PARENT SESSION
Contributed Oral Session 48: Landscape Ecology: Animal Dynamics
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 520 B, Level 5, Palais des congrès de Montréal
Mistletoe parasitism in agricultural landscapes: an example of landscape structure affecting ecological processes.
MacRaild, Lindy*,1, Bennett, Andrew1, Radford, James1, 1 Deakin University, Burwood, Victoria, Australia
ABSTRACT- Mistletoes of the genera Amyema and Muellerina are hemi-parasites of eucalypt trees in southern Australia. Seed dispersal to new host trees depends on bird vectors, particularly the Mistletoebird Dicaeum hirundinaceum. Thus, the occurrence of mistletoes in modified landscapes depends on a complex ecological interaction between individual mistletoe plants, host plants and the dispersal vector. In this study we examined the relationship between landscape structure, particularly the extent and pattern of tree cover, and the distribution of mistletoes in rural landscapes in south-east Australia. Mistletoes were surveyed at 15 sites (each 0.8 ha) in each of 24 landscapes of 100 km2, with landscapes selected to sample a gradient in tree cover from 60% down to 2%. Five species of mistletoe were recorded. The most common species Amyema miquelii had a patchy distribution, with 1270 individuals recorded at 85 sites from 20 of the 24 landscapes. The incidence and abundance of A. miquelii were examined at two spatial scales; first in relation to a suite of landscape variables, including tree cover and configuration, climate, land-use, elevation and geographic location; and second, at the individual site level. Mistletoe incidence in landscapes was positively related to the extent of tree cover (R2adj = 0.295). No other variables contributed in the landscape-level model. At the site level, distance to the nearest large (>100 ha) remnant of native vegetation and the amount of surrounding vegetation within 3 km were key determinants of the incidence of A. miquelii. The behaviour of the Mistletoebird, a woodland specialist, provides a link between responses at different scales. Isolated habitat is less likely to be visited by Mistletoebirds, but as the extent of tree cover increases, a larger population can be supported, with a greater dispersal of mistletoe possible. This research demonstrates the interaction between landscape structure and ecological processes that underpin the distribution and abundance of individual species.
Key words: Landscape, Ecological processes, Mistletoe parasitism, Habitat loss