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9 results on '"Bedolla, Angéline"'

1. Observer-driven pseudoturnover in vegetation monitoring is context-dependent but does not affect ecological inference

Author

Boch, Steffen, Küchler, Helen, Küchler, Meinrad, Bedolla, Angéline, Ecker, Klaus T., Graf, Ulrich H., Moser, Tobias, Holderegger, Rolf, and Bergamini, Ariel

Subjects
pseudoturnover, fen, vegetation survey, inter-observer difference, dry grassland, ecological indicator value, flood plain, long-term biodiversity monitoring, observer error, raised bog
Abstract

Aims Resurveys of vegetation plots are prone to several errors that can result in misleading conclusions. Minimizing such errors and finding alternative approaches for analyzing resurvey data are therefore important. We focused on inter-observer error and excluded other sources of variation. Our main questions were: How large is the inter-observer error (i.e. pseudoturnover) in vegetation surveys, and can it be reduced by simple data aggregation approaches? Which factors are affecting pseudoturnover and does it vary between morphological species groups or change over time? Is ecological inference robust against inter-observer differences? Location Switzerland. Methods Over seven years, we double-surveyed a total of 224 plots that were marked once in the field and then sampled by two observers independently on the same day. Both observers conducted full vegetation surveys, recording all vascular plant species, their cover, and additional plot information. We then calculated mean ecological indicator values and pseudoturnover. Results Average pseudoturnover was 29% when raw species lists were compared. However, by applying simple aggregation steps to the species list, pseudoturnover was reduced to 17%. Pseudoturnover further varied among habitat types and declined over the years, indicating a training effect among observers. Most overlooked taxa, responsible for pseudoturnover, had low cover values. Mean ecological indicator values were robust against inter-observer differences. Conclusions To minimize pseudoturnover, we suggest continuous training of observers and species-list aggregation prior to analysis. As mean ecological indicator values were robust against inter-observer differences, we conclude that they can provide a reliable estimate of temporal vegetation and ecological changes., Applied Vegetation Science, 25 (3), ISSN:1402-2001, ISSN:1654-109X

Published
2022

3. Response of Swiss forests to management and climate change in the last 60years

Author

Küchler, Meinrad, Küchler, Helen, Bedolla, Angéline, Wohlgemuth, Thomas, Küchler, Meinrad, Küchler, Helen, Bedolla, Angéline, and Wohlgemuth, Thomas

Abstract

Context : Forest vegetation is forecasted to shift upslope several hundred metres by 2100 due to climate warming. However, only a small number of detailed assessments in selected regions have confirmed a climate response on the part of forest vegetation. Aim s : This study aimed to analyse the relative contributions of temperature and other factors to range shifts in forest vegetation by comparing old and revisited relevés in Swiss forests. Methods : In order to investigate such range shifts, we revisited 451 relevé plots in forests in all parts of Switzerland. Collected data comprise two independent samples, one dating from the 1950s (age 60 sample) on 126 plots and the other dating from the 1990s (age 15 sample) on 325 plots. We defined an indicator value for elevation to estimate the upslope and downslope range shifts of forest species. The influence of different site factors on range shifts was assessed by variance partitioning using Landolt's (2010) averaged species indicator values. Vegetation changes were analysed by balancing both increasing and decreasing frequencies of plant species. Results : Our findings show significant differences between the two survey periods, where the averaged species indicator for elevation varied greatly in both the age-60 and the age-15 samples. In addition, a significant upslope shift in the herbaceous forest layer (herbs and tree regeneration) of about 10m per decade since the mid-twentieth century is evident. Downslope shifts were detected in the shrub/tree layer at lower elevations, which may be explained by factors other than climate warming. Conclusions : To date, the impact of global warming on tree species composition in Swiss forests has been weaker in comparison to the effects arising from forest management and land use change. Understorey vegetation, however, shows a strong signal of upslope shift that may be explained most adequately by a combination of climate change and other factors.

Published
2021

4. Regeneration potential of a degraded alpine mountain bog: complex regeneration patterns after grazing cessation and partial rewetting.

