Seed germination and invasion success of Poa annua L. in Antarctica

Abstract

One of the first steps to successful invasion of plant species that reproduce sexually is seed germination, which may be highly influenced by climatic conditions. We studied <em>Poa annua</em>, a cosmopolitan species found across all climatic zones and the only alien species that has successfully colonized the Antarctic. Our research questions were: (i) if harsh polar conditions restrict seed germination of <em>P. annua</em> and (ii) if the germination capacity of the Antarctic population of the species is due to high germination aptitude in the source population. We compared germination of seeds collected from eight populations around the world (maritime Antarctica, S Chile, W Argentina and E Argentina, NE USA, SW Croatia, C Poland and S Poland). We followed germination of seeds collected in the field and acquired from plants cultivated under unified optimal conditions. We found significant differences between populations in germination characteristics of seeds collected in the field. These could be associated with seed ripening in different locations. Seeds obtained under favorable conditions differed in stratification requirements. The germination potential of the Antarctic population is lowered by unfavorable polar conditions impacting seed maturation. Thus, the species’ invasion in the Antarctic seems highly restricted by the harsh environment. Environmental unsuitability may restrict invasions of other species in the same way potentially. However, this environmental barrier protecting Antarctica from invasions may be broken under a climate warming scenario.

Evaluation of factors influencing the eradication of annual bluegrass (Poa annua L.) from Point Thomas Oasis, King George Island, Maritime Antarctica

“…Our findings are published in accessible scientific journals and information regarding the extirpation scheme, location (GPS coordinates), and abundance of the local population at the beginning of the action and locations from where the species has been removed is available (Galera et al 2017(Galera et al , 2019Table 2, factor 15). We also showed that the biology of the invasive population of P. annua on Thomas Point Oasis is distinct from other populations of this species (Wódkiewicz et al 2014(Wódkiewicz et al , 2018Galera et al 2015Galera et al , 2021Rudak et al 2018Rudak et al , 2019Table 2, factor 16).…”

“…In comparison with other more hospitable environments the fecundity and population performance of P. annua under Antarctic conditions is relatively low. Total yearly seed production at Point Thomas Oasis was estimated at around 100 thousand seeds with germination capacity based on our earlier findings: 1500 tussocks (Galera et al 2015) × 3.5 individuals per tussock (Rudak et al 2019) × 4 generative shoots per individual (Galera et al 2015) × 4.6 germinable seeds per generative shoot (Rudak et al 2018). It is much smaller than under temperate climate (150-650 thousand seeds per m 2 per year, Lush 1988a).…”

Influence of the population spatial structure on seed rain distribution of an invasive plant under harsh environment

“…For annual bluegrass in the Antarctic, the formation of the soil seed bank may proceed similarly as in most polar plants, when produced seeds are immediately added to the persistent seed bank (Lévesque and Svoboda 1995). Seed bank of an invasive plant in Antarctica may be viable longer than expected and with rising temperatures even more stored seeds will be fully mature and able to germinate (Rudak et al 2018). This can aid the species overcome population collapse (Galera et al 2019) and should be taken in consideration regarding any eradication programs, as the only method of removing seed bank in this scenario is the removal of plants with the soil underneath them (Galera et al 2017).…”

Polar terrestrial ecosystems: ecology, diversity, and biogeography

“…The stressors that can affect seedlings are not only related to harsh, abiotic terrestrial conditions, but also to chemical factors originating from marine activities. From this perspective, Rudak et al [13], by comparing populations from different climatic zones, studied the cosmopolitan species Poa annua with respect to its seed germination and invasion success in Antarctica. Koc et al [14] compared the effects of methanesulfonic acid, derived from marine ecosystems, on seed germination and morphophysiological changes in the seedlings of two Colobanthus species.…”