Katarzyna J. Chwedorzewska

Short Note: The first appearance and establishment of an alien vascular plant in natural habitats on the forefield of a retreating glacier in Antarctica

. 1985). However, there is no evidencefrom palaeorecords that any other vascular plants existedin this region during the Holocene, despite the fact that amajor source of potential immigrants is located only900km to the north in Tierra del Fuego (Smith 2003).With the current trend in regional warming in the maritimeAntarctic (King

Poa annua L. in Antarctic: searching for the source of introduction

The level of polymorphism, genetic variability and relatedness of a population of Poa annua L. from South Shetlands Islands was studied and compared with results obtained for populations from two potential sources of introduction (Argentina—Ushuaia and Poland—Dziekanów Leśny) using the amplified fragment length polymorphism (AFLP) approach. Five primer pairs used for AFLP profiling amplified 226 scoreable DNA fragments that were used for Clustral and Factorial analyses. The level of molecular variability among all individuals from all the analysed populations reaches 30%. Clustral and Factorial analyses show that all populations formed clear-cut uniform groups according to their locations. However, population from King George Island show high variability. High genetic diversity may be related with escalated human activity at the area of Arctowski Station, favouring introductions of P. annua from many different sources and by many different vectors.

Poa annua L. in the maritime Antarctic: an overview

Poa annua is the only flowering plant species that has established a breeding population in the maritime Antarctic, through repeated anthropogenic introduction. The first appearance of this species in the Antarctic was observed in 1953. Annual bluegrass inhabits mainly anthropogenic sites, but recently has entered tundra communities. The functioning of P. annua in the Antarctic could not have been possible without adaptations that enable the plants to persist in the specific climatic conditions typical for this zone. Poa annua is highly adaptable to environmental stress and unstable habitats: huge phenotypic and genotypic variability, small size, plastic life cycle (life-history types ranging from annual to perennial forms). The spreading of P. annua in the Antarctic Peninsula region is a classic example of the expansion process following anthropogenic introduction of an invasive species, and illustrates the dangers to Antarctic terrestrial ecosystems that are associated with increasing human traffic.

Diaspores and phyto-remains accidentally transported to the Antarctic Station during three expeditions

The aim of the project was to assess the size and species range of alien plant diaspores and phyto-remains transported into the Polish Antarctic Station during three Antarctic expeditions. Our study clearly demonstrates that many diaspores can be quite easily unintentionally transported in good conditions to the Antarctic. In the analyzed material there were present diaspores of invasive species. All identified species belong to 20 families. The most abundant were Asteraceae and Poaceae species. The most interesting finding was the presence of caryopses of Poa annua, the first alien angiosperm species which already established a stable breeding population in the Antarctic. Base on our results, we can predict that risk of establishment of anther alien plant species in the vicinity of “Arctowski” Station is very high.

Assessing the importance of human activities for the establishment of the invasive Poa annua in Antarctica

Because of its harsh environmental conditions and remoteness, Antarctica is often considered to be at low risk of plant invasion. However, an increasing number of reports have shown the presence and spread of non-native plants in Antarctica; it is therefore important to study which factors control the invasion process in this ecosystem. Here, we assessed the role of different human activities on the presence and abundance of the invasive Poa annua. In addition, we performed a reciprocal transplant experiment in the field, and a manipulative experiment of germination with P. annua and the natives Colobanthus quitensis and Deschampsia antarctica, in order to unravel the effects of physical soil disturbance on the establishment and survival of P. annua. We found a positive correlation between abundance of P. annua and level of soil disturbance, and that survival of P. annua was 33% higher in sites with disturbed soil than non-disturbed. Finally, we found that disturbance conditions increased germination for P. annua, whereas for native species germination in experimentally disturbed soil was either unchanged or reduced compared to undisturbed soil. Our results indicate that human activities that modify abiotic soil characteristics could play an important role in the abundance of this invasive species. If the current patterns of human activities are maintained in Antarctica, the establishment success and spread of P. annua could increase, negatively affecting native flora.

Diaspores of the introduced species Poa annua L. in soil samples from King George Island (South Shetlands, Antarctica).

