Tanja Milotic | Ghent University (original) (raw)
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ZooKeys
In this data paper three datasets are described containing GPS tracking and acceleration data of ... more In this data paper three datasets are described containing GPS tracking and acceleration data of Western marsh harriers (Circus aeruginosus) breeding in Belgium and the Netherlands. The Western marsh harrier is included as a threatened bird species in Annex I of the European Bird Directive due to the steep decline in population densities. In order to collect data of habitat use and migration behaviour, Western marsh harriers were equipped with light-weight solar powered GPS trackers developed by the Institute for Biodiversity and Ecosystem Dynamics (IBED) at the University of Amsterdam (University of Amsterdam Bird Tracking System, UvA-BiTS). These trackers automatically collect and store data on the bird’s activity and 3D position in time and transmit these data to ground stations. The datasets were collected by the Research Institute for Nature and Forest (INBO) and the Dutch Montagu’s Harrier Foundation. Tracked Western marsh harriers were breeding in the northeast of the Dutch p...
Journal of Biogeography, 2018
Aim In several ecosystems, the diversity of functional species traits has been shown to have a st... more Aim In several ecosystems, the diversity of functional species traits has been shown to have a stronger effect on ecosystem functioning than taxonomic diversity alone. However, few studies have explored this idea at a large geographical scale. In a multisite experiment, we unravelled the relationship between ecosystem function and functional completeness of species assemblages using dung beetles as a model group, focusing on dung removal and secondary seed dispersal. Location Seventeen grassland locations across the Western Palaearctic. Methods We used a randomized block design with different exclosure types to control the dung and seed removing activities of individual functional groups of the local dung beetle assemblage. We classified dung beetle species according to resource specialization and into functional groups based on dung processing behaviour (dwellers, tunnellers, rollers) and body size (small, large). Additionally, we assessed the role of other soil macro‐invertebrates...
Journal of Biogeography, 2018
Aim In several ecosystems, the diversity of functional species traits has been shown to have a st... more Aim In several ecosystems, the diversity of functional species traits has been shown to have a stronger effect on ecosystem functioning than taxonomic diversity alone. However, few studies have explored this idea at a large geographical scale. In a multisite experiment, we unravelled the relationship between ecosystem function and functional completeness of species assemblages using dung beetles as a model group, focusing on dung removal and secondary seed dispersal. Location Seventeen grassland locations across the Western Palaearctic. Methods We used a randomized block design with different exclosure types to control the dung and seed removing activities of individual functional groups of the local dung beetle assemblage. We classified dung beetle species according to resource specialization and into functional groups based on dung processing behaviour (dwellers, tunnellers, rollers) and body size (small, large). Additionally, we assessed the role of other soil macro‐invertebrates...
Dung beetles form an insect group that fulfils important functions in terrestrial ecosystems thro... more Dung beetles form an insect group that fulfils important functions in terrestrial ecosystems throughout the world. These include nutrient cycling through dung removal, soil bioturbation, plant growth, secondary seed dispersal and parasite control. We conducted field experiments at two sites in the northern hemisphere temperate region in which dung removal and secondary seed dispersal were assessed. Dung beetles were classified in three functional groups, depending on their size and dung manipulation method: dwellers, large and small tunnelers. Other soil inhabiting fauna were included as a fourth functional group. Dung removal and seed dispersal by each individual functional group and combinations thereof were estimated in exclusion experiments using different dung types. Dwellers were the most diverse and abundant group, but tunnelers were dominant in terms of biomass. All dung beetle functional groups had a clear preference for fresh dung. The ecosystem services in dung removal and secondary seed dispersal provided by dung beetles were significant and differed between functional groups. Although in absolute numbers more dwellers were found, large tunnelers were disproportionally important for dung burial and seed removal. In the absence of dung beetles, other soil inhabiting fauna, such as earthworms, partly took over the dung decomposing role of dung beetles while most dung was processed when all native functional groups were present. Our results, therefore, emphasize the need to conserve functionally complete dung ecosystems in order to maintain full ecosystem functioning.
Endozoochory is one of the main drivers shaping temperate grassland communities by maintaining pl... more Endozoochory is one of the main drivers shaping temperate grassland communities by maintaining plant populations of its constituents and enabling plants to colonize new habitats. Successful endozoochorous dispersal implies that seeds not only get consumed and survive the digestive tract but are also able to develop into viable seedlings in a dung environment. 2.We experimentally assessed the germination probability and timing of 15 annual and perennial temperate European grassland species in cattle and horse dung and in different climatic conditions (greenhouse and outdoor conditions). 3.Interspecific variation in germinability and germination timing are found, while life strategy had only an effect on germination timing. We found adverse effects of both cattle and horse dung on the germination characteristics of all tested grassland species, but the effects of cattle dung were more pronounced. In comparison with the control treatment, fewer seeds emerged in dung and more time was needed to germinate. Also, germination metrics clearly differed between the artificial greenhouse and outdoor conditions, with generally a lower germinability in outdoor conditions. 4.According to our results, a large cost seems to be associated with endozoochorous dispersal in this stage of the life cycle, as seed dispersal effectiveness strongly depends on the quality of the deposition site with a lowered survival and germination probability when seeds are deposited in dung. This article is protected by copyright. All rights reserved.
