The effects of different rich nitrogen levels(16,6,0.5,0 mg.kg-1) on photosynthesis of Liquidambar formosana Hance.under fully flooded,canopy semi-submerged and roots waterlogging were studied.The results show that the net photosynthetic rate(Pn) in leaves of L.formosana decreased significantly under flooding,but the declining degree of Pn in leaves of L.formosana treated with higher nitrogen levels(16,6 mg.kg-1) was clearly smaller than that with low nitrogen levels(0.5 mg.kg-1),zero nitrogen level(0 mg.kg...