Andreas Gigon - Academia.edu (original) (raw)
Papers by Andreas Gigon
Handbuch der Umweltwissenschaften, Jul 13, 2004
Die Frage nach der Stabilitat gehort zu den grosen, zentralen Fragen in der Okologie. Uber den Be... more Die Frage nach der Stabilitat gehort zu den grosen, zentralen Fragen in der Okologie. Uber den Begriff der Stabilitat herrscht eine derartige Verwirrung, dass er vermieden werden sollte. Es wird die Verwendung des Begriffes Stabilitatseigenschaften vorgeschlagen. Es kann zwischen naturlichen und anthropogenen Stabilitats- und Instabilitatseigenschaften unterschieden werden. Aufgrund des dynamischen Verhaltens von okologischen Kenngrosen und des Vorkommens oder Fehlens von Storfaktoren konnen die Stabilitatseigenschaften in die folgenden Typen eingeteilt werden: Konstanz, Zyklizitat, Resistenz und Resilienz (Elastizitat). Eine weitere, besondere Stabilitatseigenschaft ist die Persistenz: Fortbestehen eines okologischen Systems als identifizierbare Einheit. Analog konnen auch die Instabilitatseigenschaften in sechs Typen eingeteilt werden. Zu allen Typen werden Beispiele aus der Feldokologie gegeben. Alle Typen von Stabilitats- wie Instabilitatseigenschaften konnen vom Menschen je nach Standpunkt positiv oder negativ bewertet werden. Als Hilfsmittel fur die Beschreibung der Stabilitatseigenschaften wird eine Checkliste mit 10 Punkten gegeben. Sie betreffen u. a. den raumzeitlichen Rahmen, die Referenzdynamik, die quantitativen Mase und statistische Verfahren zur Beurteilung von Systemveranderungen. Auf die letztgenannten Aspekte wird speziell eingegangen. An zwei Fallbeispielen wird das Dargelegte weiter erlautert. Moglichkeiten und Grenzen der Beurteilung von Stabilitatseigenschaften werden aufgezeigt. Keywords: Diversitatsindex; Dynamik; Eingriff; Elastizitat; Erholung; Evenness; Instabilitatseigenschaft; Kalkung; Konstanz; Mosaik-Zyklus-Konzept; Okologie; Okosystem; Persistenz; Rauber-Beute-System; Resilienz; Resistenz; Simulation; Stabilitat; Standardabweichung; Storung; Sukzession; System; Varianz; Zyklizitat
Botanica Helvetica, Dec 1, 2005
This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information, please consult the Terms of use.
Journal of Vegetation Science, Feb 1, 1996
. This paper is a tribute to A.S. Watt who published his ‘Pattern and process in the plant commun... more . This paper is a tribute to A.S. Watt who published his ‘Pattern and process in the plant community’ almost 50 years ago. Watt's interpretation of the plant community “as a working mechanism, which maintains and regenerates itself” is still highly relevant, although the keywords have changed. ‘Process’ in Watt's view involves both upgrade and downgrade aspects, whereas ‘Pattern’ was not specified, neither quantified. Nowadays. process is mainly approached as ‘disturbance’, that is natural disturbance and ‘pattern’ as patch structure. Together they make up the ‘patch dynamics’ of the community. Some implications of patch dynamics for phytosociology are discussed. A ‘Wattian’ concept of the plant community combines the Gleasonian idea of individualistic behaviour of species with the Clementsian (or rather Braun‐Blanquetian) notion of community dynamics. Later work by Harper (demography), Grubb (regeneration niche) and earlier work of Sernander (forest gap dynamics) is significant for the understanding of the patch‐dynamic nature of the community.Recent interest in plant species mobility can easily be linked to the concept of patch dynamics. Examples of mobility in a limestone grassland are given and a system of mobility types is proposed.Some perspectives for the study of patch dynamics are mentioned. Numerical pattern analysis should have a more prominent place in this type of study; the significance of the study of small permanent plots in a stand is emphasized, and unprejudiced demographic studies, as well as experimental studies of small‐scale species replacement are recommended.
