A memorial service will be held Tuesday, Nov. 21, for Howard F. Gregor, an internationally known agricultural geographer and professor emeritus at the University of California, Davis, who died Nov. 2 in his Davis home from complications that followed a fall two years ago. He was 80 years old. The service will be held from 4:30 p.m. to 5:30 p.m. in the Davis Community Church, located at 412 C St. in Davis. A reception will follow. A native of Wisconsin, Professor Gregor was a member of the UC Davis geography department from 1960 until his retirement in 1990. His research focused on the impact of the physical and social environment on the economic activities of different populations. He did pioneering work on the changing patterns of agriculture in California, studying water use and the influence of urbanization on the state's agricultural industry. He is survived by his wife, Marjorie Gregor of Davis, and daughter, Marsha E. Gregor and her husband Eric J. Splaver, both of Los Angeles. He also leaves three grandchildren, Garrett, Ethan and Gabriella Gregor Splaver, all of Los Angeles. In lieu of flowers the family requests that any memorial contributions be sent to the Salvation Army or the Yolo Hospice.