it affects the resources because it could damage or use them all. like in a desert animals might compete for a watering hole. or if there are a lot of herbivores in one area then some other predatorsmight come and then it would be a battle ground and without the herbivores then some things will grow out of control and then it might not be suitable for living.
In any ecosystem, the availability of resources is often limited due to competition. Competition results when two organisms require the same limited resource, such as food, water, shelter, or sunlight.