The authors wish to thank Ms. Lili Lyddon for illustrating all the figures in the book. Our special thanks to our reviewers as follows:

Chapter 1 J. W. Walker, W. K. Lauenroth, W. A. Laycock, F. E. Smeins, R. H. Hart, F. S. Guthery.

Chapter 2 Mike Galyean, John Walker, Wayne Greene, Don Adams, Chris Krysl

Chapter 3 Fritz Senft, Mark Stafford Smith

Chapter 4 J. H. Richards, Carol Bilbrough, Steve Ekblad, Rhett Johnson, Johanna Pate, Lee Thornhill, Jeff Murphy.

Chapter 5 Guy McPherson, Allen McGinty, Joe Trlica, Neil West, Joel Brown

Chapter 6 Will Blackburn, Joel Brown and Jim Dobrowolski

Chapter 7 Neil Tainton, Allen Wilson, Dick Hart, Jerry Holechek, Harvey Blackburn, Clinton Owensby, David Bransby

Chapter 8 John Kie, Fred Guthery, David Swift

Chapter 9 None

Chapter 10 None

We also wish to express our appreciation to Dr. Joe Schuster, Earl Gilmore and Carl Menzies for their administrative encouragement throughout the writing process. Particular thanks are given to Richard Abel, editor, Timber Press for his editorial guidance. Special thanks also to Sylvia Dudash and Marcella Smith for typing and managing the many drafts of this book. Finally, we express our sincere gratitude to the Texas A&M University System for providing us the professional environment in which to create this book.