1. Successful restoration of semi-natural grasslands on grasslands previously subject to intensiv... more 1. Successful restoration of semi-natural grasslands on grasslands previously subject to intensive management needs to overcome manifold barriers. These include high soil fertility, the dominance of a few fast-growing plant species, degraded soil faunal communities, and missing propagules of the targeted above-and belowground flora and fauna. A combination of removing the topsoil and introducing propagules of target plants has become one of the major tools for nature conservation agencies and practitioners to reduce soil fertility and restore former species-rich grasslands in various European countries. 2. Using topsoil removal as a restoration measure has provoked an ongoing debate between supporting nature conservation and rejecting soil protection agencies. Although it favours speciesrich plant communities, it strongly disturbs soil communities, and affects physical and chemical soil properties and processes. Currently, there is a lack of long-term data to assess how restored grassland ecosystems develop and recover after topsoil removal. Here we used two well-established bioindicators, soil nematodes and plants, to quantify restoration success of topsoil removal in comparison with alternative restoration measures and target communities 22 years after intervention. 3. The nematode community composition indicated reduced nutrient availability in the restored systems, as was aimed at by topsoil removal. Nevertheless, after this 22-year period following topsoil removal, nematode composition and structure revealed successful recovery. 4. Plant communities benefitted from the reduction of soil nutrients after topsoil removal as indicated by higher numbers of plant species and higher Shannon diversity. Furthermore, topsoil removal strongly promoted the re-establishment of plant species of the target plant community. 5. Synthesis and applications. Overall, our study demonstrates, how a massive intervention by topsoil removal proved successful in converting intensively managed into species-rich grasslands, in contrast to the mild intervention by repeated mowing and removing of the harvested plant material. We 3 show that, in the long run, potential negative effects of topsoil removal on the soil fauna can be successfully overcome and plant communities develop into the targeted species-rich grassland.
1. Evaluation of restoration activities is indispensable to assess the extent to which targets ha... more 1. Evaluation of restoration activities is indispensable to assess the extent to which targets have been reached. Usually, the main goal of ecological restoration is to restore biodiversity and ecosystem functioning, but validation is often based on a single indicator, which may or may not cope with whole-ecosystem dynamics. Network analyses are, however, powerful tools, allowing to examine both the recovery of various biotic and abiotic properties and the integrated response at community and ecosystem level. 2. We used restoration sites where topsoil was removed from former intensively managed grassland and seeds were added. These sites were between 3 to 32 years old. We assessed how plants, soil biota, soil properties, and correlation-based interactions between biotic communities and their abiotic environment developed over time and compared the results with (i) intensively managed (not restored), and (ii) well-preserved targeted semi-natural grasslands. 3. Plant, nematode, fungal, and prokaryotic diversity and community structures of the restored grasslands revealed clear successional patterns and followed similar trajectories towards targeted semi-natural grasslands. All biotic communities reached targeted diversity levels no later than 18 years post restoration. 4. Ecological networks of intensively managed and short-term (~4 years) restored grasslands were less tightly connected compared to those found in mid-and long-term (~18-30 years) restored and target grasslands. Restoration specifically enhanced interactions among biotic communities, but reduced interactions between biotic communities and their abiotic environment as well as interactions among abiotic properties in the short-and mid-term. 5. Synthesis and applications: Overall, our study demonstrated that topsoil removal and seed addition were successful in restoring diverse, tightly coupled and well-connected biotic communities similar to those found in the semi-natural grasslands that were restoration targets. Network analyses proved to be powerful in examining the long-term re-establishment of functionally connected biotic communities in restored ecosystems. Thus, we provide an approach Confidential Review copy Journal of Applied Ecology to holistically assess restoration activities by notably considering the complexity of ecosystems, much in contrast to most traditional approaches.
Aims: To develop a consistent ecological indicator value system for Europe for five of the main p... more Aims: To develop a consistent ecological indicator value system for Europe for five of the main plant niche dimensions: soil moisture (M), soil nitrogen (N), soil reaction (R), light (L) and temperature (T). Study area: Europe (and closely adjacent regions). Methods: We identified 31 indicator value systems for vascular plants in Europe that contained assessments on at least one of the five aforementioned niche dimensions. We rescaled the indicator values of each dimension to a continuous scale, in which 0 represents the minimum and 10 the maximum value present in Europe. Taxon names were harmonised to the Euro+Med Plantbase. For each of the five dimensions, we calculated European values for niche position and niche width by combining the values from the individual EIV systems. Using T values as an example, we externally validated our European indicator values against the median of bioclimatic conditions for global occurrence data of the taxa. Results: In total, we derived European ...
