CO2 enrichment reduces reproductive dominance in competing stands of Ambrosia artemisiifolia (common ragweed)
CO2 enrichment reduces reproductive dominance in competing stands of Ambrosia artemisiifolia (common ragweed)
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DOI：
10.1007/s00442-005-0250-x
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发表时间：
2006-02-01
期刊：
影响因子：
2.7
通讯作者：
Bazzaz, FA
中科院分区：
文献类型：
--
作者：
Stinson, KA;Bazzaz, FA
生长在茂密林分中的植物可能无法平等地获取或利用因二氧化碳升高而获得的额外碳。因此，在CO2升高的条件下，优势植物和从属植物之间的生殖差异可能会发生改变。我们假设CO2升高会比光饱和的优势种更能促进遮荫的、从属的蒿属植物个体的生殖分配。在CO2浓度为360亩和720亩的条件下，测定了竞争个体的生长和繁殖反应。为了验证二氧化碳浓度升高是否会改变林分的大小和繁殖不平等，我们比较了林分高度生长和末梢、根和生殖器官生物量的变异系数（CV）。升高的CO2增加了植物生长各方面的生物量，降低了CV，特别是生殖生物量。在CO2浓度升高的情况下，繁殖分配高于环境处理，且这种差异在小型植物中更为明显，而在大型植物中，这种差异在CO2浓度升高的情况下，CV和总林分生产力之间的正相关关系更为明显，这表明在日益拥挤的条件下，小型植物的生长增强削弱了大型植物的相对生物量优势。我们得出结论，CO2升高促进了林分水平的繁殖，而CO2诱导的下级蒿属植物的生长增益使小型和大型植物的繁殖产量差异最小化。因此，在未来的种群中，更多的个体可能产生更多的种子和花粉。
Plants growing in dense stands may not equally acquire or utilize extra carbon gained in elevated CO2. As a result, reproductive differences between dominant and subordinate plants may be altered under rising CO2 conditions. We hypothesized that elevated CO2 would enhance the reproductive allocation of shaded, subordinate Ambrosia artemisiifolia L. (Asteraceae) individuals more than that of light-saturated dominants. We grew stands of A. artemisiifolia at either 360 or 720 mu L L-1 CO2 levels and measured the growth and reproductive responses of competing individuals. To test whether elevated CO2 altered size and reproductive inequalities within stands, we compared stand-level coefficients of variation (CV) in height growth and final shoot, root, and reproductive organ biomasses. Elevated CO2 enhanced biomass and reduced the CV for all aspects of plant growth, especially reproductive biomass. Allocation to reproduction was higher in the elevated CO2 than in the ambient treatment, and this difference was more pronounced in small, rather than large plant positive relationships between the CV and total stand productivity declined under elevated CO2, indicating that growth enhancements to smaller plants diminished the relative biomass advantages of larger plants in increasingly crowded conditions. We conclude that elevated CO2 stimulates stand-level reproduction while CO2-induced growth gains of subordinate A. artemisiifolia plants minimize differences in the reproductive output of small and large plants. Thus, more individuals are likely to produce greater amounts of seeds and pollen in future populations of this allergenic weed.