Blackberries (Rubus spp.) weed or native?

Blackberries are delicious…but they are also one of Australia’s worst environmental woody weeds.

Blackberries were introduced in the 1840s in New South Wales, and the plants quickly spread throughout the Country via birds and other animals. In the 185os, von Mueller deliberately spread blackberry seeds into the Victorian bush so that hikers could enjoy a snack on their travels. They can tolerate a wide range of environmental conditions but are less successful in drier climates. There are approximately 250 species of Rubus worldwide, with around 25 occurring in Australia, including 8 natives. The many variants and species of European blackberry are difficult to identify to species level so are all commonly referred to Rubus fruticosus spp. aggregate. Today, they are collectively considered a ‘weed of national significance’ and are a serious threat to our native vegetation.

What is less commonly known is that Australia has a few native species of Rubus. In Victoria, the most common is Native Raspberry, Rubus parvifolius. It occurs throughout the State and often co-occurs with the introduced species. Unfortunately, the native and introduced species look superficially similar, so the native species is often misidentified as a weed and treated as such. So, I thought I’d write a post detailing the differences between these two.

In the following pairs of photos, the native species, Rubus parvifolius is always on the right. All photos were taken by myself.

Leaves

The leaves of both species are very similar, as you can see below. Both usually have five leaflets, although R. parvifolius are smaller and sometimes only has three. In R. fruticosus the leaves usually join at the same point and are therefore ‘palmate’, but since the basal leaves of R. parvifolius join lower, the whole arrangement is ‘pinnate’. Both plants have a pale or white underside of the leaf (shown below). Both also have have distinct leaf venation but this is strongest in R. parvifolius which has deep veins and an almost wrinkled or pleated appearance.

Leaf spotting characters: check if the two lowest leaflets come from the same point as the other leaves, or further down. Check the leaf surface for deep veins.

Thorns

Blackberries are very thorny. This makes them even more difficult to manage, but also makes them great refuges for small animals. Both the introduced and native species have thorns, but their shape is different. R. fruticosus thorns are directly straight (see below left) and are quite long. R. parvifolius thorns are often much smaller and curved away from the shoot tip (see below right). This is probably the most reliable spotting character but be sure to look at a few thorns on each plant as there are always one or two that don’t fit in.

Thorn spotting character: are the thorns curved or straight?

Flowers and fruits

The flower arrangement for both the introduced and native species is generally paniculate, meaning that the flowers are arranged alternately along a small set of flower stalks. This feature is relatively inconsistent though, particularly in R. fruticosus, and racemes or cymes  of flowers are common, and can be solitary in R. parvifolius. Both plants have flowers with five petals and five sepals. Petal colours are similar and can be white to pink in R fruticosus, and pink to red in R. parvifolius. Blackberries are prolific fruit producers and the very tend to go black when ripe for most species variants, whereas R. parvifolius has low fruit production and are red when ripe.

Flower spotting character: flower colour darker pink to red is more likely to be R. parvifolius.

I hope the next time you see a ‘blackberry’ bush, you take a second look to check if it is a native or introduced species.

 

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Orchid hunting

Until recently I have never done any work with orchids, so they have been a bit of a mystery to me. I didn’t know where they were, what they looked like, when they flowered, or what their general biology was. I guess I’ve been waiting for an opportunity to spend some time finding this out…and now I finally have!

My new job as an environmental consultant has thrown me into a number of different situations that are at the foreign to me, one of those being a project on native terrestrial orchids in Victoria. What a perfect excuse to get out, take lots of photos, and learn about this fascinating group of plants.

Many native orchids produce very few leaves (often only one!) so they can be extremely difficult to spot when they are not flowering. They make up for this lack of showiness with some of the most spectacular and unique flowers you will ever see. Spring is a great time to catch many of these orchids flowering, so now’s the time.

There are hundreds of species of native orchids known to occur in Victoria, so I will never see them all. But, there are a few key groups that make up some of the more common ones you are likely to find. Here is a collection of some of my favourites that I’ve stumbled across the past few weeks in Western Victoria – I really hope to keep building this collection over time.

