Staffan Karlsson

This paper accounts for the development of the academic endeavour to determine the firm-level relationship between investments in R&D and productivity. The impact of 28 highly cited publications within this line of study is investigated using a combination of bibliometric techniques and citation function analysis. We show how the attention paid to...

The seasonal dynamics of growth and nitrogen uptake were measured in pine (Pinus sylvestris) and birch (Betula pubescens ssp. tortuosa) seedlings growing in a subarctic environment. Whole-plant dry matter accumulated at about the same rate in both species. A higher rate of early summer assimilation did occur in Pinus as revealed by the simultaneous...

The seasonal patterns of biomass allocation in flowering and nonflowering specimens of Pinguicula alpina L., P. villosa L., and P. vulgaris L. were compared in a subarctic environment. Pinguicula alpina had a large perennial root system, comprising 50% of the nonreproductive biomass. The other two species had smaller, annual roots, representing 5–1...

We investigate methodological problems in measuring research productivity on the national level by comparing official R&D statistics from the OECD with publication data from the ISI Web of Science. Special attention is paid to the results for the USA, Canada and the UK. This problematizes the approach taken in studies where R&D statistics are used...

The Department of Research Policy Analysis at the Swedish Research Council (SRC) maintains and develops a database for bibliometric analyses. This document describes the properties of the SRC bibliometric database, data preparation, analysis tools and methods, and the resulting bibliometric indicators used at the SRC in detail.

Many stoloniferous plant species have the ability to exploit resource-rich patches via plastic growth responses. The most efficient responses are shortened spacers and increased branching frequency. Here we experimentally investigate the ability of the stoloniferous plant Linnaea borealis to respond to patches of increased light intensity and reduc...

Rhododendron lapponicum est une éricacée qui forme des clones d'arbustes nains et dont la croissance végétative coïncide en grande partie avec la formation des fleurs et des fruits. Une expérience de retrait de fleurs et un ensemble de données descriptives ont été utilisés pour déterminer s'il existait des relations et des compromis potentiels entr...

Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of t...

Which is the most appropriate currency (biomass, energy, water, or some mineral nutrient) for expressing resource allocation in plants has been repeatedly discussed. Researchers need to assess to which extent interindividual, interpopulational, or interspecific comparisons of resource allocation could be affected by the allocation currency chosen....

Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of t...

High-latitude peatlands are important soil carbon sinks. In these ecosystems, the mineralization of carbon and nitrogen are constrained by low temperatures and low nutrient concentrations in plant litter and soil organic matter. Global warming is predicted to increase soil N availability for plants at high-latitude sites. We applied N fertilizer as...

The relative variation in leaf nitrogen concentration and photosynthetic capacity among individuals and sites are compared for mountain birch populations (Betula pubsecens Ehrh. ssp tortuosa (Ledeb.) Nyman). Leaf nitrogen concentration and photosynthetic capacity showed significant differences among individuals; 35 and 26% of the total sum of squar...

The seasonal course of photosynthetic rate, and light and temperature relations were studied in the dwarf shrubs Vaccinium uliginosum L., deciduous, and Vaccinium vitisidaea L., evergreen, at a subarctic site in northern Sweden, Using the photosynthetic characteristics and meteorological data from the site, the seasonal and life-span carbon dioxide...

The relationship between micro-site nitrogen status (total soil N conc., total vegetation N, and leaf N conc.) and performance (biomass) for two evergreen and two deciduous dwarf shrubs was studied in a subarctic heath. One deciduous species, Vaccinium uliginosum, dominated on sites having the highest vegetation nitrogen content and highest leaf ni...

The carbon allocation to current-year shoots of the deciduous Vaccinium uliginosum L. and the evergreen V. vitis-idaea L. was studied in a field experiment using 14C. During the first week after labelling, 0–50% and 30–80% of the initially assimilated 14C was lost in V. vitis-idaea and V. uliginosum respectively. Later on, the losses were smaller....

The pattern of plant resource investment in reproduction is expected to have important implications for plant life histories and their evolution. This chapter discusses the main concepts and research trends in resource economical analyses of plant reproduction. In particular, it focuses on four concepts: the principle of allocation, reproductive ef...

Current understanding of the extent, causes for, and consequences of variation in nutrient composition in plants is limited. Important questions to be addressed include to what extent nutrients covary, how flexible nutrient ratios are within a population or species, how reproduction influences nutrient ratios, and how much the ratios of nutrients t...

Variation in in situ growth performance of the mountain birch as indicated by the widths of annual rings was analysed and related mainly to temperature and herbivory using ring width series from five heath forest sites in the Lake Torneträsk area, northern Sweden. Climate explained 48–64% of the variation in age-corrected mean ring width series. In...

