Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2004
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Magne Sætersdal Ivar Gjerde Hans Blom Per Gerhard Ihlen Elisabeth W. Myrseth Reidun Pommeresche John Skartveit Torstein Solhøy Olav AasAbstract
Vascular plants were investigated as a potential surrogate group in complementary small scale site selection, such as woodland key habitats in Scandinavia. We compared the response of vascular plants to environmental gradients to that of seven other plant, fungal and animal groups within a forest reserve in western Norway using data from 59 plots of 0.25 ha. We also examined whether the spatial changes in species (beta-2 index) of vascular plants matched that of the other groups. All seven groups responded to the same gradients in nutrient richness and humidity as the vascular plants. Furthermore, changes in species composition of vascular plants were reflected in comparable degrees of change among the “target“ groups. The lower the degree of change in species composition between plots in the “target“ groups relative to that of vascular plants, the higher the percentage “target“ species encompassed in a complementary selection of sites based on vascular plants. We conclude that in practical site selection of small scale sites of conservation value, such as woodland key habitats, vascular plants may be used in combination with an inventory of important habitats for rare and/or redlisted forest species, such as dead wood, old trees, deciduous trees, and cliffs.
Abstract
Using information from a regional survey of vascular plants of 130 sites in western Norway, a selection of sites based on a heuristic iterative complementarity-based nature reserve selection procedure was performed. The results indicate that conservation of traditionally managed hay meadows is of major importance as they contributed 60.1% of all native species recorded; afforested grasslands (deciduous woodlands < 70 years old) contributed 26.8%, whereas artificially fertilized hay meadows and intensively cultivated grasslands taken together contributed 13.1% of the species. The species composition of the meadows was significantly nested. Thus, if you conserve the most species-rich meadows, you also conserve most of the species in the less species-rich meadows. Nestedness in meadows was significantly correlated with within-meadow habitat diversity and soil pH. The most species-rich meadows were traditional meadows, characterized by high habitat diversity and high soil pH. These meadows will support nearly all species including habitat specialists and regionally rare species, whilst artificially fertilized hay meadows only support the generalist subset, i.e. common species. Area was not significantly correlated with nestedness suggesting that it is more important to cover many habitats than to preserve large traditional meadows just because they are large.
Abstract
We estimated time from death to fall (standing time) of Norway spruce (Picea abies (L.) Karst.) snags in a submountainous old-growth forest in south-central Norway, applying four calculation methods to 124 dendrochronologically cross-dated still-standing snags and 64 fallen logs. The calculation methods consistently estimated expected standing time of snags at 26–34 years, with a median of 16–21 years and 20% of snags standing for >48–58 years. The survival function from all methods took the approximate form of a negative exponential, with a 3%–4% annual fall rate for snags. In the distribution of time since death, a small peak in dead trees 20–30 years ago (late 1970s) coincides with a historic epidemic of bark beetles. The method using only time since death of still-standing snags appears to be the most feasible for estimating total standing time of snags in old-growth forests with constant tree mortality.
Authors
Karl Thunes John Skartveit Ivar Gjerde Josef Stary Torstein Solhøy Arne Fjellberg Sverre Kobro Sueo Nakahara R. Zur Strassen Gijsbertus Vierbergen Ryszard Szadziewski Daniel V. Hagan William. L. Grogan Jr Terje Jonassen Kjetil Aakra Johannes Anonby Lita Greve Berend Aukema Kai Heller Verner Michelsen Jean-Paul Haenni Alexandr F. Emeljanov Per Douwes Kai Berggren Jutta Franzen R. Henry L. Disney Sabine Prescher Kjell Arne Johanson Boris Mamaev Sigitas Podenas Stig Andersen Stephen D. Gaimari Emilia Narchuk Geir Einar Ellefsen Søli Laszlo Papp Fred Midtgaard Arild Andersen Michael von Tschirnhaus Gerhard Bächli Kjell Magne Olsen Hans A. Olsvik Mihaly Földvari Jan Emil Raastad Lars Ove Hansen Per DjursvollAbstract
No abstract has been registered
2003
Abstract
In this study of 130 sites with different management we investigated whether vascular plant species richness is significantly reduced when traditionally managed hay meadows are abandoned and reforested. We also compared the effects of reforestation with those of intensified land-use to see which have the largest effects on species richness. Finally, we investigated the relative importance of relevant ecological factors for species richness.While the use of artificial fertilizers in traditionally managed hay meadows has resulted in significantly lower species richness, and intensive cultivation in even lower species richness, abandonment with reforestation has not decreased the species richness significantly.Productivity and habitat diversity have determined the species richness of meadows on the scale (0.035.1 ha) of this study. Low productivity is a prerequisite for high species richness in meadows. Maximum species richness was observed in unproductive, old, traditionally managed hay meadows with a high soil pH and high habitat diversity. The high species richness of these meadows suggests that they are in urgent need of conservation.
