Global climate change could exacerbate biological invasions by changing competitive interactions,and hence,threaten ecosystem biodiversity and stability.Replacement control,which relies on the growth advantage of native plants,is one of the most effective methods to suppress invasion.In the present study,distinctive photosynthetic responses to warming of invasive (Alternanthera philoxeroides) and native (Sambucus chinensis) plants were compared to determine the invasive potential of alien plants,and to screen native species for replacement control under climate change scenarios.Plants were grown in two different air temperatures (unwarmed or ambient temperature and warmed at (0.76±0.10)℃ by using an infrared heater) for a 5-month short-term period,and photosynthetic pigment concentrations and gas exchange characteristics were determined.The results showed that warming significantly and positively improved the chlorophyll a/b ratio by 6.21％ in A.philoxeroides (P＜0.01),but negatively by 5.55％ in S.chinensis (P＜0.05).Meanwhile,chlorophyll b,rather than both chlorophyll a and carotenoid,was significantly higher in S.chinensis than in A.philoxeroides,at ambient (P＜0.001)and increased temperatures (P＜0.05).Increased temperatures significantly increased the net photosynthetic rate by 9.23％ in A.philoxeroides (P＜0.01),but decreased the water use efficiency by 10.64％ (P＜0.01) due to a respective increase in stomatal conductance by 11.10％ (P ＜ 0.05) and transpiration rate by 21.46％ (P ＜ 0.001).In contrast,increased temperatures significantly enhanced stomatal conductance by 10.95％ in S.chinensis (P＜0.001),but had no effect on other gas exchange traits.Under the control conditions,the stomatal conductance and intercellular CO2 concentration were 7.03％ (P＜0.05) and 4.57％ (P＜0.001) higher,but the net photosynthetic rate and water use efficiency were 10.30％ (P＜0.001) and 11.92％ (P＜0.05) lower in A.philoxeroides than in S.chinensis,respectively.However,under increased temperatures no significant differences in net photosynthetic rate and stomatal conductance were observed between the two plant species.In contrast,under increased temperatures,water use efficiency was 26.45％ higher in S.chinensis than in A.philoxeroides (P＜0.001),possibly because of lower transpiration rates in S.ehinensis.Increased temperatures,species,and their interactions did not have significant effects on photosynthetic-light curve parameters.In general,S.chinensis had a stronger photosynthetic capacity than the invasive A.philoxeroides in terms of chlorophyll b content,net photosynthetic rate,and water use efficiency,especially in control conditions.However,the photosynthetic advantage of S.chinensis was eliminated with increased temperatures.Collectively,our results suggested that S.chinensis could potentially be used in ecological restoration to replace A.philoxeroides in invaded habitats.%利用红外加热器模拟增温,比较入侵植物喜旱莲子草和本地种接骨草的光合特性对增温响应的差异,以预测气候变暖背景下入侵植物的入侵潜力,并为筛选替代控制植物提供依据.结果表明:增温导致喜旱莲子草和接骨草的叶绿素a/b值分别比对照显著提高6.21％和降低5.55％.无论增温与否,接骨草的叶绿素b含量显著高于喜旱莲子草,而叶绿素a/b值则相反.增温导致喜旱莲子草净光合速率显著提高9.23％,由于气孔导度增大引起蒸腾速率大幅度增加,使得其水分利用效率比对照显著降低10.64％.增温仅导致接骨草的气孔导度显著增加10.95％,而对其他气体交换特征无显著影响.对照条件下,尽管接骨草的气孔导度和胞间CO2浓度分别显著低于喜旱莲子草7.03％和4.57％,但是前者的净光合速率和水分利用效率分别显著高于后者10.30％和11.92％.增温条件下,两种植物的净光合速率和气孔导度无显著差异,由于接骨草的蒸腾速率显著低于喜旱莲子草18.02％,故其水分利用效率显著高于后者26.45％.增温、物种及其两者的交互作用对光补偿点、光饱和点、最大净光合速率、暗呼吸速率和初始量子效率等光响应参数影响均不显著.总之,对照条件下,接骨草凭借较高的叶绿素b含量、净光合速率和水分利用效率,比喜旱莲子草具有更强的光合能力.但增温后,接骨草的光合优势被削弱.研究从光合生理角度证明接骨草有望作为喜旱莲子草的替代控制植物,但是未来气候变化背景下喜旱莲子草的入侵潜力可能增强.
展开▼