The basic structure of an orchid flower is 3 sepals and 3 petals, but the basal petal ‘labellum’ and dorsal sepal in particular are in many cases highly modified to create an astounding diversity of forms. Most of the terrestrial forms are geophyte monocots meaning they ‘die off’ after the flowering season and regrow from below-ground tubers the following season.

Thelymitra

Thelymitras (Sun orchids), or Thelys, are common in Victoria and are a well-known feature of Victorian orchids. They come in an amazing range of colours and sizes, all stunning. They are referred to as Sun-orchids due to their flowers opening and closing depending on the sun (tip: best to spot them on a sunny day). Generally speaking, Thelys have one leaf and a small tuber; their flowers have symmetrical arrangements (petals and sepals look the same); and they can be insect or self-pollinated.

Caladenia

So here we arrive at some of the more diverse and spectacular flowers. Caladenias (Spider orchids) have a very similar vegetative structure to Thelys, i.e. similar size, shape, and having a single leaf. But the flower shape almost couldn’t be more different (in particular the labellum that is distinctly different to the other petals/sepals). The structure and function of each flower is different and the pollination strategies of each one is far too complex for this blog.

Pterostylis

Despite being one of the most inconspicuous orchids, due to its green flowers (Greenhoods), this is probably the genus most people will see in real life. The dorsal sepal arches over the rest of the flower giving it its green hood. Pterostylis species tend to have larger tubers, which indicates a potential to live for a long period and resist difficult growing conditions. Many of these orchids have a hinge on the labellum which flicks up inside the hood when touched – the idea being to ‘catch’ insects in there making it more likely that they will pick up the pollen.

…and a few other gems.

Here is a collection of some others that I’ve seen that will give a flavour of some of the other types not covered in the lists above. Glossodia (Waxlip orchid), Diuris (Donkey orchid), and Calochilus (Bearded orchid).

The orchid season is coming to a close soon so although I’m hoping to see a few more of these amazing plants in flower, I might have to wait until next year for many of them. But I’ll be ready for them!

If you are really keen on Victorian orchids, you might want to head to the Victorian Native Orchid Society website.

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New Paper: dense stands and thinning

Our paper on dense stands and thinning has been accepted and is available on early view online:

Jones C.S., Duncan D.H., Rumpff L., Thomas F.M., Morris W.K. and Vesk P.A. (2015) Empirically validating a dense woody regrowth ‘problem’ and thinning ‘solution’ for understory vegetation. Forest Ecology and Managementdoi:10.1016/j.foreco.2014.12.006

This paper is based on two separate field projects done to evaluate dense regrowth stands of eucalypts and the effect of thinning management. Dense regrowth stands are increasing in extent worldwide. They generally occur on cleared land where there is a reduction in the landuse (usually livestock grazing) pressure. In some places, this regrowth is considered a bad thing, such as in parts of Europe where the grasslands that may have been grazed for centuries are valuable in their own right. In Australia, this regrowth is generally considered a good thing for biodiversity as it represents a transition back to the pre-cleared vegetation state. However, the regrowth stand is often structurally simplistic with a high density of stems the same size. These stems grow more slowly than in natural systems due to competition between them. This competition also suppresses the understorey vegetation, which was the focus of our research.

Dense eucalypt stand in central Victoria

Dense eucalypt stand in central Victoria

We evaluated our results in relation to published benchmarks of stem density and understorey vegetation cover. We found that stands with stem density greater than benchmark levels (Gibbons et al. 2010) suppress native understorey vegetation cover below its benchmark levels. Thinning stems can restore native understorey vegetation in the short term, providing the soil seedbank has not been removed and there is no excessive grazing. This is the desired outcome from thinning, but the catch is that BOTH native and exotic species can recover following thinning. In places that were weedy prior to the dense stand forming, or are adjacent to highly weedy areas, this could result in a negative impact of thinning on the understorey. Land tenure and environmental factors also influence the response of stands to thinning treatments, so although some very positive outcomes can be achieved, much needs to be considered before thinning is applied to any particular stand.

We hope you enjoy the paper! Please feel free to contact me regarding any of this work.

