Chamorro Daniel, Luna Belén, Moreno José M
Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Av. Carlos III s/n 45071 Toledo, Spain.
Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Av. Carlos III s/n 45071 Toledo, Spain
Am J Bot. 2017 Jan;104(1):83-91. doi: 10.3732/ajb.1600278. Epub 2017 Jan 19.
Species differ in their temperature germination niche. Populations of a species may similarly differ across the distribution range of the species. Anticipating the impacts of climate variability and change requires understanding the differential sensitivity to germination temperature among and within species. Here we studied the germination responses of four hard-seeded Cistaceae seeders to a range of current and future temperatures.
Seeds were collected at sites across the Iberian Peninsula and exposed or not exposed to a heat shock to break dormancy, then set to germinate under four temperature regimes. Temperatures were varied daily and seasonally, simulating the temperature range across the gradient, plus an increased temperature simulating future climate. Time to germination onset and cumulative germination at the end of each season were analyzed for the effects of temperature treatments, seasons, and local climate (temperature of the germination period, T) at each site.
T was a significant covariate of germination in all species but Cistus populifolius. Temperature treatments significantly affected Cistus ladanifer, C. salviifolius, and Halimium ocymoides. Germination occurred in simulated autumn conditions, with little germination occurring at later seasons, except in unheated seeds of H. ocymoides. Exposure to a heat shock changed the sensitivity to temperature treatments and the relationships with T.
Germination responses to temperature differ not only among species but also within species across their latitudinal range. The responses were idiosyncratic and related to the local climate of the population. This germination variability complicates generalizing the impacts of climate variability and climate change.
不同物种的温度萌发生态位存在差异。一个物种的种群在其分布范围内可能同样存在差异。预测气候变率和变化的影响需要了解物种间以及物种内对萌发温度的不同敏感性。在此，我们研究了四种硬实半日花科种子植物对一系列当前和未来温度的萌发响应。
在伊比利亚半岛各地采集种子，对其进行或不进行热激处理以打破休眠，然后将其置于四种温度条件下萌发。温度每日和季节性变化，模拟整个梯度范围内的温度，再加上一个模拟未来气候的升温条件。分析每个季节结束时的萌发起始时间和累积萌发率，以研究温度处理、季节以及每个地点的当地气候（萌发期温度，T）的影响。
除了多叶岩蔷薇外，T是所有物种萌发的显著协变量。温度处理对岩蔷薇、鼠尾草叶岩蔷薇和神香草状唇萼薄荷有显著影响。萌发发生在模拟秋季条件下，后期季节萌发较少，除了神香草状唇萼薄荷未加热的种子。热激处理改变了对温度处理的敏感性以及与T的关系。
对温度的萌发响应不仅在物种间存在差异，而且在物种内的纬度范围内也存在差异。这些响应具有特异性，且与种群的当地气候有关。这种萌发变异性使概括气候变率和气候变化的影响变得复杂。