Phytocoenologia, Jun 23, 1997
Springer eBooks, 1987
Why do certain plants grow on certain habitats and not on others? What are the causes for florist... more Why do certain plants grow on certain habitats and not on others? What are the causes for floristic differences between plant communities? If these questions are asked for “normal”, i. e., relatively species rich constant natural or seminatural plant communities (more than 10–20 phanerogams) and if no single extreme, e. g., climatic or toxic factor or human interference occurs, the answers are whole constellations of factors (see, e. g., Billings 1974, p. 26). Then a further question arises. Which is the most important factor? In general, single factors on the ecophysiological level are sought, i. e., factors acting directly (immediately) on the plant, like for example aluminum-ion content of the soil, frost, drought, trampling, browsing etc.
Journal of Ecology, Mar 1, 1972
One of the differences between acidic and neutral or alkaline mineral soils is that in acidic soi... more One of the differences between acidic and neutral or alkaline mineral soils is that in acidic soils the predominant form in which nitrogen is available to plants through the microbial mineralization of organic soil matter is, in general, the ammonium ion, and in neutral or alkaline soils it is nitrate. The reason for this is that the activity of the nitrifying bacteria Nitrosomonas and Nitrobacter is reduced in acidic mineral soils which have a pH value of 5 0 and below and consequently (in some acidic soils) little or no nitrification takes place. The question arises as to what effect, if any, the form of nitrogen in the soil has on the growth and distribution of plants in the field. This paper reports the results of a laboratory experiment in which the responses of seedlings, grown in solution culture whose source of nitrogen was either the nitrate or the ammonium form, were measured. Five species were chosen because they were naturally restricted to acidic or to calcareous soils, or else showed wider edaphic tolerance. The nutrient solutions used were maintained at pH values of 4-2, 5-8 and 7-2, representing mean values for acidic, intermediate and circum-neutral soil types. The aim of the experiment was to test the hypothesis that some calcifuge species grow better when nitrogen is available in the ammonium form, that some calcicoles grow better when the nitrate form is available and that widely tolerant species respond equally well to either form of nitrogen. The hypothesis was formulated from (i) the theoretical consideration that, nitrogen being the nutrient element of which the greatest number of atoms is taken up from the soil (Viets Jnr 1965), its form (ionic charge and oxidation state) must have an effect on the metabolism of the plant and therefore on growth and competitive ability, and (ii) several sets of experimental evidence: the oft-quoted statement that nitrogen in acidic soils occurs predominantly in the ammonium form and in calcareous soils in the nitrate form (Jackson 1967); the mass data for crop plants showing differential response to the form of nitrogen supplied in culture media (Hewitt 1966); and the ecological implications of the work of Evers (1964) and Bogner (1968). Evers and Bogner showed differential responses of naturally occurring species in sand and solution culture. Bogner, using a range of pH values (3 3, 6O0, 8 0) and nitrogen concentrations of 98 ppm (7 x I0'3 M),
Applied Vegetation Science, May 1, 1999
ABSTRACT
Applied Vegetation Science, Feb 24, 1998
In order to stress successes in restoration and conservation of species, regionally, nationally o... more In order to stress successes in restoration and conservation of species, regionally, nationally or globally, a new instrument has been developed, the 'Blue Lists', 'registers of those Red List species that show a durable overall stabilization or increase of abundance in the region (nation, world) considered'. 'Blue Data Books' include additional information on the ecology, conservation, and promotion of the species. For describing the overall change of abundance of every individual species six categories are defined. Furthermore, the effects of nature conservation techniques (NCT) on a species are evaluated using six additional categories. In a test area of 3 431 km 2 in northern Switzerland, information was compiled on the change in abundance of the 708 Red List species of higher plants (spermatophyta) over the last 10-15 yr. Overall, 33 % of these species showed a stabilization or even increase in abundance; these are Blue List species; ca. 20 % showed a decline and for almost 50 % the change in abundance is not known. NCTs have been successfully applied to more than 50 % of all the species, at least locally. For about a further 30 %, the required NCTs are known but have not yet been tried out. If these techniques were applied on a large scale, the decline of very many species in the test area could be stopped.
