Abstract: This paper dealt with the effect of human activities including tourism, religion activity, and industrial waste gas on atmospheric CO₂ concentration of subtropical forests and carbohydrate content of two species of woody plants: Schima superba and Pinus massoniana. The results show that human activities not only changed the daily variation, but also the vertical distribution of CO₂ within forests. Comparing to control site (core area of Biosphere Reserve),the CO₂ concentration in disturbed sites is increased 4～11 μl·L^-1.The total contents of soluble sugars and non structural carbohydrate in leaves of two woody plants are decreased with increasing intensity of human activities, and the trends of decrease are consistent with increasing CO₂ concentration. The contents of soluble sugars and starch are more sensitive to human activities in upper canopy than in lower canopy. On the other hand, human activities show little influence on the content of cellulose in leaves of forest trees. The different response of carbohydrate metabolism to human activities was observed between Schima superba and Pinus massoniana.

Key words: Human activities, CO₂, Schima superba, Pinus massoniana, Carbohydrate, Physocarpus amurensis, P opulifolius, chlorophyll fluorescence, soil drought, photosynthesis capacity