Centre for Sustainable Ecosystem Solutions, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia.
Sci Rep. 2020 Feb 7;10(1):2180. doi: 10.1038/s41598-020-58914-7.
Hieracium pilosella and H. aurantiacum are invading alpine regions in New South Wales, Australia. In a glasshouse experiment we investigated germination and growth rates of these two species at temperatures simulating the altitudes where invasions are occurring from autumn to spring. We measured germination rates, growth rates and the development of stolons and ramets using seedlings and plantlets from established plants. Germination was low in H. aurantiacum and unaffected by altitude or seed age. H. pilosella showed site to site variability in germination but had greater germination. No species produced flower spikes. Both species grew rapidly and put at least twice as much biomass into roots compared to shoots. H. aurantiacum could begin to produce stolons after 27 days and seedlings grew a little larger than for H. pilosella. Hieracium aurantiacum put significantly more resources into ramets, allocating between 4-15% of biomass. H. pilosella produced 2.6 stolons month, in contrast to 9.8 stolons month for H. aurantiacum. Furthermore, plantlets from established plants had vastly different growth rates. Plantlets of H. aurantiacum produced 2.1 leaves day from late summer to winter where H. pilosella was 3 times slower for the same period but faster following winter. Both species were able to maintain strong growth over cooler months suggesting hawkweeds have the capacity for fast growth in the invaded range under high nutrients and lower competition. H. aurantiacum is likely to be a more effective invader than H. pilosella spreading through stolons and the development of weed mats.
绒毛千里光和橙头千里光正在入侵澳大利亚新南威尔士州的高山地区。在温室实验中，我们模拟了从秋季到春季入侵发生的海拔高度，研究了这两个物种在这些温度下的发芽和生长速度。我们使用来自已建立植物的幼苗和植物苗来测量发芽率、生长速度以及匍匐茎和分株的发育。橙头千里光的发芽率较低，不受海拔或种子年龄的影响。绒毛千里光的发芽率存在地点间的差异，但发芽率更高。两个物种都没有产生花穗。两种物种都生长迅速，根部的生物量至少是茎部的两倍。橙头千里光在 27 天后就可以开始产生匍匐茎，而幼苗比绒毛千里光长得更大。橙头千里光将显著更多的资源分配给分株，分配比例为 4-15%的生物量。绒毛千里光每月产生 2.6 条匍匐茎，而橙头千里光每月产生 9.8 条匍匐茎。此外，来自已建立植物的植物苗具有截然不同的生长速度。橙头千里光的植物苗从夏末到冬季每天产生 2.1 片叶子，而绒毛千里光在同一时期的生长速度慢 3 倍，但在冬季后更快。两个物种都能够在较凉爽的月份保持强劲的生长，这表明千里光在高养分和低竞争的入侵范围内具有快速生长的能力。橙头千里光很可能比绒毛千里光更有效地入侵，通过匍匐茎和杂草垫的发展进行传播。