Gaia (Heidelberg), Mar 1, 2000
ABSTRACT
Handbuch Naturschutz und Landschaftspflege, Jul 13, 2004
Mountain Research and Development, May 1, 1983
ABSTRACT
Biodiversity and Conservation, Jul 23, 2008
Regular mowing of grassland is often necessary for plant conservation, but uncut vegetation is ne... more Regular mowing of grassland is often necessary for plant conservation, but uncut vegetation is needed by many arthropods for overwintering. This may lead to conXicting management strategies for plant and arthropod conservation. Rotational fallows are a possible solution. They provide a spatio-temporal mosaic of mown and unmown areas that may combine beneWts to both plants and arthropods. We tested if rotational fallows enhance spider overwintering in fen meadows. Rotational fallows consisted of three adjoining strips 10 m wide and 35-50 m long. Each year, one of these strips was left unmown (fallow) in an alternating manner so that each strip was mown two out of three years. Spiders were sampled during spring with emergence traps in nine pairs of currently unmown fallow strips and completely mown reference plots. Fallows signiWcantly enhanced orb-weavers (Araneidae), sac spiders (Clubionidae) and ground spiders (Gnaphosidae). However, only 4.7% of the total variation in community composition was attributable to fallows. Community variation was larger between landscapes (34.5%) and sites (38.2%). Also diversity was much higher between landscapes (45 species) and sites (22 species) than between fallows and mown reference plots (10 species). We conclude that the Wrst priority for spider conservation is to preserve as many fen meadows in diVerent landscapes as possible. Locally, rotational fallows enhance overwintering of the above-mentioned spider families, which are sensitive to mowing in other grassland types as well. Thus, rotational fallows would probably foster spider conservation in a wide range of situations. However, stronger eVects can be expected from larger and/or older fallow areas.
Biodiversity and Conservation, Dec 14, 2008
Abstract To investigate recent changes in the floristic composition and nature conser-vation valu... more Abstract To investigate recent changes in the floristic composition and nature conser-vation value of nutrient-poor, semi-natural grasslands of the Swiss Alps, we resurveyed 151 phytosociological relevés in four regions, originally recorded between 1975 and 1985. In the original ...
Handbuch der Umweltwissenschaften, Jul 13, 2004
Die Frage nach der Stabilitat gehort zu den grosen, zentralen Fragen in der Okologie. Uber den Be... more Die Frage nach der Stabilitat gehort zu den grosen, zentralen Fragen in der Okologie. Uber den Begriff der Stabilitat herrscht eine derartige Verwirrung, dass er vermieden werden sollte. Es wird die Verwendung des Begriffes Stabilitatseigenschaften vorgeschlagen. Es kann zwischen naturlichen und anthropogenen Stabilitats- und Instabilitatseigenschaften unterschieden werden. Aufgrund des dynamischen Verhaltens von okologischen Kenngrosen und des Vorkommens oder Fehlens von Storfaktoren konnen die Stabilitatseigenschaften in die folgenden Typen eingeteilt werden: Konstanz, Zyklizitat, Resistenz und Resilienz (Elastizitat). Eine weitere, besondere Stabilitatseigenschaft ist die Persistenz: Fortbestehen eines okologischen Systems als identifizierbare Einheit. Analog konnen auch die Instabilitatseigenschaften in sechs Typen eingeteilt werden. Zu allen Typen werden Beispiele aus der Feldokologie gegeben. Alle Typen von Stabilitats- wie Instabilitatseigenschaften konnen vom Menschen je nach Standpunkt positiv oder negativ bewertet werden. Als Hilfsmittel fur die Beschreibung der Stabilitatseigenschaften wird eine Checkliste mit 10 Punkten gegeben. Sie betreffen u. a. den raumzeitlichen Rahmen, die Referenzdynamik, die quantitativen Mase und statistische Verfahren zur Beurteilung von Systemveranderungen. Auf die letztgenannten Aspekte wird speziell eingegangen. An zwei Fallbeispielen wird das Dargelegte weiter erlautert. Moglichkeiten und Grenzen der Beurteilung von Stabilitatseigenschaften werden aufgezeigt. Keywords: Diversitatsindex; Dynamik; Eingriff; Elastizitat; Erholung; Evenness; Instabilitatseigenschaft; Kalkung; Konstanz; Mosaik-Zyklus-Konzept; Okologie; Okosystem; Persistenz; Rauber-Beute-System; Resilienz; Resistenz; Simulation; Stabilitat; Standardabweichung; Storung; Sukzession; System; Varianz; Zyklizitat
Botanica Helvetica, Dec 1, 2005
This page was generated automatically upon download from the ETH Zurich Research Collection. For ... more This page was generated automatically upon download from the ETH Zurich Research Collection. For more information, please consult the Terms of use.