AimsClassification of European bog vegetation (Oxycocco‐Sphagnetea class); identification of diag... more AimsClassification of European bog vegetation (Oxycocco‐Sphagnetea class); identification of diagnostic species for the class and vegetation subgroups (orders and alliances); development of an expert system for automatic classification of vegetation plots; and production of distribution maps of the Oxycocco‐Sphagnetea class and its alliances.LocationEurope.MethodsA data set of vegetation‐plot records was compiled to include various bog types over most of the European continent. An unsupervised classification (beta‐flexible linkage method, Sørensen distance measure) and detrended correspondence analysis (DCA) ordination were applied. Formal definitions of syntaxa based on species presence and covers, and respecting the results of the unsupervised classification, were developed and included in a classification expert system.ResultsThe Oxycocco‐Sphagnetea class, its two orders (Sphagno‐Ericetalia tetralicis and Sphagnetalia medii) and seven compositionally distinct alliances were forma...
Vegetation shift in Scots pine forests in the Valais accelerated by large disturbances In the pas... more Vegetation shift in Scots pine forests in the Valais accelerated by large disturbances In the past dozen years, several studies have concluded a vegetation shift from Scots pine to oak (pubescent and sessile) forests in the low elevated zones of the Valais. It is, however, not fully clear in which way such a vegetation shift actually occurs and on which processes such a shift would be based. Two studies, one on the tree demography in the intact Pfynwald and the other on the tree regeneration on the large Leuk forest fire patch, serve to discuss different aspects of the shift from Scots pine to oak. The forest stands of Pfynwald consist of 67% Scots pines and 14% oaks. Regenerating trees are 2–3.5 times more frequent in small gaps than under canopy. In gaps of the Upper Pfynwald, seedlings and saplings of Scots pine are three times more abundant than oaks, while both species regenerate in similar quantities under canopy. In the Lower Pfynwald, young oaks – especially seedlings – are ...
In Scots pine forests in the inner valleys of the European Alps high mortality of unknown causes ... more In Scots pine forests in the inner valleys of the European Alps high mortality of unknown causes has recently been observed. In 2002-2003 we assessed forests in the Swiss Rhone valley on a systematic grid ranging in altitude between 440 m and 1550 m a.s.l. We tested if mortality rates since the National Forest Inventory (NFI) in 1983/85 differed between species, geographic regions, altitudinal ranges or potential drought stress (extrapolated difference between annual precipitation (P) and modeled potential evapotranspiration (PET) for the period 1961-90). We also correlated annual pine mortality for a local long-term forest research site (LWF) with climatic data. At the LWF site 59% of the pines died between 1996 and 2004. Annual mortality rates varied substantially between years and were highest following the drought years 1998 and 2003. Mortality related best to P-PET of the prior summer (May-August). Pine mortality on NFI plots was higher than elsewhere in Switzerland, while mortality of other species was not. Below 1100 m a.s.l. mortality rates of pines, but not of other species, were higher than above. We found a significant negative relationship between mortality rates and P-PET in pines, but not in the other species. Therefore, we postulate that drought stress triggers the observed pine decline.
In Switzerland, steppe vegetation is restricted to dry soils in inner alpine dry valleys in the W... more In Switzerland, steppe vegetation is restricted to dry soils in inner alpine dry valleys in the West (Valais) and the East (Grisons). They harbour many specialist and threatened species. In 2011, a long-term program was established to monitor changes in Swiss habitats of national importance. Here, we studied patterns of vascular plant diversity in a subset of 148 steppe plots of 10 m 2 from this program. Plots were either grazed or abandoned. On average, we found 23.3 species per plot. The proportion of steppe specialists and of threatened species out of the total species richness was 29.3% and 12.2%, respectively. The total number of species increased with elevation and peaked at intermediate productivity levels. In contrast, the proportion of threatened and steppe specialist species was generally negatively related to higher productivity and wood covertwo factors considered as indicators of habitat degradation. Abandonment vs. pasture had no effects on total species richness. Productivity was positively related to ecological indicator values for moisture, competition and ruderality, as well as the community mean traits of plant height and specific leaf area, but negatively with the indicator value for light. Similarly, wood cover was positively associated with higher ecological indicator values for productivity, moisture and competition, as well as the community mean trait of plant height, but negatively with the indicator value for light and ruderality. The negative response of threatened and steppe specialist vascular plant species to habitat degrading factors suggests their proportional richness to be a better indicator of habitat quality than the total species richness. We conclude that management regimes which guarantee low productivity and wood cover and avoid intensification by fertilization and irrigation are essential for the conservation of steppe habitats. Beside periodic clearing of woody species, low-intensity grazing might prevent shrub encroachment.
