What characteristics make a community stable?
The characteristics that make a community stable are
(i) Less variation in productivity from year to year.
(ii) Resistance or resilience to occasional disturbances (natural or man-made).
(iii) Resistance to invasions by alien species.
What could have triggered mass extinctions of species in the past?
Nobody knows the real reason but the scientists believe that any one of the following could have triggered mass extinction of species in the past.
(i) Fall of sea levels.
(ii) Change in temperature (freezing or warming).
(iii) Asteroid/meteorite hitting the planet.
(iv) Poisonous hydrogen sulphide emissions from the sea.
(v) Nova/super nova/gamma ray burst.
(vi) Plate tectonics.
What accounts for the greater ecological diversity of India?
The greater ecological diversity of India is because of the geographical diversity in terms of varying topography, e.g., deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows all are present in India. This results in building of different varieties of ecosystems with greater ecological diversity.
According to David Tilman, greater the diversity, greater is the primary productivity. Can you think of a very low diversity man-made ecosystem that has high productivity?
The man-made ecosystems like agricultural field of paddy or wheat show very low diversity, but possess high productivity. These are also an example of monoculture.
What does 'Red' indicate in the IUCN Red list (2004)?
Red in the IUCN Red list (2004) refers to the taxa with the highest risk of extinction.