Skip header and navigation

1 records – page 1 of 1.

Grazing responses in herbs in relation to herbivore selectivity and plant traits in an alpine ecosystem.

https://arctichealth.org/en/permalink/ahliterature89173
Source
Oecologia. 2009 Aug;161(1):77-85
Publication Type
Article
Date
Aug-2009
Author
Evju Marianne
Austrheim Gunnar
Halvorsen Rune
Mysterud Atle
Author Affiliation
Department of Botany, Natural History Museum, University of Oslo, Oslo, Norway. marianne.evju@nhm.uio.no
Source
Oecologia. 2009 Aug;161(1):77-85
Date
Aug-2009
Language
English
Publication Type
Article
Abstract
Herbivores shape plant communities through selective foraging. However, both herbivore selectivity and the plant's ability to tolerate or resist herbivory may depend on the density of herbivores. In an alpine ecosystem with a long history of grazing, plants are expected to respond to both enhanced and reduced grazing pressures, and the interaction between plant traits and changes in species abundance are expected to differ between the two types of alteration of grazing regime. To understand the mechanisms behind species response, we investigated the relationship between sheep selectivity (measured in situ), plant traits and experimentally derived measures of change in species abundance as a response to the enhancement (from low to high density) or cessation (from low to zero density) of sheep grazing pressure over a six-year time period for 22 abundant herb species in an alpine habitat in south Norway. Sheep selected large, late-flowering herbs with a low leaf C/N ratio. Species that increased in abundance in response to enhanced grazing pressure were generally small and had high root/shoot ratios, thus exhibiting traits that reflect both resistance (through avoidance) and tolerance (through regrowth capacity) strategies. The abundance of selected species remained stable during the study period, and also under the enhanced grazing pressure treatment. There was, however, a tendency for selected species to respond positively to cessation of grazing, although overall responses to cessation of grazing were much less pronounced than responses to enhanced grazing. Avoidance through short stature (probably associated with increased light availability through the removal of tall competitors) as well as a certain amount of regrowth capacity appear to be the main mechanisms behind a positive response to enhanced grazing pressure in this study. The plant trait perspective clearly improves our insight into the mechanisms behind observed changes in species abundance when the disturbance regime is altered.
PubMed ID
19412704 View in PubMed
Less detail