ANSWER:
After the volcanic eruption,lava cools down,vegetation reappears and microscopic plants grow,then the macroscopic plants and animals come at that place,then gradually the whole system builds and ecosystem recovers.
EXPLANATION:
Biodiversity means diverse population of plants and animals. After the volcanic eruption,both plants and animals donot exist because of high temperature and not suitable environment. With the passage of the time, the lava cools down and vegetation stars reappearing. First of all lichens and microscopic plants and after that macroscopic plants and animals come at that place.Thus suitable conditions reappear and gradually the whole ecosystem recovers.
The species was a keystone species.
Keystone species are the species that ''hold the ecosystem together''.
They have an important role in the trophic networks (food chains) and often they can even afflict changes in the abiotic part of the ecosystem (change the composition of soil, purify the water, lower the effect of the wind etc)
Therefore, when a keystone species is removed it affects greatly the whole ecosystem.
Roan fur in cattle, in which white and red hair is equally expressed.
A) after 1911 gradual increase in deaths pattern explains that smoking causes cancer !
b) after 2001 , the graph will continue decreasing, because of the steps taken by government, the steps by people itself !! that all helps in decreasing deaths and cancer number after 2001 !