Finally: My Research Results

Treeline

The aim of my research was to investigate the Victorian treeline physiognomy (i.e. the general position, form and appearance of the treeline) after a major disturbance, building on a previous data set collected shortly after wildfire. This research investigated the key questions that might indicate permanent change over the medium to long term. It was assessed by evaluating seedling elevation, density and key factors driving seedling establishment at treeline ecotones burned during the 2003 wildfires, and then re-examining the specific locations initially measured.

Locations

Seedlings found in the Victorian Alps after fire are establishing themselves in the alpine zone at higher elevations than the current treeline, and in greater numbers in the subalpine zone in locations where competition is constrained, litter is minimised, and there are adequate amounts of original trees with girths of approximately 50cm. Subsequently, the models suggest that the Victorian treeline physiognomy has slightly changed due to the 2003 alpine fires.

Model1

The analysis of increase in treeline elevation after fire was limited by few seedlings establishing above the current treeline. Despite this, a comparison of the burnt and unburnt transect models indicates that seedling establishment probabilities above the treeline are greater after fire compared to locations long absent of fire. This implies an increase in seedlings at elevations higher than the treeline after fire. The model calculates that there is a 31% chance of seedling establishment two metres above the treeline, and an 18% chance five metres above the treeline. Even higher elevations estimate much smaller probabilities. Subsequently, it is likely that only single trees will sparingly establish within the tree species zone, and consequently become outpost trees.

Model 2

An increase in treeline density after fire is supported by modelling, as seedling numbers are predicted to reach a maximum when fire is a recent occurrence. However, the Time Since Fire predictor variable was found to have 25% less influence than Litter, and 20% less influence than Evenness in maximising seedling numbers as calculated during sensitivity analysis. This suggests that fire may initially facilitate additional seedling numbers, however the magnitude of the density change is more dependent on the amount of competition in the area coupled with the quantity of litter cover. Locations that exhibit evenness across quadrat features are much more likely to support multiple seedlings, most likely due to a reduction in competition, and where a niche space can be realised. Secondly, a reduction in the amount of litter coverage within a location increases the number of seedlings. This is probably because litter acts as a barrier to seedling germination and emergence. In contrast, a decrease in litter allows greater seedling numbers to establish.

Model 3

Modelling of factors that influence seedling establishment after fire determined that apart from competition and litter, the amount of trees and their age are significant macro level factors influencing subalpine seedling establishment. Seedling counts were highest due to significant influences of competition and litter, and this was verified by models which determined a 91% probability of seedling establishment when competition and litter was minimised.
Tree characteristics were found to be imperative to seedling establishment. Tree girths between 20cm and 50cm are the only circumferences that can result in seedling probabilities above 90%, with substantial probability decreases above and below these girths. By relating girth to the age of the tree, this outcome ultimately defines the optimal reproductive age of the stand to facilitate seedling establishment after fire. Using previously created models that evaluate the relationship of Eucalyptus pauciflora subsp. Niphophila, tree girths of 20cm to 50cm correspond to tree ages of approximately 24 years to 42 years.
Finally, the quadrat must have a sufficient amount of trees to facilitate seedling success. A seedling establishment probability of above 90% was modelled to occur in locations where tree coverage ranges between 45% and 50% of the total area of the quadrat.

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Monitoring Environmental Impcats

Monitoring Environmental Impacts is now complete, another subject done and dusted. The highlight was of course the field trip where we got to get out and take some real world measurements and then interpret what we had found. Our initial results looked encouraging, but the final results were really impressive. Our premise that willow infested riverbanks display greater levels of fine sediment was confirmed by measurements at control and impact sites over multiple sediment characteristic tests. In case you weren’t paying attention, here is a brief recap of our investigation:

control siteIncreased sedimentation in rivers has become a global crisis with the US Environmental Protection Agency listing sediment as the greatest impairment on waterways. Riverbed substrate alteration due to fine sediment deposition can be directly attributed to the human impacts of agricultural runoff, reduced riparian vegetation, and urbanisation.