Endozoochory is a potential dispersal mode for numerous plant species. Although germination follo... more Endozoochory is a potential dispersal mode for numerous plant species. Although germination following endozoochory is well-documented, less is known about the costs and benefits associated with this dispersal mode in later life stages of established plants. The chemical and physical nature of dung differs between herbivores and might have specific effects on seedling establishment, growth and flowering. We conducted a growth experiment using 12 temperate grassland species with a known potential for endozoochory. We studied the effects of cattle and horse dung on the juvenile, growth and reproductive phase. Being a ruminant and a hindgut fermenter, respectively, cattle and horses are two physiologically contrasting herbivore species, producing structurally quite different dung types. They are additionally interesting model species as both are frequently introduced in temperate Europe grassland management. Seedling biomass and growth rate, height, ramification, flowering and biomass of grown plants were measured in an attempt to quantify the benefits of endozoochorously dispersed seeds compared to seeds dispersed by other means and thus growing in a virtually dung-free environment. Few species were affected by the presence of dung in the juvenile phase while most species generally benefitted from being deposited in dung in later life stages. Positive responses of Agrostis capillaris, Agrostis stolonifera, Alopecurus myosuroides, Helianthemum nummularium, Poa annua, Trifolium repens and Trifolium pratense were found, while dung had a negative effect on Juncus bufonius. The initial losses of viable seeds through the digestive system of herbivores might, therefore, be partially compensated by enhanced growth and flowering in some species.
Endozoochory of temperate grassland species is a widespread phenomenon and may accelerate and/or ... more Endozoochory of temperate grassland species is a widespread phenomenon and may accelerate and/or increase germination in some plant species. However, the mechanisms causing this altered germination success are only partly understood. In this study, germination of common grassland species was evaluated after simulated herbivore digestion in a standardized lab environment. Ruminants (cattle) and hindgut fermenters (horses) were used as model organisms in this simulation experiment. Three major digestive processes were studied through mechanical, thermal and chemical treatments of the seeds simulating mastication, body temperature and digestive fluids, respectively. Congeneric groups of annuals and perennials were tested with 15 species belonging to the plant families Cistaceae, Cyperaceae, Fabaceae, Poaceae and Urticaceae. No differences between the impact of the simulated herbivore gut environments of cattle and horses could be found, but major differences in germination behaviour were found among plant species. For most of the tested plant species, treatments had a decelerating and inhibiting effect on germination compared to the untreated seeds. However, species of the Cistaceae and Fabaceae benefitted from mechanical treatments. Species of the Cyperaceae and Poaceae were hardly impaired by any of the treatments and even germinated better after chemical treatments. Thermal treatments, simulating the body temperature, prohibited germination in most cases. The germination success of Urtica urens was significantly higher after all treatments, which suggests seeds are specifically well adapted to gut passage, and hence to endozoochorous dispersal.
Instituut voor Natuur-en Bosonderzoek Het Instituut voor Natuur-en Bosonderzoek (INBO) is het Vla... more Instituut voor Natuur-en Bosonderzoek Het Instituut voor Natuur-en Bosonderzoek (INBO) is het Vlaams onderzoeks-en kenniscentrum voor natuur en het duurzaam beheer en gebruik ervan. Het INBO verricht onderzoek en levert kennis aan al wie het beleid voorbereidt, uitvoert of erin geïnteresseerd is.
Grazing is a commonly used management technique, e.g. to stop the expansion of competitive plant ... more Grazing is a commonly used management technique, e.g. to stop the expansion of competitive plant species, to enlarge plant species richness or to create spatial heterogeneity, favouring biodiversity in general. In order to accomplish an effective and efficient grazing management both herbivore and manager needs have to be accounted for. Several ungulate species are commonly used in nature. Several intra- and interspecific dissimilarities in animal morphology and physiology appear, and important differences in animal nutritional requirements and habitat selection are found. Therefore, not all herbivore species will be equally suited to fulfil management needs.
Because of the considerable variation in biological (e.g. floristic composition), physical (e.g. scrub density, forage yield, water availability, forage accessibility) and chemical characteristics (forage quality), not all terrains are equally fit for all herbivores. This reveals the necessity to determine the carrying capacity of the system. Therefore a grazing capacity model (GCM) is being developed. This dynamic model considers crucial variables on both the terrain and the grazer level, such as forage yield, forage quality, palatability of plant species, accessibility of the area, soil erosion vulnerability, animal nutritive requirements, animal behaviour and general habitat health. It predicts the optimal grazer species and density, taking the seasonal variation in animal needs and terrain characteristics into account. In this short paper the outline of the model is presented together with the results of two case studies in coastal and estuarine special protection zones within the Natura 2000 network in Flanders (Nature Reserves Westhoek and IJzermonding).