In 1955, the mountain birch forest in the Abisko valley of northern Sweden was defoliated by caterpillars of the moth Epirrita autumnata with death of stems of the polycormic trees as a result. Since then, some stands have recovered from surviving trees, producing new shoots while other stands became rejuvenated from basal sprouts. Usually, basal s...

Several important fitness components in herbaceous perennial plants are commonly related to plant size: flowering probability, reproductive allocation and fecundity. However, evidence for such size-dependence of fitness components is mostly anecdotal and unconnected to other life history traits. Here we report size-dependence for flowering probabil...

We discuss the effects of a geometrid moth (the autumnal moth Elpirrita autumnata) on the long-term dynamics of the mountain birch Betula pubescens ssp. czerepanovii forest of north-western Europe. The moth population density varies strongly among years and show peaks at about 9-year intervals. Most of the population peaks have relatively marginal...

The pattern of responses of adult trees of Mountain Birch ( Betula pubescens ssp. czerepanovii ) to an outbreak of a folivorous insect ( Epirrita autumnata ) causing ≈90% defoliation was studied over 8 years in a subarctic area in northern Sweden. Tree recovery was monitored in terms of the numbers, area, mass and nitrogen content of leaves, the nu...

The relationship between the climate and budburst of the mountain birch was evaluated for two areas in subarctic (ca 69°N) Fennoscandia; at Abisko, Swedish Lapland, and at Kevo, Finnish Lapland. Thermal time (TT, degree‐day sums) to budburst was calculated for experimental conditions in the laboratory and for in situ observations of budburst. Two t...

We tested the hypotheses that (i) reproductive ramets of Linnaea borealis L. (Caprifoliaceae) compensate for reproductive investments by enhanced resorption of nitrogen (N) and phosphorus (P) from leaves before abscission, and that (ii) resorption is decreased by increased soil nutrient availability. We also investigated (iii) the significance of r...

Potential factors that trigger the onset of reproduction in shoot modules were studied in the dwarf shrub Rhododendron lapponicum in subarctic Swedish Lapland. The following questions were addressed: (1) Can the large size effect that commonly is found on onset of reproduction be explained as an effect of the amount of nitrogen and/or phosphorus ac...

Effects of different winter soil temperature on summertime growth rate of individual seedlings of mountain birch (Betula pubescens ssp. czerepanovii) were evaluated in an outdoor pot experiment in subarctic Sweden. The hypothesis tested was that low winter soil temperature could decrease growing-season nutrient uptake capacity and growth rate by in...

Growth and nitrogen (N) economy of mountain birch are reported here in response to temperature change. Mechanisms of temperature effects on plant growth in temperate–arctic regions are discussed in the light of decreasing growth rates and increasing leaf‐N contents along altitudinal and latitudinal temperature gradients. Mountain birch ( Betula pub...

Life history theory predicts that reproduction incurs costs in terms of future growth and survival. In infertile environments reproductive events may accelerate nutrient turnover such that losses of limiting nutrients cannot be replenished by uptake from the soil. We compared the effect of reproduction on nitrogen (N) turnover and N use‐efficiency,...

1 Seedlings of mountain birch Betula pubescens ssp. czerepanovii were grown outdoors, under different environmental conditions, during their first growing season at Abisko, northern Sweden. Winter survival of seedlings was studied in relation to their growth and nitrogen (N) acquisition rate during the previous growing season. 2 Effects of fertiliz...

This study addresses the question of whether a trade‐off between the annual nitrogen (N) productivity ( aNP ) and the mean residence time ( MRT ), an index of N conservation, occurs both among and within species. We hypothesized that a trade‐off between aNP and MRT observed among species might not hold within species. Seven perennial graminoids and...

This paper (1) describes soil temperature conditions in an area close to the altitudinal and latitudinal distribution limit of the mountain birch, and (2) evaluates whether soil temperature is likely to impose a limit on nitrogen uptake and subsequent reductions in growth and survival. Soil temperature was monitored at two depths (-5 and -10 cm) du...

This paper (1) describes soil temperature conditions in an area close to the altitudinal and latitudinal distribution limit of the mountain birch, and (2) evaluates whether soil temperature is likely to impose a limit on nitrogen uptake and subsequent reductions in growth and survival. Soil temperature was monitored at two depths (–5 and –10 cm) du...

