What are ways in which preserving biodiversity locally might have a global effect?
If we preserve the environment locally others will notice us, then those people might do the same thing and people will see them. pretty soon we have a global effect. Also If we preserve local environment we could inspire someone to wright a law that will protect the environment.

How do habitat destruction and loss of species effect more than just one area?
It can effect more than one area if other areas depend on that area for resources. For example if a mountain pond becomes contaminated with a harm full substance from a factory. And that substance kills plants and animals, and a deer drinks from the pond and the is eaten by a mountain lion, and then scavengers eats the mountain the substance has contaminated a whole new area.

How does preserving biodiversity enhance the life of people?
First of all we depend on NATURAL resources to survive. Key word NATURAL. So it stands to reason that we would want to preserve nature. If not because we should care, then because we need certain things from nature. Also if those two things aren't enough of a reason then we should preserve nature for future generations.