Hemiparasitic shrubs increase resource availability and multi-trophic diversity of eucalypt forest birds

David Watson, Hugh McGregor, Peter Spooner

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


1. Parasitic plants are components of many habitats and have pronounced effects on animaldiversity; shaping distributions, influencing movement patterns and boosting species richness.Many of these plants provide fleshy fruit, nectar, foliar arthropods and secure nest sites, but therelative influence of these nutritional and structural resources on faunal species richness andcommunity structure remains unclear.2. To disentangle these factors and quantify the resources provided by parasitic plants, wefocused on the hemiparasitic shrub Exocarpos strictus (Santalaceae). Twenty-eight Eucalyptuscamaldulensis forest plots were studied in the Gunbower-Koondrook forest in southeastern Australia,comparing riparian forests with an Exocarpos-dominated understorey with otherwise similarhabitats with or without equivalent cover of the non-parasitic Acacia dealbata. Analyses ofavian richness and incidence (overall and in six feeding guilds) were complemented by explicitmeasures of resources in both shrub types; foliage density, standing crop of fleshy fruit and foliararthropod abundance and biomass.3. Avian species richness was c. 50% greater and total incidences for five guilds were significantlygreater in forests with the parasitic shrub, with no appreciable differences between theother two habitat types. In addition to plentiful fleshy fruits, Exocarpos supported abundant arthropodsin their foliage ' significantly higher in biomass than for equivalent volumes of Acaciafoliage. Exocarpos had a shorter and denser structure, providing a greater range of microhabitatsthan the more open growing Acacia.4. Our results demonstrate that structural and nutritional resources (both direct and indirect)provided by Exocarpos affect diversity and community composition, with each set of resourcesaffecting different organismal groups. Rather than an exceptional system or anaberrant result,we suggest the influence of Exocarpos on species richness relates to their parasitic habit, supportingthe hypothesis that parasitic plants mobilize resources from their hosts and make them availableto a range of trophic levels.
Original languageEnglish
Pages (from-to)889-899
Number of pages11
JournalFunctional Ecology
Issue number4
Publication statusPublished - Aug 2011


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