Resurveys of historical plots are important to study vegetation changes over time. However, there... more Resurveys of historical plots are important to study vegetation changes over time. However, there is a high potential of relocation error, as historical plots were usually not permanently marked, which might result in misleading interpretations of changes. Quasi-permanent plots can relatively well be relocated, because of available information on their position (e.g. GPS coordinates). This minimizes relocation error. Quasi-permanent plots have thus been suggested to be suitable for vegetation resurveys. Land-use abandonment and intensification are the major drivers of habitat degradation and thereby cause biodiversity loss. To counteract the ongoing decline of biodiversity in Swiss grasslands, the dry grasslands of national importance, comprising a total of 3631 sites across Switzerland (0.5% of its total area) were legally protected in 2010. These grassland sites represent various vegetation types and cover a wide elevational gradient. From 1995 to 2006, several thousand quasi-permanent vegetation plots of 28 m 2 were surveyed in the nationally important dry grassland sites. For each plot, GPS coordinates and a metric measure of post-processed GPS inaccuracy were recorded. In a set of 384 sites, 538 of the historical plots were resurveyed between 2011 and 2017. We tested the effects of GPS inaccuracy and elevation on temporal changes of species richness, species turnover and mean ecological indicator values. Overall, mean indicator values for light and stress significantly decreased, and those for moisture, nutrients and ruderality significantly increased within only one decade. However, the temporal change of the mean indicator values for nutrients and moisture was more pronounced at higher than at lower elevation, indicating a particularly strong decrease of habitat quality at high elevation sites. While changes of in mean indicator values were largely robust to relocation error, the temporal turnover of key species significantly increased with increasing GPS inaccuracy. These results indicate that quasi-permanent plots are suitable to study changes in mean indicator values, but probably not to compare species composition and turnover across time.
Die Schweiz hat sich verpflichtet, ihre große biologische Vielfalt zu schützen und den Lebensraum... more Die Schweiz hat sich verpflichtet, ihre große biologische Vielfalt zu schützen und den Lebensraumverlust und das Aussterben bedrohter Arten zu unterbinden. Deshalb hat die Schweiz unter anderem seit Beginn der 1990er-Jahre rund 6.000 »Objekte von nationaler Bedeutung« ausgewiesen, darunter Hoch-und Flachmoore, Trockenwiesen und-weiden (TWW), Auen und Amphibienlaichgebiete. Die Wirkungskontrolle Biotopschutz ist ein 2011 langfristig angelegtes Programm zum Monitoring dieser Lebensräume. Luftbildanalysen und Felderhebungen bilden die Datengrundlage, um Veränderungen in den Biotopen von nationaler Bedeutung aufzuzeigen und die Wirksamkeit der Schutzmaßnahmen zu kontrollieren. Analysen zeigen, dass Moore und TWW zunehmend verbuschen, Moore trockener und nährstoffreicher werden und die lokale Anzahl der Amphibienarten abnimmt. Um diesen Trend, und damit den Lebensraum-und Artenverlust aufzuhalten, sollten die Schutzbemühungen auf nationaler Ebene möglichst rasch verstärkt werden.
To assess whether short-term changes in mire vegetation can be detected using the phytosociologic... more To assess whether short-term changes in mire vegetation can be detected using the phytosociological approach, paired vegetation relevés from two surveys of 112 mire sites of Switzerland were assigned to phytosociological alliances through a numerical approach. About 30% of the plots were assigned to different alliances in the two surveys. These transitions were analysed based on species frequencies and interpreted ecologically using Landolt's indicator values. Transitions between different alliances were more frequently related to the appearance of new species rather than to the disappearance of species. Transitions from and to peat bog communities were frequent. Many plots with fen vegetation were transformed into other wetland types. Fen-grassland increased in abundance, mainly at the cost of small-sedge fens. To reestablish the function of the Swiss mires as peat producers, we recommend to raise the mean summer water table to a maximum depth of 10 cm.
