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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