The mountain birch (Betula pubescens ssp. czerepanovii) is considered to have originated through introgressive hybridization between B. pubescens and B. nana. It is intermediate between the putative parent species in terms of growth form and distribution. Consequently, we hypothesized that the mountain birch should have growth characteristics inter...

Plants can be expected to utilize different sources of nitrogen with different proportions of 15N at different times of the year. We expected this to be reflected in a seasonal variation in the natural abundance of plant 15N, and that this pattern would vary among life-forms or species. To test this hypothesis, we studied the δ15N of eight differen...

Nutrient conservation plays an important role in plants adapted to infertile environments. Nutrients can be conserved mainly by extending the life span of plant parts and/or by minimizing the nutrient content of those parts that are abscissed. Together these two parameters (life span and resorption) define the mean residence time (MRT) of a nutrien...

Physiological integration in clonal plants, which can be assumed to be dependent on vascular connections among ramets, is associated with several potential benefits, especially in nutrient-poor environments. However, some experimental evidence indicates that ectohydric bryophytes, i.e. species lacking specialised tissues for internal water conducti...

We measured photosynthetic performance in four subarctic carnivorous plants, Pinguicula alpina, P. villosa, P. vulgaris and Drosera rotundifolia, in order to test if there is a cost of combining photosynthetic and trapping devices into the same organ (leaves). We compared these data with published results on photosynthetic rates in subarctic non-ca...

Reproductive and somatic biomass, nitrogen (N), and phosphorus (P) pools were compared between females and males in 1st-year plants of Silene dioica. We estimated irretrievable resources allocated to seeds, pollen, flowers, and unrecovered summer leaf investment by collecting plant parts at abscission throughout the season. At the end of the season...

High- and low-altitude ecotypes of mountain birch (Betula pubescens ssp. czerepanovii) showed clear differences in their responses to various experimental conditions, including two temperature regimes and four fertilisation rates. There was, however, no simple way to characterise the elevational ecotypes in terms of relative growth rate, nitrogen (...

1 The effect of supplementary feeding on growth and reproduction of three carnivorous plants species was investigated over a 6-year period. Pinguicula alpina, P. villosa and P. vulgaris populations growing at two altitudes in a subarctic environment were fed with fruit flies (Drosophila melanogaster). 2 Fed plants increased in size relative to cont...

The reproductive effort and relative somatic costs were quantified in terms of biomass, nitrogen, and phosphorus for 13 plant populations representing eight species in a subarctic environment, Swedish Lapland. Reproductive effort varied about fivefold between populations (from ca 0.1 to 0.5). Correlations among reproductive effort in terms of bioma...

Five evergreen and four deciduous species of woody plants were experimentally defoliated to address the question of whether the relative importance of resource resorption from leaves to support new growth varies between these life-forms or whether the species show individualistic response patterns. The deciduous and evergreen species were defoliate...

Intra-specific relationships between growth traits and nitrogen economy were studied for seedlings of mountain birch (Betula pubescens spp. tortuosa) originating from three climatically different regions within the northern forest margin in sub-arctic Fennoscandia. The experiment was carried out using potted seedlings grown in Abisko, northern Swed...

Effects of plant size and altitude on reproductive effort (RE) and somatic costs of reproduction were examined for Ranunculus acris L. and Trollius europaeus L. (Ranunculaceae) in subarctic Swedish Lapland. We estimated investment and cost during one reproductive season in terms of biomass (indexed B), nitrogen (N), and phosphorus (P). Above the tr...

The annual above-ground turnover of nutrients was compared among 14 wild plant species representing four life-forms (woody evergreen, woody deciduous, graminoid, herb) and growing in two contrasting habitat types, a meadow birch forest rich in nutrients and a nutrient-poor bog. Variations in plant nutrient-turnover characteristics were related to h...

Patterns of growth and nitrogen utilization in seedlings of mountain birch (Betula pubescens ssp. tortuosa) were monitored by growth analysis over two growing seasons in Abisko, northern Sweden. The seedlings were grown in pots with peat, which were placed outdoors under a clear roof (natural light and temperature) or in a greenhouse (natural light...

1 The consequences of investment in different long-shoot functions during one year for long-shoot growth the following season were studied in mountain birch in a subarctic environment in northern Sweden. Relationships between shoot length growth, axillary bud production (lateral meristems) and male catkin production of `progeny' and `parent' shoots...

Stomatal conductances of mountain birch leaves were determined by field measurements using a steady-state porometer under varying weather and radiation conditions. The stomatal conductances were related to atmospheric environmental parameters (water vapor deficit, air temperature, soil moisture potential, and photoactive radiation) by a nonlinear r...