How may Landolt indicator values be re-calibrated to improve the performance of predictive models... more How may Landolt indicator values be re-calibrated to improve the performance of predictive models? Location: Mires Gross Moos Schwändital (1250 m a.s.l.) in the Prealps, Burgmoos (465 m. a.s.l.) on the Central Plateau and La Burtignière (1000 m a.s.l.) in the Jura, Switzerland. Methods: Habitat distribution models based on high resolution remotely sensed data and vegetation field data are applied to monitor 130 mires. Instead of plant species or communities we used mean indicator values of vegetation records as response variables. To improve the differential power of indicator values for wetland habitat conditions, we calibrated these values using field data. Different methods were tested with our predictive models in three mires to see which calibration method is best in enhancing model performance. To assess the effect of the uneven distribution of vegetation records along environmental gradients, calibrations based on random and evenly distributed samples were compared. As a test of the predictive power of the models we used r 2 between ground truth and model prediction. This approach is illustrated through an application with nutrient indicator values in the mire La Burtignière. Results: Model performances were not the same for the three mires. The predictive power was better for the nutrient values, soil reaction and humus values than for light and moisture values. 2000 records were sufficient as basis for re-calibration. Models based on original Landolt indicator values were overall the weakest compared with re-calibrated values. By comparing the predictive power of Models based on randomly or evenly selected records were about equally predictive. Conclusions: 1. A habitat-specific re-calibration of the Landolt indicator values enhances the predictive mapping of the Swiss mire ecosystems. 2. The re-calibration based on weighted averaging gives a better performance than the one based on Gaussian logistic regression. 3. The uneven distribution of indicator values due to the over-representation of mire habitats does not hamper model performance. 4. 2000 vegetation records are a sufficient basis for an optimal re-calibration of the vegetation types. An illustration of the method is given by using the soil fertility pattern of the mire La Burtignière.
1. Successful restoration of semi-natural grasslands on grasslands previously subject to intensiv... more 1. Successful restoration of semi-natural grasslands on grasslands previously subject to intensive management needs to overcome manifold barriers. These include high soil fertility, the dominance of a few fast-growing plant species, degraded soil faunal communities, and missing propagules of the targeted above-and belowground flora and fauna. A combination of removing the topsoil and introducing propagules of target plants has become one of the major tools for nature conservation agencies and practitioners to reduce soil fertility and restore former species-rich grasslands in various European countries. 2. Using topsoil removal as a restoration measure has provoked an ongoing debate between supporting nature conservation and rejecting soil protection agencies. Although it favours speciesrich plant communities, it strongly disturbs soil communities, and affects physical and chemical soil properties and processes. Currently, there is a lack of long-term data to assess how restored grassland ecosystems develop and recover after topsoil removal. Here we used two well-established bioindicators, soil nematodes and plants, to quantify restoration success of topsoil removal in comparison with alternative restoration measures and target communities 22 years after intervention. 3. The nematode community composition indicated reduced nutrient availability in the restored systems, as was aimed at by topsoil removal. Nevertheless, after this 22-year period following topsoil removal, nematode composition and structure revealed successful recovery. 4. Plant communities benefitted from the reduction of soil nutrients after topsoil removal as indicated by higher numbers of plant species and higher Shannon diversity. Furthermore, topsoil removal strongly promoted the re-establishment of plant species of the target plant community. 5. Synthesis and applications. Overall, our study demonstrates, how a massive intervention by topsoil removal proved successful in converting intensively managed into species-rich grasslands, in contrast to the mild intervention by repeated mowing and removing of the harvested plant material. We 3 show that, in the long run, potential negative effects of topsoil removal on the soil fauna can be successfully overcome and plant communities develop into the targeted species-rich grassland.
