关键词: 三江平原, 湿地, 土壤, 总硫

Abstract: With Yangling, Yongshou, Fuxian, Ansai, Mizhi and Shenmu, the six counties from the south to the north in the Loess Plateau as study sites, this paper studied the photosynthetic characteristics and leaf traits of Pinus tabulaeformis and Robinia pseudoacacia. The results showed that among the six sites, there were significant differences in the photosynthetic rate (P_n), photosynthetic nitrogen use efficiency (PNUE), water use efficiency (WUE), leaf mass per area (LMA), nitrogen content (N_mass), and chlorophyll content (Chl) of P. tabulaeformis and R. pseudoacacia, suggesting that the photosynthetic capacity and leaf traits of the two species differed with sites. From the south to the north, the P_n, PNUE and WUE of P. tabulaeformis increased slightly while those of R. pseudoacacia decreased significantly, indicating that in drought habitat, P. tabulaeformis could still maintain high photosynthetic capacity, but the photosynthetic capacity of R. pseudoacacia was greatly restrained. Also from the south to the north, the LMA of P. tabulaeformis and R. pseudoacacia had a slight increasing trend, while N_mass and Chl decreased slightly. The variation ranges of the three parameters were greater for R. pseudoacacia than for P. tabulaeformis, indicating that P. tabulaeformis had stronger drought-tolerant capability than R. pseudoacacia, which was not only exhibited in physiological metabolism, but also in leaf morphological acclimation. The correlation analysis between photosynthetic parameters and leaf traits of P. tabulaeformis and R. pseudoacacia in the six sites showed that there was a significant negative correlation between LMA and N_mass. The P_n and PNUE of both test species had no correlations with LMA and N_mass, but had significant positive correlation with Chl. The WUE of the species was negatively correlated with LMA, but positively correlated with N_mass.

Key words: Sanjiang Plain, Wetland, Soil, Total sulfur