Journal of Vegetation Science, Feb 1, 1996
. This paper is a tribute to A.S. Watt who published his ‘Pattern and process in the plant commun... more . This paper is a tribute to A.S. Watt who published his ‘Pattern and process in the plant community’ almost 50 years ago. Watt's interpretation of the plant community “as a working mechanism, which maintains and regenerates itself” is still highly relevant, although the keywords have changed. ‘Process’ in Watt's view involves both upgrade and downgrade aspects, whereas ‘Pattern’ was not specified, neither quantified. Nowadays. process is mainly approached as ‘disturbance’, that is natural disturbance and ‘pattern’ as patch structure. Together they make up the ‘patch dynamics’ of the community. Some implications of patch dynamics for phytosociology are discussed. A ‘Wattian’ concept of the plant community combines the Gleasonian idea of individualistic behaviour of species with the Clementsian (or rather Braun‐Blanquetian) notion of community dynamics. Later work by Harper (demography), Grubb (regeneration niche) and earlier work of Sernander (forest gap dynamics) is significant for the understanding of the patch‐dynamic nature of the community.Recent interest in plant species mobility can easily be linked to the concept of patch dynamics. Examples of mobility in a limestone grassland are given and a system of mobility types is proposed.Some perspectives for the study of patch dynamics are mentioned. Numerical pattern analysis should have a more prominent place in this type of study; the significance of the study of small permanent plots in a stand is emphasized, and unprejudiced demographic studies, as well as experimental studies of small‐scale species replacement are recommended.
Phytocoenologia, Jun 23, 1997
Springer eBooks, 1987
Why do certain plants grow on certain habitats and not on others? What are the causes for florist... more Why do certain plants grow on certain habitats and not on others? What are the causes for floristic differences between plant communities? If these questions are asked for “normal”, i. e., relatively species rich constant natural or seminatural plant communities (more than 10–20 phanerogams) and if no single extreme, e. g., climatic or toxic factor or human interference occurs, the answers are whole constellations of factors (see, e. g., Billings 1974, p. 26). Then a further question arises. Which is the most important factor? In general, single factors on the ecophysiological level are sought, i. e., factors acting directly (immediately) on the plant, like for example aluminum-ion content of the soil, frost, drought, trampling, browsing etc.
Journal of Ecology, Mar 1, 1972
One of the differences between acidic and neutral or alkaline mineral soils is that in acidic soi... more One of the differences between acidic and neutral or alkaline mineral soils is that in acidic soils the predominant form in which nitrogen is available to plants through the microbial mineralization of organic soil matter is, in general, the ammonium ion, and in neutral or alkaline soils it is nitrate. The reason for this is that the activity of the nitrifying bacteria Nitrosomonas and Nitrobacter is reduced in acidic mineral soils which have a pH value of 5 0 and below and consequently (in some acidic soils) little or no nitrification takes place. The question arises as to what effect, if any, the form of nitrogen in the soil has on the growth and distribution of plants in the field. This paper reports the results of a laboratory experiment in which the responses of seedlings, grown in solution culture whose source of nitrogen was either the nitrate or the ammonium form, were measured. Five species were chosen because they were naturally restricted to acidic or to calcareous soils, or else showed wider edaphic tolerance. The nutrient solutions used were maintained at pH values of 4-2, 5-8 and 7-2, representing mean values for acidic, intermediate and circum-neutral soil types. The aim of the experiment was to test the hypothesis that some calcifuge species grow better when nitrogen is available in the ammonium form, that some calcicoles grow better when the nitrate form is available and that widely tolerant species respond equally well to either form of nitrogen. The hypothesis was formulated from (i) the theoretical consideration that, nitrogen being the nutrient element of which the greatest number of atoms is taken up from the soil (Viets Jnr 1965), its form (ionic charge and oxidation state) must have an effect on the metabolism of the plant and therefore on growth and competitive ability, and (ii) several sets of experimental evidence: the oft-quoted statement that nitrogen in acidic soils occurs predominantly in the ammonium form and in calcareous soils in the nitrate form (Jackson 1967); the mass data for crop plants showing differential response to the form of nitrogen supplied in culture media (Hewitt 1966); and the ecological implications of the work of Evers (1964) and Bogner (1968). Evers and Bogner showed differential responses of naturally occurring species in sand and solution culture. Bogner, using a range of pH values (3 3, 6O0, 8 0) and nitrogen concentrations of 98 ppm (7 x I0'3 M),
