IAVS conference 2011 – Lyon, France

This is a much belated post that took me far too long to publish but far too nice to forget.

One of the perks of doing research is attending conferences. It is great to be able to share your work with others and find out what is happening at other institutions in Australia and internationally. In 2011 I attended the International Association of Vegetation Science (IAVS) conference in Lyon, France. The theme of the 2011 symposium was ‘vegetation in and around water: patterns, processes and threats’. I presented some of my work on assessing riparian vegetation condition in Victoria.

The IAVS is an international organisation with a very broad scope of interest in vegetation science. They publish two research journals: Journal of Vegetation Science and Applied Vegetation Science. Their next (2013) annual meeting will be held in Tartu, Estonia.

Lyon, is a beautiful city and was a fantastic location for the conference. My travelling tip for Lyon: take advantage of the bike hire system, it is the perfect mode of transport for this city.

Lyon - bike hire

Lyon – bike hire

Lyon

Lyon

In addition to attending the conference, I was also able to spend some time with some of the alpine researchers from the Université Joseph Fourier’s Laboratoire d’Ecologie Alpine near the Col du Lautaret 90km east of Grenoble. This was an amazing place, particularly at that time of the year when the alpine meadows were in flower. This is quite a contrast to the Victorian Alps of southern Australia.

Alpine meadow - Col du Lautaret, France

Alpine meadow – Col du Lautaret, France

The French Alps

The French Alps

Alpine science

Alpine science at the Laboratoire d’Ecologie Alpine

And finally, what sort of trip to France in July would this be without some of the Tour de France… particularly in the first year the race was won by an Australian. Go Cadel!

Cadel Evans 2011 Tour de France winner

Cadel Evans 2011 Tour de France winner

Advertisements
Posted in Uncategorized | Tagged , , , , , , , , | Leave a comment

Feeling a bit twitchy

I am by no means a hardcore twitcher, or birdwatcher, but on a recent visit to the south coast of NSW (Australia) I took the opportunity to try to observe and identify some of the species.

The south coast of NSW is a beautiful part of Australia and contains vast areas of native vegetation within National Parks and State Forests. The patchy landscape of dense forest and cleared agricultural land near the coast provides a wide range of habitats for fauna species and the bird life is highly diverse.

The highlight of my brief twitch was stumbling across a pair of Tawny Frogmouths (Podargus strigoides) roosting in a Broad-leaved Apple tree (Angophora subvelutina). At first, one of the pair was looking directly at me, but as soon as I lost eye contact it took up the position of pretending to be a branch and was very difficult to see.

Tawny Frogmouth (Podargus strigoides)

Tawny Frogmouth (Podargus strigoides) pair: one front on, the other in cryptic pose

Tawny Frogmouth (Podargus strigoides) pair: both in cryptic pose

Tawny Frogmouth (Podargus strigoides) pair: both in cryptic pose

A second highlight was locating a nest of Rainbow Lorikeets in a very tall Sydney Blue Gum (Eucalyptus saligna). There were at least 8 adult birds congregating around a tree hollow – or what looked like a pair of hollows – around 15m from the ground. The birds would come and go throughout the day but often in this large group.

Rainbow Lorikeet (Trichoglossus haematodus) nest

Rainbow Lorikeet (Trichoglossus haematodus) nest

I’ll finish here with a group of some other birds that I saw. I’m not sure if I have started something here but I am definitely feeling the twitch a little more after this trip. Hopefully I will see some more interesting things on the next trip.

Posted in Birds | Tagged , , , , , , | Leave a comment

Livestock grazing of riparian vegetation #1

This topic is the core of my PhD and I have a lot to say, so I will let it out slowly and this will be the first of a series of posts.

Livestock grazing has attracted the attention of ecologists for many decades. We have learnt a lot but the story is not complete. The effects of livestock grazing on vegetation remain a controversial and important subject. This is highlighted by the recent controversy in Victoria on grazing in the high country – if you are interested in this issue feel free to read the posts from some fellow QAEcologists here, here and here.

My work does not deal with alpine grazing but is concerned with livestock grazing in native vegetation within the floodplains of the Victorian Riverina. The Victorian Riverina subregion has the highest proportion of cleared vegetation in Australia, with only 5.1% native vegetation remaining in 2001 (NLWRA 2001). Much of the remaining vegetation occurs in narrow strips along roadsides and creeks (Figure 1).

