5种常见水土保持树种的气体交换特性研究

为了了解水土保持树种的气体交换特性,对无患子(Sapindus mukorossi)、南酸枣(Choerospondias axillaris)、香樟(Cinnamomum camphora)、秃瓣杜英(Elaeocarpus glabripetalus)和毛竹(Phyllostachys edulis)等常见树种的光合蒸腾特性进行研究。结果表明,香樟、无患子、南酸枣和毛竹的净光合速率(Pn)日变化曲线呈双峰型,有明显的"光合午休"现象;秃瓣杜英的Pn日变化曲线则呈单峰型,未出现"光合午休"现象。5种树种的Pn以香樟毛竹无患子南酸枣秃瓣杜英;蒸腾速率(Tr)以香樟无患子毛竹南酸枣秃瓣杜英;水分利用效率(WUE)以秃瓣杜英毛竹南酸枣无患子香樟。单因素方差分析表明:不同树种间的Tr、气孔导度(Gs)和WUE存在显著差异,而Pn和胞间CO2浓度(Ci)的差异不显著。相关性分析表明,Pn与Tr、Gs和光合有效辐射(PAR)呈正相关关系;Tr与Gs呈正相关关系,与WUE呈负相关关系;Gs与WUE呈负相关关系;Ci与PAR和空气CO2浓度(Ta)呈负相关关系。香樟和无患子的Tr相对较大,而WUE较低,在养护过程应加强浇水及遮阴以降低其水分蒸腾的速率;秃瓣杜英、南酸枣和毛竹的Tr相对较低,而WUE相对较高,能够科学地利用土壤水分,可适应较干燥的外界环境。

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

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.