The mature Tapiscia sinensis,Quercus fabri and Betula luminifera which grew in the Yushe National Forest Park of karst plateau area were selected as experimental materials.Differences of photosynthetic inorganic carbon utilization traits between these three species were analyzed through the determination of photosynthesis,chlorophyll content,chlorophyll a fluorescence (Chlf),carboxylation efficiency (CE),respiration rate (Resp),carbonic anhydrase activity (WA) and stable carbon isotope ratios (δ¹³C),so as to select appropriate plants for community construction,finally achieve the recovery and restoration of this ecological environment.Results showed that:(1)T.sinensis,Q.fabri and B.luminifera were widely distributed.The optimal soil pH for T.sinensis was 4.5-5.5,while Q.fabri would prefer neutral to sub acidity soil and fertile acidic erinaceous soil was good for B.luminifera.Q.fabri and B.luminifera were resistant to drought and barren,but T.sinensis was not resistant to drought and high temperature.(2)P_n,T_r and G_s of leaf of T.sinensis were significantly higher than that of Q.fabri and B.luminifera.The P_n,T_r and G_s in B.luminifera and Q.fabri were only 69.5%,48.2%,66.7% and 28.6%,21.7%,22.2% of T.sinensis,respectively.The chlorophyll content of B.luminifera was twice of that in T.sinensis and Q.fabri,but WUE of them had no significant difference.(3)Net photosynthetic rates in leaves of these three plant species increased as CO₂ concentration increased,but the CO₂ compensation and saturation points between these three plant species were significantly different.CO₂ compensation points of T.sinensis and B.luminifera were lower than 50 μmol·mol^-1,while compensation point of Q.fabri was between 250-300 μmol·mol^-1.CO₂ saturation point of T.sinensis was approximately 1 200 μmol·mol^-1,B.luminifera was approximately 2 300 μmol·mol^-1,while saturation point of Q.fabri was significantly higher than 2 300 μmol·mol^-1.(4)CE,Resp and CA activities of these three plant species were in the order:T.sinensis>B.luminifera>Q.fabri;while δ¹³C of T.sinensis was the lowest,while the values of δ¹³C of B.luminifera and Q.fabri were higher.CE,Resp and CA activities in Q.fabri and B.luminifera were only 5.1%,25.7%,4.0% and 45.3%,54.6%,6.8% of T.sinensis,respectively,and they varied significantly with different plant species.The values of δ¹³C of Q.fabri and B.luminifera were significantly higher than that of T.sinensis.The results indicated that T.sinensis could obtain inorganic carbon from atmospheric CO₂ or intracellular bicarbonate by CA with higher activity and its CO₂ utilization ability and inorganic carbon assimilation efficiency was also higher,as a result,its production was higher.B.luminifera could only absorb inorganic carbon from atmospheric CO₂,but it had higher CO₂ utilization ability,its production was lower than that of T.sinensis but higher than that of Q.fabri.Q.fabri could only absorb inorganic carbon from atmospheric CO₂ too,its CO₂ capture and utilization ability was also lower than that of T.sinensis and B.luminifera.Its requirement of inorganic carbon was the least.So it grew slowly,and its production was the lowest.