The model clearly reveals that grazing capacity is a dynamic feature, with seasonal, inter-annual, interspecific as well as intraspecific variation, differentiating GC in space, time and between herbivores. Additionally the GC outcome varies according to the used forage variable; lowest feasible Animal Unit numbers are generally found when using digestible energy as forage need variable, while phytomass generally results in significantly higher GC outcomes. Since all three forage need variables are relevant to the herbivore under consideration, it can be concluded that the manager should consistently follow the model at the lower predicted number of AU’s per season.
For the studied coastal areas, the optimal herd densities per season show large differences. Model estimates of number of AU’s in winter (and spring) are far lower then in summer and autumn, suggesting that year round grazing is feasible only when a seasonally differentiated herd density is applied. The best grazer choice depends on food availability and quality as well as on specific management needs.
NATUUR. FOCUS, Jan 1, 2008
Het uitbreiden van bossen kan door boompjes te planten of door terreinen spontaan te laten verbos... more Het uitbreiden van bossen kan door boompjes te planten of door terreinen spontaan te laten verbossen. Bij spontane verbossing kan door de inzet van grote grazers de vegetatie-ontwikkeling sterk beïnvloed worden. Op een reeks voormalige landbouwgronden onderzochten we onder welke omstandigheden en in welk patroon bosontwikkeling optreedt bij extensieve begrazing. Onder begrazing gebeurt bosontwikkeling hoofdzakelijk via struwelen en ruigtes, waarin jonge bomen beschermd zijn tegen vraat. Door een combinatie van betreding en selectief graasgedrag zijn grote grazers eveneens in staat om bosontwikkeling op gang te brengen. Dit artikel brengt door de boompjes het toekomstig bos in kaart.
Instituut voor Natuur-en Bosonderzoek Instituut voor Natuur-en Bosonderzoek Het Instituut voor Na... more Instituut voor Natuur-en Bosonderzoek Instituut voor Natuur-en Bosonderzoek Het Instituut voor Natuur-en Bosonderzoek (INBO) is het Vlaams onderzoeks-en kenniscentrum voor natuur en het duurzame beheer en gebruik ervan. Het INBO verricht onderzoek en levert kennis aan al wie het beleid voorbereidt, uitvoert of erin geïnteresseerd is. Wijze van citeren: Van Uytvanck J, Milotic T, Hoffmann M. (2008). Effecten van extensieve begrazing op spontane verbossingsprocessen -middellange en lange termijneffecten. Rapporten van het Instituut voor Natuur-en Bosonderzoek 2008 (INBO.R.2008.53). Instituut voor Natuur-en Bosonderzoek, Brussel. depotnr D/2008/3241/386 rapportnr INBO.R.2008.53
Grass and Forage Science, Jan 1, 2010
The effects of grazing by sheep at a stocking density of c. 1 sheep ha-1 from August to April on ... more The effects of grazing by sheep at a stocking density of c. 1 sheep ha-1 from August to April on total vegetation cover, diversity of plant species, above-ground plant biomass and concentration of crude protein, neutral-detergent fibre and acid-detergent fibre of salt-marsh vegetation was assessed over a 2-year period on a newly created salt-marsh area on the Belgian coast. Assessments were made in both grazed and ungrazed areas in four elevation zones: low, intermediate, high and floodmark zone. The cover of dominant salt-marsh species (Salicornia europaea, Limonium vulgare and Elymus athericus), plant diversity, plant biomass and chemical composition of herbage were compared between grazed and ungrazed plots, and between 2005 (initial state) and 2007 (after a 2-year grazing period) using paired t-tests. Grazing by sheep maintained plant diversity in the high zone, whereas diversity decreased in the ungrazed plots. Grazing had no apparent effect on total vegetation cover and composition of the vegetation. Concentration of crude protein in herbage increased and that of neutral-detergent fibre decreased in the high and intermediate zones. Expansion of the dominant species of the high zone, E. athericus, was not affected by the stocking density used in the study.
Ecological Restoration …, Jan 1, 2000
Ecological Restoration in …, Jan 1, 2000
Ecological Restoration …, Jan 1, 2000
ZooKeys
In this data paper three datasets are described containing GPS tracking and acceleration data of ... more In this data paper three datasets are described containing GPS tracking and acceleration data of Western marsh harriers (Circus aeruginosus) breeding in Belgium and the Netherlands. The Western marsh harrier is included as a threatened bird species in Annex I of the European Bird Directive due to the steep decline in population densities. In order to collect data of habitat use and migration behaviour, Western marsh harriers were equipped with light-weight solar powered GPS trackers developed by the Institute for Biodiversity and Ecosystem Dynamics (IBED) at the University of Amsterdam (University of Amsterdam Bird Tracking System, UvA-BiTS). These trackers automatically collect and store data on the bird’s activity and 3D position in time and transmit these data to ground stations. The datasets were collected by the Research Institute for Nature and Forest (INBO) and the Dutch Montagu’s Harrier Foundation. Tracked Western marsh harriers were breeding in the northeast of the Dutch p...
