Abstract: Comparative study was processed in photosynthetic characteristics of birch in Maoershan region.The results showed:both the real photosynthetic capacity and the potential photosynthetic capacity of sexual birch are higher than those of a sexual birch (in mesophytic habit)(P < 0.05);the photosynthetic capacity of birch growing in mesophytic habit are higher than those of birch in hydrophytic habit (for sexual population)(P < 0.05);the photosynthetic capacity of seedlings is the lowest among birch in different ages while it also has the highest light compensation point no matter for sexual population or a sexual population (P < 0.05).

Key words: Birch, habits, sexual population, sexual population, photosynthetic characteristics