辽宁地区两种菊科入侵植物与本地植物光合特性比较

为明确外来植物生理生态学性状及其与其强入侵性的关系,本研究采用野外原位气体交换参数测定的方法,分析了菊科入侵植物豚草、三裂叶豚草与其共生本地植物紫菀光合特性和叶片性状的差异。结果表明,豚草、三裂叶豚草、紫菀3种植物的光饱和点(LSP)均高于800μmol·m~(-2)·s~(-1),且两种入侵植物的LSP显著高于紫菀,表观量子效率(AQY)则显著低于紫菀;3种植物的最大净光合速率(P_(nmax))大小顺序为豚草三裂叶豚草紫菀,其中,豚草和三裂叶豚草的P_(nmax)分别比紫菀高出151.28%、82.80%,且差异显著。两种入侵植物的比叶面积(SLA)、叶片的单位质量氮含量(N_(mass))、叶片单位质量磷含量(P_(mass))、光合能量利用效率(PEUE)、光合氮利用效率(PNUE)均显著高于紫菀,但3者叶片单位质量建成成本(CC_(_(mass)))差异不显著。综上所述,辽宁的两种菊科入侵植物相对于本地共生种来说有着较高的气体交换参数和叶片特性指标,且其光合特性和叶片特性也存在着密切的联系,表现在这些菊科入侵植物有着更高的P_(nmax)、PNUE、PEUE和水分利用效率(WUE)等光合特性指标和能量利用指标,使得入侵植物能够更有效地捕获和利用环境资源,成为其得以成功入侵的原因之一。

Comparison of gas exchange characteristics between two invasive plants and a co-occurring native plant in Liaoning Province

Biological invasion is one of the century''s most serious environmental problems.A comparative study of invaders and co-occurring natives is an effective approach to gaining insights into the invasiveness of exotic plants.Ambrosia artemisiifolia L.and A.trifida L.are two aggressive North American annual weeds in China,whereas A.trifida occurs mainly in Northeast China.They usually invade cultivated fields and reduce crop productivity,causing significant ecological and socio-economic impacts in introduced areas.Besides its economic impact on crop yield,A.artemisiifolia also represents a major health problem since its pollen is a strong allergen and one of the main causes of hay fever.To explore the traits contributing to invasiveness of A.artemisiifolia and A.trifida and to test the relationship between plasticity of these traits and invasiveness,we conducted a comparative study of two invasive species and their co-occurring native Asteraceae plant,Aster tataricus,in tataricus in terms of gas exchange and efficiencies in resource utilization.We tested the hypothesis that A.artemisiifolia and A.trifida had growth-related ecophysiological advantages over the natives in its non-native range,which resulted in its rapid growth and enhanced its invasiveness.Photosynthesis,specific leaf area (SLA),and the efficiency of resource use (light,phosphorus,and nitrogen) were examined in field.Leaf construction cost (CC) is considered as a quantifiable measure of energy demand for biomass production and is related to energy use efficiency as it includes component of both morphological and physiological traits.The results showed that the light saturation point (LSP) of A.artemisiifolia,A.trifida were significantly higher than that of the native species A.tataricus.The order of P_nmax was that A.artemisiifolia > A.trifida > A.tataricus,and this parameter of two invasive species were significantly higher than that of A.tataricus by 151.28%,82.80%,respectively.The specific leaf area (SLA),leaf N content per unit mass (N_mass),leaf P content per unit mass (P_mass),photosynthetic energy use efficiency (PEUE),photosynthetic nitrogen use efficiency (PNUE) of two invasive plants were significantly higher than those of the native,but the difference of leaf construction cost per unit mass (CC_mass) between the three plant species was not significant.In summary,the two Asteraceae invasive plant species has higher gas exchange characteristics and leaf traits as compared with co-family non-invasive plant species,and their photosynthetic characteristics and leaf characteristics were closely linked.The two Asteraceae invasive plant species had higher photosynthetic characteristics and energy use parameters,including P_nmax,PNUE,PEUE,water use efficiency (WUE),leading to more effectively resources capturing and utilization efficiency,which may be one of the reasons for successful invasion of these Asteraceae invasive plants in the studied area.