Postglacial species arrival and diversity buildup of northern ecosystems took millennia.

What drives ecosystem buildup, diversity, and stability? We assess species arrival and ecosystem changes across 16 millennia by combining regional-scale plant sedimentary ancient DNA from Fennoscandia with near-complete DNA and trait databases. We show that postglacial arrival time varies within and between plant growth forms. Further, arrival times were mainly predicted by adaptation to temperature, disturbance, and light. Major break points in ecological trait diversity were seen between 13.9 and 10.8 calibrated thousand years before the present (cal ka BP), as well as break point in functional diversity at 12.0 cal ka BP, shifting from a state of ecosystem buildup to a state where most habitat types and biotic ecosystem components were in place. Trait and functional diversity stabilized around 8 cal ka BP, after which both remained stable, although changes in climate took place and species inflow continued. Our ecosystem reconstruction indicates a millennial-scale time phase of formation to reach stable and resilient levels of diversity and functioning.

Sedimentary ancient DNA shows terrestrial plant richness continuously increased over the Holocene in northern Fennoscandia.

The effects of climate change on species richness are debated but can be informed by the past. Here, we generated a sedimentary ancient DNA dataset covering 10 lakes and applied novel methods for data harmonization. We assessed the impact of Holocene climate changes and nutrients on terrestrial plant richness in northern Fennoscandia. We find that richness increased steeply during the rapidly warming Early Holocene. In contrast to findings from most pollen studies, we show that richness continued to increase thereafter, although the climate was stable, with richness and the regional species pool only stabilizing during the past three millennia. Furthermore, overall increases in richness were greater in catchments with higher soil nutrient availability. We suggest that richness will increase with ongoing warming, especially at localities with high nutrient availability and assuming that human activity remains low in the region, although lags of millennia may be expected.

Giant invasive Heracleum persicum: Friend or foe of plant diversity?

The impact of invasion on diversity varies widely and remains elusive. Despite the considerable attempts to understand mechanisms of biological invasion, it is largely unknown whether some communities' characteristics promote biological invasion, or whether some inherent characteristics of invaders enable them to invade other communities. Our aims were to assess the impact of one of the massive plant invaders of Scandinavia on vascular plant species diversity, disentangle attributes of invasible and noninvasible communities, and evaluate the relationship between invasibility and genetic diversity of a dominant invader. We studied 56 pairs of Heracleum persicum Desf. ex Fisch.-invaded and noninvaded plots from 12 locations in northern Norway. There was lower native cover, evenness, taxonomic diversity, native biomass, and species richness in the invaded plots than in the noninvaded plots. The invaded plots had nearly two native species fewer than the noninvaded plots on average. Within the invaded plots, cover of H. persicum had a strong negative effect on the native cover, evenness, and native biomass, and a positive association with the height of the native plants. Plant communities containing only native species appeared more invasible than those that included exotic species, particularly H. persicum. Genetic diversity of H. persicum was positively correlated with invasibility but not with community diversity. The invasion of a plant community by H. persicum exerts consistent negative pressure on vascular plant diversity. The lack of positive correlation between impacts and genetic diversity of H. persicum indicates that even a small founder population may cause high impact. We highlight community stability or saturation as an important determinant of invasibility. While the invasion by H. persicum may decrease susceptibility of a plant community to further invasion, it severely reduces the abundance of native species and makes them more vulnerable to competitive exclusion.

Fern rhizomes as fodder in Norway.

BACKGROUND: Although ferns are often known under collective names in Norway, e.g. blom, a substantial number of vernacular names for individual fern species are known, in particular for useful or poisonous taxa. In the past, the rhizomes (Norwegian: moldfôr) of selected species were collected for fodder. Only scattered records of such use are available from southern Norway, and the tradition's core area is found in the two North Norwegian counties of Nordland and Troms, in accordance with the longer winters encountered in the north, frequently leading to fodder shortage in early spring. The tradition extends northeastwards into Finnmark, but is less well documented there. Although numerous sources mention the use of fern rhizomes for fodder, the fern species hiding behind the tradition are incompletely known. This paper aims at reviewing available data in terms of identifyng the species used for fodder, the history and geographical distribution of such use, and other relevant traditions, e.g. the timing and mode of collection, and the way the rhizomes were used. METHODS: The study is based on data extracted from a variety of archival and literature sources; the latter retrived from my database of more than 7500 publications providing information on plant names and plant uses in Norway. RESULTS: More than 200 individual records mention the use of fern rhizomes for fodder in Norway. Only a fraction of these, typically made by botanist recording data on plant uses, provides information on the identity of the species used. Based on these, Dryopteris filix-mas and Matteuccia struthiopteris stand out as the most important species serving as sources of fern rhizomes for fodder. Locally, Dryopteris expansa was the preferred species, and this taxon may to some extent be overlooked in the records so far available. With a few exceptions, Norwegian folk tradition singles out Athyrium filix-femina as a harmful and poisonous species, causing livestock to go blind and lame, but whether this is true or not, remains unknown; the symptoms are in fact documented elsewhere as a consequence of poisoning due to Dryopteris filix-mas. In coastal north Norway, fern rhizomes were regularly collected for fodder, both in late autumn and early spring, and used to remedy a recurrent shortage of fodder in late winter and spring. Locally, the tradition of collecting fern rhizomes lived on until the 1940's or 1950's. Although mainly a tradition of the ethnic Norwegians, it had also been adopted by the farmers belonging to the Finnish and Sámi ethnic minorities. CONCLUSION: Fern rhizomes have a long tradition as an additional fodder for livestock in Norway. Preferred species were Matteuccia struthiopteris and Dryopteris filix-mas, locally also Dryopteris expansa. Athyrium filix-femina was considered to be poisonous, and usually avoided.

