Why should you conserve natural resources by buying less stuff?

Because there is a limited amount of resources on Earth and everything has a carbon footprint, so if you don't buy an item there is less demand, less supply, less made, better for the Earth.

oak trees? ? what was listed

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.