Thinned eucalypt stand showing thick understorey vegetation recovery ~6 years following thinning.

Thinned eucalypt stand showing thick understorey vegetation recovery ~6 years following thinning.

Refs:

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 260, 2125-33.

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Botanical illustration

Being the son of a talented watercolour artist (go Mum!), I have always been interested in art – both looking at it and making it. Over the years I have found that my favourite medium is graphite pencil, and my favourite subjects are hands and plants. Last summer I attended a botanical illustration course with the Friends of Royal Botanic Gardens, Melbourne. I thoroughly enjoyed it and was grateful for the spark to renew my interest in doing some more of my own work.

Banana - watercolour by Jennifer Jones

Banana – watercolour by Jennifer Jones (aka Mum)

Above all, my favourite part of doing drawing is seeing the image gradually come together from such simple lines to something with real life. Below are some examples of some things I have been playing with recently. I am currently in the process of doing some larger and more challenging pieces now which is exciting. If only I had more time! My Mum is holding an exhibition of her work at the SoART gallery in Narooma in October this year, I will be hopefully putting a couple of drawings in there in case anyone is in the area.

Thelymitra

Thelymitra

Grevillea ant

Ant on Grevillea flower

Pine cone

Pine cone

Snow Gum fruits

Snow Gum fruits

There are many local flora and fauna artists/illustrators producing amazing things – here is a brief list of some (please tell me if you are also one, or know of more):

Helen Burrows

Mali Moir

Milly Formby

David Mackay

Kate Cranney (one of QAECOs own!)

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Wyperfeld National Park: woody regeneration

Part of my new research position at the University of Melbourne allows me to be involved in the field work of my colleagues. This is excellent as it enables me to get involved in other projects, gain new skills, learn new species, and see new places.

One such project is a kangaroo grazing impact study within Wyperfeld National Park (WNP) in north-west Victoria. WNP is the third largest park in Victoria (over 3500 km^2) and is part of the Victorian mallee. The study area is an area of Pine-Buloke (Callitris gracilis and Allocasuarina luehmannii) vegetation, which occurs in occasionally flooded parts of the park.

Here I’ll discuss a few thoughts on woody regeneration in a new field area for me.

Pine-Buloke woodland

Pine-Buloke woodland

Recruitment bottlenecks

A focus of this project is the recruitment of the pine and buloke trees. Wooded areas must have adequate regeneration to retain the long-term canopy structure. In many areas within this vegetation type, some older trees are dying but there are no young trees to replace them. Bottlenecks to woody plant recruitment can happen in many growth stages e.g. seed or seedling, and for many reasons e.g. grazing, lack of rain, lack of flooding, timber harvesting, etc. Management therefore needs to target this bottleneck(s) appropriately to maximise the benefits.

This system is a clear example where woody recruitment is being inhibited, but the direct cause and location of this bottleneck is yet unclear. See the QAECO blog I wrote with José and Cindy for some more info on recruitment in this system. I can’t wait to find out what it is!

Callitris Pine thickets

So you may be aware that I have done a lot of work in the last few years working on dense stands of eucalypts… if not you can refer to here, and here.

During the visit to Wyperfeld National Park, we stumbled across a site populated by a handful of very large old Slender Cypress Pines (Callitris gracilis) surrounded by hundreds of saplings. This is exactly the same process as I have described for eucalypts where the site had been cleared, grazed, and following a release of grazing pressure as well as favourable climate, mass seedling recruitment occurred. This is not a surprising observation necessarily, but it is interesting in that it highlights the consistency of this ‘phenomenon’ across space and species, providing those starting conditions are provided.

Dense regeneration of Callitris s...

Dense regeneration of Callitris gracilis

I look forward to some more thinking about all of this. If anyone reads this and knows of examples of the same thing for other species, please let me know.

Woody plant regeneration has become a particular interest to me, and I am finding myself doing more and more work in this area. If it allows me to keep exploring and researching such interesting vegetation, in interesting locations, with interesting people, then I will be very happy for it to continue.

