What is an ecosystem? How do human beings influence the ecology of a region?

All plants and animals in an area are interdependent and interrelated to each other and their dependence on the environment is called an ecosystem. Human beings influence the ecology of a region in the following ways:
(i) They utilise the vegetation and wildlife.
(ii) The greed of human beings leads to overutilisation of these resources.
(iii) They cut trees and kill animals, thereby creating an ecological imbalance.
(iv) As a result, some of the plants and animals have reached on the verge of extinction.