Sedimentation in Victorian waterways increased as a result of the introduced tree species Salix spp. Commonly known as Willows, they were originally planted along waterways and in wetlands to combat human induced streamside vegetation loss and river bank erosion. The proliferation of underwater root mats that trap sediment in the river substrate has been identified as a major factor why willow trees disproportionately contribute to increased sedimentation.

impact siteA control-impact monitoring comparison was implemented, where the riverbed substrate of willow infested areas and natural native zones was evaluated. Three tests were performed at each sample location to characterise the sediment substrate profile:

  • Sediment depth: A measurement of the depth of sediment on top of the substrate.
  • Sediment cover: A visual estimate of fine sediment percentage coverage over the substrate.
  • Sediment size: A measurement of the percentage proportion of sediment sizes.

The aim of all three tests is to establish if there is a profusion of fine sediment at the impact site compared to coarse sediment at the control site.

Sediment depth

Significant large particle sediment depths are required to circulate water and oxygen through the interstitial space that macroinvertebrates utilise. Large particle sediment ranging in depths from 200mm to 400mm provided the highest faunal diversity of macroinvertabrates found in riverbeds.

The measured data shows that sediment depth is significantly deeper at the control site than at the impact site. 80% of control site samples measured greater than 100mm in depth, whereas 80% of impact site samples measured less than 100mm in depth. The average sediment control site depth was 196mm, with the average sediment impact site depth measuring only 79mm.

Sediment Depth

Sediment cover

Fine sediment cover on the riverbed substrate has long been known to cause major aquatic ecosystem disruption by adjusting temperature, reducing light penetration, changing electrolytic properties and aiding in the retention of organic matter. Studies have found that platypus would not forage in riverbeds with 50% or more fine sediment cover.

The measured data shows that the percentage of fine sediment coverage is significantly higher at the impact site than at the control site. The impact site exhibits 76% of samples with greater than 50% fine sediment coverage, whereas the control site presents only 17% of samples with greater than 50% fine sediment coverage. The average fine sediment cover at the impact site was found to be 56%, whilst it was only 18% at the control site.

Sediment Cover

Sediment size

Increasing levels of fine sediment deposition has been found to severly affect invertabrates by altering substrate composition which subsequently changes biotic suitability for many taxa. Studies on numerous rivers found that macroinvertabrate density was severely reduced once 50% of sediment distribution was classed below 1000um.

The measured data showed that 67% of the control site sediment was 1000um or greater, whereas 73% of the impact site sediment was 710um or less. This characteristic is exemplified in the cumulative frequency curve that clearly presents the particle size distribution differences between the control and impact sites.

Sediment Size

Cumulative Dist

This investigation confirmed that there was a profusion of fine sediment located at the impact site, with the control site exhibiting deeper, coarser sediment on the riverbed substrate and less fine sediment coverage overlay.

The sediment depth, sediment cover and sediment size tests all produced statistically distinct differences when analysing the control and impact sites. All the tests were analysed using the Mann-Whitney U-Test and the hypotheses outcomes calculated. The majority of the hypotheses supported the belief that there were disparities in sediment ranks between the control and impact sites.

It can therefore be concluded that the impact site has a greater proportion of fine sediment than the control site. With scientific literature supporting the assertion that willow trees trap sediment on the riverbed substrate, we can construe that the willow infestation at the impact site has contributed to the elevated fine sediment levels at the impact site, with a subsequent detrimental impact on the associated aquatic ecosystem.

Campus Tour Highlight Number 25 – Botany Building

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Constructed 1928. Built in brick as opposed to stone for reasons of economy. Inside contains a Napier Waller’s stained glass window, Orchids.
This is my new favourite building on campus. I’ve only recently discovered it, as it’s right up the top of Tin Alley hiding behind Union House. Fantastically designed building reminiscent of a by-gone era. Spectacular gardens out the front (as you expect from the faculty of Botany!). I went and had a preliminary chat with a few of the academic staff about research topics. Really encouraging and helpful. They even specialise in the obscure black art of recreational ecology – something which I’m increasingly interested in. I’m thinking about formulating my research around this area of science: incorporating energy transfer models of the impact of humans in wilderness areas.