1. Evaluation of restoration activities is indispensable to assess the extent to which targets ha... more 1. Evaluation of restoration activities is indispensable to assess the extent to which targets have been reached. Usually, the main goal of ecological restoration is to restore biodiversity and ecosystem functioning, but validation is often based on a single indicator, which may or may not cope with whole-ecosystem dynamics. Network analyses are, however, powerful tools, allowing to examine both the recovery of various biotic and abiotic properties and the integrated response at community and ecosystem level. 2. We used restoration sites where topsoil was removed from former intensively managed grassland and seeds were added. These sites were between 3 to 32 years old. We assessed how plants, soil biota, soil properties, and correlation-based interactions between biotic communities and their abiotic environment developed over time and compared the results with (i) intensively managed (not restored), and (ii) well-preserved targeted semi-natural grasslands. 3. Plant, nematode, fungal, and prokaryotic diversity and community structures of the restored grasslands revealed clear successional patterns and followed similar trajectories towards targeted semi-natural grasslands. All biotic communities reached targeted diversity levels no later than 18 years post restoration. 4. Ecological networks of intensively managed and short-term (~4 years) restored grasslands were less tightly connected compared to those found in mid-and long-term (~18-30 years) restored and target grasslands. Restoration specifically enhanced interactions among biotic communities, but reduced interactions between biotic communities and their abiotic environment as well as interactions among abiotic properties in the short-and mid-term. 5. Synthesis and applications: Overall, our study demonstrated that topsoil removal and seed addition were successful in restoring diverse, tightly coupled and well-connected biotic communities similar to those found in the semi-natural grasslands that were restoration targets. Network analyses proved to be powerful in examining the long-term re-establishment of functionally connected biotic communities in restored ecosystems. Thus, we provide an approach Confidential Review copy Journal of Applied Ecology to holistically assess restoration activities by notably considering the complexity of ecosystems, much in contrast to most traditional approaches.
Aims: To develop a consistent ecological indicator value system for Europe for five of the main p... more Aims: To develop a consistent ecological indicator value system for Europe for five of the main plant niche dimensions: soil moisture (M), soil nitrogen (N), soil reaction (R), light (L) and temperature (T). Study area: Europe (and closely adjacent regions). Methods: We identified 31 indicator value systems for vascular plants in Europe that contained assessments on at least one of the five aforementioned niche dimensions. We rescaled the indicator values of each dimension to a continuous scale, in which 0 represents the minimum and 10 the maximum value present in Europe. Taxon names were harmonised to the Euro+Med Plantbase. For each of the five dimensions, we calculated European values for niche position and niche width by combining the values from the individual EIV systems. Using T values as an example, we externally validated our European indicator values against the median of bioclimatic conditions for global occurrence data of the taxa. Results: In total, we derived European ...
AimsClassification of European bog vegetation (Oxycocco‐Sphagnetea class); identification of diag... more AimsClassification of European bog vegetation (Oxycocco‐Sphagnetea class); identification of diagnostic species for the class and vegetation subgroups (orders and alliances); development of an expert system for automatic classification of vegetation plots; and production of distribution maps of the Oxycocco‐Sphagnetea class and its alliances.LocationEurope.MethodsA data set of vegetation‐plot records was compiled to include various bog types over most of the European continent. An unsupervised classification (beta‐flexible linkage method, Sørensen distance measure) and detrended correspondence analysis (DCA) ordination were applied. Formal definitions of syntaxa based on species presence and covers, and respecting the results of the unsupervised classification, were developed and included in a classification expert system.ResultsThe Oxycocco‐Sphagnetea class, its two orders (Sphagno‐Ericetalia tetralicis and Sphagnetalia medii) and seven compositionally distinct alliances were forma...
Vegetation shift in Scots pine forests in the Valais accelerated by large disturbances In the pas... more Vegetation shift in Scots pine forests in the Valais accelerated by large disturbances In the past dozen years, several studies have concluded a vegetation shift from Scots pine to oak (pubescent and sessile) forests in the low elevated zones of the Valais. It is, however, not fully clear in which way such a vegetation shift actually occurs and on which processes such a shift would be based. Two studies, one on the tree demography in the intact Pfynwald and the other on the tree regeneration on the large Leuk forest fire patch, serve to discuss different aspects of the shift from Scots pine to oak. The forest stands of Pfynwald consist of 67% Scots pines and 14% oaks. Regenerating trees are 2–3.5 times more frequent in small gaps than under canopy. In gaps of the Upper Pfynwald, seedlings and saplings of Scots pine are three times more abundant than oaks, while both species regenerate in similar quantities under canopy. In the Lower Pfynwald, young oaks – especially seedlings – are ...