Applied Vegetation Science, May 1, 1999
ABSTRACT
Applied Vegetation Science, Feb 24, 1998
In order to stress successes in restoration and conservation of species, regionally, nationally o... more In order to stress successes in restoration and conservation of species, regionally, nationally or globally, a new instrument has been developed, the 'Blue Lists', 'registers of those Red List species that show a durable overall stabilization or increase of abundance in the region (nation, world) considered'. 'Blue Data Books' include additional information on the ecology, conservation, and promotion of the species. For describing the overall change of abundance of every individual species six categories are defined. Furthermore, the effects of nature conservation techniques (NCT) on a species are evaluated using six additional categories. In a test area of 3 431 km 2 in northern Switzerland, information was compiled on the change in abundance of the 708 Red List species of higher plants (spermatophyta) over the last 10-15 yr. Overall, 33 % of these species showed a stabilization or even increase in abundance; these are Blue List species; ca. 20 % showed a decline and for almost 50 % the change in abundance is not known. NCTs have been successfully applied to more than 50 % of all the species, at least locally. For about a further 30 %, the required NCTs are known but have not yet been tried out. If these techniques were applied on a large scale, the decline of very many species in the test area could be stopped.
Gaia (Heidelberg), Mar 1, 2000
ABSTRACT
Handbuch Naturschutz und Landschaftspflege, Jul 13, 2004
Mountain Research and Development, May 1, 1983
ABSTRACT
Biodiversity and Conservation, Jul 23, 2008
Regular mowing of grassland is often necessary for plant conservation, but uncut vegetation is ne... more Regular mowing of grassland is often necessary for plant conservation, but uncut vegetation is needed by many arthropods for overwintering. This may lead to conXicting management strategies for plant and arthropod conservation. Rotational fallows are a possible solution. They provide a spatio-temporal mosaic of mown and unmown areas that may combine beneWts to both plants and arthropods. We tested if rotational fallows enhance spider overwintering in fen meadows. Rotational fallows consisted of three adjoining strips 10 m wide and 35-50 m long. Each year, one of these strips was left unmown (fallow) in an alternating manner so that each strip was mown two out of three years. Spiders were sampled during spring with emergence traps in nine pairs of currently unmown fallow strips and completely mown reference plots. Fallows signiWcantly enhanced orb-weavers (Araneidae), sac spiders (Clubionidae) and ground spiders (Gnaphosidae). However, only 4.7% of the total variation in community composition was attributable to fallows. Community variation was larger between landscapes (34.5%) and sites (38.2%). Also diversity was much higher between landscapes (45 species) and sites (22 species) than between fallows and mown reference plots (10 species). We conclude that the Wrst priority for spider conservation is to preserve as many fen meadows in diVerent landscapes as possible. Locally, rotational fallows enhance overwintering of the above-mentioned spider families, which are sensitive to mowing in other grassland types as well. Thus, rotational fallows would probably foster spider conservation in a wide range of situations. However, stronger eVects can be expected from larger and/or older fallow areas.
Biodiversity and Conservation, Dec 14, 2008
Abstract To investigate recent changes in the floristic composition and nature conser-vation valu... more Abstract To investigate recent changes in the floristic composition and nature conser-vation value of nutrient-poor, semi-natural grasslands of the Swiss Alps, we resurveyed 151 phytosociological relevés in four regions, originally recorded between 1975 and 1985. In the original ...