Some interactions have positive, others seemingly negative consequences. Not everything that we see as negative is detrimental to the long-term function of ecosystems, however. An animal eats a plant to survive. This is good for the animal, but bad for the plant. Some plants respond well to being grazed, while others may die.
Death is part of natural renewal.
A dead tree feeds insects, provides a home for birds, and ultimately falls to the ground and creates humus. Catastrophic floods and hurricanes can alter the landscape in the blink of an eye. These disturbances set changes in motion that over time alter the nature and composition of plant communities. The landscape as we see it today is the product of all this change, seen and unseen, dramatic and subtle, fast and slow. Ultimately, the system prevails in spite of the individual and local dramas that are played out over time.