Abstract The soil seed bank and seed germination capacity of Poa annua in the vicinity of the Polish Antarctic Station (South Shetlands, Antarctica) were investigated. It was documented that annual bluegrass can reproduce sexually and produce a functional seed bank of close to 5000 seeds/m2 under maritime Antarctic conditions. Comparison of germination between Poa annua and two native plant species revealed that Poa annua seeds can germinate as fast or even faster than native species, and are more vigorous. Our studies show that in the Antarctic Poa annua can successfully reproduce sexually and produce fully developed, viable caryopses that are able to survive the maritime Antarctic winter, not only in a soil bank, but also directly in the previous years inflorescences.

Spatial structure of the soil seed bank of Poa annua L.—alien species in the Antarctica

Poa annua L. (annual bluegrass) is the only non–native flowering plant species that has successfully established a breeding population in the maritime Antarctic and has been shown to maintain a soil seed bank. The characteristic of the spatial structure of the Antarctic population of this species is the formation of distinct dense clumps—tussocks. In the temperate zone the species is only loosely tufted. We focused on the characteristics of seed deposition associated with the tussocks and some aspects of the spatial heterogeneity of the soil seed bank of P. annua in the Antarctic. We wanted to assess the microspatial structure of the soil seed bank of annual bluegrass at Arctowski Station. Therefore we compared the number of seeds deposited underneath and in the vicinity of P. annua clumps. Our results indicate that P. annua in the Antarctic maintains a soil seed bank comparable to species typical for the polar tundra. The microspatial structure of P. annua soil seed bank in the Antarctic is highly associated with the presence of tussocks. Seeds are deposited underneath the tussock rather than in the vicinity of the clump. Our results also indicate that seeds are able to survive the Antarctic winter and readily germinate under optimal conditions.

Response of Poa annua to extreme conditions: comparison of morphological traits between populations from cold and temperate climate conditions

Poa annua is an expansive species that has developed a stable breeding population on the west shore of Admiralty Bay, King George Island (Antarctica). We investigated whether the colonization success of this species in extreme climatic conditions is associated with morphological variability. We compared the differences in 12 traits among P. annua populations thriving in Admiralty Bay, Tatra Mountains and Warsaw. Our expectations that plants occurring in maritime Antarctic and mountain conditions should exhibit similar morphological characteristics were not confirmed. Comparison of individual morphometric traits indicated high variability within as well as between the studied populations. Plants from the Admiralty Bay population differed significantly from plants from the Warsaw and Tatra populations in 9 of the 12 studied traits. We discovered more similarities between the Polish populations (Warsaw and Tatra) than between the populations from harsh environments (maritime Antarctic and Tatra). The Tatra population exhibited intermediate morphological characteristics in relation to plants from the other two studied populations. In parallel, the climatic conditions expressed in mean monthly air temperature were intermediate in the Tatra location. Four traits analyzed by other authors in the sub-Antarctic populations and by us in the maritime Antarctic population were consistently lower than for the Tatra and Warsaw populations. This finding is in accordance with our working hypothesis (i.e., plants growing in harsh cold conditions exhibit similar morphological characteristics). Our results might suggest that the morphological response to environmental stress of plants occurring in mountain and polar conditions may be similar.

Studies on genetic changes in rye samples (Secale cereale L.) maintained in a seed bank

The aim of this study was to identify genetic changes in rye seeds induced by natural ageing during long-term storage and consecutive regeneration cycles under gene bank conditions. Genomic DNA from four rye samples varying in their initial viability after one and three cycles of reproduction was analyzed by AFLP (amplified fragment length polymorphism) fingerprinting. Seven EcoRI/MseI primer combinations defined 663 fragments, and seven PstI/MseI primer combinations defined 551 fragments. The variation in the frequency of the seventy-four EcoRI/MseI bands was statistically significant between samples. These changes could be attributed to genetic changes occurring during storage and regeneration. However, the PstI/MseI fragments appeared to be uninfluenced by seed ageing, regeneration and propagation. A combined Principle Coordinate Analysis revealed differences between samples with different initial viability. We showed that materials with low initial viability differ in their response from highly viable ones, and that the changes exhibited in the former case are preserved through regeneration cycles.

Genetic and morphological variation of Saxifraga caespitose L. from Spitsbergen (Svalbard): a preliminary study

Saxifraga caespitose is a taxonomically difficult and poorly studied circumpolar arctic–alpine species. Two different phenotypes with distinct growth habits were collected at two shared localities in Spitsbergen. The natural genetic variation of both phenotypes was tested by AFLPs in order to investigate whether the differences at the phenothypical level are reflected at the genetic level. Low level of molecular variability between “tall” and “short” plants may suggest that the morphological variation could be due to phenotypic plasticity rather than genetic background.