Friday, 11 July 2014

Tree munching machines and 70's rock

TREES - the dominant vegetation type at the WWHFE.

While checking out Robert Krulwich's recent blog post titled 'Watch It Swallow An Entire Tree In Seconds' I was exposed to a machine used in forestry that is capable of consuming a 10 m tall tree in 15 seconds. Although interesting, that is perhaps a topic for another time. 

What I wanted to bring to your attention was some lyrics I saw deep in the comments section beneath Robert's blog. They resonated with me because the song writer obviously had a good grip on species interactions, and it was great to see these ideas expressed in song. Also as one progresses through the lyrics clear philosophical connections to society can also be made. The song 'The Trees' was written by Neil Peart from the band Rush (1968 - present). It's a pretty bangin' song - it helps I'm currently re-listening to the music I loved when I was a teenager and in my early 20's (hint: lots of 1970's rock/blues/reggae; see this week's album list here).

I was first caught by the lyrics which I read like a poem:

There is unrest in the forest

There is trouble with the trees

For the maples want more sunlight

And the oaks ignore their pleas

The trouble with the maples

(And they're quite convinced they're right)

They say the oaks are just too lofty

And they grab up all the light

But the oaks can't help their feelings

If they like the way they're made

And they wonder why the maples

Can't be happy in their shade

There is trouble in the forest

And the creatures all have fled

As the maples scream 'Oppression!'

And the oaks just shake their heads

So the maples formed a union

And demanded equal rights

'The oaks are just too greedy

We will make them give us light'

Now there's no more oak oppression

For they passed a noble law

And the trees are all kept equal

By hatchet, axe and saw

My attention was immediately sparked in the first two verses. Here Peart writes about competition between maples and oaks for light. In this case the oak are the dominant vegetation, yet this will not always be the case (even without the hatchets, axes and saws). Most ecosystems are dynamic (meaning they change over time) and this dynamism is often linked closely to disturbance. Fire, particularly intense wild fires (as compared to planned burns), has the potential to dramatically alter vegetation structure. Consider tall Mountain Ash (Eucalyptus regnans) forests. The Mountain Ash are the dominant structural element and are killed by fire (but will release large amounts of seed immediately after fire). All is not lost for the species (as long as fire doesn’t return too soon) as seeds will germinate and replace the dead adults (see here). However, before that stand replacement occurs a battle for light is forged between the Mountain Ash seedlings and all other plant species with the capacity to grow tall (e.g. tree ferns, wattles). This is a story that is played out in many global ecosystems, and more than likely also at the Wog Wog Habitat Fragmentation Experiment, with fragmentation as the disturbance instead of fire. I did investigate changes in light regime within fragments as part of my thesis. Following this I asked myself: can such changes in light regime (and other associated environmental changes as a result of fragmentation) cause a shift in the dominant vegetation, or promote a dominant species to become more dominant? This is something Dale Nimmo, John Morgan, Kika Tarsi and myself are investigating in our current manuscript (stay tuned).

For all the influence this song had on my thinking I was left with a slightly bitter taste when I came across an interview in 'Modern Drummer' magazine (April/May 1980 issue) where Neil Peart played down an important message in the lyrics, he says "No. It was just a flash. I was working on an entirely different thing when I saw a cartoon picture of these trees carrying on like fools. I thought, 'What if trees acted like people?' So I saw it as a cartoon really, and wrote it that way. I think that's the image that it conjures up to a listener or a reader. A very simple statement." 

None-the-less I still thought it was cool, and worth sharing, as it demonstrates that a simple statement conjured up in a few moments can influence the thinking of another many years later.
Hope you enjoy Rush - The Trees!


'Clink' Cheers

Monday, 10 February 2014

Progress Update

For anyone who may be paying close attention to the Wog Blog you may notice the lack of posts in the year 2014 (a total of 0). This is largely because as of November 2013 I have been in limbo following the submission of my thesis (I may let you know what I've been up to in a future post). Yes, my thesis is currently being assessed.

As there is still no news I will leave the thesis update there. For the rest of this post I wanted to reflect on a previous post 'Building a skill set for post-PhD employment in the nonacademic arena'. In this post I talked about my uncertainty when it came to post-PhD employment/career. I mentioned how I wasn't sure if I was "one of those scientists" who is not only capable, but is skillful and talented when it  comes to producing good ecological research. I suppose those comments came at time where I was interacting with very good scientists (as colleagues) and didn't feel quite up to par. Now I see that learning is rapid in this industry, and a year is a long time (and by extension you can learn a lot in a year). So the comparisons I made weren't really fair on myself as I was comparing my abilities against others who had much more experience (i.e. post-docs and academics). Although I still have a lot to learn, now more than ever, I am excited by the prospect of continuing with academic research. Finding the funding and eventual employment is still going to be tricky, but I am ready to throw myself into it.

'Clink' Cheers

Thursday, 14 November 2013

Changes in plant species density in an experimentally fragmented forest landscape: are the effects scale-dependant?

