more important in determining the presence of many other species in that ecosystem. All top predators (Tiger, Lion, Crocodile, Elephant) are considered as keystone species because they regulate all other animal population indirectly. Hence top predators are given much consideration in conservation. If key-stone species is lost, it will result in the degradation of the whole ecosystem. For example, certain plant species (Ebony tree, Indian-laurel) exclusively depends upon bats for its pollination. If the bat population is reduced, then regeneration of particular plants becomes more difficult

Foundation Species:

Foundation species is a dominant primary producer in an ecosystem both in terms of abundance and influence. Example: kelp in kelp forests and corals in coral reefs.

Flagship Species:

A flagship species is a species chosen to represent an environmental cause, such as an eco-system in need of conservation. These species are chosen for their vulnerability, attractive-ness or distinctiveness in order to engender support and acknowledgement from the public at large. Example: Indian Tiger, African Elephant, Giant Panda of China, the Leather-back Sea Turtle, etc.

2.5.4 The Red Data Book

Is a public document that is created for recording endangered and rare species of plants, animals, fungi as well as some local subspecies present in a particular region. The Red Data Book helps us in providing complete information for research, studies and also for monitoring the programmes on rare and endangered species and their habitats. This book is mainly created to identify and protect those species which are on the verge of extinction. The name of this book has its origins in Russia, it was originally known as the Red Data Book of the Russian Federation or the RD-BRF. The book was based on research con-ducted between 1961 and 1964 by biologists in Russia. Hence, it is also called the Russian Red Data Book.

Currently, the International Union for Conservation of Nature maintains the Red Data Book. IUCN is the world’s most detailed inventory centre of the global conservation status of biological species. The International Union for Conservation of Nature (IUCN) was founded in 1948 with an aim to maintain a complete record of every species that ever lived.

The Red Data Book contains the complete list of threatened species. The main aim behind this documentation is to provide complete information for research and analysis of different species.

The Red Data Book contains colour-coded information sheets, which are arranged according to the extinction risk of many species and subspecies.

• Black represents species that are confirmed to be extinct.
• Red represents species that are endangered.
• Amber for those species whose status is considered to be vulnerable.
• White is assigned for species that are rare.
• Green for species that were formerly endangered, but their numbers have started to recover.
• Grey coloured for the species that are classified as vulnerable, endangered, or rare but sufficient information is not available to be properly classified.

Recap

Objective type questions

Answer to Objective type questions

Self Assessment Questions

Assignment

Suggested Reading

Reference