Since alluvial meadows of river valleys of the Cnidion dubii are protected by the EU Habitats Dir... more Since alluvial meadows of river valleys of the Cnidion dubii are protected by the EU Habitats Directive, reconciling farmers’ demands for forage quality with the objective of maintaining them in good conservation status is an important issue in grassland research. In a long-term experiment from 2010 to 2018, we investigated the impact of fertilizing on forage quality and species assembly on a species-rich and twice-mown alluvial grassland in the Dessau Elbe floodplain (Germany). The experiment was composed of an unfertilized control, PK, N60, N60PK and N120PK applications. A significant improvement in forage quality was achieved by nitrogen fertilization only for crude protein, with higher feeding requirements for sheep met only in individual years. The legume cycle was inhibited by the application of nitrogen and high grass cover was maintained, but not increased, at the highest nitrogen application after an exceptional summer flood. The target forbs persisted in numbers over the s...
In highly productive farmlands, field margins could offer habitats and refuges for many plant and... more In highly productive farmlands, field margins could offer habitats and refuges for many plant and animal species. But species-rich field margins are rapidly declining due to field enlargements and unfavourable management practices. In European farmland, management is usually restricted to repeated mulching during the growing season or mulching once a year between September and February. Under nutrient-rich conditions, both methods benefit competitive perennial grasses at the expense of species richness. Diversification of species-poor grass margins on nutrient-rich sites is difficult to achieve and we lack evidence which method works best. Starting in late summer 2010, we implemented a large-scale field experiment on nutrient-rich Chernozem soil, where we examined the effect of sward disturbance intensity, sowing of target species, and mowing time on the development of field margin vegetation over seven years. After disturbance of the existing species-poor grass sward with two intensities (tilling once or three times), a seed mixture of 49 wild plants from a regional seed propagation was sown in early October 2010. After an establishment phase in 2011, the sites were mown once a year, in either June or September, with removal of biomass. In addition, both cutting times were applied to speciespoor grass margins without disturbance and sowing treatments. We recorded the plant species composition yearly from 2010 until 2016. Although the early establishment rate of the sown species was higher on sites disturbed three times, the number of successfully established target species on sites with different sward disturbance intensities converged during the observation period. Mowing in September resulted in higher grass cover and considerably decreased the cover of the sown target species. On the other hand, mowing in June resulted in significantly higher plot occupancy and cover of the sown target species. In general, the immigration success of target forbs into adjacent undisturbed and unsown grass margins was very low even after seven years, although mowing once a year with biomass removal increased the number of mostly ruderal species. Diversification of grass margins was very successful with active species introduction in combination with initial sward disturbance and management adapted to nutrient-rich site conditions. Therefore, restored field margins in highly productive farmlands should be mown in early summer to sustain long-term biodiversity.
In many bird species, reproductive success is dependent on nest quality. However, detailed data o... more In many bird species, reproductive success is dependent on nest quality. However, detailed data on nest composition are scarce, and quantitative analyses have generally used only rough categories, without species identification. Bryophytes dominate the nests of many passerine bird species, but little is known about whether birds have preferences for certain species. In this study, we determined the bryophyte species composition in nests of blue tits Cyanistes caeruleus and great tits Parus major in a forest near Oslo, Norway. We also sampled the abundance of the bryophyte species in plots on the forest floor surrounding a subset of the great tit nests. Blue tits and great tits both used 15 bryophyte species as nest materials, mainly the same pleurocarpous species but in different proportions. The tits preferred highly branched bryophyte species, i.e., Pleurozium schreberi, Rhytidiadelphus squarrosus, and Sanionia uncinata but avoided common forest floor bryophyte species that are sp...
Globally, climate change greatly impacts the production of major crops, and there have been many ... more Globally, climate change greatly impacts the production of major crops, and there have been many attempts to model future yields under warming scenarios in recent years. However, projections of future yields may not be generalisable to all crop growing regions, particularly those with diverse topography and bioclimates. In this study, we demonstrate this by evaluating the links between changes in temperature and precipitation and changes in wheat, barley, and potato yields at the county-level during 1980–2019 in Norway, a Nordic country with a range of climates across a relatively small spatial scale. The results show that the impacts of climate variables on yield vary widely by county, and that for some crops, the strength and direction of the link depends on underlying local bioclimate. In addition, our analysis demonstrates the need for some counties to focus on weather changes during specific crucial months corresponding with certain crop growth stages. Furthermore, due to the l...