Sand dune (Mt Jackson)

Sand dune in WNP

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Eucalyptus melliodora (Yellow Box)

This post was inspired by the Twitter sensation #FavEuc by the team at QAECO. The request to vote for your favourite eucalypt (see my previous post on different eucalypt genera) got me thinking, there are so many and they are all great in their own right, but if I had to choose, which would get the nod. As you can gather from the title, my favourite is Eucalyptus melliodora (Yellow Box). These eucalypts are common in Victoria and were one of the more common species in my PhD field sites along the Broken-Boosey Creek system. E. melliodora occurs in Victoria, NSW, and Queensland, and is a great example of an Australian native woodland gem.

Eucalyptus melliodora (Yellow Box)

Eucalyptus melliodora (Yellow Box)

So as a tribute to this magnificent species, I have put together some information on why I like it so much:

Juvenile leaves

Perhaps the reason for my initial fondness of this species was its gorgeous juvenile leaves. The small elliptic blue-green leaves stand out beautifully in contrast to those of E. microcarpa (Grey Box) with which it often co-occurs.

Eucalyptus melliodora (Yellow Box) juvenile leaves

Eucalyptus melliodora (Yellow Box) juvenile leaves

Eucalyptus melliodora (Yellow Box) juvenile leaves

Eucalyptus melliodora (Yellow Box) juvenile leaves

Eucalyptus melliodora (Yellow Box) juvenile leaves

Eucalyptus melliodora (Yellow Box) juvenile leaves

Bark

The bark is quite variable and is more of a standout as it gets a bit larger. The flaky golden bark of a large old YB is a stunning site (as appreciated by others), and could entertain you for hours looking over it, picking bits off, watching all the insects who live amongst the complex golden world that is enormous to them.

Eucalyptus melliodora (Yellow Box) bark

Eucalyptus melliodora (Yellow Box) bark

Flowers

Now this is a great attribute of these trees, not only are their flowers classic ‘Euc’ flowers, but their production is so impressive. There have been many occasions in the field where I have been able to hear a large flowering YB because of the swarm of bees that were enjoying its bounty. Needless to say, it is a fantastic tree for honey production, perhaps the best of all the eucalypts.

Eucalyptus melliodora (Yellow Box) flowers

Eucalyptus melliodora (Yellow Box) flowers

I hope this is enough to at least give you some idea of what I see in this tree, and if you already feel a similar fondness for it you might consider voting for it on the QAECO website.

 

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The effect of dense stands on understorey vegetation

My previous post on dense stands briefly described what they are, why they occur, and their effects on tree growth and understorey vegetation. Much of my research on dense stands has been focused on the response of understorey vegetation to the density and age of the stand, so here is a post on some of these results.

Study area

The area I surveyed for this study was the Box-Ironbark woodlands and forests of central Victoria. These vegetation types have been extensively cleared but now contain many sites that would be considered overly dense stands. I surveyed 64 sites with dense tree stands and combined this with an additional study of 46 sites in a similar area. I surveyed a range of understorey and overstorey vegetation attributes – if you would like to know about my survey method just let me know.

A dense stand of Eucalyptus microcarpa (Grey Box) within the study area.

A dense stand of Eucalyptus microcarpa (Grey Box) within the study area.

Tree density

So firstly it is important to consider what densities I am talking about, and how much higher these are than what they ‘should’ be. The expected (or desired) density of trees in a given vegetation type can be estimated from existing high quality vegetation of that type. This was done for a range of vegetation types, including those in my study area, by Gibbons et al. 2010. They estimated ranges of densities for different tree sizes that are expected in a high quality site.

I compared the densities recorded from my data with the ranges in the Gibbons et al. report. This showed that the observed densities far exceeded the expected densities for many sites, particularly in the smallest size class 5-20 cm DBH. This allowed me then to examine the response of understorey vegetation to stem densities above, within, and below the expected natural levels.

Stem densities of eucalypts within four diameter classes. Grey lines connect densities for different size categories at a single site. Rectangles indicate the benchmark range of stem densities within each size class for Grey Box woodland (black) and Red Stringybark forest (grey) vegetation types from Gibbons et al. (2010).

