Oregon State University, 321 Richardson Hall, Environmental Science Program, Corvallis, Oregon 97331 USA.
Am J Bot. 2002 Sep;89(9):1431-8. doi: 10.3732/ajb.89.9.1431.
The prolific amount of growth and reproduction in invasive plants may be achieved by greater net photosynthesis and/or resource-use efficiency. I tested the hypotheses that leaf-level photosynthetic capacity and resource-use efficiency were greater in two invasive species of Rubus as compared with two noninvasive species that have overlapping distributions in the Pacific Northwest. The invasive species had significantly higher photosynthetic capacity and maintained net photosynthesis (A) over a longer period of the year than the noninvasive species. The construction cost (CC) of leaf tissue per unit leaf mass was comparable among the four species, but the invasive species allocated less nitrogen (N) per unit leaf mass. On a leaf area basis, both leaf CC and N were higher for the invasive species. The specific leaf area (SLA) was also lower in the invasive species, indicating less photosynthetic area per gram leaf tissue. The invasive species achieved high A at lower resource investments than the noninvasive species, including having higher maximum photosynthetic rate (A(max)) per unit dark respiration (R(d)), greater A(max) per unit leaf N (photosynthetic nitrogen-use efficiency), and greater water-use efficiency as measured by instantaneous rates of A per unit transpiration (A/E) and by integrated A/E inferred from stable carbon isotope ratios (δ(13)C). Using discriminant analysis, these photosynthetic characteristics were found to be powerful in distinguishing between the invasive and noninvasive Rubus. A(max) and A/E were identified as the most useful variables for distinguishing between the species, and therefore, may be important factors contributing to the success of these invasive species.
入侵植物大量的生长和繁殖可能是通过更高的净光合作用和/或资源利用效率实现的。我通过测试以下两个假设来验证这一观点，即与在太平洋西北地区有重叠分布的两个非入侵物种相比，两种入侵的悬钩子属植物的叶片水平光合作用能力和资源利用效率更高。结果表明，入侵物种的光合作用能力显著更高，并且比非入侵物种具有更长的净光合作用（A）维持时间。四种植物的叶片组织构建成本（CC）相当，但入侵物种的单位叶质量分配的氮（N）较少。基于叶面积，入侵物种的叶片 CC 和 N 都更高。入侵物种的比叶面积（SLA）也较低，表明每克叶组织的光合面积较小。与非入侵物种相比，入侵物种在较低的资源投资下就能实现高 A，包括单位暗呼吸（R(d)）的最大光合速率（A(max)）更高、单位叶 N 的 A(max)更高（光合氮利用效率）以及通过单位蒸腾的瞬时 A （A/E）和通过稳定碳同位素比（δ(13)C）推断的综合 A/E 来衡量的水分利用效率更高。通过判别分析，这些光合特征在区分入侵和非入侵悬钩子属植物方面非常有效。A(max)和 A/E 被确定为区分物种最有用的变量，因此，可能是这些入侵物种成功的重要因素。