Journal of Biogeography, 2018
Aim In several ecosystems, the diversity of functional species traits has been shown to have a st... more Aim In several ecosystems, the diversity of functional species traits has been shown to have a stronger effect on ecosystem functioning than taxonomic diversity alone. However, few studies have explored this idea at a large geographical scale. In a multisite experiment, we unravelled the relationship between ecosystem function and functional completeness of species assemblages using dung beetles as a model group, focusing on dung removal and secondary seed dispersal. Location Seventeen grassland locations across the Western Palaearctic. Methods We used a randomized block design with different exclosure types to control the dung and seed removing activities of individual functional groups of the local dung beetle assemblage. We classified dung beetle species according to resource specialization and into functional groups based on dung processing behaviour (dwellers, tunnellers, rollers) and body size (small, large). Additionally, we assessed the role of other soil macro‐invertebrates...
Journal of Biogeography, 2018
Aim In several ecosystems, the diversity of functional species traits has been shown to have a st... more Aim In several ecosystems, the diversity of functional species traits has been shown to have a stronger effect on ecosystem functioning than taxonomic diversity alone. However, few studies have explored this idea at a large geographical scale. In a multisite experiment, we unravelled the relationship between ecosystem function and functional completeness of species assemblages using dung beetles as a model group, focusing on dung removal and secondary seed dispersal. Location Seventeen grassland locations across the Western Palaearctic. Methods We used a randomized block design with different exclosure types to control the dung and seed removing activities of individual functional groups of the local dung beetle assemblage. We classified dung beetle species according to resource specialization and into functional groups based on dung processing behaviour (dwellers, tunnellers, rollers) and body size (small, large). Additionally, we assessed the role of other soil macro‐invertebrates...
Dung beetles form an insect group that fulfils important functions in terrestrial ecosystems thro... more Dung beetles form an insect group that fulfils important functions in terrestrial ecosystems throughout the world. These include nutrient cycling through dung removal, soil bioturbation, plant growth, secondary seed dispersal and parasite control. We conducted field experiments at two sites in the northern hemisphere temperate region in which dung removal and secondary seed dispersal were assessed. Dung beetles were classified in three functional groups, depending on their size and dung manipulation method: dwellers, large and small tunnelers. Other soil inhabiting fauna were included as a fourth functional group. Dung removal and seed dispersal by each individual functional group and combinations thereof were estimated in exclusion experiments using different dung types. Dwellers were the most diverse and abundant group, but tunnelers were dominant in terms of biomass. All dung beetle functional groups had a clear preference for fresh dung. The ecosystem services in dung removal and secondary seed dispersal provided by dung beetles were significant and differed between functional groups. Although in absolute numbers more dwellers were found, large tunnelers were disproportionally important for dung burial and seed removal. In the absence of dung beetles, other soil inhabiting fauna, such as earthworms, partly took over the dung decomposing role of dung beetles while most dung was processed when all native functional groups were present. Our results, therefore, emphasize the need to conserve functionally complete dung ecosystems in order to maintain full ecosystem functioning.
Endozoochory is one of the main drivers shaping temperate grassland communities by maintaining pl... more Endozoochory is one of the main drivers shaping temperate grassland communities by maintaining plant populations of its constituents and enabling plants to colonize new habitats. Successful endozoochorous dispersal implies that seeds not only get consumed and survive the digestive tract but are also able to develop into viable seedlings in a dung environment. 2.We experimentally assessed the germination probability and timing of 15 annual and perennial temperate European grassland species in cattle and horse dung and in different climatic conditions (greenhouse and outdoor conditions). 3.Interspecific variation in germinability and germination timing are found, while life strategy had only an effect on germination timing. We found adverse effects of both cattle and horse dung on the germination characteristics of all tested grassland species, but the effects of cattle dung were more pronounced. In comparison with the control treatment, fewer seeds emerged in dung and more time was needed to germinate. Also, germination metrics clearly differed between the artificial greenhouse and outdoor conditions, with generally a lower germinability in outdoor conditions. 4.According to our results, a large cost seems to be associated with endozoochorous dispersal in this stage of the life cycle, as seed dispersal effectiveness strongly depends on the quality of the deposition site with a lowered survival and germination probability when seeds are deposited in dung. This article is protected by copyright. All rights reserved.