Stem densities of eucalypts within four diameter classes. Grey lines connect densities for different size categories at a single site. Rectangles indicate the benchmark range of stem densities within each size class for Grey Box woodland (black) and Red Stringybark forest (grey) vegetation types from Gibbons et al. (2010).

Understorey response

I looked at the understorey vegetation cover in sites with the different stem densities in the smallest and most abundant size class (5-20 cm DBH). This showed that when stem densities were above the expected natural levels, the cover of native and exotic understorey plants was much lower than when densities were below or within those levels, and much lower than the levels expected for these same vegetation types (according to EVC benchmarks).

Total understorey foliage projective cover for densities of eucalypt stems in the 5-20cm DBH class. Open boxes are native species, grey boxes are exotic species. Horizontal dotted lines indicate the range of EVC benchmarks for understoreycover within vegetation types included in the surveys. 'EX' are sites where the density exceeds the benchmark cover range stated by Gibbons et al. (2010) for equivalent vegetation types, 'BCH' are sites with stem density within the benchmark range, and 'LO' are sites with density below.

Total understorey foliage projective cover for densities of eucalypt stems in the 5-20cm DBH class. Open boxes are native species, grey boxes are exotic species. Horizontal dotted lines indicate the range of EVC benchmarks for understoreycover within vegetation types included in the surveys. ‘EX’ are sites where the density exceeds the benchmark cover range stated by Gibbons et al. (2010) for equivalent vegetation types, ‘BCH’ are sites with stem density within the benchmark range, and ‘LO’ are sites with density below.

Summary

So what does this mean for dense eucalypt stands? This study showed that tree densities within the study sites were in many cases much higher than those expected in a ‘natural’ stand of that vegetation type. This was most evident in the smallest size class (5-20 cm DBH). Stem densities that exceeded that of known ‘natural’ stands had less than a fifth of the native understorey vegetation cover of other stands and a third of exotic cover.

So, if high stem densities suppress the understorey vegetation, is this a very bad thing for ecosystem value or function? How long does it last for, i.e. do the stands self-thin and return to ‘natural’ levels that then allow the understorey to return? If management is to be considered, what options are available and what is the likely response?

I will continue with some of these questions, with a particular focus on ecological thinning in my next post on this topic.

References:

Gibbons P. et al. (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 260, 215-33.

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Dense woody vegetation: thickets

As a side project to my PhD research, I have spent some considerable time over the last two and half years researching dense woody vegetation, or ‘thickets’. There has been recent interest in this area due to their increased occurrence in the landscape. This post gives a brief overview of dense stands.

What is a dense stand (thicket)?

A dense stand usually refers to patch of similar aged woody plants (often eucalypt trees) that are growing much more densely than would normally occur in an undisturbed ‘natural’ setting.

Dense eucalypt stand in central Victoria

Dense eucalypt stand in central Victoria

How do they arise?

There are four things usually required to create a dense stand:

  1. Space – cleared land free from heavy plant competition
  2. Source – a seed source such as a paddock tree or roadside vegetation
  3. Freedom – no/little grazing by insects or mammals
  4. Rain – sufficient rainfall to trigger a mass germination event

These are precisely the conditions that we see on agricultural pastures. Grazing animals will usually eat seedlings and so these stands won’t occur in heavily stocked pastures, but if the stock are removed or the numbers reduced and rainfall stimulates the mass recruitment of seedlings then these are ideal conditions for creation of dense stands. Some great examples of this were recently posted by Ian Lunt.

Dense stands are becoming more common in the landscape due to changes in land management practices. Some landholders are grazing less, some are fencing off parts of properties for environmental management (e.g. fencing off creeks), some are leaving and being replaced by ‘lifestyle’ farmers who are less focused on intensive agriculture.

A mass recruitment event creating a thicket around a large paddock tree (Eucalyptus microcarpa - Grey Box).

A mass recruitment event creating a thicket around a large paddock tree (Eucalyptus microcarpa – Grey Box).

What effects do they have? Are they bad?

The two primary reasons why land managers care about dense stands are: reduced tree growth, and suppressed understorey vegetation, both as a result of competition for resources.

