Ecology and Environment Research Group, Hawkesbury Campus (K12), University of Western Sydney, Locked Bag 1797, Penrith South, DC, 1797, Australia.
Oecologia. 2010 Feb;162(2):293-302. doi: 10.1007/s00442-009-1456-0. Epub 2009 Sep 19.
Ambient temperature and water availability regulate seasonal timing of germination. In fire-prone landscapes, the role of fire-related cues in affecting the range of temperatures and water potentials (psis) across which germination can occur is poorly known, especially in non-Mediterranean landscapes. We examined interactive effects of temperature (15 or 25 degrees C), psi (0 to -0.9 MPa), and fire-related cues (heat and smoke) on germination for seeds of three shrub species from fire-prone southeastern Australia. Incubation temperature affected germination of untreated seeds of Kunzea ambigua and Kunzea capitata (Myrtaceae) (reduction at 25 degrees C), but germination was uniformly low in Epacris obtusifolia (Ericaceae). Decreasing psi reduced germination across both incubation temperatures. Fire cues increased germination at both incubation temperatures and across psis, although in Kunzea the increase was smaller and occurred over a narrower range of psis at 25 degrees C. Hydrotime analysis suggested that fire cues reduced the amount of water necessary for germination of Kunzea seeds. Post-fire germination of the three study species may occur during the warm season, although it is reduced and confined to wet periods for the two Kunzea species. Warm season germination of the study species is consistent with a trade-off between the increased risk of failure of a cohort of seedlings, and benefits of early establishment of a cohort that may survive in an environment with aseasonal rainfall.
环境温度和水分供应调节种子的季节性萌发时间。在火灾多发的景观中，火相关线索在影响可发生萌发的温度和水势（ψ）范围方面的作用知之甚少，特别是在非地中海景观中。我们研究了温度（15 或 25°C）、ψ（0 至-0.9 MPa）和火相关线索（热和烟）对来自澳大利亚东南部火灾多发地区的三种灌木物种种子萌发的交互作用。孵育温度影响未处理的 Kunzea ambigua 和 Kunzea capitata（桃金娘科）种子的萌发（25°C 时减少），但 Epacris obtusifolia（杜鹃花科）的萌发率始终较低。随着 ψ 的降低，在两个孵育温度下的萌发率都降低了。火线索在两个孵育温度和整个 ψ 范围内都增加了萌发，尽管在 Kunzea 中，在 25°C 时，增加的幅度较小，并且发生在较窄的 ψ 范围内。水时分析表明，火线索减少了 Kunzea 种子萌发所需的水量。三种研究物种的火灾后萌发可能发生在温暖季节，但对于两种 Kunzea 物种，萌发减少且仅限于湿润期。研究物种温暖季节的萌发与幼苗群体失败风险增加和早期建立可能在季节性降雨环境中存活的群体的益处之间的权衡有关。