In Scots pine forests in the inner valleys of the European Alps high mortality of unknown causes ... more In Scots pine forests in the inner valleys of the European Alps high mortality of unknown causes has recently been observed. In 2002-2003 we assessed forests in the Swiss Rhone valley on a systematic grid ranging in altitude between 440 m and 1550 m a.s.l. We tested if mortality rates since the National Forest Inventory (NFI) in 1983/85 differed between species, geographic regions, altitudinal ranges or potential drought stress (extrapolated difference between annual precipitation (P) and modeled potential evapotranspiration (PET) for the period 1961-90). We also correlated annual pine mortality for a local long-term forest research site (LWF) with climatic data. At the LWF site 59% of the pines died between 1996 and 2004. Annual mortality rates varied substantially between years and were highest following the drought years 1998 and 2003. Mortality related best to P-PET of the prior summer (May-August). Pine mortality on NFI plots was higher than elsewhere in Switzerland, while mortality of other species was not. Below 1100 m a.s.l. mortality rates of pines, but not of other species, were higher than above. We found a significant negative relationship between mortality rates and P-PET in pines, but not in the other species. Therefore, we postulate that drought stress triggers the observed pine decline.
In Switzerland, steppe vegetation is restricted to dry soils in inner alpine dry valleys in the W... more In Switzerland, steppe vegetation is restricted to dry soils in inner alpine dry valleys in the West (Valais) and the East (Grisons). They harbour many specialist and threatened species. In 2011, a long-term program was established to monitor changes in Swiss habitats of national importance. Here, we studied patterns of vascular plant diversity in a subset of 148 steppe plots of 10 m 2 from this program. Plots were either grazed or abandoned. On average, we found 23.3 species per plot. The proportion of steppe specialists and of threatened species out of the total species richness was 29.3% and 12.2%, respectively. The total number of species increased with elevation and peaked at intermediate productivity levels. In contrast, the proportion of threatened and steppe specialist species was generally negatively related to higher productivity and wood covertwo factors considered as indicators of habitat degradation. Abandonment vs. pasture had no effects on total species richness. Productivity was positively related to ecological indicator values for moisture, competition and ruderality, as well as the community mean traits of plant height and specific leaf area, but negatively with the indicator value for light. Similarly, wood cover was positively associated with higher ecological indicator values for productivity, moisture and competition, as well as the community mean trait of plant height, but negatively with the indicator value for light and ruderality. The negative response of threatened and steppe specialist vascular plant species to habitat degrading factors suggests their proportional richness to be a better indicator of habitat quality than the total species richness. We conclude that management regimes which guarantee low productivity and wood cover and avoid intensification by fertilization and irrigation are essential for the conservation of steppe habitats. Beside periodic clearing of woody species, low-intensity grazing might prevent shrub encroachment.
Resurveys of historical plots are important to study vegetation changes over time. However, there... more Resurveys of historical plots are important to study vegetation changes over time. However, there is a high potential of relocation error, as historical plots were usually not permanently marked, which might result in misleading interpretations of changes. Quasi-permanent plots can relatively well be relocated, because of available information on their position (e.g. GPS coordinates). This minimizes relocation error. Quasi-permanent plots have thus been suggested to be suitable for vegetation resurveys. Land-use abandonment and intensification are the major drivers of habitat degradation and thereby cause biodiversity loss. To counteract the ongoing decline of biodiversity in Swiss grasslands, the dry grasslands of national importance, comprising a total of 3631 sites across Switzerland (0.5% of its total area) were legally protected in 2010. These grassland sites represent various vegetation types and cover a wide elevational gradient. From 1995 to 2006, several thousand quasi-permanent vegetation plots of 28 m 2 were surveyed in the nationally important dry grassland sites. For each plot, GPS coordinates and a metric measure of post-processed GPS inaccuracy were recorded. In a set of 384 sites, 538 of the historical plots were resurveyed between 2011 and 2017. We tested the effects of GPS inaccuracy and elevation on temporal changes of species richness, species turnover and mean ecological indicator values. Overall, mean indicator values for light and stress significantly decreased, and those for moisture, nutrients and ruderality significantly increased within only one decade. However, the temporal change of the mean indicator values for nutrients and moisture was more pronounced at higher than at lower elevation, indicating a particularly strong decrease of habitat quality at high elevation sites. While changes of in mean indicator values were largely robust to relocation error, the temporal turnover of key species significantly increased with increasing GPS inaccuracy. These results indicate that quasi-permanent plots are suitable to study changes in mean indicator values, but probably not to compare species composition and turnover across time.