Lecture No. 1

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And so it begins. First day of lectures. This semester I only have one subject to stare down: Sustainability, Governance and Leadership (SGL). It is a subject that explores the meaning of Sustainability and the human constructs that go along with it. It extends many of the themes I learnt whilst undertaking my Graduate Certificate In Sustainability. So I’m not too concerned of my brain exploding on the first day.
SGL is taught in an intensive mode over 6 Fridays with four hours of lectures and two hours of tutorials per day. To begin, we are introduced to one of the OEP co-ordinators and a brief summation of SGL. I was surprised to hear that in our class of around 100, there are 28 different nationalities represented! This certainly makes for diverse opinions and a real range of critical thoughts. Our first lecture continues and introduces us to the concepts of sustainability, governance, and leadership.
We subsequenlty have three guest speakers who give lectures on readings that we have previously studied. (Yes – I had to study around 100 pages of papers before the first day even began!). The topics the guest speakers covered were really interesting, and given in such a way as to not exactly “teach” you something, but to give you enough information so that you can start to critically analyze a concept, then go away and do some investigation and come to your own conclusions. I heard numerous times throughout the day “You guys are Masters level now, and we expect greater degree of critical analysis and original ideas than you have probably previously provided.” Hmmm. What have I got myself into?
We were then broken into groups of about 15 for tutorials where we could disseminate what we had read during the week, and heard in the lectures. These tutorials were nuts. We (tried) to cover about 10 different concepts in about 50 minutes, analyzing the concept and giving our opinion. It almost fried my brain. Our group is really diverse which makes for interesting discussions. We have students from Australia, Ecuador (2), Chile, China, Indonesia, France and Cyprus. Everyone had something valuble to contribute. It also gave us the chance to meet some of the people in our course for the first real time.
So what did I learn? I came away from each lecture with a few points which resoated and I could follow up on, such as:

Contemporary Ecological Challenges
– Habitat change is the greatest threat to endangered species (not say, climate change), with 80% of endangered species threatened by habitat change.
–  In Australia, invasive species is one of our biggest problems, especially foxes and feral cats.
– The amount of research of flora is actually very small (we know very little about trees and plants). There is a big knowledge gap here.

Forms of, and Challenges of, Environmental Governance
– We are governing the environment with frameworks that are not fit for purpose.
– Therefore, what is the right mix of governance rules, regulations and markets for the best outcomes for the environment?
– Examples of simplistic solutions are all around us, but how do we over-arch them under one umbrella framework?

The Precautionary Principle in Environmental decision making
– Do we need the precautionary principle if the markets are running correctly? Are they broken? What are the values of the market?
– The PP is very normalative and doesn’t deal with complex systems. (Note the difference between the meaning of complex and complicated).
– In practice the PP can be an absolute mess, and serves no purpose for us. Essentially we are trying to to impose order on a non linear, chaotic situation.

Tired by the end of the day. But I better start reading next weeks papers. I have an assignment due in 2.5 weeks.

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Book Launch – Four Degrees of Global Warming: Australia in a Hot World

Four Degrees

Four Degrees of Global Warming: Australia in a Hot World

Melbourne Sustainable Society Institute

Wednesday, 4 December 2013 from 6:00 PM to 8:00 PM

Carrillo Gantner Theatre, 761 Swanston Street, University of Melbourne

Register here:
http://four-degrees.eventbrite.com.au

The 2011 conference Four Degrees or More? Australia in a hot world, held in Melbourne, provided an integrated overview of the likely consequences of rapid global warming for Australia and its region. Now, the newly-published book Four Degrees of Global Warming: Australia in a hot world, edited by Associate Professor Peter Christoff, updates the expected consequences of a four-degree world. Contributing authors include many of Australia’s most eminent and internationally recognised climate scientists, climate policy makers and policy analysts. This book provides an accessible and detailed examination of the likely impacts of a four-degree world on Australia’s social, economic and ecological systems.

The Four Degrees of Global Warming launch offers policy makers, politicians, students, and anyone interested climate change access to the most recent research on the potential Australian impacts of global warming as well as possible responses.

Speakers:

Dr Malte Meinshausen Honorary Senior Research Fellow, School of Earth Sciences, University of Melbourne

Prof David Karoly Professor of Atmospheric Science School of Earth Sciences, ARC Centre of Excellence for Climate System Science, University of Melbourne

Prof Lesley Hughes Professor, Ecology, Macquarie University

Dr Mark Howden Chief Research Scientist, (Primary Industries) CSIRO

Prof Emeritus Tony McMichael Professor, Emeritus of Population Health, Australian National University

Prof Robyn Eckersley Professor, Head of Political Science, University of Melbourne

A/Prof Peter Christoff Climate Change Policy, Melbourne School of Land and Envrionment, University of Melbourne