Areas like forests or wetlands are hard to replace. Damage to hurts animals and humans. Most wetlands that are destroyed by overuse may be a source of drinking water, as well as being a thriving and diverse ecosystem. That is not always visible to the human eye.
Over-harvesting also applies to other animals. Population numbers may drop as a result and in many cases cause the extinction of a species. Overfishing is a typical example. Nowadays, you can only fish, shoot deer or birds at certain times of the year. The season when they mate, reproduce and lay eggs or have young is protected. Areas of especial natural beauty or scientific interest are also protected. Taking bird eggs is also now against the law, at least in the United Kingdom.
One thing which acts against conservation is the overpopulation of the world. The greatest single reason why the world loses forests is that some people want the land for other purposes. A few people gain, but everyone shares the cost. This is called the tragedy of the commons.