Biodiversity losses - class-X

Loss of biodiversity includes decline in plant production, lowered resistance to environmental perturbations and increased variability in processes of ecosystem.

Decrease or loss of biodiversity can be brought by pollution in environment and habitat, forest fires and loss of habitat and overgrazing. While afforestation or planting of forest trees cause conservation of natural habitat thus saving the biodiversity.

The major causes of biodiversity decline are land use changes, pollution, changes in atmospheric CO$ _2$ concentrations, changes in the nitrogen cycle and acid rain, climate alterations and the introduction of exotic species, all coincident to human population growth. The geometric rise in human population levels during the twentieth century is the fundamental cause of the loss of biodiversity. It exacerbates every other factor having an impact on rainforests. It has led to an unceasing search for more arable land for food production and livestock grazing, and for wood for fuel, construction, and energy. 

Biodiversity refers to the variety of organisms in an ecosystem. However, the biodiversity of an ecosystem is lost when there is fragmentation of the habitat or invasion by any alien species. The interference of the man with the nature and exploitation of its resources can result in the loss of the biodiversity. 

Man makes special efforts to conserve the animals, which are likely to become extinct without special efforts of man to conserve biodiversity and animals are a part of biodiversity. 

Habitat loss and fragmentation (habitat destruction) are the most important causes for driving animals and plants to extinction. 

Hunting for flesh & skin, destruction of habitats by deforestation & polluted air & water leads to extinction of wildlife.

When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. Extinction is also known as the process of dying out. The process is a completely natural part of evolution. But sometimes extinctions happen at a higher and a faster rate than usual. Factors such as large body size, small population, massive habitat loss and position at a higher trophic level favor extinction

Parthenium or carrot grass is an alien species. When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive and cause decline or extinction of indigenous species. Such species are also called exotic or introduced species. Thus, Parthenium is a threat to biodiversity as it competes with our local species for the limited resources. So, the correct answer is 'Parthenium- Threat to biodiversity'.

• Poaching has been defined as illegal hunting or capturing of wild animals, usually associated with land use rights. 
• According to Encyclopædia Britannica, poaching was performed by impoverished peasants for subsistence purposes and a supplement for meagre diets.
•  Hence, Wildlife population are decreasing due to Poaching.
• So, the correct answer is 'Poaching'.

The extinction and disappearance of some species from planet take place due to the destruction of their natural habitat, poaching and killing habits. Whereas, planting of more trees (afforestation), preservation of forests and prevention of overgrazing causes conservation of natural habitat thereby saving the species from extinction.

Habitat destruction is the process in which the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction is the greatest contributor to the extinction of many species. This destruction is ongoing in both terrestrial and aquatic biomes, with approximately 80% of all extinctions being attributed to human caused habitat destruction. Terrestrially the destruction includes forests, deserts and grasslands, but the latter may account for the greatest losses due to the agricultural and urban conversion.

Extinction is the end of an organism or of a group of organisms, normally a species. Humans cause extinction of a species through over harvesting, pollution, habitat destruction, invasion of invasive species, over hunting and other influences. Although, earthquakes and diseases are the results of human activities but it does not cause any extinction of plant species. 

Destruction of habitat is the process in which natural habitat is rendered unable to support the species that lived in it. Increasing urbanization and industrialization has resulted in encroachment of forest areas leading to destruction of habitat. As a result, the natural flora and fauna have been endangered and some have become extinct. Thus the correct answer is option C.

Polar bears are found in arctic region where the ice caps are present and temperature is quite low. Hence, melting ice due to global warming is the greatest threat to the biodiversity of polar bears.

The important causes of biodiversity losses or species extinctions, that the world is facing now, are largely due to human activities. There are four major causes -
(i) Habitat loss and fragmentation (includes deforestation and pollution).
(ii) Over-exploitation (includes hunting, fishing and other such activities).
(iii) Alien species invasions.
(iv) Co-extinctions.

The factor that destroys plant biodiversity is destruction of habitats, wildlife species get extinct because of destruction of forest by deforestation.

Deforestation refers to destruction of forest by extensive cutting of trees, since wild animals live in forests, they lose their habitat which leads to extinction of species

When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. Extinction is also known as the process of dying out. The process is a completely natural part of evolution. But sometimes extinctions happen at a higher and a faster rate than usual. Factors such as large body size, small population and position at a higher trophic level favour extinction.

