Publications

catechin content and consumption ratio of the collared lemming.	chemical- plant defences as mechanisms affecting herbivore populations have been debated during the past decade. several authors have questioned the hypothesis, but the present study shows that collared lemmings ( dicrostonyx groenlandicus) in northeast greenland prefer food plants with a lower catechin content. dicrostonyx species are known to have specialised on shrubs, especially dryas spp. and salix spp., rather than graminoids like other related microtines. bioassays were conducted using fo ...	2003	12698346
are heat and cold resistance of arctic species affected by successive extreme temperature events?	extreme temperature events are projected to increase in frequency in a future climate. as successive extremes could occur more frequently, patches of vulnerable tundra vegetation were exposed to two consecutive heat waves (hws) of 10 d each, with a 5-d recovery period in between. surface temperatures during the hws were increased approximately 6 degrees c using infrared irradiation sources. in three of the four target species (pyrola grandiflora, polygonum viviparum and carex bigelowii), plant c ...	2006	16608454
molecular diversity of nifh genes from bacteria associated with high arctic dwarf shrubs.	biological nitrogen fixation is the primary source of new n in terrestrial arctic ecosystems and is fundamental to the long-term productivity of arctic plant communities. still, relatively little is known about the nitrogen-fixing microbes that inhabit the soils of many dominant vegetation types. our objective was to determine which diazotrophs are associated with three common, woody, perennial plants in an arctic glacial lowland. dryas integrifolia, salix arctica, and cassiope tetragona plants ...	2006	16649061
variation in leaf physiology of salix arctica within and across ecosystems in the high arctic: test of a dual isotope (delta13c and delta18o) conceptual model.	leaf carbon isotope discrimination (delta(13)c) varies with the balance between net photosynthesis (a) and stomatal conductance (g ( s )). inferences that can be made with delta(13)c are limited, as changes could reflect variation in a and/or g ( s ). investigators have suggested that leaf delta(18)o enrichment above source water (delta(18)o) may enable differentiation between sources of variation in delta(13)c, as leaf delta(18)o varies with transpiration rate (e), which is closely correlated w ...	2007	17106719
the effect of experimental warming on the root-associated fungal community of salix arctica.	the effect of experimental warming on the root-associated fungal community of arctic willow (salix arctica) was studied in three distinct habitats at a tundra site in the canadian high arctic. plots were passively warmed for 5-7 years using open-top chambers and compared to control plots at ambient temperature. fungal communities were assessed using terminal restriction fragment length polymorphisms. we found the following: (1) the root-associated fungal community in these high arctic tundra hab ...	2008	18180749
improved uv-b screening capacity does not prevent negative effects of ambient uv irradiance on psii performance in high arctic plants. results from a six year uv exclusion study.	long-term responses of ambient solar ultraviolet (uv) radiation were investigated on salix arctica and vaccinium uliginosum in a high arctic heath ecosystem in zackenberg, northeast greenland. over a period of six years, uv exclusion was conducted in the growing season by means of filters: 60% uv-b reduction, 90% uv-b+uv-a reduction, uv transparent filter control, and an open control without filter. plant responses were evaluated using specific leaf area, leaf content of uv-b absorbing compounds ...	2010	20688417