As you requires I am here suggest you books for reading for Indian Forest Service (IFS) Exam.

IFS Exam Books :
Indian Polity:
Introduction to the Indian Constitution by DD Basu
Our Parliament by Subhash Kashyap

Indian Economy:
NCERT and other books on Evolution of the Indian Economy
Indian Economy by Dutta Sunderam

General Science:
NCERT books on science,
a science magazine or newspaper supplements on science.

For History:
NCERT books of class XI and XII,
Wonder that was India by AL Basham,
Freedom Struggle by Bipan Chandra

For Geography:
Class XII books of Geography (NCERT),
a good Atlas.

Current Events:
A national newspaper,
A Competitive Magazine.