Die Schweiz hat sich verpflichtet, ihre große biologische Vielfalt zu schützen und den Lebensraum... more Die Schweiz hat sich verpflichtet, ihre große biologische Vielfalt zu schützen und den Lebensraumverlust und das Aussterben bedrohter Arten zu unterbinden. Deshalb hat die Schweiz unter anderem seit Beginn der 1990er-Jahre rund 6.000 »Objekte von nationaler Bedeutung« ausgewiesen, darunter Hoch-und Flachmoore, Trockenwiesen und-weiden (TWW), Auen und Amphibienlaichgebiete. Die Wirkungskontrolle Biotopschutz ist ein 2011 langfristig angelegtes Programm zum Monitoring dieser Lebensräume. Luftbildanalysen und Felderhebungen bilden die Datengrundlage, um Veränderungen in den Biotopen von nationaler Bedeutung aufzuzeigen und die Wirksamkeit der Schutzmaßnahmen zu kontrollieren. Analysen zeigen, dass Moore und TWW zunehmend verbuschen, Moore trockener und nährstoffreicher werden und die lokale Anzahl der Amphibienarten abnimmt. Um diesen Trend, und damit den Lebensraum-und Artenverlust aufzuhalten, sollten die Schutzbemühungen auf nationaler Ebene möglichst rasch verstärkt werden.
To assess whether short-term changes in mire vegetation can be detected using the phytosociologic... more To assess whether short-term changes in mire vegetation can be detected using the phytosociological approach, paired vegetation relevés from two surveys of 112 mire sites of Switzerland were assigned to phytosociological alliances through a numerical approach. About 30% of the plots were assigned to different alliances in the two surveys. These transitions were analysed based on species frequencies and interpreted ecologically using Landolt's indicator values. Transitions between different alliances were more frequently related to the appearance of new species rather than to the disappearance of species. Transitions from and to peat bog communities were frequent. Many plots with fen vegetation were transformed into other wetland types. Fen-grassland increased in abundance, mainly at the cost of small-sedge fens. To reestablish the function of the Swiss mires as peat producers, we recommend to raise the mean summer water table to a maximum depth of 10 cm.
How may Landolt indicator values be re-calibrated to improve the performance of predictive models... more How may Landolt indicator values be re-calibrated to improve the performance of predictive models? Location: Mires Gross Moos Schwändital (1250 m a.s.l.) in the Prealps, Burgmoos (465 m. a.s.l.) on the Central Plateau and La Burtignière (1000 m a.s.l.) in the Jura, Switzerland. Methods: Habitat distribution models based on high resolution remotely sensed data and vegetation field data are applied to monitor 130 mires. Instead of plant species or communities we used mean indicator values of vegetation records as response variables. To improve the differential power of indicator values for wetland habitat conditions, we calibrated these values using field data. Different methods were tested with our predictive models in three mires to see which calibration method is best in enhancing model performance. To assess the effect of the uneven distribution of vegetation records along environmental gradients, calibrations based on random and evenly distributed samples were compared. As a test of the predictive power of the models we used r 2 between ground truth and model prediction. This approach is illustrated through an application with nutrient indicator values in the mire La Burtignière. Results: Model performances were not the same for the three mires. The predictive power was better for the nutrient values, soil reaction and humus values than for light and moisture values. 2000 records were sufficient as basis for re-calibration. Models based on original Landolt indicator values were overall the weakest compared with re-calibrated values. By comparing the predictive power of Models based on randomly or evenly selected records were about equally predictive. Conclusions: 1. A habitat-specific re-calibration of the Landolt indicator values enhances the predictive mapping of the Swiss mire ecosystems. 2. The re-calibration based on weighted averaging gives a better performance than the one based on Gaussian logistic regression. 3. The uneven distribution of indicator values due to the over-representation of mire habitats does not hamper model performance. 4. 2000 vegetation records are a sufficient basis for an optimal re-calibration of the vegetation types. An illustration of the method is given by using the soil fertility pattern of the mire La Burtignière.
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