Abstract: The distribution types of 192 genera of Quercus mongolica community in10 sites of northeast China and one site of Hebei Province were analyzed, and the proportion of each type to the total as well as the ratio of temperate genera to tropical genera (T/Rratio) in each site were calculated. Among the distribution types in northeast China, those of the temperate and tropical genera accounted for 72.0% and 9.7%, respectively. The latitude and altitude could affect the genera distributed in temperate zone and their T/Rratio. The T/Rratio increased with increasing latitude, while the number of tropical genera decreased if the altitudes were the same or similar. Altitude could affect T/Rratio more obviously, causing its fluctuation with latitude. The regression equation of T/Rratio with latitude and altitude was given, and the reasons producing this distribution pattern were also explained.

Key words: Northeastern China, Quercus mongolica, Phytogeographical elements, T/R ratio, Regression equation, carbon footprint, wheat-maize rotation system, greenhouse gas (GHG), net global warming potential (NGWP), irrigation amount