入侵种银胶菊和三叶鬼针草与本地种气体交换特性的比较

Comparison of gas exchange characteristics between invasive Parthenium hysterophorus and Bidens pilosa and co-occurring native Cirsium setosum(Asteraceae)

以菊科入侵植物银胶菊(Parthenium hysterophorus)和三叶鬼针草(Bidens pilosa)以及与其共生的菊科本地植物小蓟(Cirsium setosum)为对象,比较了3种植物气体交换参数和叶片特性的差异。结果表明,银胶菊和三叶鬼针草的净光合速率(net photosynthetic rate,P_n)、叶绿素含量、比叶面积(specific leaf area,SLA)、叶片单位质量P含量(leaf P content per unit mass,P_(mass))、光合能量利用效率(photosynthetic energy use efficiency,PEUE)和光合氮利用效率(photosynthetic nitrogen use efficiency,PNUE)均显著高于小蓟。植物叶片P_n与水分利用效率(water use efficiency,WUE)、叶片P_(mass)、SLA呈极显著正相关,植物叶片单位质量N含量(leaf P content per unit mass,N_(mass))与叶片SLA、单位质量建成成本(leaf construction cost per unit mass,CC_(mass))、叶绿素含量呈极显著正相关。与本地植物相比,较高的气体交换参数和叶片生化指标有可能是银胶菊和三叶鬼针草成功入侵的原因之一。

The severe damage caused by some invasive species on natural ecosystems is prompting increasing global concern. Many studies have focused on exotic invasive species. Generally, exotic invasive plants have higher resource capture abilities and utilization capacities, and lower leaf construction costs （CC） compared with native plants. However, the physiological mechanisms that determine their invasiveness are poorly understood. Both Parthenium hysterophorus and Bidens pilosa are annual herbs originating from tropical and Central America. These have been introduced into China unintentionally through agriculture, or intentionally for ornamental purposes, and have become an extremely serious agricultural and rangeland weed, threatening native fauna, and are a physical nuisance. We hypothesized that exotic invaders may have higher resource capture abilities and utilization efficiencies compared with native species. To test this hypothesis, ecophysiological traits including net photosynthetic rate （Pn）, water use efficiency （WUE）, photosynthetic nitrogen use efficiency （PNUE）, photosynthetic energy use efficiency （PEUE）, specific leaf area （SLA）, leaf P content per unit mass （Pmass）, leaf N content per unit mass （Nmass）, chlorophyll content, and mass-based and area-based leaf construction cost （CCmass and CCarea） were measured. We compared the above traits between P. hysterophorus, B. pilosa, and the co-occurring native （Cirsium setosum） populations in Shandong, China. The results showed that the Pn, chlorophyll content, leaf SLA, leaf Pmass, PEUE, and PNUE of P. hysterophorus and B. pilosa were significantly higher than those of C. setosum （P〈0.05）. Stomatal conductance （Gs）, transpiration rate （Tr）, leaf Nmass, and leaf CCmass of P. hysterophorus were significantly higher than those of C. setosum, only （P〈0.05）. B. pilosa was significantly higher than C. setosum in WUE, only （P〈0.05）. Correlation analysis demonstrated that leaf WUE, Pmass, and SLA were significantly positively correlated with Pn （P〈0.01）. Leaf CCmass did not increase significantly with increasing Pn. Leaf SLA, CCmass, and chlorophyll content were significantly positively correlated with Nmass （P〈0.01）. Compared with native plants, higher gas exchange characteristics and leaf biochemical indicators may contribute to the successful invasion of P. hysterophorus and B. pilosa. The results indicated that these two invasive species had a higher resource capture ability and resource utilization efficiency than native species, suggesting that these traits may be a common biological foundation underlying successful invasion by both exotic species.