Answer:
It can stop it from being killed due to a local "disaster", like a fire, for example.
Explanation:
By planting seeds far from the parent plant, you are increasing the probability the genetics from the plant will survive because they are further from one another. So, for example, let's say there is a forest fire, if they are close to one another, both the parent plant and seeds are likely to perish. If they are separated by space, potentially one of the two won't be in the path of the fire and will survive.