Author

Graf, Ulrich H., Bergamini, Ariel, Bedolla, Angéline, Boch, Steffen, Küchler, Helen, Küchler, Meinrad, and Ecker, Klaus

Abstract

A typical degraded mountain bog in the Swiss Alps was restored by cessation of grazing and partial rewetting. We observed the development of the vegetation over 15 years, starting immediately after the grazing cessation (4 years before rewetting). Cessation of grazing stimulated the recolonisation of bare peat and the establishment of bryophytes. While many typical bog forest species benefited from grazing cessation, the relative abundance of Cyperaceae decreased. Rewetting (in our case: closing ditches with sheet piles and filling them with sawdust) as an additional restoration measure, had a stabilising effect on most environmental factors (e.g. water availability, soil aeration). Furthermore, rewetting had a stabilising effect on stress tolerators and promoted typical species of bog hummocks and hollows. The abundances of species of nearly all groups changed far less dynamically in the rewetted area than in the area that remained drained. It turned out that cessation of grazing as the only restoration measure was insufficient to maintain the vegetation of bogs, whereas the combination of grazing cessation and rewetting directed the site towards the desired development. However, even eleven years after rewetting and 15 years after cessation of grazing, the site had not yet reached a state that was close to an undisturbed alpine bog. [ABSTRACT FROM AUTHOR]

Published
2022
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7. Reaktion des Schweizer Waldes auf Nutzung und Klimawandel: Schlussbericht im Programm 'Wald und Klimawandel'

Author

Küchler, Meinrad, Küchler, Helen, and Bedolla, Angéline

Subjects
Klimawandel, Waldvegetation, Zeigerwerte
Abstract

Die Veränderung der Schweizer Waldvegetation wurde anhand von wiederholten Vegetationsaufnahmen untersucht, um die Bedeutung des Klimawandels im Verhältnis zu anderen Faktoren zu schätzen. Die beobachteten Änderungen der Anteile einzelner Baumarten am Bestand und die Änderungen der Höhenverteilungen konnten mit Einflüssen erklärt werden, die nicht vom Klima abhängen. Die Zeigerwertanalyse der Krautvegetation ergab jedoch eine Höhenverschiebung, welche nur teilweise unabhängig von einer Klimaerwärmung erklärt werden konnte. Die Höhenverschiebung der Vegetation war geringer als die von Klimaprojektionen vorausgesagte. Aufgrund dieser Resultate gehen wir davon aus, dass bei Eintreffen eines moderaten Klimaszenarios dem Schweizer Wald landesweit betrachtet genügend Zeit bleibt, um sich ohne grossflächige Schadensphänomene an die neuen Bedingungen anzupassen. Handlungsbedarf dürfte vor allem beim Schutz vor Naturgefahren entstehen. Nicht nur wegen des Klimawandels, aber dadurch verstärkt, drängen sich mittelfristig auch Anpassungen bei der Holzproduktion auf.

Published
2013
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9. Response of Swiss forests to management and climate change in the last 60years

Author

Küchler, Meinrad, Küchler, Helen, Bedolla, Angéline, Wohlgemuth, Thomas, Küchler, Meinrad, Küchler, Helen, Bedolla, Angéline, and Wohlgemuth, Thomas

Abstract

Context : Forest vegetation is forecasted to shift upslope several hundred metres by 2100 due to climate warming. However, only a small number of detailed assessments in selected regions have confirmed a climate response on the part of forest vegetation. Aim s : This study aimed to analyse the relative contributions of temperature and other factors to range shifts in forest vegetation by comparing old and revisited relevés in Swiss forests. Methods : In order to investigate such range shifts, we revisited 451 relevé plots in forests in all parts of Switzerland. Collected data comprise two independent samples, one dating from the 1950s (age 60 sample) on 126 plots and the other dating from the 1990s (age 15 sample) on 325 plots. We defined an indicator value for elevation to estimate the upslope and downslope range shifts of forest species. The influence of different site factors on range shifts was assessed by variance partitioning using Landolt's (2010) averaged species indicator values. Vegetation changes were analysed by balancing both increasing and decreasing frequencies of plant species. Results : Our findings show significant differences between the two survey periods, where the averaged species indicator for elevation varied greatly in both the age-60 and the age-15 samples. In addition, a significant upslope shift in the herbaceous forest layer (herbs and tree regeneration) of about 10m per decade since the mid-twentieth century is evident. Downslope shifts were detected in the shrub/tree layer at lower elevations, which may be explained by factors other than climate warming. Conclusions : To date, the impact of global warming on tree species composition in Swiss forests has been weaker in comparison to the effects arising from forest management and land use change. Understorey vegetation, however, shows a strong signal of upslope shift that may be explained most adequately by a combination of climate change and other factors.

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