Abstract: Using specially designed chambers and an infrared gas analyzer, we examined the photosynthetic responses of six woody species to elevated CO2, from 325 μmol·mol-1 to 650 μmol·mol-1. Six temperate forest woody species under natural growth conditions in the Quercus liaotungensis forest in Beijing Mountainous Areas were tested: Quercus liaotungensis koidz. , Fraxinus mandshurica Rupr. , Tilia mongolica Maxim. , Acer mono Maxim. , Abelia biflora Turcz. and Corylus mandshurica . The results showed that the six species displayed variable degrees of enhancement in net photosynthetic rates to elevated CO2, from 37% (Abelia biflora Turcz. ) to 93% (Quercus liaotungensis koidz. ), with an average value of 75%. Shrub species were less affected than tree species. Remarkable enhancement in net photosynthetic rates with elevated CO2 were found during the diurnal courses in both summer and autumn.

Key words: Net photosynthesis, CO2 doubling, Quercus liaotungensis koidz, forest, Beijing Mountainous Areas