Endozoochory is a potential dispersal mode for numerous plant species. Although germination follo... more Endozoochory is a potential dispersal mode for numerous plant species. Although germination following endozoochory is well-documented, less is known about the costs and benefits associated with this dispersal mode in later life stages of established plants. The chemical and physical nature of dung differs between herbivores and might have specific effects on seedling establishment, growth and flowering. We conducted a growth experiment using 12 temperate grassland species with a known potential for endozoochory. We studied the effects of cattle and horse dung on the juvenile, growth and reproductive phase. Being a ruminant and a hindgut fermenter, respectively, cattle and horses are two physiologically contrasting herbivore species, producing structurally quite different dung types. They are additionally interesting model species as both are frequently introduced in temperate Europe grassland management. Seedling biomass and growth rate, height, ramification, flowering and biomass of grown plants were measured in an attempt to quantify the benefits of endozoochorously dispersed seeds compared to seeds dispersed by other means and thus growing in a virtually dung-free environment. Few species were affected by the presence of dung in the juvenile phase while most species generally benefitted from being deposited in dung in later life stages. Positive responses of Agrostis capillaris, Agrostis stolonifera, Alopecurus myosuroides, Helianthemum nummularium, Poa annua, Trifolium repens and Trifolium pratense were found, while dung had a negative effect on Juncus bufonius. The initial losses of viable seeds through the digestive system of herbivores might, therefore, be partially compensated by enhanced growth and flowering in some species.
Endozoochory of temperate grassland species is a widespread phenomenon and may accelerate and/or ... more Endozoochory of temperate grassland species is a widespread phenomenon and may accelerate and/or increase germination in some plant species. However, the mechanisms causing this altered germination success are only partly understood. In this study, germination of common grassland species was evaluated after simulated herbivore digestion in a standardized lab environment. Ruminants (cattle) and hindgut fermenters (horses) were used as model organisms in this simulation experiment. Three major digestive processes were studied through mechanical, thermal and chemical treatments of the seeds simulating mastication, body temperature and digestive fluids, respectively. Congeneric groups of annuals and perennials were tested with 15 species belonging to the plant families Cistaceae, Cyperaceae, Fabaceae, Poaceae and Urticaceae. No differences between the impact of the simulated herbivore gut environments of cattle and horses could be found, but major differences in germination behaviour were found among plant species. For most of the tested plant species, treatments had a decelerating and inhibiting effect on germination compared to the untreated seeds. However, species of the Cistaceae and Fabaceae benefitted from mechanical treatments. Species of the Cyperaceae and Poaceae were hardly impaired by any of the treatments and even germinated better after chemical treatments. Thermal treatments, simulating the body temperature, prohibited germination in most cases. The germination success of Urtica urens was significantly higher after all treatments, which suggests seeds are specifically well adapted to gut passage, and hence to endozoochorous dispersal.
Instituut voor Natuur-en Bosonderzoek Het Instituut voor Natuur-en Bosonderzoek (INBO) is het Vla... more Instituut voor Natuur-en Bosonderzoek Het Instituut voor Natuur-en Bosonderzoek (INBO) is het Vlaams onderzoeks-en kenniscentrum voor natuur en het duurzaam beheer en gebruik ervan. Het INBO verricht onderzoek en levert kennis aan al wie het beleid voorbereidt, uitvoert of erin geïnteresseerd is.
Grazing is a commonly used management technique, e.g. to stop the expansion of competitive plant ... more Grazing is a commonly used management technique, e.g. to stop the expansion of competitive plant species, to enlarge plant species richness or to create spatial heterogeneity, favouring biodiversity in general. In order to accomplish an effective and efficient grazing management both herbivore and manager needs have to be accounted for. Several ungulate species are commonly used in nature. Several intra- and interspecific dissimilarities in animal morphology and physiology appear, and important differences in animal nutritional requirements and habitat selection are found. Therefore, not all herbivore species will be equally suited to fulfil management needs.
Because of the considerable variation in biological (e.g. floristic composition), physical (e.g. scrub density, forage yield, water availability, forage accessibility) and chemical characteristics (forage quality), not all terrains are equally fit for all herbivores. This reveals the necessity to determine the carrying capacity of the system. Therefore a grazing capacity model (GCM) is being developed. This dynamic model considers crucial variables on both the terrain and the grazer level, such as forage yield, forage quality, palatability of plant species, accessibility of the area, soil erosion vulnerability, animal nutritive requirements, animal behaviour and general habitat health. It predicts the optimal grazer species and density, taking the seasonal variation in animal needs and terrain characteristics into account. In this short paper the outline of the model is presented together with the results of two case studies in coastal and estuarine special protection zones within the Natura 2000 network in Flanders (Nature Reserves Westhoek and IJzermonding).
The model clearly reveals that grazing capacity is a dynamic feature, with seasonal, inter-annual, interspecific as well as intraspecific variation, differentiating GC in space, time and between herbivores. Additionally the GC outcome varies according to the used forage variable; lowest feasible Animal Unit numbers are generally found when using digestible energy as forage need variable, while phytomass generally results in significantly higher GC outcomes. Since all three forage need variables are relevant to the herbivore under consideration, it can be concluded that the manager should consistently follow the model at the lower predicted number of AU’s per season.
