Elminster's Ecologies is a 2nd Edition boxed set containing several 32-page books detailing the ecology of the Forgotten Realms. It is written in-character as Elminster and other characters. In addition to the credited authors, Monte Cook is also credited as a designer. From the box:
The world is vast and varied, comprising towering mountains, dense jungles, and sprawling seas. There are regions so cold that their snow never melts, others so hot that their rain turns to steam as it touches the ground. It is this variety of environments that accounts for the variety of life. In my travels I have noted 73 distinct types of pine trees... I estimate the number of fishes at well over five thousand. The number of insect species likely exceeds the number of grains of sand on the shores of Dragon Reach.
Every environment, no matter how hostile to humankind, is compatible with some form of life. The diversity and adaptability of organisms are staggering
