How can an ecosystem become unstable?
- Removal of native species.
- Introduction of new species.
- Pollution, toxification of an area.
Whether for food, livestock protection, or just displacement by expanding human presence, many native species are often eliminated by human incursions.
Crops, animals, and decorative plants or pets brought into an ecosystem by humans can affect the sustainability of an ecosytem.
Waste production of all sorts can easily overwhelm a previously stable ecosystem due to human activity.