Trampling enhances the dominance of graminoids over forbs in flooded grassland mesocosms
Colaborador(es): Striker, Gustavo Gabriel
| Mollard, Federico Pedro Otto
| Grimoldi, Agustín Alberto
| León, Rolando Juan Carlos
| Insausti, Pedro
.
ISSN: 1402-2001.Tipo de material: Artículos y capítulos. Recurso electrónico.Tema(s): COMMUNITY STRUCTURE | FLOODING | GRASSLAND RECOVERY | GRAZING | LOTUS TENUIS | TRAMPLING | BOS | HYMENACHNE | POACEAE | Recursos en línea: Haga clic para acceso en línea | LINK AL EDITOR.
En: Applied Vegetation Science vol.14, no.1 (2011), p.95-106Resumen: Questions: What are the interactive effects of flooding and cattle trampling upon the structural attributes and the floristic composition of a plant community? Do the effects on the plant community persist over an extended recovery period?. Location: Flooding Pampa grasslands, Argentina [36°30' S, 58°30' W].Methods: We assessed the effects of 40-d of flooding, trampling and the combination thereof on plant cover and biomass, vertical distribution of foliage and floristic composition in lowland grassland mesocosms. We considered a 120-d recovery period to evaluate the persistence of flooding and trampling effects on the plant community. Results: Flooding, with or without trampling, increased cover and biomass of the graminoid species, especially marsh grasses, which developed a taller canopy, whereas most of the forb species were negatively affected. This was enhanced by trampling, as the aerial biomass of the dominant legume Lotus tenuis decreased by 90 percent , while three major forb species disappeared. Trampling under flooding conditions did not reduce the total above-ground biomass production, as the growth enhancement of graminoids was enough to compensate for the breakdown of the forbs. Below-ground biomass was lower when both perturbations occurred simultaneously. After 120-d of recovery, graminoids continued to be dominant while the remaining forbs [including L. tenuis] recovered only partially. Below-ground biomass recovered fully at the end of the growing season.Conclusions: The combination of flooding and trampling shifts the community co-dominance of graminoids and forbs towards a persistent dominance of graminoid species. When both perturbations are combined, the above-ground production of the grassland is unaffected and root biomass is rapidly recovered. However, the loss of the legume L. tenuis deserves attention because this is the unique nitrogen-fixing species of the ecosystem, which improves the forage quality for livestock production.
Questions: What are the interactive effects of flooding and cattle trampling upon the structural attributes and the floristic composition of a plant community? Do the effects on the plant community persist over an extended recovery period?. Location: Flooding Pampa grasslands, Argentina [36°30' S, 58°30' W].Methods: We assessed the effects of 40-d of flooding, trampling and the combination thereof on plant cover and biomass, vertical distribution of foliage and floristic composition in lowland grassland mesocosms. We considered a 120-d recovery period to evaluate the persistence of flooding and trampling effects on the plant community. Results: Flooding, with or without trampling, increased cover and biomass of the graminoid species, especially marsh grasses, which developed a taller canopy, whereas most of the forb species were negatively affected. This was enhanced by trampling, as the aerial biomass of the dominant legume Lotus tenuis decreased by 90 percent , while three major forb species disappeared. Trampling under flooding conditions did not reduce the total above-ground biomass production, as the growth enhancement of graminoids was enough to compensate for the breakdown of the forbs. Below-ground biomass was lower when both perturbations occurred simultaneously. After 120-d of recovery, graminoids continued to be dominant while the remaining forbs [including L. tenuis] recovered only partially. Below-ground biomass recovered fully at the end of the growing season.Conclusions: The combination of flooding and trampling shifts the community co-dominance of graminoids and forbs towards a persistent dominance of graminoid species. When both perturbations are combined, the above-ground production of the grassland is unaffected and root biomass is rapidly recovered. However, the loss of the legume L. tenuis deserves attention because this is the unique nitrogen-fixing species of the ecosystem, which improves the forage quality for livestock production.
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