For the studied coastal areas, the optimal herd densities per season show large differences. Model estimates of number of AU’s in winter (and spring) are far lower then in summer and autumn, suggesting that year round grazing is feasible only when a seasonally differentiated herd density is applied. The best grazer choice depends on food availability and quality as well as on specific management needs.
NATUUR. FOCUS, Jan 1, 2008
Het uitbreiden van bossen kan door boompjes te planten of door terreinen spontaan te laten verbos... more Het uitbreiden van bossen kan door boompjes te planten of door terreinen spontaan te laten verbossen. Bij spontane verbossing kan door de inzet van grote grazers de vegetatie-ontwikkeling sterk beïnvloed worden. Op een reeks voormalige landbouwgronden onderzochten we onder welke omstandigheden en in welk patroon bosontwikkeling optreedt bij extensieve begrazing. Onder begrazing gebeurt bosontwikkeling hoofdzakelijk via struwelen en ruigtes, waarin jonge bomen beschermd zijn tegen vraat. Door een combinatie van betreding en selectief graasgedrag zijn grote grazers eveneens in staat om bosontwikkeling op gang te brengen. Dit artikel brengt door de boompjes het toekomstig bos in kaart.
Instituut voor Natuur-en Bosonderzoek Instituut voor Natuur-en Bosonderzoek Het Instituut voor Na... more Instituut voor Natuur-en Bosonderzoek Instituut voor Natuur-en Bosonderzoek Het Instituut voor Natuur-en Bosonderzoek (INBO) is het Vlaams onderzoeks-en kenniscentrum voor natuur en het duurzame beheer en gebruik ervan. Het INBO verricht onderzoek en levert kennis aan al wie het beleid voorbereidt, uitvoert of erin geïnteresseerd is. Wijze van citeren: Van Uytvanck J, Milotic T, Hoffmann M. (2008). Effecten van extensieve begrazing op spontane verbossingsprocessen -middellange en lange termijneffecten. Rapporten van het Instituut voor Natuur-en Bosonderzoek 2008 (INBO.R.2008.53). Instituut voor Natuur-en Bosonderzoek, Brussel. depotnr D/2008/3241/386 rapportnr INBO.R.2008.53
Grass and Forage Science, Jan 1, 2010
The effects of grazing by sheep at a stocking density of c. 1 sheep ha-1 from August to April on ... more The effects of grazing by sheep at a stocking density of c. 1 sheep ha-1 from August to April on total vegetation cover, diversity of plant species, above-ground plant biomass and concentration of crude protein, neutral-detergent fibre and acid-detergent fibre of salt-marsh vegetation was assessed over a 2-year period on a newly created salt-marsh area on the Belgian coast. Assessments were made in both grazed and ungrazed areas in four elevation zones: low, intermediate, high and floodmark zone. The cover of dominant salt-marsh species (Salicornia europaea, Limonium vulgare and Elymus athericus), plant diversity, plant biomass and chemical composition of herbage were compared between grazed and ungrazed plots, and between 2005 (initial state) and 2007 (after a 2-year grazing period) using paired t-tests. Grazing by sheep maintained plant diversity in the high zone, whereas diversity decreased in the ungrazed plots. Grazing had no apparent effect on total vegetation cover and composition of the vegetation. Concentration of crude protein in herbage increased and that of neutral-detergent fibre decreased in the high and intermediate zones. Expansion of the dominant species of the high zone, E. athericus, was not affected by the stocking density used in the study.
Ecological Restoration …, Jan 1, 2000
Ecological Restoration in …, Jan 1, 2000
Ecological Restoration …, Jan 1, 2000
Endozoochory, or the dispersal of plant seeds via ingestion by vertebrate animals and the consecu... more Endozoochory, or the dispersal of plant seeds via ingestion by vertebrate animals and the consecutive deposition of seeds in dung, is a widespread phenomenon in temperate grassland species. The first steps in this dispersal cycle have been extensively studied in recent decades while less is known about the next steps, or the post-dispersal fate of deposited seeds. In this PhD the germination, establishment, growth and flowering of temperate grassland species was experimentally assessed through dung addition and inter- and intraspecific competition experiments. Furthermore, the role of different functional groups of dung beetles in secondary seed dispersal and dung degradation has been studied in a large-scaled multi-site experiment in different climate and biogeographic zones in the Western Palaearctic.
