School of Ecosystem and Forest Sciences - Research Publications
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ItemA global comparison of the climatic niches of urban and native tree populations(WILEY, 2018-05-01)
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ItemConserving herbivorous and predatory insects in urban green spaces(NATURE PUBLISHING GROUP, 2017-01-19)Insects are key components of urban ecological networks and are greatly impacted by anthropogenic activities. Yet, few studies have examined how insect functional groups respond to changes to urban vegetation associated with different management actions. We investigated the response of herbivorous and predatory heteropteran bugs to differences in vegetation structure and diversity in golf courses, gardens and parks. We assessed how the species richness of these groups varied amongst green space types, and the effect of vegetation volume and plant diversity on trophic- and species-specific occupancy. We found that golf courses sustain higher species richness of herbivores and predators than parks and gardens. At the trophic- and species-specific levels, herbivores and predators show strong positive responses to vegetation volume. The effect of plant diversity, however, is distinctly species-specific, with species showing both positive and negative responses. Our findings further suggest that high occupancy of bugs is obtained in green spaces with specific combinations of vegetation structure and diversity. The challenge for managers is to boost green space conservation value through actions promoting synergistic combinations of vegetation structure and diversity. Tackling this conservation challenge could provide enormous benefits for other elements of urban ecological networks and people that live in cities.
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ItemGlobal review of incentive schemes for the retention and successful establishment of trees on private urban land: Literature Review - Interim report(Horticulture Innovation Australia (HIA), The University of Melbourne, 2019)This project has been funded by Hort Innovation, using the nursery research and development levy and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.
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ItemNo Preview AvailableTrees provide energy saving benefits to adjacent buildings for a small water cost(Australian Sustainable Cities and Regions Network, 2011)
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ItemThe conservation value of urban green space habitats for Australian native bee communities(ELSEVIER SCI LTD, 2015-07-01)Networks of urban green space can provide critical resources for wild bees, however it is unclear which attributes of green spaces provide these resources, or how their management can be improved to benefit a diversity of bee species. We examined bee communities in three dominant urban green space habitats: (1) golf courses (2) public parks and (3) front gardens and streetscapes in residential neighbourhoods in Melbourne, Australia and assessed which local and landscape attributes influenced bee communities. There was a greater abundance and richness of bee species in public parks compared to golf courses and residential neighbourhoods, where the latter habitat was dominated by European Honeybees (Apis mellifera). The occurrence of A. mellifera was positively associated with increases in flowering and native plants. Ground-nesting Homalictus species occurred more frequently in older golf courses and public parks surrounded by low impervious surface cover, and with a low diversity of flowering plants. Cavity nesting, floral specialists within the Colletidae family occurred more often in green space habitats with greater native vegetation, and occurred infrequently in residential neighbourhoods. The lack of appropriate nesting habitat and dominance of exotic flowering plants in residential neighbourhoods appeared to positively impact upon the generalist A. mellifera, but negatively affected cavity and ground nesting floral specialist bee species (e.g. Halictidae and Colletidae). Our results highlight the need to include urban areas in pollinator conservation initiatives, as providing resources critical to diverse bee communities can assist in maintaining these key pollinators in urban landscapes.
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ItemNo Preview AvailableLand use change and the impact on greenhouse gas exchange in north Australian savanna soils(COPERNICUS GESELLSCHAFT MBH, 2012-01-01)Abstract. Savanna ecosystems are subjected to accelerating land use change as human demand for food and forest products increases. Land use change has been shown to both increase and decrease greenhouse gas fluxes from savannas and considerable uncertainty exists about the non-CO2 fluxes from the soil. We measured methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) over a complete wet-dry seasonal cycle at three replicate sites of each of three land uses: savanna, young pasture and old pasture (converted from savanna 5–7 and 25–30 yr ago, respectively) in the Douglas Daly region of Northern Australia. The effect of break of season rains at the end of the dry season was investigated with two irrigation experiments. Land use change from savanna to pasture increased net greenhouse gas fluxes from the soil. Pasture sites were a weaker sink for CH4 than savanna sites and, under wet conditions, old pastures turned from being sinks to a significant source of CH4. Nitrous oxide emissions were generally very low, in the range of 0 to 5 μg N2O-N m−2 h−1, and under dry conditions soil uptake of N2O was apparent. Break of season rains produced a small, short lived pulse of N2O up to 20 μg N2O-N m−2 h−1, most evident in pasture soil. Annual cumulative soil CO2 fluxes increased after clearing, with savanna (14.6 t CO2-C ha−1 yr−1) having the lowest fluxes compared to old pasture (18.5 t CO2-C ha−1 yr−1) and young pasture (20.0 t CO2-C ha−1 yr−1). Clearing savanna increased soil-based greenhouse gas emissions from 53 to ∼ 70 t CO2-equivalents, a 30% increase dominated by an increase in soil CO2 emissions and shift from soil CH4 sink to source. Seasonal variation was clearly driven by soil water content, supporting the emerging view that soil water content is a more important driver of soil gas fluxes than soil temperature in tropical ecosystems where temperature varies little among seasons.
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ItemNo Preview AvailableSeasonal variation and fire effects on CH4, N2O and CO2 exchange in savanna soils of northern Australia(ELSEVIER, 2011-11-15)Tropical savanna ecosystems are a major contributor to global CO2, CH4 and N2O greenhouse gas exchange. Savanna fire events represent large, discrete C emissions but the importance of ongoing soil-atmosphere gas exchange is less well understood. Seasonal rainfall and fire events are likely to impact upon savanna soil microbial processes involved in N2O and CH4 exchange. We measured soil CO2, CH4 and N2O fluxes in savanna woodland (Eucalyptus tetrodonta/Eucalyptus miniata trees above sorghum grass) at Howard Springs, Australia over a 16 month period from October 2007 to January 2009 using manual chambers and a field-based gas chromatograph connected to automated chambers. The effect of fire on soil gas exchange was investigated through two controlled burns and protected unburnt areas. Fire is a frequent natural and management action in these savanna (every 1–2 years). There was no seasonal change and no fire effect upon soil N2O exchange. Soil N2O fluxes were very low, generally between −1.0 and 1.0μg Nm−2h−1, and often below the minimum detection limit. There was an increase in soil NH4+ in the months after the 2008 fire event, but no change in soil NO3−. There was considerable nitrification in the early wet season but minimal nitrification at all other times. Savanna soil was generally a net CH4 sink that equated to between −2.0 and −1.6kg CH4ha−1y−1 with no clear seasonal pattern in response to changing soil moisture conditions. Irrigation in the dry season significantly reduced soil gas diffusion and as a consequence soil CH4 uptake. There were short periods of soil CH4 emission, up to 20μg Cm−2h−1, likely to have been caused by termite activity in, or beneath, automated chambers. Soil CO2 fluxes showed a strong bimodal seasonal pattern, increasing fivefold from the dry into the wet season. Soil moisture showed a weak relationship with soil CH4 fluxes, but a much stronger relationship with soil CO2 fluxes, explaining up to 70% of the variation in unburnt treatments. Australian savanna soils are a small N2O source, and possibly even a sink. Annual soil CH4 flux measurements suggest that the 1.9million km2 of Australian savanna soils may provide a C sink of between −7.7 and −9.4 Tg CO2-e per year. This sink estimate would offset potentially 10% of Australian transport related CO2-e emissions. This CH4 sink estimate does not include concurrent CH4 emissions from termite mounds or ephemeral wetlands in Australian savannas.