The DCA (four axes) and GNMDS (3-dimensional solution) ordination results of the species composit... more The DCA (four axes) and GNMDS (3-dimensional solution) ordination results of the species compositional data from the 1031 plots. These data were collected in 80 permanently marked plots (8 plots in each of 10 blocks) in a boreal forest in SE Norway over the years 1993-2003, 2005, and 2011.Nine plots were devoid of species in 1994, The plots were experimentally disturbed before after 1993. The treatments were: T1 (removal of vegetation), T2 (removal of vegetation and the litter layer), T3 (removal of vegetation, the litter, and the mor soil layers), T4 and T5 (removal of vegetation, organic, and bleached soil layers; with T4 bordering intact vegetation on two sides, whereas T5 had a minimum distance of 0.5 m to intact vegetation). Three of the plots in each block served as controls (C)
A description of how matrix elements were modified to allow for variation among years in the 11 d... more A description of how matrix elements were modified to allow for variation among years in the 11 different types of disturbance matrices.
In the last 50–60 years, agricultural intensification and later urban development have threatened... more In the last 50–60 years, agricultural intensification and later urban development have threatened the rare and valuable gully landscape formed on marine clay. We studied landscape changes in eastern Akershus county in south-east Norway, which has one of the world’s largest concentrations of marine gullies. Interpretation of aerial photos showed that about 25% of the gully area has been lost. Only 39.5% of the remaining area is original gullies, and 60.5% of the area has been affected by landscape change. The largest loss of gully area was between 1955 and 1991, mainly through land levelling and transformation to intensively managed agricultural landscape. The most densely populated areas also lost gullies to residential areas and industry. Gullies support high plant and animal diversity, and future management should be based on landscape ecological principles. Gully fragments should also be preserved to maintain connectivity between the many different habitats belonging to the gullies.
Production in the field layer of a wooded hay meadow in Sogn, Western Norway, was studied by comp... more Production in the field layer of a wooded hay meadow in Sogn, Western Norway, was studied by comparing two sites, one in active use and the other abandoned since 1975. We also studied how production in the field layer varied with the composition of the vegetation and the influence of trees, and the extent to which production from the trees (foliage) contributed to total production in the hay meadow. Production in the field layer was significantly higher at the site in active use than at the abandoned site, despite the annual removal of hay from the former. Field layer production was lowest nearest the tree trunk and increased significantly with increasing distance from the trunk at both sites. Production was also significantly related to vegetation gradients (as revealed by ordination analyses). We estimated the average annual production in the field layer at the site in active use to be 582 g/m2. This is high production compared with production in other meadow types, especially giv...
Item does not contain fulltext1. Species composition is a vital attribute of any ecosystem. Accor... more Item does not contain fulltext1. Species composition is a vital attribute of any ecosystem. Accordingly, ecological restoration often has the original, or ‘natural’, species composition as its target. However, we still lack adequate methods for predicting the expected time to compositional recovery in restoration studies. 2. We describe and explore a new, ordination regression-based approach (ORBA) for predicting time to recovery that allows both linear and asymptotic (logarithmic) relationships of compositional change with time. The approach uses distances between restored plots and reference plots along the successional gradient, represented by a vector in ordination space, to predict time to recovery. Thus, the approach rests on three requirements: (1) the general form of the relationship between compositional change and time must be known; (2) a sufficiently strong successional gradient must be present and adequately represented in a species compositional data set; and (3) a restoration target must be specified. We tested the approach using data from a boreal old-growth forest that was followed for 18 years after experimental disturbance. Data from the first nine years after disturbance were used to develop models, the subsequent nine years for validation. 3. Rates of compositional recovery in the example data set followed the general pattern of decrease with time since disturbance. Accordingly, linear models were too optimistic about the time to recovery whereas the asymptotic models provided more precise predictions. 4. Synthesis and applications. Our results demonstrate that the new approach opens for reliable prediction of recovery rates and time to recovery using species compositional data. Moreover, it allows us to assess whether recovery proceeds in the desired direction and to quantitatively compare restoration speed, and hence effectiveness, between alternative management options
I denne rapporten oppsummerer vi de viktigste resultatene fra prosjektet “Steintipper i fjellet”.... more I denne rapporten oppsummerer vi de viktigste resultatene fra prosjektet “Steintipper i fjellet”. I prosjektet har vi i tidsrommet 2008–2010 undersøkt vegetasjonssammensetningen på 19 steintipper og omgivelsene til disse tippene på Vestlandet. Vi har i tillegg benyttet oss av tidligere innsamlete data fra 1990-tallet for fem av disse steintippene. Vi har undersøkt hvilke faktorer som betyr mest for å forklare forskjeller i vegetasjonen mellom steintipper og deres omgivelser. Vi har også undersøkt hvor raskt vegetasjonen på steintippene endrer seg (suksesjonshastigheten), og hvilken retning denne vegetasjonsendringen ta
Since alluvial meadows of river valleys of the Cnidion dubii are protected by the EU Habitats Dir... more Since alluvial meadows of river valleys of the Cnidion dubii are protected by the EU Habitats Directive, reconciling farmers’ demands for forage quality with the objective of maintaining them in good conservation status is an important issue in grassland research. In a long-term experiment from 2010 to 2018, we investigated the impact of fertilizing on forage quality and species assembly on a species-rich and twice-mown alluvial grassland in the Dessau Elbe floodplain (Germany). The experiment was composed of an unfertilized control, PK, N60, N60PK and N120PK applications. A significant improvement in forage quality was achieved by nitrogen fertilization only for crude protein, with higher feeding requirements for sheep met only in individual years. The legume cycle was inhibited by the application of nitrogen and high grass cover was maintained, but not increased, at the highest nitrogen application after an exceptional summer flood. The target forbs persisted in numbers over the s...