Camera traps placed in the field, photograph warm-bodied animals that pass in front of an infrare... more Camera traps placed in the field, photograph warm-bodied animals that pass in front of an infrared sensor. The imagery represents a rich source of data on mammals larger than ~200 grams, providing information at the level of species and communities. Camera-trap surveys generate observations of specific mammals at a certain location and time, including photo evidence that can be evaluated by experts to map species distribution patterns. The imagery also provides information on the species composition of local communities, identifying which species co-occur and in what proportion. Moreover, the images contain information on activity patterns and other interesting aspects of animal behaviour. Because surveys can be standardized relatively easily, camera traps are well suited for documenting shifts in the behaviour, distribution and community composition, for example in response to climate and land-use change. Imagery from camera traps can thus serve as a baseline for subsequent surveys.In less than two decades, camera traps have become the standard tool for surveying mammals. They are simple to use and non-invasive, requiring no special permits. As a consequence they are widely used by professionals and hobbyists alike. Together, tens of thousands of users have the potential to form a huge sensor network. Unfortunately however, imagery and data collected are currently rarely integrated. Rather, they are lost at a massive scale. Users tend to retain only a subset of the photos and discard the rest. Or the material ends up on an external hard disk that will at some point fail or be erased as these scientific data tend to be used within the scope of specific projects. Very few of the wealth of material becomes available for scientific research and monitoring. Moreover, joint projects are rare and there is little coordination between camera-trap users.A solution to this problem is provided by Agouti, a platform for the organization, processing and storage of camera-trap imagery (www.agouti.eu). The aim of Agouti is, on the one hand, to standardize and facilitate collaborative camera-trap surveys, and on the other hand to compile and secure imagery and data for scientific research and monitoring, by encouraging users to share their material. Agouti provides an interface that allows users to collaborate on projects, organize and manage their surveys, upload and store imagery, and annotate images with species identifications and characteristics. Images can also be annotated through basic image recognition and crowd sourcing via a connection with the citizen science platform Zooniverse, which creates the potential to reach new audiences. Exporting data and imagery in the Camera Trap Metadata Standard (Forrester et al. 2016) will be supported in the near future. This will allow data to be archived outside of Agouti in research repositories such as Zenodo and by further mapping to Darwin Core to be made discoverable on the Global Biodiversity Information Facility (GBIF).Agouti provides both professionals and the public with a practical solution for retaining camera-trap surveys and simultaneously engages people in contributing data to science in a standardized and organized manner, to the benefit of science and conservation.
The Research Institute for Nature and Forest (INBO) is co-managing three biologging networks as p... more The Research Institute for Nature and Forest (INBO) is co-managing three biologging networks as part of a terrestrial and freshwater observatory for LifeWatch Belgium. The networks are a GPS tracking network for large birds, an acoustic receiver network for fish, and a camera trap network for mammals. As part of our mission at the Open science lab for biodiversity, we are publishing the machine observations these networks generate as standardized, open data. One of the challenges however, is finding the appropriate standards and platforms to do so.In this talk, we will present the three networks, the type of biologging data they collect and how we (plan to) standardize these to specific community standards and to Darwin Core (Wieczorek et al. 2012). Data from the bird tracking network have been published in 2014 as one of the first biologging datasets on the Global Biodiversity Information Facility (GBIF) (Stienen et al. 2014). We are now planning to upload the data to Movebank instead and contribute to a generic mapping between the Movebank format and Darwin Core. Data from the acoustic receiver network are being mapped using the Darwin Core guidelines proposed by the Machine Observations Interest Group of Biodiversity Information Standards (TDWG). Images generated by the camera trap network are managed in the annotation system Agouti, for which we plan to export the data in the Camera Trap Metadata Language (Forrester et al. 2016). We also aim to write a software package to deposit camera trap images and data on Zenodo and map the observation data to Darwin Core.We hope that our work will contribute to discussions and guidelines on how to best map biologging data to Darwin Core, which is one of the aims of the Machine Observations Interest Group of Biodiversity Information Standards (TDWG).
Aquatic biotelemetry techniques have proven to be valuable tools to generate knowledge on species... more Aquatic biotelemetry techniques have proven to be valuable tools to generate knowledge on species behaviour, gather oceanographic data and help in assessing effects from anthropogenic disturbances. These data types support international policies and directives, needed for species and habitat conservation. As aquatic systems are highly interconnected and cross administrative borders, optimal data gathering should be organized on a large scale. This need triggered the development of regional, national and international aquatic animal tracking network initiatives around the globe. In Belgium, a national acoustic receiver network for fish tracking, called the Permanent Belgian Acoustic Receiver Network, was set up in 2014 with different research institutes collaborating. It is a permanent network with 160 acoustic receivers and since the start, over 800 animals from 16 different fish species have been tagged and generated more than 17 million detections so far. To handle all the (meta)data generated, a data management platform was built. The central database stores all the data and has an interactive web interface that allows the users to upload, manage and explore (meta)data. In addition, the database is linked to an R-shiny application to allow the user to visualize and download the detection data. The permanent tracking network is not only a collaborative platform for exchange of data, analysis tools, devices and knowledge. It also creates opportunities to perform feasibility studies and Ph.D. studies in a cost-efficient way. The Belgian tracking network is a first step towards a Pan-European aquatic tracking network.
