Answer: Subsistence agriculture.
Explanation: Subsistence agriculture is a type of farming in which farmers cultivate and grow food crops and livestocks to meet their needs and that of their family.
In this type of agriculture, farm products is aimed to survival and it doesn't involve use of large-scale irrigation, chemical fertilizer, or machinery and technology.
Answer: It would unbalance the ecosystem.
Due to the fact that if some species die off, the other species that rely on those species for food or protection would loose that food/ protection which may lead to their extinction and their extinction would lead to another extinction and so on.