| Current PhD Students |
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Recent PhD Students
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Sean Michael Gleason
(Supervised with Dr Dan Metcalf, CSIRO)
Project Information |
Publications | PhD Project
Plant-soil interactions and nutrient limitation in an Australian rainforest: effects of soil type and species composition.
General research passions: Complementary resource use in forest systems, plant-soil interactions in terrestrial and wetland forests, diversity-productivity mechanisms, invasive species biology and control, ecophysiology of invasion and plant-plant interactions, rare plant conservation, science-based natural resources management
Project
I am investigating plant-soil and plant-plant interactions in diverse rainforest communities in northeast Queensland. I am particularly interested in mechanisms that drive diversity-productivity relationships. Why are diverse forests more productive than less diverse forests (Hooper et al. 2002, van Ruijven and Berendse 2005)? Do species growing on nutrient-poor soils interact synergistically in a way that conserves belowground nutrients and enhances forest-level productivity?
Complementary resource use may come about through asynchrony of resource utilisation among species – species may differ in where roots and leaves are located and when resource uptake/carbon fixation occurs. Resource use patterns among species may then serve to increase resource interception and/or increase resource use efficiency (RUE) at the forest-level in a way that single-species forest could not (Hiremath and Ewel 2001). The idea of complementary resource use has been tested theoretically (Tilman 1988) and in agroforestry / forestry systems (DeBell et al. 1989, Ewel et al. 1991, Binkley and Giardina 1997, Haggar and Ewel 1997, Khanna 1998, Parrotta 1999, Dommergues and Subba Rao 2000, Kaye et al. 2000, Binkley 2003, Binkley et al. 2003), but rarely in naturally occurring forest communities.
I am measuring tree-level and plot-level net primary productivity (NPP), nutrient uptake, nutrient use efficiency, soil nutrient availability, root density patterns, and leaf patterns, within directly adjacent forests occurring on nutrient poor schist and nutrient rich basalt. This allows me to look at temporal and spatial patterns of resource supply and use among many species occurring on different soils. Additional glasshouse and field fertilization experiments allow me to evaluate the RUE of seedlings and mature tress when nutrient limitation is removed. These experiments should allow me to evaluate the nutrient economy of rainforest species and how these species interact when nutrients are limited and abundant. It is hoped that this research will provide insights into why diverse communities are productive and how soil resources influence species-level and plot-level nutrient economy.
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