I have recently been notified that a second chapter of my thesis has been published (early view) in the journal Austral Ecology. This work forms the basis of my thesis as it investigates the influence of fragmentation on plant diversity (while other chapters explore mechanisms - altered by fragmentation - that may influence plant diversity). While I use the term ‘plant diversity’ in this blog - as it is a term most can relate to - the term I actually refer to in the paper is ‘species density’ a more appropriate term for what was measured (simply the number of species within a given area).

This work was conducted with colleagues, James Camac, Brett Melbourne and John Morgan, and you can find a copy of the article here.

We were interested in investigating how the harvesting of native vegetation, and subsequent conversion to a pine plantation, influences the diversity of native plants within the forest fragments left behind. Currently the pine plantation is tall and well established, leading to subtle changes in light, temperature and moisture within small fragments (see here). Therefore, we predicted that changes in plant diversity might also accompany these changes in microclimate within small fragments. Studying the impacts of fragmentation on plant diversity are important as it is typically assumed that diversity is reduced within fragments (reductions in habitat area and population size can lead to local extinction); however, this has not been adequately tested in situations where pine plantations are the ‘matrix’.

By using a series of nested quadrats (Figure 1) within each fragment we were not only able to see how diversity is influenced by fragmentation, but also how the scale of investigation influences the changes in diversity (as diversity may change at only small or large scales). Once data was collected, we were also interested in seeing if species commonness (how common species are across the experimental landscape) influenced the patterns in plant diversity.

Figure 1. Nested sampling design using 16 small (1 m2) quadrats nested within the central quadrat. The nine 16 m2 quadrats are nested within a single 144 m2 quadrat located in the centre of each fragment (= 12) and control area (= 4).

Our models revealed that the influence of fragmentation on plant diversity was dependent on several factors, namely the size of fragments (i.e. small versus control), the spatial scale of observations (i.e. 1 m2 versus 144 m2), and the species group being considered (i.e. uncommon versus common). Interestingly, we observed higher plant diversity in small fragments - contrary to predictions (Figure 2; for further discussion on scale and commonness see the full article as it will not be dealt with here).

Figure 2. Back-transformed mean species density (with 95% confidence intervals) for total species density, common species density, and uncommon species density, across three spatial scales for all fragment sizes and continuous forest.

Although increased plant diversity within small fragments has been shown, it is generally attributed to the presence of exotic species (that are promoted following a fragmentation disturbance). However, this is not the case here as exotic species are rare at the Wog Wog Habitat Fragmentation Experiment. Therefore, we suspect that native plants were able to persist during the early stages of plantation development (when conditions would have been drier, hotter and brighter due to loss of tree canopy), and have since been able to flourish as the plantation developed a dense canopy. In fact we feel that during a period of prolonged drought (the Big Dry 1997-2009) the plantation matrix has buffered small fragments from declines in plant diversity, but this requires further investigation.

Whether the observed increases in plant diversity in small fragments will be sustained into the future is unknown, and will depend largely on the fate of the matrix. If the plantation is harvested an extreme shift in plant diversity and composition within fragments is to be expected as the filters maintaining high levels of plant diversity in small fragments are removed.

Sunday, 11 August 2013

Pine plantations modify local conditions in forest fragments in southeastern Australia: insights from a fragmentation experiment

All of a sudden it is August, and I haven’t blogged since December. How time flies…  

With this blog I bring good news. With my colleagues, Dale Nimmo and John Morgan, I have published my first scientific article. The article will form part of my PhD thesis that is to be completed very soon (sometime in 2013). You can find a copy of the article here.

We were interested in looking at the more subtle effects of fragmentation, such as changes to soil chemistry, litter dynamics, and the local climate within fragments. These changes were of particular interest because the Wog Wog experimental fragments are imbedded in a pine plantation, which could result in different changes to those previously described in agricultural landscapes.

Briefly, we found fragmentation causes a series of changes to local environmental conditions, including increased canopy cover (due to the pine matrix ‘overtopping’ the forest fragments), leading to increased soil moisture and reduced temperatures in small fragments.

Mean (a) % canopy cover and (b) % soil moisture with 95% confidence intervals (CI) for all fragment sizes and continuous forest. Dashed vertical lines show means of control plots for comparison.

Therefore, small fragments (0.25 ha) appear to have a slightly different environment to medium (0.88 ha) and large (3.06 ha) fragments, and the areas of nearby continuous forest.

So why do we care?

Changes like this may not cause too much grief to a Swamp Wallaby cruising through the landscape, but it could have implications for the plants that occur in these small fragments, and could have flow-on effects to other parts of the ecosystem (microorganisms, insects, reptiles, birds and mammals). It is very important to document these changes now as it wont be long before the pines get harvested, and we will have to wait another 25 years before we get another opportunity to ask these questions at the WWHFE.

Also while I have your attention. If you are interested in fragmentation research you MUST check out a recent video by Don Driscoll on ‘The Matrix’. Very cool and entertaining stuff.

