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.
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 compos...
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.
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 compos...
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