Trees in dense stands grow much slower, have fewer large boughs, have smaller canopies, and produce fewer flowers later. Reduced tree growth is therefore an issue for the provision of resources by large trees, i.e. hollows, flower (nectar) production, and litter/logs.

Suppression of the understorey vegetation is a serious concern for provision of habitat, food, soil stability and structure, and amenity. If the understorey is suppressed for long enough, long-term detrimental effects can be caused by erosion of topsoil (not stabilised by plants) and loss of the soil seed bank (loss of recovery potential).

Naturally, for both of these issues with dense stands, there is a continuous scale of effects. ‘Some’ reduced tree or understorey growth from open stands might be ok, whereas ‘lots’ from very dense stands would be highly undesirable. Different environments will also respond differently to these stands. It is therefore very difficult to know how much is too much, how much is bad, and when we might want to do something about it. Studies that attempt to use good quality, relatively undisturbed, examples of vegetation to estimate what the vegetation ‘should’ be like in these systems (e.g. Phil Gibbons et al. in 2008 and 2010), can be useful for setting targets for management.

Suppression of the understorey vegetation beneath dense eucalypts

Suppression of the understorey vegetation beneath dense eucalypts

Do they self thin? Is there a need for management?

This is a great question and the answer comes down to time. Yes, dense stands do self thin, as competition for resources becomes so intense that some individuals die off. As some mortality occurs those resources are taken up by the remaining individuals. Eventually, this is likely to result in a more natural vegetation state, however this may take many decades or even centuries to occur. Management (such as thinning) is likely to be important if we want to achieve some desired state or attributes sooner.

In future posts on this topic I will present some of the research I have been doing with some people from the QAECO lab. Much of which focuses on the understorey suppression aspects of dense stands, and how it responds to management. Stay tuned…

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Evaluating riparian vegetation condition

After a brief interlude to write posts about some of the things I just find interesting, I am returning to some work from my thesis.

In post #1 I described the effect of livestock grazing on the cover of different vegetation life forms. Here I focus on the amount of cover at these sites, and if it is a good amount or not.

Vegetation change in itself is certainly not a bad thing at all. Vegetation communities are constantly changing and it would be ridiculous to think that we could ever manage a completely static environment. Change becomes a negative when the vegetation is no longer able to provide the functions that are expected of it, e.g. habitat or food for fauna. Negative changes such as this occur naturally in the landscape from events such as fires, floods, droughts, etc. and there is little we can do to influence these naturally occurring events. Our primary concern, as researchers and managers are the negative effects that caused by humans.

We can only tell if vegetation has been negatively impacted if we know what relative condition it is in. Previously I wrote a post about what is vegetation condition, which described the use of benchmarks against structured sampling methods to evaluate how different the vegetation of a given site is from what it ‘should’ be in the absence of human disturbance. I am referring to the Victorian government’s standardised process known as Vegetation Quality Assessment. Accompanying the standard assessment method and the calculation process of condition scores, is the set of benchmark attributes for each vegetation type (or specifically, Ecological Vegetation Class, EVC) in Victoria.

So if these benchmarks of vegetation condition are freely available, can I use them to evaluate the condition of my study sites, even though I used a different survey method? Well, yes, and I did. Using a different survey method makes it impossible to generate the condition score based on the standardised methods, but I can still use the benchmark attributes to asses specific native vegetation attributes of my sites. For this post I will focus on vegetation cover.

This site looks ok but does it have the amount and diversity of vegetation that would be expected of a high quality site?

This site looks ok but does it have the amount and diversity of vegetation that would be expected of a high quality site? Does it have nearly enough of some things and far too few of other things?

To determine the condition of the native vegetation attributes at my sites I needed to do 3 things:

1. Determine the cover of each attribute for each site

2. Determine the vegetation type (EVC) for each site

3. Compare observed cover values against benchmark values

COVER: So firstly I needed to find out the cover of different attributes within my sites. I surveyed 180 sites along creeks in northern Victoria (for some more background on my study look here, and more on survey methods look here). I separated each site into an inner (near the creek) and outer (away from the creek) zone to explore differential effects  with distance from the water. The results for the cover of different life forms, bare ground, litter and tree cover are shown below. The spread of data is similar in the inner and outer zones, but there were commonly large differences between zones for a specific site (as indicated by lines). This information is interesting in itself and tells us that average cover for many of these life forms was low – but is that ok? How much cover should there be? Comparing these values against the benchmarks can help us evaluate this.

