Characteristics of Gas Exchange of Five Common Water and Soil Conservation Tree Species

Abstract:

In order to understand the gas exchange characters of water and soil conservation tree species, the photosynthetic and transpiration characters of five common urban forest tree species in Hanzhou, including Sapindus mukorossi, Choerospondias axillaris, Cinnamomum camphora, Elaeocarpus glabripetalus and Phyllostachys edulis, were studied. The results showed that the daily dynamic curve of photosynthetic rate (Pn) in Cinnamomum camphora, S. mukorossi, Choerospondias axillaris and P. edulis indicated bimodal type with obvious "noon break" phenomenon, while those in E. glabripetalus indicated single peak type without "noon break". The Pn was in the order of Cinnamomum camphora > P. edulis > S. mukorossi > Choerospondias axillaris > E. glabripetalus, while the transpiration rate (Tr) showed Cinnamomum camphora > S. mukorossi > P. edulis > Choerospondias axillaris > E. glabripetalus, and the water use efficiency (WUE) was E. glabripetalus > P. edulis > Choerospondias axillaris > S. mukorossi > Cinnamomum camphora. Tr, Gs and WUE had significant differences (P < 0.01) among five tree species by ANOVA analysis, while Pn and Ci had not significant difference. Pearson correlation analysis showed that Pn had significant positive correlation with Tr, Gs, PAR, and did Tr with Gs. WUE had significant negative correlation with Tr, Gs, and did Ci with PAR and Ta. Therefore, Cinnamomum camphora and S. mukorossi had high Tr with low WUE, so it was better to strengthen water and shading for reduce Tr in conservation process. P. edulis, Choerospondias axillaris and E. glabripetalus had low Tr with high WUE, showing that they could scientifically use soil moisture and adapt to drought environment.

Key words:Water and soil conservation species;Transpiration rate;Photosynthesis;Gas exchange