The process of applying for an
Honours project in my Lab is easy. Firstly, let me know that you are keen to
discuss undertaking research under my supervision and we can talk about
potential projects. If you wish to apply for a project, I expect a grade
average in Botany subjects >75%. I will generally supervise one to two
students per year and I select these on the basis that I think that will
conduct a good thesis, are inquisitive about the natural world, are likely to
become plant ecologists, are motivated and independent workers, and have
something to contribute to the Plant Ecology Lab more broadly. Students with
good recommendations will be looked upon favourably.
Below, I list some ideas I have been
thinking about as potential projects. All are necessarily vague at this stage
but give an indication of the studies that currently occupy my thinking. If you
have some ideas, I’m also happy to discuss those.
Project
1: Common species declines and niche limitation
Common
plant declines don't get much more dramatic than that of Microseris (Yam Daisy) - a once
common and extensive forb in Themeda
grasslands of the Victorian Volcanic Plains, they are now incredibly hard
to find. While such declines have been noted for some time, they probably
continue unabated and it’s still unclear what factors favour the
maintenance of such species. Taking historical data (sites where it was
recorded, regardless of abundance measures) we could first ask: what
evidence is there for continuing decline of the species in plains
grasslands over the last few decades (using species detection theory to
enhance our estimates). Then, in an experimental study, we might ask: how
does seed limitation versus microsite limitation affect Microseris patterns - have
grasslands changed so much that Microseris
re-entry is prohibited by lack of germination and adult niches. This might entail
a study sowing seed into different microsites (control native grassland,
canopy removed but no soil disturbance, soil disturbance but no canopy
removal, canopy removal and soil disturbance). It's thought Yam Daisies
proffered from soil disturbance by aboriginal digging/bandicoot digging,
but such processes have long been lost from plains grasslands. Might this
be a key factor in the decline of the species?
Where: grasslands
on the western volcanic plains
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Project 2: Heterogeneity, species diversity and conservation
management
In
Australia, native grasslands are highly endangered because they have been
transformed by agriculture over most of their historic range. Hence, they
are being acquired and managed for conservation of their important
biodiversity. On the northern
riverine plains, for example, many sheep grazing properties are being
acquired for conservation by Parks Victoria and the Trust for Nature.
Because many / most of these have been grazed by sheep, they are somewhat
degraded (but stable). Grazing is used as management tool because it can
maintain species richness (at high numbers in small quadrats) - based on
the idea that competitive exclusion reduces small scale diversity. But,
and this is the point of the project, is it the 'best' way to manage
grasslands for their structural, functional and floristic diversity? Maybe
grazing maintains a subset of native species (i.e. the grazing-tolerant
ones) but reduces heterogenity across sites. While alpha diversity is high, beta
diversity across the landscape may be low when grazed - i.e. grazing
promotes species similarity from one point to the next, whereas destocking
enhances variation in composition. Conservation managers are loathe to
remove stock from native grasslands because they are acutely aware that
destocking might lead to declines in alpha
diversity. This fails to recognise that destocking might lead to increases
in beta diversity because it
promotes heterogeneity via microsite differentiation. We could survey a
range of grasslands (with different management regimes - grazed, recently
destocked, long destocked) and ask: does grazing promote alpha and beta diversity. Does destocking lead to loss of species, or
shifts in species composition? Should we manage for habitat variability
more explicitly across grasslands.
The
game changer here would be to accept that changing long-term grazing might
actually lead to instability in the system, but improved conservation
outcomes because it favours more species ultimately (at landscape scales).
Alternatively, we could ask: does grazing nullify the ability of certain
species to establish because it reduces their germination niche availability
- this might be the mechanism that underpins why grazing favours some
species over others.
Where: this is a field-based project
located across the grassland ecosystems of northern Victoria
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Project 3: Establishment of native
shrubs in temperate woodlands
| Many native temperate woodlands have being undergoing a
process of woody plant encroachment over the last few decades in response
to land use change. Good examples include Kunzea increases in the foothills forests of the
Where: this
is a field-based project located in grassy woodland near Geelong
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Project 4: Building a framework for temperate ecosystem dynamics that includes rainfall variability
Climate
fluctuation is the ‘norm’ in southern Australia, with climate variation
driven by El Nino/La Nina oscillations.
Most ecological focus of climate variability has been on the effects
that drought has on tree mortality in woodlands and forests. But what about
the effects of La Nina, above-average rainfall years? In non-fire prone
ecosystems such as Box-Ironbark forest and herb-rich semi-arid woodlands,
where fire is not the cue for germination, might recruitment of key species
such as Acacia be linked to
rainfall variability. Hence, might La Nina recruitment vs. El Nino
mortality be the chief driver of population processes in many ecosystems
(as opposed to fire-driven systems where time since fire is of primary
importance). If population processes are clearly linked to rainfall
variability, this should be observable in the stand structure of species
i.e pulsed recruitment that coincides with wet years. Additionally, what
traits of species that are responsive to rainfall variability – we know
this for fire but not climate-driven recruitment.
Where: this is a field-based project
located in ecosystems such as Yellow Gum woodlands of far western Victoria
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Project 5: Woodland tree recruitment and patch-dynamic theory
Tree–grass
coexistence in savanna ecosystems – or the ability of grassy and woody
vegetation to co-occur without either life-form becoming dominant – is not
well understood, although rainfall and disturbance regimes are generally
implicated. According to
patch-dynamics theory, woody vegetation does not become dominant because
dense episodic recruitment is mirrored (over time) by episodic mortality
(caused by drought). Alternatively, following dense episodic recruitment,
trees self-thin over time as slightly larger trees out-compete smaller
trees in an even-aged stand. Tree spacing and size inequality may be
related to self-thinning because patterns of tree distribution can be the
result of competitive interactions among individuals. For example, regular
spacing could indicate competitive interactions and self-thinning among
individuals in a population, such that larger trees are further from
neighbours than small trees. Both concepts generally apply to trees that
recruit en masse (e.g. Red Gums)
but I think they could be applied to understand recruitment dynamics in the
iconic eucalypt woodlands of eastern Australia. Hence, this project will
investigate the applicability of the patch-dynamics model of tree–grass
coexistence as a means of explaining the recruitment of temperate woodland
trees and the capacity of woodlands to resist thickening into forests.
Where: this is a field-based project
located in woodland ecosystems
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