Aerial photo

Figure 1. Aerial photo of Broken and Boosey Creeks in the Victorian Riverina

The remnant riparian vegetation is under significant threat from weed invasion and grazing. Many of the riparian remnants are licenced to be grazed by sheep or cattle. Some sites are also fenced from adjacent farms. However, a licence does not necessarily mean a remnant is grazed (or how heavily grazed) and a fence does not necessarily mean a remnant is more heavily influenced by the adjacent farm. I used three separate indicators of grazing for analysis: presence/absence of a fence, presence/absence of grazing licence, and presence/absence of recent heavy grazing.

Based on some of my previous work showing the change in vegetation cover with increasing distance from the creek edge (see my post on sampling for details), I separated remnant sites into two zones – Inner (first 25 m) and Outer (all outside 25 m) – for examining the effect of livestock grazing.

Using the zoned sites, I wanted to firstly determine the specific effect of grazing on each of the vegetation life forms. This is not directly possible with these data as I’m not modelling the specific change of cover at a given site that is grazed or not grazed. Instead I’ve done this by comparing vegetation attributes of sites that have been grazed to sites that have not been grazed. Boosted Regression Tree (BRT) analysis was used to do this, since they are an effective tool for modelling the influence of a particular variable while accounting for effects of other variables. I built models including management and environmental variables and used bootstrapping to perform multiple runs of the model (let me know if you want any more information about the modelling process).

These models estimated the cover of native vegetation life forms when grazed and ungrazed. All but the smallest native life forms had lower cover in grazed sites, as did plant litter (Figure 2). Bare ground was higher in grazed sites. Small native shrubs showed the weakest response to grazing, perhaps due to their prostrate growth form. Exotic life forms were much less sensitive to grazing, and in the case of small herbs increased in cover when grazed (Figure 2). These general findings are well supported in the literature, which highlights that over time, intense grazing will result in vegetation dominated by species with traits suited to grazing, such as short lived (annuals), low-growing perennials, small seeds, high regrowth potential, plasticity in response to grazing, and high fecundity (Landsberg et al. 1999; McIntyre and Lavorel 2001). The data in Figure 2 only include comparisons of inner zones.

Figure 2. The modelled comparison between cover in grazed (grey) and ungrazed (black) sites accounting for variation in other environmental variables. Life forms are: MS: medium shrubs, SS: small shrubs, MTG: medium tufted graminoids, MH: medium herbs, SH: small herbs, MNG: medium non-tufted graminoids, BG: bare ground and LT: litter.

Figure 2. The modelled comparison between cover in grazed (grey) and ungrazed (black) sites accounting for variation in other environmental variables. Life forms are: MS: medium shrubs, SS: small shrubs, MTG: medium tufted graminoids, MH: medium herbs, SH: small herbs, MNG: medium non-tufted graminoids, BG: bare ground and LT: litter. Appending letters refer to natives (.N) and exotics (.EX).

So this is great, we can detect correlative effects of grazing on vegetation cover in this system from my data. However, this is not particularly helpful if these effects are much weaker than other factors. For management to be effective it must have a relatively strong influence on the vegetation. This is partially taken into account in the BRT models above, however I did an additional test of this influence by comparing the management variables (grazing, licencing and fencing) against a range of environmental variables using hierarchical partitioning.

This method determined the contribution of each variable to the goodness of fit for the response variable (native vegetation cover). These individual contributions were summed into ‘management’ and ‘environmental’ variables to compare the combined influence. Grazing management was less influential than environmental variables but was higher and more variable in the inner zone (Figure 3). This suggests that the vegetation (and ground layer) cover is more susceptible to grazing management near the creek.

Figure 3.

Figure 3. The combined contributions of management (dark) and environmental (light) variables on explained variance of native vegetation cover.

Hopefully I have explained this satisfactorily so that you can see that within this study site I have detected correlative responses of understorey life forms to grazing variables, and that these management indicators appear to be significant drivers of understorey cover.

Feel free to ask if anything is unclear. Also, for a great brief summary of grazing effects see Ian Lunt’s latest post in the Conversation here.

Chris

References:

Landsberg J., Lavorel S. & Stol J. (1999) Grazing response groups among understorey plants in arid rangelands. Journal of Vegetation Science 10, 683-96

McIntyre S. & Lavorel S. (2001) Livestock grazing in subtropical pastures: steps in the analysis of attribute response and plant functional types. Journal of Ecology 89, 209-26

NLWRA. (2001) National land & water resources audit: Australian native vegetation assessment. National Heritage Trust

Posted in PhD Research | Tagged , , , , , , , , , , | 1 Comment

What are friends for…

It is very easy to live in a city like Melbourne and not REALLY pay attention to its plethora of small and large parks and reserves scattered throughout. I, like most of us, was oblivious to the role of volunteers in managing these areas. That was until I was exposed to vegetation management through my degree at the University of Melbourne.