Percentage cover of ground layer, native understorey and midstorey life forms, and tree canopy across all sites. Each point indicates cover within a site, where closed circles (•) are cover within the inner zone and open circles (ο) within the outer zone. Black plus signs indicate the median values. Grey lines connect cover from the inner and outer zone within the same site. Points without connecting lines occur for sites with insufficient data in either zone to generate a cover estimate. Data are presented on a logit scale. I added 0.0025 to scores of zero, equating to one hit every 400 points, to enable plotting on the logit scale. Vertical lines are medians. Note change of scale for litter and tree cover.

Percentage cover of ground layer, native understorey and midstorey life forms, and tree canopy across all sites. Each point indicates cover within a site, where closed circles (•) are cover within the inner zone and open circles (ο) within the outer zone. Black plus signs indicate the median values. Grey lines connect cover from the inner and outer zone within the same site. Points without connecting lines occur for sites with insufficient data in either zone to generate a cover estimate. Data are presented on a logit scale. I added 0.0025 to scores of zero, equating to one hit every 400 points, to enable plotting on the logit scale. Vertical lines are medians. Note change of scale for litter and tree cover.

BENCHMARKS: The next step in comparing vegetation to the benchmarks is to determine vegetation type or EVC for each site. Normally this would be done on delimited patches (‘habitat zones’) of similar vegetation but in this study I determined an EVC for each zone (inner and outer) within each site, based on statewide EVC mapping. If you want to know more about how I did this just let me know.

COMPARISON: Benchmark Comparisons were made by subtracting the benchmark cover value from the observed cover from my surveys. So anything below ‘0’ meant that the cover was below the benchmark level, i.e. below what it ‘should’ be in a good quality site. Small shrubs, litter, and tree cover were the only attributes that were generally at or above the benchmark levels, while all others were below. Medium tufted graminoids (such as Austrostipa scabra) and medium herbs (such as Calocephalus citreus) were by far the worst performing. Interestingly, despite the differences in cover between inner and outer zones at many sites, the difference to benchmark levels was roughly equivalent across attributes. This suggests that the different benchmark levels for each zone were appropriately accounting for these differences.

Difference in percentage point cover between observed and EVC benchmark cover of ground layer, native understorey and midstorey life forms, and tree canopy cover. Box plots show the range of cover differences across all sites. White boxes indicate inner zone covers; grey boxes indicate outer zone covers. Boxes indicate the median and inter-quartile range and whiskers extend to the most extreme data point which is no more than 1.5 times the inter-quartile range from the box.

Difference in percentage point cover between observed and EVC benchmark cover of ground layer, native understorey and midstorey life forms, and tree canopy cover. Box plots show the range of cover differences across all sites. White boxes indicate inner zone covers; grey boxes indicate outer zone covers. Boxes indicate the median and inter-quartile range and whiskers extend to the most extreme data point which is no more than 1.5 times the inter-quartile range from the box.

It is clear that some of these vegetation attributes are well below the desired levels within my study area. This information can help inform management of the current status of these sites, suggest which life forms should be targeted, and the amount of change that might be required to restore the sites.

This is just a small part of the picture and it needs to be evaluated in the context of land management at each site, but I think it is a neat use of existing resources to help evaluate vegetation condition at a site to inform management.

Cheers.

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Birds of Albert Park: Quiz

Well I thought I’d go out on a limb (excuse the pun) and see if anyone is paying any attention to these bird posts by seeking some audience participation.

Many of the birds in Albert Park are quite striking, or common, or large; all attributes that makes their identification relatively straight forward. Venturing out to look for birds you are undoubtedly going to come across what many would call a ‘little brown bird’, and Albert Park has its own.

These little birds were very agile flyers, and were in a large group of about 8-10 individuals chasing each other around the trees when I saw them in May this year.

Anyone know what they are called?

'Little Brown Birds'

‘Little Brown Birds’

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