Abstract
We studied four south-facing and three north-facing boreal spruce forest stands (ca. 0.1ha each) in SE Norway with the aim of testing the hypothesis that former logging has long-term effects on boreal forest-floor vegetation. The stand series comprised unlogged natural forests and forests that were selectively or clear cut 6070 years prior to our study. Each stand was described with respect to history of forestry impact and tree-stand structure.Environmental, species number, species abundance and species composition (vegetation gradients obtained as ordination axes) variables obtained for 25 m1m plots in each stand were tested for among-stand differences. Significant among-stand differences were found, partly related to former forest management and partly due to among-stand differences in topography.Differences among stands related to management were found for tree stand density, highest in managed stands, and for Dryopteris expansa agg. and Luzula pilosa abundances, peaking in formerly clear-cut stands. Species number (at plot or stand scales) was weakly related to former management.On southerly as well as northerly aspects, gradients in species composition were found that separated plots according to former management. Differences among stand conditioned on topography resulted in opposite patterns in the two series of stands because among southerly stands the clear cut was the least while among northerly the clear cut was the most strongly sloping. Low-inclination sites tended more strongly to be paludified and to have high Sphagnum cover, and to have low abundance of specific microsites with small mosses and hepatics. Vegetation gradients related to soil moisture and microtopography were found for both aspects.A strong gradient in species composition related to tree influence at within-stand scales was found, with variation in species number. Existence of such a gradient should provide for significant biotic effects (of short or long duration) of the environmental changes that take place during forest re-growth: (1) the immediate creation of small or large tree-layer gaps by tree felling; and (2) the closing of the tree layer during the regeneration phase.Most notably, the phases at which the tree layer reaches minimum and maximum cover, respectively, may act as `bottlenecks\" for survival of forest-floor species. We conclude that forestry impacts understorey vegetation by way of changes in tree-layer structure and, to a lesser extent, substrate availability and the local environment, during forest regrowth. The extent and duration of this impact will depend on a complex set of factors.Our results are consistent with the view that if maintenance of species diversity is aimed at, environmental considerations should be built into forest management practices, preferably by mimicking the natural structural dynamics of the tree layer.
Abstract
We fogged trees in two pine dominated forests in Norway with a synthetic pyrethroid in order to compare the canopy-dwelling fauna of arthropods between costal (Kvam) and boreal (Sigdal) sites and between old (250-330 years) and mature (60-120 years) trees at Sigdal. Almost 30,000 specimens were assigned to 510 species; only 93 species were present at both sites. Species diversity, as established by rarefaction, was similar in old and mature trees. However, the number of species new to Norway (including nine species new to science) was significantly higher in the old trees. We suggest that the scarcity of old trees, habitat heterogeneity and structural differences between old and mature trees may explain these patterns. Productivity and topographic position at the site of growth explained the between-tree variation in species occurrence for the more abundant species, which were mainly Collembola and Oribatida. Species diversity was similar at the boreal and coastal sites, but there were clear differences in species composition
2002
Abstract
No abstract has been registered