We estimated the cost of reproduction and reproductive effort in three iteroparous plant species, Pinguicula alpina, P. villosa and P. vulgaris, in a subarctic environment. The phenotypic costs of reproduction were quantified by comparing resource pools (dry weight, nitrogen or phosphorus) in reproductive and non-reproductive plants. Two types of n...

Uptake of nitrogen from prey and substrate and partitioning of prey-derived nitrogen were studied in the carnivorous plant species Pinguicula alpina, P. villosa, P. vulgaris and Drosera rotundifolia in a subarctic environment. Efficiency in nitrogen uptake from prey was evaluated by tracing 15N from 15N-enriched Drosophila flies fed to the plants....

Uptake of nitrogen from prey and substrate and partitioning of prey- derived nitrogen were studied in the carnivorous plant species Pinguicula alpina, P. villosa, P. vulgaris and Drosera rotundifolia in a subarctic environment. Efficiency in nitrogen uptake from prey was evaluated by tracing 15N from 15N-enriched Drosophila flies fed to the plants....

Direct and indirect effects of soil temperature on the nitrogen economy and growth characteristics of mountain birch, Betula pubescens ssp. tortuosa, seedlings were assessed in a subarctic environment close to the species' altitudinal distribution limit. One-year-old seedlings were grown for one season in silica sand at three soil temperatures (5,...

Prey capture allowed P. vulgaris to increase its seed output, manifested as an increase in the amount of seeds (total mass) produced per reproductive plant and as a higher frequency of reproductive events, as well as its survival rate. Pinguicula alpina and P. villosa only showed a marginal fitness increase. The difference in response between butte...

There is a close relationship between mountain birch seedling growth rate and nitrogen status. In addition to soil N availability, soil temperature is an important determinant of N uptake rate and thus of plant status and growth. At a soil temperature of 5°C rates of both root N uptake and growth are close to zero regardless of soil N availability,...

The relative somatic cost of reproduction (RSC) is compared with reproductive effort (RE) for some subarctic plants. The relationship between RSC and RE varied between species, between habitats within species and to some extent between resources. In some cases RSC was substantially less than RE. Possible physiological mechanisms enhancing resource...

1. Resorption of nitrogen and dry matter prior to leaf fall was monitored in 40 mountain birch trees [Betula Ehrh. pubescens ssp tortuosa (Ledeb.) Nyman] at four sites during 4 consecutive years. The variation in resorption of dry matter and nitrogen was related to the tree individual, summer temperature sum, leaf weight:area ratio, leaf nitrogen c...

1. Possible determinants of the area-based light-saturated photosynthetic rate (P-s, mu mol CO2 m(-2) s(-1)) for Rhododendron lapponicum from a subarctic site in northern Sweden were studied. P-s was determined in the laboratory on detached branches, under non-limiting water conditions, constant light and temperature, and related to leaf nitrogen a...

The number and biomass of prey captured were estimated for Pinguicula alpina, P. villosa and P. vulgaris in a subarctic environment. Seasonal captures were estimated for one site per species for 4–5 years. Captures were related to reproductive status (reproductive/non-reproductive) and to leaf area. For one species (P. vulgaris) the catch was also...

The significance of internal nitrogen and phosphorus cycling for growth and reproduction was evaluated for the evergreen dwarf shrub Rhododendron lapponicum in a subarctic environment. The evaluation was made by analysing the seasonal dynamics of branch nitrogen and phosphorus pools and studying the effects of experimentally depleting the resources...

1 The population dynamics of the perennial geophytes Pinguicula alpina, P. villosa and P vulgaris are presented for the first 8 years of an on-going study in the Swedish Subarctic. 2 Between-year variation in density was highest for P villosa, and this species also had the steepest depletion curve, suggesting that it has a shorter life-span than th...

This paper gives a general overview of factors that limit the northern distribution of trees, and a specific account of those factors that affect the distribution of mountain birch (Betula pubescens Ehrh.) in northern Scandinavia and Iceland.

Leaf longevities were determined for 16 species of evergreen shurbs (Ericaceae and Empetraceae) at different habitats at three latitudes (c. 47, 55–58 and 68N) in central and north Europe to determine whether any general trends exist in variation in leaf longevity within and among species. Among these species and sites, mean leaf longevity varied b...

Growth responses and accumulation of N and P were studied in two pygmy south-west Australian species of Drosera following supplementary feeding of arthropods (collembolans, Hypogastrura vernalis and fruit flies, Drosophila melanogaster) and/or a balanced mineral nutrient supplement (N as nitrate) via the roots. One feeding experiment used glasshous...