Scented grasses in Norway--identity and uses.

BACKGROUND: Some grass species are richer in coumarin and thus more sweetly scented than others. These have been eagerly sought after in parts of Norway, but the tradition has been weakly documented, both in terms of the species collected, their vernacular names, and uses. METHODS: Based on literature data and a substantial body of information collected during my own ethnobotanical field work, artefacts and voucher specimens, the grass species are identified, and their uses clarified. RESULTS: In Norwegian literature, the tradition of collecting and using scented grasses has received little attention, and past authors largely refer it to Anthoxanthum spp. The tradition's concentration to the Sámi strongholds of northernmost Norway, and most authors' lacking knowledge of the Sámi language, have contributed to the weak and misleading coverage in previous publications. Coumarin-rich grass species are well known in folk tradition in northernmost Norway, as luktegress (Norwegian, "scent grass"), háissasuoidni (North Sámi, "scent grass"), hajuheinä (Finnish, "scent grass"), or similar terms. They have been (and still are) frequently collected, and used as perfume, for storing with clothes, and a number of other purposes. Despite literature records identifying the species used as Anthoxanthum odoratum coll. (including A. nipponicum), the main source utilized in North Norway is Hierochloë odorata, both ssp. arctica and ssp. odorata. Anthoxanthum nipponicum and Milium effusum are alternative, but infrequently used sources of material, depending on local tradition and availability. CONCLUSION: By far the most important grass species hiding behind the "scented grass" tradition in Norway is Hierochloë odorata. Anthoxanthum nipponicum is also used, but much less frequently, and only a single record confirms the use of Milium effusum. Only the foliage of Hierochloë provides suitable material for making traditional braids. The three major ethnic groups in Norway have all utilized scented grasses as perfume and for storing with clothes, but the tradition's geographical concentration to the far north of Norway (Finnmark and NE Troms), suggests that it has originally mainly been a Sámi tradition, adopted by their neighbours.

Reconstructing the invasion history of Heracleum persicum (Apiaceae) into Europe.

Sparse, incomplete and inappropriate historical records of invasive species often hamper invasive species management interventions. Population genetic analyses of invaders might provide a suitable context for the identification of their source populations and possible introduction routes. Here, we describe the population genetics of Heracleum persicum Desf. ex Fisch and trace its route of introduction into Europe. Microsatellite markers revealed a significantly higher genetic diversity of H. persicum in its native range, and the loss of diversity in the introduced range may be attributed to a recent genetic bottleneck. Bayesian cluster analysis on regional levels identified three and two genetic clusters in the native and the introduced ranges, respectively. A global structure analysis revealed two worldwide distinct genetic groups: one primarily in Iran and Denmark, the other primarily in Norway. There were also varying degrees of admixture in England, Sweden, Finland and Latvia. Approximate Bayesian computation indicated two independent introductions of H. persicum from Iran to Europe: the first one in Denmark and the second one in England. Finland was subsequently colonized by English populations. In contrast to the contemporary hypothesis of English origin of Norwegian populations, we found Finland to be a more likely source for Norwegian populations, a scenario supported by higher estimated historical migration from Finland to Norway. Genetic diversity per se is not a primary determinant of invasiveness in H. persicum. Our results indicate that, due to either pre-adaptations or rapid local adaptations, introduced populations may have acquired invasiveness after subsequent introductions, once a suitable environment was encountered.

Plant species introduced by foreigners according to folk tradition in Norway and some other European countries: xenophobic tales or not?

BACKGROUND: In their quest to understand and interpret nature, people have frequently sought religious or divine origins for plant species and their characteristics. Less often, historical events or persons are involved. This study comprises eleven cases of the latter kind, all claiming that plant species have been introduced by foreigners or at least from foreign lands. METHODS: Based on literature data and a few cases recorded during my own ethnobotanical field work, eleven European examples of pseudo-historical plant origins are presented here, including Cakile maritima, Cicuta virosa, Lathyrus japonicus, Leymus arenarius, Primula vulgaris, and Scopolia carniolica in Norway, Heracleum mantegazzianum and/or H. persicum in Denmark, Phoenix dactylifera and P. theophrastii in Greece, and Jacobaea vulgaris in Scotland. RESULTS: The only common trait in these stories is that foreigner or at least foreign lands are claimed as sources of the plant species. In most cases, the "historical" explanations given in folk tradition are demonstrably at odds with reality. In those cases that involve poisonous or potentially harmful species (Cicuta virosa, Heracleum mantegazzianum and/or H. persicum, Jacobaea vulgaris), or the "useless" Phoenix theophrastii, with its inedible fruits, the stories may be interpreted as xenophobic, blaming foreigners for introducing dangerous or worthless species. The remaining examples merely suggest a search for exotic and seemingly rational, if erroneous, origins for plant species and stands that people considered strange and unusual. CONCLUSION: The spreading vectors assumed in folk tradition are correct and well documented, e.g. ship cargos (including goods and packing materials), which are responsible for introducing ballast plants and other anthropochores, and wartime activities, introducing a broad range of species (polemochores). They do not, however, apply to the species included in this study, which are either indigenous plants or introduced ornamentals. The foreigners appearing in the folk tales serve mostly as suitably exotic explanations for what is perceived "alien" plants.

