Abstract：
OBJECTIVE: As winter and spring temperatures continue to increase, the timing of flowering and leaf out is advancing in many seasonally cold regions. This advancement could put plants that flower early in the spring at risk of decreased reproduction in years when there are late freeze events. Unfortunately, relatively little is known about floral freezing tolerance in forest communities. In this study, we examined the impact of freezing temperatures on the flowers of woody plants in a region where there is rapid winter warming in North America.
METHODS: We subjected the flowers of twenty-five woody species to a hard (-5ºC) and a light freeze (0ºC). We assessed tissue damage using electrolyte leakage. In a subset of species, we also examined the impact of a hard freeze on pollen tube growth. To determine if the vulnerability of flowers to freezing damage relates to flowering time and to examine the responsiveness of flowering time to spring temperature, we recorded the date of first flower for our study species for three years.
CONCLUSIONS: Across species, we found that floral freezing tolerance was strongly tied to flowering time with the highest freezing tolerance occurring in plants that bloomed earlier in the year. We hypothesize that these early blooming species are unlikely to be impacted by a false spring. Instead, the most vulnerable species to a false spring should be those that bloom later in the season. The flowering time in these species is also more sensitive to temperature, putting them at a great risk of experiencing a false spring. Ultimately, floral damage in one year will not have a large impact on species fitness, but if false springs become more frequent, there could be long-term impacts on reproduction of vulnerable species.
METHODS: We subjected the flowers of twenty-five woody species to a hard (-5ºC) and a light freeze (0ºC). We assessed tissue damage using electrolyte leakage. In a subset of species, we also examined the impact of a hard freeze on pollen tube growth. To determine if the vulnerability of flowers to freezing damage relates to flowering time and to examine the responsiveness of flowering time to spring temperature, we recorded the date of first flower for our study species for three years.
CONCLUSIONS: Across species, we found that floral freezing tolerance was strongly tied to flowering time with the highest freezing tolerance occurring in plants that bloomed earlier in the year. We hypothesize that these early blooming species are unlikely to be impacted by a false spring. Instead, the most vulnerable species to a false spring should be those that bloom later in the season. The flowering time in these species is also more sensitive to temperature, putting them at a great risk of experiencing a false spring. Ultimately, floral damage in one year will not have a large impact on species fitness, but if false springs become more frequent, there could be long-term impacts on reproduction of vulnerable species.
摘要：
目标：随着冬季和春季气温的持续升高，在许多季节性寒冷地区，开花和落叶的时机正在推进。这种进步可能会使在春季早期开花的植物在出现晚期冻结事件的年份中面临繁殖减少的风险。不幸的是,对森林群落的花卉抗冻性知之甚少。在这项研究中,我们研究了冻结温度对北美冬季变暖迅速的地区木本植物花朵的影响。
方法：我们对25种木本植物的花朵进行了硬冷冻（-5ºC）和轻度冷冻（0ºC）。我们使用电解质渗漏评估组织损伤。在物种的一个子集中，我们还研究了硬冻对花粉管生长的影响。为了确定花朵对冰冻伤害的脆弱性是否与开花时间有关，并检查开花时间对春季温度的响应性，我们记录了三年来研究物种的第一朵花的日期。
结论：跨物种，我们发现花卉的耐冻性与开花时间密切相关，在今年早些时候开花的植物中耐冻性最高。我们假设这些早期开花的物种不太可能受到虚假春天的影响。相反，对假春天最脆弱的物种应该是那些在季节晚些时候开花的物种。这些物种的开花时间对温度也更敏感，让他们冒着经历虚假春天的巨大风险。最终,一年内的花卉损害不会对物种适应性产生大的影响，但是如果假弹簧变得更加频繁，可能会对脆弱物种的繁殖产生长期影响。
方法：我们对25种木本植物的花朵进行了硬冷冻（-5ºC）和轻度冷冻（0ºC）。我们使用电解质渗漏评估组织损伤。在物种的一个子集中，我们还研究了硬冻对花粉管生长的影响。为了确定花朵对冰冻伤害的脆弱性是否与开花时间有关，并检查开花时间对春季温度的响应性，我们记录了三年来研究物种的第一朵花的日期。
结论：跨物种，我们发现花卉的耐冻性与开花时间密切相关，在今年早些时候开花的植物中耐冻性最高。我们假设这些早期开花的物种不太可能受到虚假春天的影响。相反，对假春天最脆弱的物种应该是那些在季节晚些时候开花的物种。这些物种的开花时间对温度也更敏感，让他们冒着经历虚假春天的巨大风险。最终,一年内的花卉损害不会对物种适应性产生大的影响，但是如果假弹簧变得更加频繁，可能会对脆弱物种的繁殖产生长期影响。
