作 者 ：王俊峰, 冯玉龙
期 刊 ：植物生态学报 2004年 28卷 6期 页码：781-786
关键词：生物量分配；叶片形态；生长特性；紫茎泽兰；兰花菊三七；入侵性；
Keywords:Biomass allocation, Leaf morphology, Growth characteristic, Eupatorium adenophorum, Gynura sp., Invasiveness,
摘 要 ：比较研究了不同光强下生长的（透光率分别为12.5%、36%、50%、100%）两种入侵性不同的外来种——紫茎泽兰（Eupatorium adenophorum）和兰花菊三七（Gynura sp.）的生物量分配、叶片形态和生长特性。结果表明: 1）两种植物叶片形态对光环境的反应相似。弱光下比叶面积（SLA）、平均单叶面积（MLS）和叶面积比（LAR）较大，随着光强的升高，SLA、MLS、LAR和叶根比（LARMR）降低。2）100%光强下紫茎泽兰叶生物量比（LMR）、叶重分数（LMF）和叶面积指数高于低光强下的值，也高于兰花菊三七，支持结构生物量比（SBR）则相反。强光下紫茎泽兰叶片自遮荫严重，这可能是其表现入侵性的重要原因之一；兰花菊三七分枝较多，避免了叶片自遮荫，较多的分枝利于种子形成对其入侵有利。3）随生长环境光强的升高，两种植物的净同化速率（NAR）、相对生长速率（RGR）和生长对NAR的响应系数均升高（但100%光强下兰花菊三七RGR降低），平均叶面积比（LARm）和生长对LARm的响应系数均降低，但不同光强下LARm对生长的影响始终大于NAR。4）随着光强的减弱，两种植物都增加高度以截获更多光能，但它们的生物量分配策略不同，紫茎泽兰根生物量比（RMR）降低，SBR增大，而兰花菊三七SBR降低，RMR增大。紫茎泽兰的生物量分配策略更好的反应了弱光环境中的资源变化情况。结论：紫茎泽兰对光环境的适应能力强于兰花菊三七。
Abstract:The high biodiversity and economic costs associated with invasive plants have promoted research to identify traits associated with invasiveness. At present, most research has been based on comparisons between invasive and native species but, in this paper, two invasive species with different levels of invasiveness, Eupatorium adenophorum and Gynura sp., were studied. Both species were grown under four different relative irradiances (RI 12.5%, 36%, 50%, 100%) for 50 days, and we then measured their biomass allocation, leaf morphology and growth properties to compare their light acclimation abilities and growth strategies.The two species exhibited typical leaf morphological responses to different light conditions. At low light levels, plants enhanced light interception by means of increased biomass allocation to leaves and formation of large, thin leaves with high specific leaf area (SLA), leading to a high leaf area ratio (LAR). At high light levels, plants reduced transpiration losses and increased carbon gain by making small-sized, thick leaves with a low SLA, leading to a low LAR and leaf area to root mass ratio. Under most light regimes, E. adenophorum was higher in leaf mass ratio (LMR), leaf mass fraction (LMF), LAR, root mass ratio (RMR) and root mass to crown mass ratio (R/C), but lower in supporting organ biomass ratio (SBR), MLA and branch number as compared to Gynura sp. Leaf mass ratio, LMF, and leaf area index of E. adenophorum were the highest under 100% irradiance than under other light regimes and higher than for Gynura sp.; however, for SBR, these patterns were reversed. Under 100% irradiance, leaves were much more self-shaded in E. adenophorum than in Gynura sp. This might be an adaptive strategy that supports the vigorous invasiveness of this species because a high-shaded canopy could prevent other plant species from surviving and competing. The number of branches of Gynura sp. was greater under 100% irradiance than under other light regimes and significantly more than for E. adenophorum. This might be an adaptive strategy for Gynura sp. because a greater number of branches can produce more flowers and thus more seeds. For both species, an increase in light intensity resulted in an increase in net assimilation rates (NAR) and growth response coefficient of NAR (GRCNAR), whereas mean leaf area ratio (LARm) and growth response coefficient of LARm (GRCLARm) decreased. GRCLARm was higher than GRCNAR at all times. The relative growth rate (RGR) of E. adenophorum increased with an increase in light intensity but decreased in Gynura sp. With a decrease in light intensity, both E. adenophorum and Gynura sp. grew taller and produced more branches to intercept more light energy. The biomass allocation strategy differed between the two species: RMR decreased and SBR increased in E. adenophorum, while RMR increased, and SBR decreased in Gynura sp. All of the results presented above indicate that E. adenophorum was able to acclimate better to different light conditions, especially to low light regimes, than Gynura sp., and its better ability to acclimate might explain its greater invasiveness.