Abstract: By using gas analyzer Li-6400, the foliar gas exchange and chlorophyll fluorescence of Koelreuteria bipinnata var. integrifoliola were measured under the CO₂  concentrations  of 380 and 600 μmol·mol^-1, and the measured curves were fitted by different models. The results showed that the maximum electron transport rate fitted by rectangular hyperbola and double exponential equation were far higher than the measured data, rectangular hyperbola, non-rectangular hyperbola, and single exponential equation could not fit the rapid light curve with dynamic down-regulation of PSⅡ, and only double exponential equation and modified rectangular hyperbola could fit the rapid light curve with dynamic down-regulation of PSⅡ and correctly calculate the saturation irradiance, indicating that modified rectangular hyperbola could not only well fit the rapid light curve of K. bipinnata var. integrifoliola, but also make the simulated maximum electron transport rate and saturation irradiance accord with the measured data. Moreover, modified rectangular hyperbolic model could judge whether the simulated electron transport rate and CO₂ assimilation synchronously reached the maximum values through fitting the rapid light curves and light response curve of plant photosynthesis.

Key words: Agricultural landscape, Agroecosystem mosaics, Landscape ecology