In highly productive farmlands, field margins could offer habitats and refuges for many plant and... more In highly productive farmlands, field margins could offer habitats and refuges for many plant and animal species. But species-rich field margins are rapidly declining due to field enlargements and unfavourable management practices. In European farmland, management is usually restricted to repeated mulching during the growing season or mulching once a year between September and February. Under nutrient-rich conditions, both methods benefit competitive perennial grasses at the expense of species richness. Diversification of species-poor grass margins on nutrient-rich sites is difficult to achieve and we lack evidence which method works best. Starting in late summer 2010, we implemented a large-scale field experiment on nutrient-rich Chernozem soil, where we examined the effect of sward disturbance intensity, sowing of target species, and mowing time on the development of field margin vegetation over seven years. After disturbance of the existing species-poor grass sward with two intensities (tilling once or three times), a seed mixture of 49 wild plants from a regional seed propagation was sown in early October 2010. After an establishment phase in 2011, the sites were mown once a year, in either June or September, with removal of biomass. In addition, both cutting times were applied to speciespoor grass margins without disturbance and sowing treatments. We recorded the plant species composition yearly from 2010 until 2016. Although the early establishment rate of the sown species was higher on sites disturbed three times, the number of successfully established target species on sites with different sward disturbance intensities converged during the observation period. Mowing in September resulted in higher grass cover and considerably decreased the cover of the sown target species. On the other hand, mowing in June resulted in significantly higher plot occupancy and cover of the sown target species. In general, the immigration success of target forbs into adjacent undisturbed and unsown grass margins was very low even after seven years, although mowing once a year with biomass removal increased the number of mostly ruderal species. Diversification of grass margins was very successful with active species introduction in combination with initial sward disturbance and management adapted to nutrient-rich site conditions. Therefore, restored field margins in highly productive farmlands should be mown in early summer to sustain long-term biodiversity.
In many bird species, reproductive success is dependent on nest quality. However, detailed data o... more In many bird species, reproductive success is dependent on nest quality. However, detailed data on nest composition are scarce, and quantitative analyses have generally used only rough categories, without species identification. Bryophytes dominate the nests of many passerine bird species, but little is known about whether birds have preferences for certain species. In this study, we determined the bryophyte species composition in nests of blue tits Cyanistes caeruleus and great tits Parus major in a forest near Oslo, Norway. We also sampled the abundance of the bryophyte species in plots on the forest floor surrounding a subset of the great tit nests. Blue tits and great tits both used 15 bryophyte species as nest materials, mainly the same pleurocarpous species but in different proportions. The tits preferred highly branched bryophyte species, i.e., Pleurozium schreberi, Rhytidiadelphus squarrosus, and Sanionia uncinata but avoided common forest floor bryophyte species that are sp...
Globally, climate change greatly impacts the production of major crops, and there have been many ... more Globally, climate change greatly impacts the production of major crops, and there have been many attempts to model future yields under warming scenarios in recent years. However, projections of future yields may not be generalisable to all crop growing regions, particularly those with diverse topography and bioclimates. In this study, we demonstrate this by evaluating the links between changes in temperature and precipitation and changes in wheat, barley, and potato yields at the county-level during 1980–2019 in Norway, a Nordic country with a range of climates across a relatively small spatial scale. The results show that the impacts of climate variables on yield vary widely by county, and that for some crops, the strength and direction of the link depends on underlying local bioclimate. In addition, our analysis demonstrates the need for some counties to focus on weather changes during specific crucial months corresponding with certain crop growth stages. Furthermore, due to the l...
