Regeneration by seeds in alpine meadow and heath vegetation in sub-arctic Finland
Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
Cited by 4 publications
References 34 publications
Aim Eric Hultén hypothesized that most arctic plants initially radiated from Beringia in the Late Tertiary and persisted in this unglaciated area during the Pleistocene glaciations, while their distribution ranges were repeatedly fragmented and reformed elsewhere. Whereas taxonomic and fossil evidence suggest that Cassiope tetragona originated in Beringia and expanded into the circumarctic area before the onset of the glaciations, lack of chloroplast DNA (cpDNA) variation may suggest that colonization was more recent. We address these contradictory scenarios using high-resolution nuclear markers.Location Circumpolar Arctic.Methods The main analysis was by amplified fragment-length polymorphism (AFLP), while sequences of chloroplast DNA verified the use of Cassiope mertensiana as an outgroup for C. tetragona. Data were analysed using Bayesian clustering, principal coordinates analyses, parsimony and neighbour-joining, and measures of diversity and differentiation were calculated.Results The circumpolar C. tetragona ssp. tetragona was well separated from the North American C. tetragona ssp. saximontana. The genetic structure in ssp. tetragona showed a strong east-west trend, with the Beringian populations in an intermediate position. The highest level of diversity was in Beringia, while the strongest differentiation in the data set was found between the populations from the Siberian Arctic west of Beringia and the remainder. Main conclusionsThe results are consistent with a Beringian origin of the species, but the levels and geographical patterns of differentiation and gene diversity suggest that the latest expansion from Beringia into the circumarctic was recent, possibly during the current interglacial. The results are in accordance with a recent leading-edge mode of colonization, particularly towards the east throughout Canada/Greenland and across the North Atlantic into Scandinavia and Svalbard. As fossils demonstrate the presence of the species in North Greenland 2.5-2.0 Ma, as well as in the previous interglacial, we conclude that C. tetragona expanded eastwards from Beringia several times and that the earlier emigrants of this woody species became extinct. The last major westward expansion from Beringia seems older, and the data suggest a separate Siberian refugium during at least one glaciation.
Aim Eric Hultén hypothesized that most arctic plants initially radiated from Beringia in the Late Tertiary and persisted in this unglaciated area during the Pleistocene glaciations, while their distribution ranges were repeatedly fragmented and reformed elsewhere. Whereas taxonomic and fossil evidence suggest that Cassiope tetragona originated in Beringia and expanded into the circumarctic area before the onset of the glaciations, lack of chloroplast DNA (cpDNA) variation may suggest that colonization was more recent. We address these contradictory scenarios using high-resolution nuclear markers.Location Circumpolar Arctic.Methods The main analysis was by amplified fragment-length polymorphism (AFLP), while sequences of chloroplast DNA verified the use of Cassiope mertensiana as an outgroup for C. tetragona. Data were analysed using Bayesian clustering, principal coordinates analyses, parsimony and neighbour-joining, and measures of diversity and differentiation were calculated.Results The circumpolar C. tetragona ssp. tetragona was well separated from the North American C. tetragona ssp. saximontana. The genetic structure in ssp. tetragona showed a strong east-west trend, with the Beringian populations in an intermediate position. The highest level of diversity was in Beringia, while the strongest differentiation in the data set was found between the populations from the Siberian Arctic west of Beringia and the remainder. Main conclusionsThe results are consistent with a Beringian origin of the species, but the levels and geographical patterns of differentiation and gene diversity suggest that the latest expansion from Beringia into the circumarctic was recent, possibly during the current interglacial. The results are in accordance with a recent leading-edge mode of colonization, particularly towards the east throughout Canada/Greenland and across the North Atlantic into Scandinavia and Svalbard. As fossils demonstrate the presence of the species in North Greenland 2.5-2.0 Ma, as well as in the previous interglacial, we conclude that C. tetragona expanded eastwards from Beringia several times and that the earlier emigrants of this woody species became extinct. The last major westward expansion from Beringia seems older, and the data suggest a separate Siberian refugium during at least one glaciation.
Summary1. Nutrient availability, defoliation and soil disturbance are important factors that influence the richness of plant communities. However, few studies have examined the interactions between these factors, especially in harsh environments. We therefore examined the effects of fertilization, defoliation and soil disturbance on plant species richness in an alpine meadow in northern Sweden. 2. From 2002 to 2005, plots were fertilized, mowed and disturbed annually in a factorially designed experiment. Plant species richness, colonization and extinction were recorded in permanent subplots. Seedling densities and recruitment from seed of Potentilla crantzii were also estimated in order to examine the mechanisms whereby these treatments influence colonization by new species. 3. Species richness peaked in the absence of disturbance in unfertilized plots and with light disturbance in fertilized plots. Colonization by new vascular plant species, seed recruitment and seedling density were all increased by soil disturbance, suggesting that colonization was increased because conditions were more favourable for seed recruitment following the disturbance treatment. Extinction of species was highest in the mowed, intensively disturbed and unfertilized plots and lowest in the fertilized, lightly disturbed and unmowed plots. 4. Local extinction was negatively correlated with both moss and vascular plant biomass. Local colonization, seedling density and recruitment of P. crantzii were all strongly negatively correlated with the biomass of mosses. In contrast, the biomass of vascular plants was only weakly correlated with local colonization, seedling density and recruitment of P. crantzii. 5. This study suggest that the level of disturbance at which species richness peaks should move towards higher disturbance levels when productivity increases. However, lower extinction rates rather then higher colonization rates seem to be causing the increase in species richness following disturbance.
It is commonly assumed that plant establishment in the High Arctic is limited by severe abiotic conditions and by a paucity of propagules and seeds. Heavy reindeer grazing may reduce plant allocation to reproduction and removes significant proportions of flowers and seeds, thus reducing contributions to seed rain and seed bank. In contrast, foraging and trampling may break up existing mature plants, increasing the vegetative propagules in the soil. To determine the effect of grazing on colonization potential in the High Arctic, two studies were carried out: (i) a comparison of seed bank inside and outside three long-term reindeer ( Rangifer tarandus platyrhnchus (Vrolic)) exclosures and (ii) an investigation of the germinable seed and propagule bank of two neighbouring peninsulas with contrasting reindeer grazing history in northwestern Svalbard (79°N, 12°E). Seed banks inside reindeer exclosures germinated significantly more seedlings (596 seedlings·m–2) than those outside (263 seedlings·m–2). Species composition and total plant cover was similar on both peninsulas, but forage-plant cover was lower on the heavily grazed peninsula (Brøggerhalvøya) than on the adjacent lightly grazed peninsula (Sarsøyra). Brøggerhalvøya had significantly lower species richness and density of seed and propagule bank (0.21 ± 0.02 germinating species per sample, 0.15 ± 0.02 propagule species per sample, 416 ± 103 seedlings·m–2, 283 ± 78 propagules·m–2) than did Sarsøyra (0.44 ± 0.40 germinating species per sample, 0.35 ± 0.03 propagule species per sample,1016 ± 188 seedlings·m–2, 782 ± 238 propagules·m–2). These results imply that reindeer depleted both the seed and the propagule banks, thus reducing the potential for colonization of disturbed areas. Grazing may, therefore, have a lasting impact on High Arctic plant communities.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
Contact Info
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Product
Resources
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.
