关键词: 火炬树, 盐肤木, 光合性能, 建成成本, 资源利用效率

Abstract: [Objective] Rhus typhina is an exotic tree species widely planted in the Yellow River basin and North China, but there is still controversy about whether it is an invasive plant. This paper explores the eco-physiological mechanism of R. typhina invasion by comparing it with its indigenous congeners Rhus chinensis in terms of their photosynthetic performance, resource-use efficiency, and construction cost to provide a reference for the comprehensive prevention and control of R. typhina, or planting. [Method] In this study, the photosynthetic performance parameters of R. typhinaand R. chinensis were measured with a TPS-2 photosynthetic system; the light use efficiency (LUE) and water use efficiency (WUE) were calculated according to the related parameters. The total nitrogen content of leaves was analysed with a Vario Micro Cube element analyzer. The gross calorific value was evaluated with a C2000 oxygen bomb calorimeter, and the leaf photosynthetic nitrogen use efficiency (PNUE) and construction cost were thus calculated. [Result] The apparent quantum efficiency (AQY), maximum net photosynthetic rate (P_max) and respiratory rate in R. typhina were higher than those of its indigenous congeners R. chinensis, but the differences were significant (P<0.05) only in September. The light saturation and compensation point and chlorophyll content were not significantly different (P>0.05) between the two species. The LUE and PNUE of R. typhina were significantly higher than those of R. chinensis(P<0.05) in September, but the WUE of the latter was significantly higher than that of the former in July. The gross caloric value, mass-based (CC_mass) and area-based (CC_area) leaf construction cost were all lower in R. typhina than in its indigenous congeners R. chinensis, but the reverse was the case in terms of the specific leaf area (SLA). Furthermore, the two-factor analysis of variance showed that the differences of the photosynthetic performance indices, resource-use efficiency indicators and leaf construction cost between the two species were insignificant (P >0.05), but differences in the indexes among different measurement periods were very significant (P<0.01). It is therefore concluded that although the photosynthetic capacity, resource-use efficiency inR. typhina is higher compared with R. chinensis at the later stage of the annual growing season (September), there is no significant difference in those indexes between the two species as a whole. [Conclusion] Compared with its indigenous congeners R. chinensis, R. typhina has some characteristics of invasive plants in physiological and ecological property, but the competitive advantage only appeared in the later stage of the annual growing season.

Key words: Rhus typhina, Rhus chinensis, photosynthetic performance, construction cost, resource-use efficiency