Proportional allocations of current total dry matter (DM), N and P to early season asexual gemma production and late-season flowering and seed production were compared for eight pygmy rosette form and three micro stilt-form perennial pygmy sundews (Drosera spp.) in native habitat in south-western Australia. Mean allocations to gemmae for the smalle...

1. Effects of herbivory on radial growth of mountain birch (Betula pubescens ssp. tortuosa) were investigated in defoliation experiments in a subarctic environment in northern Sweden. The effects of foliage loss on the rate of photosynthesis and the annual radial increment were assessed to test whether compensation had occurred. 2. Fifty per cent d...

The hypothesis that carnivorous plants are less responsive to prey at high soil nutrient levels than at lower levels (Givnish et al. 1984) is tested on four plant species (Drosera rotundifolia, Pinguicula alpina, P. villosa and P. vulgaris) from a subarctic environment. The response, measured in terms of seven characteristics (winter bud weight, wi...

Variation among individuals and sites in photosynthetic light-response characteristics and nitrogen use efficiency in the mountain birch (Betula pubescens ssp. tortuosa) is described and related to leaf nitrogen status. Significant differences among both individuals and sites were found for light-saturated photosynthetic rate (P(max)) and leaf nitr...

Resource investment in reproduction and its consequences were compared for three iteroparous plant species, Pinguicula alpina, P. villosa and P. vulgaris, in a subarctic environment. Resource investment (dry matter, nitrogen and phosphorus) was estimated as reproductive effort, RE, and the consequences as relative somatic cost of reproduction, RSC,...

Vaccinium myrtillus required the highest photo flux density to reach light saturation; it also had a comparatively low photosynthetic rate at low photo flux densities. Mean relative photosynthetic rate over the season was lower for the deciduous species (42% of maximum for V. myrtillus and 49% for V. uliginosum) than for the evergreens (59% for V....

Allocation of the nutrients N, P and K to reproductive tissue was investigated in three species of Pinguicula from the subarctic part of Scandinavia. These species have contrasting distribution: Pinguicula alpina L. grows on calcareous soils, Pinguicula villosa L. on nutrient-poor bogs and Pinguicula vulgaris L. is widely distributed. For flowering...

In situ trapping efficiencies of Pinguicula alpina L., P. villosa L., and P. vulgaris L. were compared with each other and with those of artificial traps at a subarctic site in northern Sweden. P. vulgaris had the highest trapping efficiency i.e., 21–37 g prey trapped cm-2 day-1 and apparently has some means of attracting prey. The other two specie...

Canopy structure, shoot design, and photosynthetic light recruitment were used to compare four coexisting dwarf shrub species with respect to light utilization. All four species showed different shoot designs which probably result in different light interception properties. Leaves of Vaccinium uliginosum showed the highest levels of photosynthetic...

The relative growth rates of seedlings of the deciduous tree Betula pubescens ssp. tortuosa (Ledeb.) Nyman and the evergreen tree Pinus sylvestris L. were compared in a subarctic environment using material grown in pots. The species showed similar growth rates under low nutrient conditions, while Betula grew faster under high nutrient conditions. T...

The effects of irrigation and fertilization on nutrient content, shoot growth and photosynthetic rate of the deciduous Vaccinium uliginosum L. and the evergreen V. vitis-idaea L. were studied in a field experiment at Abisko, Swedish Lapland. V. vitis-idaea responded to fertilization with a greater increase in leaf nitrogen, phosphorus and potassium...

S ummary Growth and nutrient content were studied when various nutrients were fed to the carnivorous plant Pinguicula vulgaris L. through its leaves. Agar blocks containing different combinations of three nutrient solutions [N, P and micronutrients (M), i.e. all other essential nutrients] simulating insects were supplied in a factorially designed e...

S ummary The significance of the carnivorous habit of Pinguicula vulgaris L. was studied when plants were fed with insects and/or supplied with complete nutrient solution in the substrate. In most cases, plants supplied with insects alone or in combination with fertilizer showed higher values for dry wt, number and length of leaves, and concentrati...

Dryas octopetala has heliotropic flowers, whose petals reflect the light on the pistils, thus warming them up. The effects of this reflection on seed formation and development were studied by measuring the pistil temperature of intact flowers, of flowers with petals removed, of shaded flowers, and of flowers constrained in such a way as always to b...

2 Abstract: We studied factors that restrict colonization of grassland by Quercus durata Jeps., an oak commonly found in chaparral on serpentine soils. The study site contained a chap- arral/grassland border that had been stable for at least 50 years. Monitoring of acorns planted in the chaparral understory and grassland revealed that, although ini...