When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. A decrease in the species diversity progresses to extinction if left uncontrolled. Extinction is also known as the process of dying out. The process is a completely natural part of evolution. But sometimes extinctions happen at a higher and a faster rate than usual. Factors such as over-exploitation, large body size, small population, massive habitat loss and position at a higher trophic level favor extinction. A plant podophyllum is at the verge of extinction due to over-exploitation. So, the correct answer is 'Podophyllum'.

When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. Extinction is also known as the process of dying out. The process is a completely natural part of evolution. But sometimes extinctions happen at a higher and a faster rate than usual. Factors such as large body size, small population, massive habitat loss and position at a higher trophic level favor extinction. As forests are the main habitat for the wild animals, their loss favors the extinction of the same.

Biodiversity loss leads to the extinction of species. Factors such as habitat loss and fragmentation, over-exploitation, alien species invasion and co-extinction are causes for such losses. When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. Extinction is also known as the process of dying out. The process is a completely natural part of evolution.
So, the correct answer is 'Biodiversity loss'.

Jhum cultivation, also known as the slash and burn agriculture, is the process of growing crops by first clearing the land of forests and burning them thereafter. It is also known as shifting agriculture. The burnt soil contains potash which helps in increasing the nutrient content of the soil. This process has led to the maximum damage to the Indian forests as they are cleared for this process.

Endangered species are prone to become extinct. When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. Extinction is also known as the process of dying out. The process is a completely natural part of evolution. But sometimes extinctions happen at a higher and a faster rate than usual. Factors such as large body size, small population, massive habitat loss and position at a higher trophic level favor extinction. As forests are the main habitat for the wild animals, their loss favors the extinction of the same.

Habitat destruction, poaching, climate change and lack of resource management have resulted in a decline in biodiversity by leading to the extinction of species. Other factors such as large body size, small population, and position at a higher trophic level also favor extinction of species. When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. Extinction is also known as the process of dying out.

• When there are no more individuals of a species (plant or animal) alive anywhere in the world, the species is said to be extinct. Extinction is also known as the process of dying out. 
  
  
• The process is a completely natural part of evolution. But sometimes extinctions happen at a higher and a faster rate than usual. 
  
  
• Factors such as large body size, habitat loss, and fragmentation (a most important factor), small population and position at a higher trophic level favor extinction.
  
  

Smaller population faces more risk of extinction than larger population. Smaller population faces more random fluctuation, which may result in greater death rate than birth rate and that ultimately leads to their extinction. Moreover, in smaller population, more inbreeding occurs between the individuals of a population, that leads to decrease in population's potential by letting the expression of harmful mutations through heterozygosity. In smaller population, amount of accumulated variation is lesser than in larger population. Variation help in survival of population under changed environmental conditions.

Wildlife is an asset for our environment. It needs to be protected to maintain an optimum biodiversity. Some of the reasons for extinction of wild life are:

A biosphere reserve is a protected area for the conservation of ecosystems and genetic diversity. The biosphere reserves are formulated in order to protect the endangered and endemic plants and animals. There are certain factors which affect the nature of these reserves. Pollution results in the decrease in the number of the species. The exposure to the pollutants may develop diseases and other problems in the organisms. There is degradation of the land and the atmosphere due to the disposal of wastes which in turn affects the area under reserves. 

Sideroxylon grandiflorum is a long-lived tree in the family Sapotaceae, endemic to Mauritius. It is also known as tambalacoque or dodo tree. It is valued for its timber. Stanley Temple hypothesized that the dodo, which became extinct in the 17th century, ate tambalacoque fruits, and only by passing through the digestive tract of the dodo could the seeds germinate. Thus, due to the extinction of the dodo, the tree has become endangered. So, the correct answer is 'Sideroxylon grandiflorum'.

The California condor is a New World vulture, the largest North American land bird. It became extinct in the wild in 1987, but the species has since been reintroduced to northern Arizona and southern Utah, the coastal mountains of central and southern California, and northern Baja California. As condors forage exclusively on dead animals, they are especially susceptible to lead exposure from carcasses which are left in the field. Lead poisoning from spent ammunition is the number one cause of death among endangered condors in the wild.