Data from: Solar irradiance as the proximate cue for flowering in a tropical moist forest

We compared flowering times predicted by six possible proximate cues involving seasonal changes in rainfall and irradiance and flowering times observed over 30 years of weekly censuses for 19 tree and liana species from Barro Colorado Island (BCI), Panama. Hypotheses concerning variation in the timing and intensity of rainfall failed to predict flowering times in any species. In contrast, 10 to 12 weeks of consistent high levels of irradiance predicted flowering times well for eight species, and six or seven weeks of rapidly increasing levels of irradiance predicted flowering times well for two species. None of the six possible proximate cues predicted flowering times adequately for the nine remaining species. We conclude that high and increasing levels of irradiance are the proximate cues for flowering in many BCI species. The seasonal movements of the Intertropical Convergence Zone cause strong seasonal changes in cloud cover, atmospheric transmissivity and irradiance reaching the BCI forest. Inter-annual variation in the timing of movements of the Intertropical Convergence Zone is the most likely cause of inter-annual variation in the timing of flowering in these species. Much work remains to be done as the physiological mechanisms linking flowering and irradiance are unknown and the proximate cues for flowering remain to be identified for many other BCI species.

我们对比了基于6种涉及降雨与辐照度（irradiance）季节性变化的潜在近因刺激（proximate cue）所预测的开花时间，与针对巴拿马巴罗科罗拉多岛（Barro Colorado Island, BCI）的19种乔木和藤本植物开展30年每周普查所观测到的开花时间。针对降雨时间与强度变化的相关假说，无法准确预测任一物种的开花时间。与之相对，连续10至12周的稳定高辐照度水平可较好预测8个物种的开花时间，而辐照度快速升高的6至7周时长则可有效预测2个物种的开花时间。对于剩余的9个物种，6种候选近因刺激均无法充分预测其开花时间。我们得出结论：高辐照度以及辐照度升高是巴罗科罗拉多岛多数物种开花的近因刺激因子。热带辐合带（Intertropical Convergence Zone, ITCZ）的季节性移动，会使抵达巴罗科罗拉多岛森林的云量、大气透射率与辐照度产生显著的季节性波动。热带辐合带移动时间的年际差异，正是这些物种开花时间年际变化的最可能成因。目前仍有大量研究工作亟待开展：连接开花与辐照度的生理机制尚未阐明，且巴罗科罗拉多岛其余多数物种的开花近因刺激因子仍有待识别。