One of the main objectives of imperialism and colonialism was to exploit the colonies and their inhabitants to generate economic wealth for the mother country and her corporations. As a result, large numbers of people were forced into slavery or the system of indentured laborers, and vast areas of natural habitats were cleared and converted to monocultural plantations.
Another impact of imperialism was the export of Western values - resource exploitation, consumerism and materialism to the colonies. In the meantime, the Enlightenment began to shift West societies towards values such as democracy, independent judiciary, free press and escape from religious tyranny. These, when well developed offer checks and balances against excessive concentration of power and corruption, and some safeguards against environmental predation.
After the colonies gained independence, the newly independent citizens uncritically embraced most of the negative values and have vigorously continued the practices of their early colonial masters.
One man who fought against the blind adoption of materialistic values was of course Gandhi. Alas, no one can be a prophet in his own land.
As a result, in the former colonies, the environment, especially natural habitats and their species, is being destroyed at a scale that is unprecedented in history.