Dazzling books about many aspects of Nature can be found in local libraries and bookstores. Often you can "borrow" books online, if you have a library card. However, you need to know some naturalist-writers to look for. Important ones are profiled on Wikipedia's Nature Writing page.
Many of the great classics of nature writing can be downloaded or read online for free at the Project Gutenberg website. At the right is part of Project Gutenberg's download page for Jack London's The Call of the Wild. To go to that page, click on the image. Project Gutenberg offers ebooks published so long ago (100 years and more) that they're no longer copyright protected. Here are some Nature-writing classics available at Project Gutenberg: