[Characteristics of canopy stomatal conuctance in plantations of three re-vegetation tree species and its sensitivity to environmental factors].

In plantations of three different re-vegetation tree species (Schima superba, Acacia auriculaeformis and Eucalyptus citriodora) in southern China, the stem sap flow of individuals at different DBH classes were monitored using Granier's thermal dissipation probes. With synchronously-measured meteorological data, the canopy stomatal conductance (g(c)) was determined and the responses of g(c) to environmental variables were analyzed. We found that daytime mean g(c) in S. superba forest on average was significantly higher than those of A. auriculaeformis and E. citriodora plantations during a year (except in March). In the three plantations, g(c) was positively logarithmically correlated with photosynthetically active radiation (PAR) (P < 0.001), with a higher sensitivity of g(c) to PAR during wet season than that of dry season. By contrast, a negative logarithmical correlation between g(c) and vapor pressure deficit (VPD) was observed, with a higher sensitivity of g(c) to VPD during the wet season. Additionally, a higher partial correlation coefficient between g(c) and VPD was observed during wet season, indicating that VPD played a more important role in regulating the behavior of stomata during wet season. In general, the sensitivity of g(c) to VPD decreased with the decreases of soil water content, but more manifest decreases were found in S. superba and E. citriodora forests than in A. auriculaeformis plantation, while the descend degree in S. superba and E. citriodora forests were equal. Overall, our results demonstrated that the native species S. superba is more suitable for re-vegetation in southern China than the exotic species A. auriculaeformis and E. citriodora.