Department of Biology, University of Maryland, College Park, MD 20742-4415, USA.
Glob Chang Biol. 2013 Aug;19(8):2348-59. doi: 10.1111/gcb.12246. Epub 2013 May 29.
Variation in species' responses to abiotic phenological cues under climate change may cause changes in temporal overlap among interacting taxa, with potential demographic consequences. Here, we examine associations between the abiotic environment and plant-pollinator phenological synchrony using a long-term syrphid fly-flowering phenology dataset (1992-2011). Degree-days above freezing, precipitation, and timing of snow melt were investigated as predictors of phenology. Syrphids generally emerge after flowering onset and end their activity before the end of flowering. Neither flowering nor syrphid phenology has changed significantly over our 20-year record, consistent with a lack of directional change in climate variables over the same time frame. Instead we document interannual variability in the abiotic environment and phenology. Timing of snow melt was the best predictor of flowering onset and syrphid emergence. Snow melt and degree-days were the best predictors of the end of flowering, whereas degree-days and precipitation best predicted the end of the syrphid period. Flowering advanced at a faster rate than syrphids in response to both advancing snow melt and increasing temperature. Different rates of phenological advancements resulted in more days of temporal overlap between the flower-syrphid community in years of early snow melt because of extended activity periods. Phenological synchrony at the community level is therefore likely to be maintained for some time, even under advancing snow melt conditions that are evident over longer term records at our site. These results show that interacting taxa may respond to different phenological cues and to the same cues at different rates but still maintain phenological synchrony over a range of abiotic conditions. However, our results also indicate that some individual plant species may overlap with the syrphid community for fewer days under continued climate change. This highlights the role of interannual variation in these flower-syrphid interactions and shows that species-level responses can differ from community-level responses in nonintuitive ways.
在气候变化下，物种对非生物物候线索的反应变化可能导致相互作用的分类群之间时间重叠的变化，从而产生潜在的人口统计后果。在这里，我们使用长期的食蚜蝇-花物候数据集（1992-2011 年）来研究非生物环境与植物-传粉者物候同步性之间的关系。研究了冻结天数、降水和融雪时间作为物候的预测因子。食蚜蝇通常在开花开始后出现，并在开花结束前结束活动。在我们 20 年的记录中，开花和食蚜蝇物候都没有明显变化，这与同一时间段内气候变量没有明显的方向性变化一致。相反，我们记录了非生物环境和物候的年际可变性。融雪时间是开花开始和食蚜蝇出现的最佳预测因子。融雪和日度是开花结束的最佳预测因子，而日度和降水是食蚜蝇期结束的最佳预测因子。随着融雪和温度的提前，开花比食蚜蝇提前更快。由于活动期延长，在融雪较早的年份，花-食蚜蝇群落之间的时间重叠天数更多，不同的物候推进速度导致更多的时间重叠。因此，即使在我们研究地点的长期记录中明显存在融雪提前的情况下，群落水平的物候同步性仍可能在一段时间内得以维持。这些结果表明，相互作用的分类群可能对不同的物候线索和相同的线索以不同的速度做出反应，但仍能在一系列非生物条件下保持物候同步性。然而，我们的研究结果也表明，在持续的气候变化下，一些个别植物物种与食蚜蝇群落的重叠天数可能会减少。这突显了这些花-食蚜蝇相互作用中年际变化的作用，并表明物种水平的反应可能以非直观的方式与群落水平的反应不同。