The DCA (four axes) and GNMDS (3-dimensional solution) ordination results of the species composit... more The DCA (four axes) and GNMDS (3-dimensional solution) ordination results of the species compositional data from the 1031 plots. These data were collected in 80 permanently marked plots (8 plots in each of 10 blocks) in a boreal forest in SE Norway over the years 1993-2003, 2005, and 2011.Nine plots were devoid of species in 1994, The plots were experimentally disturbed before after 1993. The treatments were: T1 (removal of vegetation), T2 (removal of vegetation and the litter layer), T3 (removal of vegetation, the litter, and the mor soil layers), T4 and T5 (removal of vegetation, organic, and bleached soil layers; with T4 bordering intact vegetation on two sides, whereas T5 had a minimum distance of 0.5 m to intact vegetation). Three of the plots in each block served as controls (C)
A description of how matrix elements were modified to allow for variation among years in the 11 d... more A description of how matrix elements were modified to allow for variation among years in the 11 different types of disturbance matrices.
In the last 50–60 years, agricultural intensification and later urban development have threatened... more In the last 50–60 years, agricultural intensification and later urban development have threatened the rare and valuable gully landscape formed on marine clay. We studied landscape changes in eastern Akershus county in south-east Norway, which has one of the world’s largest concentrations of marine gullies. Interpretation of aerial photos showed that about 25% of the gully area has been lost. Only 39.5% of the remaining area is original gullies, and 60.5% of the area has been affected by landscape change. The largest loss of gully area was between 1955 and 1991, mainly through land levelling and transformation to intensively managed agricultural landscape. The most densely populated areas also lost gullies to residential areas and industry. Gullies support high plant and animal diversity, and future management should be based on landscape ecological principles. Gully fragments should also be preserved to maintain connectivity between the many different habitats belonging to the gullies.
Production in the field layer of a wooded hay meadow in Sogn, Western Norway, was studied by comp... more Production in the field layer of a wooded hay meadow in Sogn, Western Norway, was studied by comparing two sites, one in active use and the other abandoned since 1975. We also studied how production in the field layer varied with the composition of the vegetation and the influence of trees, and the extent to which production from the trees (foliage) contributed to total production in the hay meadow. Production in the field layer was significantly higher at the site in active use than at the abandoned site, despite the annual removal of hay from the former. Field layer production was lowest nearest the tree trunk and increased significantly with increasing distance from the trunk at both sites. Production was also significantly related to vegetation gradients (as revealed by ordination analyses). We estimated the average annual production in the field layer at the site in active use to be 582 g/m2. This is high production compared with production in other meadow types, especially giv...
Item does not contain fulltext1. Species composition is a vital attribute of any ecosystem. Accor... more Item does not contain fulltext1. Species composition is a vital attribute of any ecosystem. Accordingly, ecological restoration often has the original, or ‘natural’, species composition as its target. However, we still lack adequate methods for predicting the expected time to compositional recovery in restoration studies. 2. We describe and explore a new, ordination regression-based approach (ORBA) for predicting time to recovery that allows both linear and asymptotic (logarithmic) relationships of compositional change with time. The approach uses distances between restored plots and reference plots along the successional gradient, represented by a vector in ordination space, to predict time to recovery. Thus, the approach rests on three requirements: (1) the general form of the relationship between compositional change and time must be known; (2) a sufficiently strong successional gradient must be present and adequately represented in a species compositional data set; and (3) a restoration target must be specified. We tested the approach using data from a boreal old-growth forest that was followed for 18 years after experimental disturbance. Data from the first nine years after disturbance were used to develop models, the subsequent nine years for validation. 3. Rates of compositional recovery in the example data set followed the general pattern of decrease with time since disturbance. Accordingly, linear models were too optimistic about the time to recovery whereas the asymptotic models provided more precise predictions. 4. Synthesis and applications. Our results demonstrate that the new approach opens for reliable prediction of recovery rates and time to recovery using species compositional data. Moreover, it allows us to assess whether recovery proceeds in the desired direction and to quantitatively compare restoration speed, and hence effectiveness, between alternative management options
I denne rapporten oppsummerer vi de viktigste resultatene fra prosjektet “Steintipper i fjellet”.... more I denne rapporten oppsummerer vi de viktigste resultatene fra prosjektet “Steintipper i fjellet”. I prosjektet har vi i tidsrommet 2008–2010 undersøkt vegetasjonssammensetningen på 19 steintipper og omgivelsene til disse tippene på Vestlandet. Vi har i tillegg benyttet oss av tidligere innsamlete data fra 1990-tallet for fem av disse steintippene. Vi har undersøkt hvilke faktorer som betyr mest for å forklare forskjeller i vegetasjonen mellom steintipper og deres omgivelser. Vi har også undersøkt hvor raskt vegetasjonen på steintippene endrer seg (suksesjonshastigheten), og hvilken retning denne vegetasjonsendringen ta
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