All parks and reserves have some type of paid management group overseeing their condition, public use, safety, access, etc. such as Parks Victoria or a particular council appointed body. However the resources available to manage these lands are usually very low and these staff can only do so much without help.

Enter the volunteer! For so many of us that do not pay attention, there are a handful of people out there who do REALLY notice and are also keen to get involved. Many parks and reserves have organised ‘friends’ groups or volunteer programs to help with management. These volunteers often assist with planting, weeding, collecting seeds, litter removal, etc. and they are incredibly valuable to the condition of these sites.

I am currently a St Kilda resident and have recently tracked down two of my local volunteer groups, St Kilda Indigenous Nursery Co-operative, and the Friends of Westgate Park, both of which seem to be great community not-for-profit groups with an interest in managing our beautiful native biota. I will be heading to the SKINC this week to get some locally indigenous plants for my tiny ‘garden’.

No doubt these types of volunteer groups exist in your area and are doing great things. I recommend you make the time to seek them out and drop by some time, it can be incredibly rewarding. For those of you studying ecology or something relevant, this can also be a great opportunity to bone up on your plant ID and management skills, which can be great for career planning – as my current supervisor Peter Vesk has told many students before.

If you can’t find a local friends group, you can always try the Conservation Volunteers who do a range of projects all over Australia (and now New Zealand) with many sites in greater Melbourne. I have done a bunch of different projects with these guys and they really good.

Do it.

Posted in Interest, Uncategorized | Tagged , , , , | Leave a comment

Sampling riparian vegetation

There are endless variations to the ways we survey vegetation – and there needs to be. A particular vegetation survey will need to meet specific requirements of accuracy, cost efficiency, relevance and purpose. For example, within the same study site, survey methods used for a study on species richness will be very different from a study on how life form cover changes over time.

This need to tailor vegetation surveys towards the specific study results in difficulties when comparing data from different sources. It is inappropriate to compare say, species richness data, between two sites (or even the same site) if the data were collected using different methods – unless you have quantified the bias in each method. This is because of the different biases and uncertainties associated with each survey method. Many of these biases are evaluated and compared in the literature but I won’t go into that any further here.

Vegetation attributes of different vegetation types are influenced by different things, for example, riparian vegetation is greatly influenced by water levels and flows whereas alpine vegetation is greatly influenced by temperatures and snow cover. Survey methods may need to accommodate these effects.

Riparian vegetation

Location along a water course and distance from the water’s edge impact vegetation attributes. This is due to the response of vegetation to available water,  the destructive effects of water flows and also other factors linked to water, e.g. livestock spend time near water to drink.  Surveys of riparian vegetation should at least acknowledge these gradients, as we do for any other environmental gradient such as altitude.

Riparian vegetation in northern Victoria

Distance from the stream

The surveys for my PhD recorded vegetation at point quadrats along transects running away from a creek edge. These data estimated the cover of a range of vegetation life forms (e.g. native shrubs and exotic annual herbs) and ground covers (e.g. litter and bare ground) across sites along this gradient of near to far from the creek edge. The data showed that many of these covers vary along this gradient. You can read the paper when it comes out to get the full details but in general some things do change a lot and others don’t.

It is then interesting to know what sorts of things may influence vegetation along this gradient. A large suite of potential drivers are candidates for this such as, rainfall, vegetation composition, livestock grazing, tree cover, etc.

An example for both of the above points is presented below for bare ground. Bare ground in my study was highest very close to the creek where low level erosion and water flows prevent plants from establishing. This effect was increased by the presence of grazing. The animals spend a lot of time near the water to drink and for shade and in the process eat and trample the vegetation close to the creek. Bare ground tended to gradually increase further from the creek, which is likely due to the proximity to the adjacent agricultural land. Let me know if you want to know more. I have done these types of assessment for all of the life forms.

Bare ground percent cover with increasing distance from creek. Each point represents data across all sites at that distance from the creek. Grey dots are data from sites where grazing was present and back dots from sites without grazing. Solid lines are a segmented linear regression of these data, dashed lines occur at the change point of these lines. Red fitted lines are loess models of the data.

Increased plant suppression and soil erosion on stream bank due to livestock

Distance along the stream

The additional gradient along the length of the stream varies in stream width (wider downstream) and the concentration of sediment, propagules and nutrients that accumulate along its path. This accumulation generally results in an increase in vegetation cover across a range of life forms. An example of this is shown in the figure below for native shrub cover. The relationship is quite poor (R-squared 0.10) as this relationship does not take into account any other site factors such as grazing, management, size, etc that will influence shrub cover.

