As we know, some species live in forests, lakes, ponds, and other different places. For example, people cut trees in the forest where some animals live and get their food. If the trees are cut, ofcourse there will be a decrease of sources of food and also there will be no home for the animals that are living in that forest. This activity of humans affect the home for the animals, which may lead to decreasing of the number of those species....
That's my answer :))))
--Rayne