Looking for a way to get a general overview of some issues relating to science? Try this directory from Google.com.
Ackerman's prose is brilliantly descriptive – that is, it appeals strongly to the senses. These links offer some good starting points for research on the senses.
Has reading about Ackerman's life and work interested you in doing some nature writing of your own? This page of nature writing links will help you on your way.
Not many people could have written about leaves, right? Do a subject search at the Library of Congress, by typing in the word "leaves." How many books do you come up with?