Mark D. Schwartz is a phenoclimatologist and distinguished professor of Geography at the University of Wisconsin-Milwaukee.  
He is co-founder of the USA National Phenology Network.  His research interests are focused on plant phenology lower atmosphere interactions during the onsets of spring and autumn in mid latitudes, detecting climatic change, and assessing vegetation condition with remote sensing imagery.  
His scholarship includes over ninety peer-reviewed publications, mostly in journals, and a 2nd edition of the edited book Phenology:  An Integrative Environmental Science.  Prof. Schwartz received his Ph.D. from the University of Kansas in 1985.