human ecology

HUMAN ECOLOGY

HUMAN ECOLOGY

67

Generally the doubling time of population is determined by the rule of 70 which states that to find the time in which a quantity doubles itself , divide 70 by the growth rate of that quantity . Here 70 is not an arbitrary number , but the natural log of 2 . Hence if the average annual growth rate of a country is n then the time in which its population would double is approximately 70 / n

Accordingly , if Indian population is growing at the rate of 1 .7 then [banner_entry_middle]

br doubling time is calculated by

70 /1 .7 Approximately 41 years

This can change if the rate of natural growth of population varies in the period

68

An intermediate disturbance hypothesis is used to explain and account for ecological balance in nature . The hypothesis states that ecological diversity is maximum when disturbance is at the intermediate level . Here disturbance signifies ecological stress . The explanation behind the hypothesis is that at low disturbance , or greater stability , the dominant species show tendency to eliminate weaker species , leading to fewer number of overall species . On the contrary , when the disturbance is high and stability low , a local extinction takes place and ecological balance is jeopardized

The hypothesis was presented by Joseph Connell in 1978 drawing on 1953 work of Hutchinson and gained worldwide popularity . The theory of too much change or too little change as cause of catastrophe was universally appealing and immediately accepted . However within the scientific community there are still many disputes and Intermediate disturbance hypothesis is considered as one of the many theories that can be used to explain ecological co-existence

69

Ocean biodiversity is today challenged on several fronts , posing a great risk to marine life and environment . Some of the major problems faced by oceans are

Rise in levels of Carbon Dioxide . Rising level of Carbon Dioxide due to automobile and industrial pollution poses a great risk for ocean biodiversity as it increases the acidity level of water and hence threatens marine life

Ocean dumping : Almost the entire world dumps a large part of its toxic and harmful industrial waste in oceans , thereby contaminating the marine environment to serious degrees

Oil spills : Human operation for extraction of natural gas and crude oil in oceans is also a major factor that threatens ocean biodiversity Apart from tanker accidents and accidental release , a huge quantity of crude oil is released in oceans in the normal activity of extraction posing risk to marine life

Over-fishing . The commercial interests of mankind present the greatest risk to oceanic biodiversity . Fishing and mining of oceans has led to extinction of many species of fishes , birds , turtles along with severely damaging the coastal ecologies such as mangrove forests and coral reefs .70

The primary cause of extinction is change and destruction of the living habitat . It may be due to outer body collision , climatic change or , as induced by humans , effect of chemicals and toxic elements . Species become extinct because their environment gets destroyed… [banner_entry_footer]