Questions: In temperate grasslands, seeds of numerous dry-fruited plant species are dispersed via... more Questions: In temperate grasslands, seeds of numerous dry-fruited plant species are dispersed via ingestion and subsequent defecation by grazing animals. Depending on the herbivore species and season, dung pats may contain a large assemblage of conspecific or heterospecific seeds competing for space, light and nutrients in the space-limited environment of an individual dung pat. In an environment rich in nutrients, such as herbivore dung, the outcome of inter- and intraspecific competition might differ from situations where nutrients are limiting. Additionally, dung pats being small and spatially isolated habitats with very specific conditions may impact competitive interactions as well. Besides the plant-soil interactions on competition known from literature, the specific quality and structure of dung pats might provoke more complex interactions between different seed densities and species combinations.Methods: We conducted a greenhouse competition experiment using three common perennial grassland species. Agrostis stolonifera, Trifolium pratense and Trifolium repens were used in two species combinations with different proportions of each species and in monocultures. Seeds were sown in three seed densities (50, 150 and 250 seeds) and the effects of cattle and horse dung on establishment, growth and flowering were tested.Results: Interactions, most probably attributable to interspecific competition, differed between species mixtures. Seeds sown in polycultures generally emerged sooner, but the resulting seedlings had lower relative growth rates compared with seeds sown in monocultures. Increased biomass was measured for each species when growing in polycultures while evidence for intraspecific competition was found in monocultures. T. pratense developed relatively more flowers when plants were growing in polycultures compared with monocultures. Few effects of seed densities were found, although higher seed densities led to lower establishment success in both monocultures and polycultures. Adding dung generally increased the time needed to emerge, relative growth rates and flowering, but decreased establishment success in monocultures.Conclusions: Both seed density and the presence of dung shape the post-dispersal fate of seeds. While high seed densities imply a cost due to lower germinability, the nutritive environment of dung acts as a compensation resulting in faster growth and an increased investment in reproductive tissues.
Extensive grazing often has a strong influence on the structure and composition of herbaceous pla... more Extensive grazing often has a strong influence on the structure and composition of herbaceous plant communities with increasing population sizes for some species and decreasing presence in others. Herbivores affect plant communities directly by selective grazing of plant species, and indirectly by either epizoochory or endozoochory. Helianthemum nummularium is considered an increaser species because its distribution increased after the introduction of large, free-ranging grazers in at least two coastal dune grassland areas in Belgium. However, its seeds lack any obvious adaptations for epizoochory, and direct observations of plant/seed consumption are scarce. Through field and lab experiments, we assessed the dispersal ability of H. nummularium via endozoochory and epizoochory. In a differentiated grazer exclusion experiment, evidence was found that plants are grazed by large domestic ungulates and small wild herbivores although these incidences were rare. Direct endozoochory evidence remained scarce. No seeds were found germinating in field-collected dung, and only few seedlings emerged following a seed feeding experiment. However, once deposited, we found higher growth rates when seeds were mixed with dung, while on the other hand establishment success lowered when seeds were sown in combination with competitively superior species. Epizoochory was plausible because both fur and hooves of cattle and horses were potentially capable of contributing to the transport of H. nummularium seeds.We conclude that herbivores play a role in seed dispersal while their selective grazing behaviour most probably creates an appropriate environment for Helianthemum establishment and maintenance.
Ecological sustainability has been recognized as one of the main aspects of sustainable developme... more Ecological sustainability has been recognized as one of the main aspects of sustainable development of rangelands, at which different kinds of animal including insects, make substantial contributions. Dung beetles, known as dung-visiting insects, play several key roles in many ecological functions from which benefit both terrestrial ecosystems and human population. Specifically, they benefit rangelands through reducing greenhouse gas emission, nutrient cycling, plant growth enhancement, trophic regulation and pollination and secondary seed dispersal. This study examined secondary seed dispersal as one of the ecological functions of dung beetles, in Chaharmahal and Bakhtiari province, Iran. We applied an experimental approach to measure ecological function (i.e. seed removal) by functional groups of dung beetles. We tested whether functional dung beetle groups influence secondary seed dispersal differently. Through repeated standardized samples of sheep dung, data obtained regularly during two different months August and November in 2013. The results show that dung beetles play a role in secondary seed dispersal. However, it is affected by seed size, so that seed removal increased in the order of, large, medium and small size, respectively. The significant differences between treatments were found for small seeds in the both months. More seeds were dispersed from treatment t02 (all combinations of functional groups except large rollers) in August, while in November more seeds from treatments t01 (dwellers plus large and small tunnelers plus large and small rollers) and t03 (the combinations of dwellers plus small tunnelers, and small rollers) were removed. As a conclusion, it is suggested that if it is to guarantee the ecological sustainability of rangelands, paying attention to the ecological functions of dung beetles is crucial.