Straka Jason R, Starzomski Brian M
School of Environmental Studies, University of Victoria, P.O. Box 3060, STN CSC, 3800 Finnerty Road, Victoria, BC, V8P 5C2, Canada,
Oecologia. 2015 May;178(1):249-60. doi: 10.1007/s00442-014-3169-2. Epub 2014 Dec 2.
Predicting demographic consequences of climate change for plant communities requires understanding which factors influence seed set, and how climate change may alter those factors. To determine the effects of pollen availability, temperature, and pollinators on seed production in the alpine, we combined pollen-manipulation experiments with measurements of variation in temperature, and abundance and diversity of potential pollinators along a 400-m elevation gradient. We did this for seven dominant species of flowering plants in the Coast Range Mountains, British Columbia, Canada. The number of viable seeds set by plants was influenced by pollen limitation (quantity of pollen received), mate limitation (quality of pollen), temperature, abundance of potential pollinators, seed predation, and combinations of these factors. Early flowering species (n = 3) had higher seed set at high elevation and late-flowering species (n = 4) had higher seed set at low elevation. Degree-days >15 °C were good predictors of seed set, particularly in bee-pollinated species, but had inconsistent effects among species. Seed production in one species, Arnica latifolia, was negatively affected by seed-predators (Tephritidae) at mid elevation, where there were fewer frost-hours during the flowering season. Anemone occidentalis, a fly-pollinated, self-compatible species had high seed set at all elevations, likely due to abundant potential pollinators. Simultaneously measuring multiple factors affecting reproductive success of flowering plants helped identify which factors were most important, providing focus for future studies. Our work suggests that responses of plant communities to climate change may be mediated by flowering time, pollination syndrome, and susceptibility to seed predators.
预测气候变化对植物群落的人口统计学后果需要了解哪些因素影响结实率，以及气候变化如何改变这些因素。为了确定花粉可获得性、温度和传粉者对高山地区种子生产的影响，我们将花粉操纵实验与温度变化测量以及沿400米海拔梯度的潜在传粉者的丰度和多样性测量相结合。我们对加拿大不列颠哥伦比亚省海岸山脉的七种优势开花植物进行了此项研究。植物形成的 viable 种子数量受花粉限制（接受的花粉量）、配偶限制（花粉质量）、温度、潜在传粉者的丰度、种子捕食以及这些因素的组合影响。早花物种（n = 3）在高海拔地区结实率较高，晚花物种（n = 4）在低海拔地区结实率较高。大于15℃的度日数是结实率的良好预测指标，尤其是在蜜蜂传粉的物种中，但在不同物种间影响不一致。一种植物，宽叶山金车，在中海拔地区的种子生产受到种子捕食者（实蝇科）的负面影响，那里开花季节的霜冻小时数较少。西方银莲花是一种由苍蝇传粉、自交亲和的物种，在所有海拔高度都有较高的结实率，可能是由于潜在传粉者丰富。同时测量影响开花植物繁殖成功的多个因素有助于确定哪些因素最为重要，为未来研究提供重点。我们的工作表明，植物群落对气候变化的反应可能由开花时间、传粉综合征和对种子捕食者的易感性介导。