Native shrub cover versus distance upstream of the creek confluence with the Murray River. Each point indicates a site. The line is a linear model of this relationship (R-squared = 0.10).

Summary

Riparian vegetation studies should attempt to account for the natural variation along these two riparian specific gradients as part of their survey design. Each different riparian system will have its own effects on vegetation and extrapolation of relationships to other systems should be done with caution.

This is just a taste of some of the work I have been doing on this particular issue. Keep your eyes peeled for more information. If you simply can’t wait until then, feel free to contact me.

Posted in PhD Research | Tagged , , , , , , , , | 1 Comment

What is vegetation condition?

Enormous amounts of time and money are contributed by researchers, government, the private sector and volunteers to protect or enhance vegetation condition. But what exactly is vegetation condition? Any statement about the condition of something must be made in relation to something else, i.e., my old car is in much worse condition than when it was new, or is in worse condition than my friend’s car.

Vegetation condition is commonly compared to what the vegetation was like before European settlement or ‘pre-1750’ vegetation. The only catch is that we don’t  know exactly what the vegetation was like then. In Victoria we have tried to estimate this condition through surveying the best representatives of each vegetation type (or each Ecological Vegetation Class – EVC) that remain today. These best condition estimates are stated as ‘benchmarks‘ for each EVC and listed on the Department of Sustainability and Environment (DSE) website.

So once you have a benchmark or something to compare against, how do you evaluate vegetation condition at a site? DSE’s version is called Vegetation Quality Assessment (VQA). They have scored a range of attributes within the benchmark sites to give a VQA score for each EVC. This method is based on the ‘habitat hectares’ method described by Parkes et al. (2003). Vegetation that has been scored using the VQA method can be compared against its relevant benchmark and assessed appropriately. There is a bit more to it than this, but you get the idea.

A similar benchmark comparison tool for assessing vegetation condition exists in NSW called BioMetric, developed by Gibbons et al. 2005 and 2009.

But this is not the only, nor necessarily the best way to assess condition. Some landscapes have been modified so much by people, or by changes in the climate itself, that trying to restore the vegetation to its ‘original’ condition is either impossible or far too expensive. At what point is it worth giving up on trying to restore a site to its original condition and instead setting a new benchmark that is more suited to the current attributes of the site? How would we set these new benchmarks?

We need to have targets for management but the benchmarks we set must be appropriate and realistic. I’m hoping some of my work will help to address parts of these questions and stimulate continued thought on this very necessary topic.

Gibbons, P., Ayers, D., Seddon, J., Doyle, S., Briggs, S. (2005). BioMetric Version 1.8. A Terrestrial Biodiversity Assessment Tool for the NSW Property Vegetation Plan Developer. Operational Manual. Department of Environment and Conservation (NSW), unpublished.

Gibbons P., Briggs S. V., Ayers D. A., Doyle S., Seddon J., McElhinny C., Jones N., Sims R. & Doody J. S. (2008) Rapidly quantifying reference conditions in modified landscapes. Biological Conservation 141, 2483-93.

Gibbons P., Briggs S. V., Murphy D. Y., Lindenmayer D. B., McElhinny C. & Brookhouse M. (2010) Benchmark stem densities for forests and woodlands in south-eastern Australia under conditions of relatively little modification by humans since European settlement. Forest Ecology and Management

Parkes D., Newell G. & Cheal D. (2003) Assessing the quality of native vegetation: The ‘habitat hectares’ approach. Ecological Management and Restoration 4, S29 – S38.

Posted in PhD Research | Tagged , , , , , , , | 1 Comment

Grampians National Park

What better way to spend the Easter break than camping in one of Victoria’s beautiful national parks. This year I visited the Grampians National Park, a 168,110ha park 240kms west of Melbourne. The sandstone mountain ranges with unique flora are a fantastic contrast to the relatively flat agricultural lands surrounding the park.

Mt Stapylton walk

The Grampians contain a vast array of vegetation types within small areas. In a single walk you may pass through tall forest, heathy scrub, tall damp scrub and mixed woodlands. Vegetation types change as a result of soil type, soil depth, water availability and fire regimes.

This Park is renowned for incredible wildflower displays throughout the year. Visiting in April (in Autumn) is not the peak time for flowering but if you keep your eyes peeled you will still see a number of herbs, grasses and shrubs in flower. Here are a few of the ones we saw:

Banksia ornata (Desert Banksia)

Astroloma conostephioides (Flame Heath)

Correa reflexa (Common Correa)

Hibbertia riparia (Erect Guinea-flower)

Posted in Interest, Uncategorized | Tagged , , , , , , , | 2 Comments