'Clink - Cheers'

Sunday, 9 December 2012

Building a skill set for post-PhD employment in the nonacademic arena

Because this blog now covers a variety of content relevant to my research I thought I would briefly discuss an interesting paper I was sent by my good friend Dale Nimmo. Before I get to the paper I will set the scene:

Dale was aware that as I draw closer to my expected end date (May 2013 for anyone interested) I am thinking more and more about my future job prospects and how I can use my PhD qualifications. Currently I am not certain of anything. I initially wanted to continue with academia and find a post-doc but I am realizing that these positions are suited to a certain type of scientist, and although I am certain I am capable, I am not sure whether I am one of those scientists. I then began to consider teaching as a possibility as I have always really enjoyed teaching undergraduate practical classes and giving guest lectures. However, these days there is much more focus on good research than good teaching, and subsequently there are less teaching roles around then there perhaps used to be. My alternatives to these two more academic roles are to either jump in ecological consultancy, or get into land management (councils, Parks Victoria etc). However, both of these roles will not fully utilize the qualifications I would have gained by that time. Just as all these alternate options are floating around in my head Dale sent me a paper titled “Graduate Student’s Guide to Necessary Skills for Nonacademic Conservation Careers” by Blickley et al. 2012 (link below).

I would recommend any PhD student in ecology read this paper, whether you intend on continuing with academia or not. The article really opened my eyes to the skills I will posses by the end of my thesis.

I don’t want to give a review here but rather to bring this article to people’s attention. Though I will say I found it very interesting to see a synthesis of non-academic job advertisements within the conservation field. I learnt a lot about the skill set I currently have, discovered other skills I didn’t know I have, and was also able to identify those skills that I may be currently lacking.
Although I still don’t know where I will end up (I have my preferences of course) I feel I am better armed with skills that will allow me to be confident in applications and interviews as I now better understand my strengths and weaknesses.

Click above for the full text article

‘Clink’ - Cheers

Sunday, 26 August 2012

How does forest fragmentation affect community (re)organization? New paper in Journal of Veg Sci

I am very excited to blog about the first paper published from the Wog Wog Habitat Fragmentation Experiment in over 10 years led by John Morgan (I have mentioned my intention to do this in a number of previous posts). I wanted to wait until it was actually printed in the journal with volume and page numbers, but with a subscription to Journal of Vegetation Science you can get yourself a copy here (or comment on this post and I can probably dish out a .pdf).

The article uses scale-occupancy curves of common plant species (essentially determining how much space species utilise) to document the patterns of spatial structure at WWHFE. Without approaches like this it is very difficult to detect species responses to habitat fragmentation (unless you are able to follow populations over the duration of the experiment which is often difficult). Essentially we are asking: Are common species becoming more common, stable, or rare in remnants? We predicted that the greatest change should occur in small remnants as these areas are likely altered by changed environmental filters more so than large remnants (e.g. see my post on microclimate).

This paper focussed on 22 common plant species. Common species were a good starting point for this type of research as it allowed us to compare curves within each species across all treatments (small remnants [0.25 ha], large remnants [3.06 ha] and continuous forest). By investigating common species we are able to make inferences about rare species (if common species are responding to fragmentation, so must rare species - if there is any indication that rare species could be declining it is a serious concern for plant conservation).

We found that experimental fragmentation may affect common plant species by affecting the local patterns of distribution (defined by scale-occupancy curves).  Where the slope of the scale-occupancy curve is flat, a species is considered common. Alternatively, when the slope of the curve is steep a species is considered rare. These effects were most obvious in small-sized remnants, relative to large remnants and intact forest, where changes in environmental filters have been most pronounced. 

Box-plot distribution of slope values (z) for 22 common understorey species in intact forest (I), large (L) and small (S) fragments. The lower and upper boundaries of the boxes represent the 25th and 75th percentile, respectively, the line in the box represents the median and dots are outliers. Small slope values indicate aggregated distributions whereas large slope values indicate scattered distributions, from Morgan & Farmilo (in press) Journal of Vegetation Science.

So what does this all mean? This study suggests many of the common species found at the study site have become more common since fragmentation. Such changes to common species may alter the structure of the vegetation (e.g. habitat), how the ecosystem functions (e.g. water availability, flammability), the interactions between species (e.g. plant competition, herbivory, pollination) and could have serious ramifications for species that rely on a system that closely resembles the original.

'Clink - Cheers'

Monday, 16 July 2012

New Page Added to Wog Blog

This is just a short note to let followers know a new page has been added to the Wog Blog. It has been titled 'Volunteers'. It provides a brief explanation of why volunteers are important, how to get them, and a complete list of all the volunteers that have assisted me with my post-grade research.

Here are some volunteers in action:

Here we have Andre, Baz, Helen, John, Luke, Pete and Simon. They all look like they are having a good time.

Until next time....

'Clink - Cheers'