Ethnobotany of Heracleum persicum Desf. ex Fisch., an invasive species in Norway, or how plant names, uses, and other traditions evolve.

BACKGROUND: Heracleum persicum was introduced to Norway as an ornamental in the 1830's. Towards the end of the 19th century, it started spreading outside gardens, later to become a frequent sight in the major towns and settlements of North Norway - and a veritable pest plant. During the last 100 years or so, a substantial ethnobotanical tradition related to the species has evolved, demonstrating that folk knowledge is not only forgotten and lost, but also charting new terrain. METHODS: This survey is based on data extracted from all relevant publications, including botanical literature, travel accounts, newspaper notes, etc., as far as they have come to my attention. In addition, information on vernacular names and various uses of the H. persicum in Norway has been extracted from my own, substantial archive of interviews, questionnaires, and correspondence related to the ethnobotany of Norway. RESULTS: Where extant, H. persicum tends to be known to everyone, even by city dwellers who otherwise generally neglect plants. People tend to love or hate it, and in Tromsø, the largest town of northern Norway, the species has become more or less emblematic of the city. Both here and in other areas of northern Norway, it is referred to by a variety of vernacular names, partly borrowed from other species, partly derived from the Latin genus name, and partly coined for this species only. In the latter group, tromsøpalme ('the palm of Tromsø') has proved by far the most popular invention. It was seemingly first used (and coined) by German soldiers during the World War II occupation of Norway, but now largely replaces other vernacular names. The plant is still popular with children, who frequently play in and with it, whereas adults have been more prone to speculate on its origins - and how to get rid of it. Salt is the most popular "herbicide" for this purpose. CONCLUSIONS: Over the years, H. persicum has accumulated at least twenty different vernacular names in Norway, and a variety of other traditions. By necessity, all these traditions are less than 180 years old, showing that even modern and urban societies may produce a substantial body of plant lore, which certainly merits ethnobotanical attention.

Ergotism in Norway. Part 1: The symptoms and their interpretation from the late Iron Age to the seventeenth century.

Ergotism is a horrendous disease with grotesque symptoms caused by ingesting specific ergot alkaloids. Mass poisoning episodes are attributable to consumption of grain - usually rye - infected with the fungus Claviceps purpurea. By focusing on possible cases of ergotism, we re-examine Norwegian history from the sagas through to the end of the seventeenth century. Our review - not intended to be exhaustive, or ex post facto to assign medical or psychiatric labels - draws attention to the very real possibility that many remarkable medical cases may have been the result of the ingestion of highly poisonous and psychoactive food substances. Where possible we highlight explanations given at the time - often rooted in religion or demonology - to explain the disease.

Ergotism in Norway. Part 2: The symptoms and their interpretation from the eighteenth century onwards.

Ergotism, the disease caused by consuming Claviceps purpurea, a highly poisonous, grain-infecting fungus, occurred at various places scattered throughout Norway during the eighteenth and nineteenth centuries. By focusing on these cases we chart the changing interpretations of the peculiar disease, frequently understood within a religious context or considered as a supernatural (e.g. ghostly) experience. However, there was a growing awareness of the disease ergotism, and from the late eighteenth century onwards it was often correctly interpreted as being due to a fungus consumed via bread or porridge. Also, nineteenth-century fairy-tales and regional legends reveal that people were increasingly aware and fearful of the effects of consuming infected grain.

Glacial survival of boreal trees in northern Scandinavia.

It is commonly believed that trees were absent in Scandinavia during the last glaciation and first recolonized the Scandinavian Peninsula with the retreat of its ice sheet some 9000 years ago. Here, we show the presence of a rare mitochondrial DNA haplotype of spruce that appears unique to Scandinavia and with its highest frequency to the west-an area believed to sustain ice-free refugia during most of the last ice age. We further show the survival of DNA from this haplotype in lake sediments and pollen of Trøndelag in central Norway dating back ~10,300 years and chloroplast DNA of pine and spruce in lake sediments adjacent to the ice-free Andøya refugium in northwestern Norway as early as ~22,000 and 17,700 years ago, respectively. Our findings imply that conifer trees survived in ice-free refugia of Scandinavia during the last glaciation, challenging current views on survival and spread of trees as a response to climate changes.