Effect of biodiversity loss:
- Decline in plant production.
- Lowered resistance to environmental perturbations such as drought.
- Increased variability in certain ecosystem processes such as plant productivity, water use, and pest and disease cycle.
Causes of biodiversity loss:
- The present loss is all due to human activity (anthropogenic)
- There are four major causes “The Evil Quartet” are as follows:
Habitat loss and fragmentation:
- Most important cause driving animals and plants to extinct.
- The tropical rain forest reduced to 6 % from 14 % of earth land surface.
- The Amazonian rain forest is called as ‘lungs of the planet ‘is being cut cleared for cultivating soya beans.
- Degradation of many habitat by pollution is also threatens the loss of diversity.
- Large areas are broken into figments also the cause of diversity loss.
Over-exploitation:
- When ‘need’ turns to ‘greed’ it leads to over-exploitation of natural resources.
- Many species extinctions in the last 500 years (Stiller’s cow, passenger pigeons) were due to over-exploitation.
- Many marine fish populations around the world are over harvested.
Alien species invasion:
- The alien species became invasive and cause decline or extinction of indigenous species.
- Nile perch introduced into Lake Victoria in east Africa led to extinction of 200 species of cichlid fish in the lake.
- Parthenium, (carrot grass), Lantana, and water hyacinth (Eichornia) posed a thread to indigenous species.
- African cat fish Clarias gariepinus for aquaculture purposed is posing a threat to indigenous catfishes in our rivers.
Co-extinction:
- When a species becomes extinct, the plant and animal species associated with it an obligatory way also become extinct.
- Extinction of Host species leads to extinction of the parasite also.
- Co-evolved plant-pollinator mutualism where extinction of one invariably lead to the extinction of the other.
BIODIVERSITY CONSERVATION:
Why should we conserve Biodiversity?
Reason for conservation biodiversity is grouped into three categories.
- Narrowly utilitarian.
- Broadly utilitarian
- Ethical
Narrowly utilitarian:
- Human derive countless direct economic benefits from nature-
- Food (cereals, pulses, fruits), firewood, fiber, construction material.
- Industrial products (tannins, lubricants, dyes, resins, perfumes)
- Products of medicinal importance.
- Bioprospecting: exploring molecular genetic and species-level diversity for products of economic importance.
Broadly Utilitarian
- Amazonian forest along produce 20% of oxygen during photosynthesis.
- Pollinator layer: bees, bumblebees, birds and bat that pollinate the plant without which seed cannot be produced by plants.
- Aesthetic pleasure we get from the biodiversity.
How do we conserve biodiversity?
In situ conservation:
- When we conserve and protect the whole ecosystem, its biodiversity at all level is protected – we save the entire forest to save the tiger. This approach is called in situ (on site) conservation.
- Biodiversity hot spot: regions with very high levels of species richness and high degree of endemism.(species confined to that region and not found anywhere else)
- Hot spot in biodiversity is also regions of accelerated habitat loss.
- Out of 34 hot spot in the world, three hot spot located in India:
- Western Ghats and Srilanka.
- Indo-Burma.
- Himalaya.
- Other protected area under in situ conservations are:
- 14 biosphere reserve
- 90 national park
- 448 wild life sanctuary
- Sacred groves: tract of forest were set aside, and all the trees and wildlife within were venerated and given total protection.
Ex situ conservation: threatened animals and plants are taken out from their natural habitat and placed in special setting where they can be protected and given special care.
- Zoological Park.
- Botanical garden
- Wildlife safari.
- Conservation of gamete by cryopreservation.
- Genetic strains are preserved in seed bank.
Convention on Biodiversity:
World Summit on Sustainable development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieve by 2010 a significant reduction in the current rate of biodiversity loss at global, regional and local level.
- “The earth Summit” held in Rio de Jeneiro in 1992 called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilization of its benefits.
CBSE Biology (Chapter Wise) Class XII ( By Mr. Hare Krushna Giri )
Email Id : [email protected]
