Of weeds and habitat

Natives are good, weeds are bad

 This is the mantra of the bushland manager.

I first learnt this mantra when I started in the industry about 13 years ago. I can’t remember exactly where I learnt this, but it can be explained by the plot of Independence Day, or pretty much any other alien invasion movie:

Alien invasion of Earth: It starts off with humans hanging around being awesome.

Weed invasion of Australia: It starts off with Australia’s bushlands hanging around being awesome (plants and animals from Australia are also referred to as ‘native’ or ‘indigenous’).


Alien invasion of Earth: Then aliens arrive in huge spaceships.

Weed invasion of Australia: Weeds arrive in huge ships, brought by European settlers.


Alien invasion of Earth: Everyone is like “Oh crap! Aliens!”

Weed invasion of Australia: Everyone is like “Oh crap! Weeds!”


Alien invasion of Earth: Aliens start to invade and mess shit up.

Weed invasion of Australia: Weeds start to invade and mess shit up.


Alien invasion of Earth: Humans fight to conquer the aliens.

Weed invasion of Australia: Bushland managers fight to conquer the weeds.


Alien invasion of Earth: Pew! Pew! Pew!

Weed invasion of Australia: Pew! Pew! Pew!


Alien invasion of Earth: Lives are lost.

Weed invasion of Australia: Native plants are lost.


Alien invasion of Earth: The human race survives, but is changed forever.

Weed invasion of Australia: Bushland in Australia survives, but is changed forever.


Australia is full of awesome plants and animals, and some bat-shit crazy ones too (we do have the most dangerous animals in the world!)  Most of these species can be found nowhere else, and our ultimate goal in bushland management is to conserve this weird and wonderful mix of species and environments.

And so bushland managers arm themselves with knapsacks, loppers and chainsaws to fight the weeds and save the natives from destruction.

This approach assumes that removing weeds will benefit our bushland. However, some weeds have been in Australia for a long time, and our native animals have started to adapt and use them as habitat.

Some examples include:

  • Blue Wrens and other little bush birds use Blackberry and/or Boxthorn as a food source and as shelter
  • Yellow-tailed Black Cockatoos eat seeds from Pine Trees
  • Golden-sun Moth use Chilean Needle Grass as habitat and potentially the larvae feed off the grass
  • Southern Brown Bandicoots use Blackberry as shelter
  • Gang Gang Cockatoos eat Hawthorn berries
  • Corellas eat Onion Grass bulbs
  • Sacred Kingfishers make nests in Willows and Date Palms

If you have any other examples, please post them in the comments below.

So…should we declare that the war on weeds over?

Shall we hang up our loppers and knapsacks, and return home to our loves ones and families?

Should we start to use that dirty ‘N’ word to describe our former foes? Naturalised?

Or will this type of thinking lead to a dystopian future – where ‘weeds’ run rampant and compromise the integrity of our bushland – the same integrity for which we have fought so hard to conserve? Will this lead to the bushland mantra being twisted into some sort of Orwellian propaganda slogan?

Animal Farm_2
Natives are good, weeds are better?

I don’t think that the war on weeds is over.  Weeds definitely do encroach on native plants and threaten ecosystems. However, weed control needs to be done in a way that doesn’t negatively impact the animals that use them as for habitat.16f2ui

Rather than removal, think replacement

When we come along to fight the war on weeds, we may be removing the last stronghold of our native animals.

Too often we assume that whatever remains is better than a weed-infested landscape.

The main reason that native animals use weeds as habitat is because there are not enough native plants around. Vast areas of bushland have been wiped out, and the only place that some animals can hide is in the weedy blackberries and boxthorns.

From my interview with Brian Bainbridge, I’ve learnt that it is vital to monitor your bushland to see what plants and animals you have (both weeds and natives). With this information, you can start to see how your management might impact these species (in both good and bad ways).

Instead of just looking at your bushland in terms of ‘weeds’ or ‘natives’, you can think in terms of habitat. Brian has a keen interest in birds, and observed that small bush birds like dense, shrubby vegetation. This is the exact type of habitat that blackberries and boxthorns provide. By replacing these weeds with suitable native substitutes, Brian was able to keep the bush birds in the landscape.

The ‘war on weeds’ idea is not defined in terms of what is being created, but by what is removed.

What about other types of animals and habitats?

If you have a keen eye and are very patient, you can spend time observing your bushland to see how it is being used by native animals. But since this takes time, here’s something that we prepared earlier (click on table for a larger view).

Well, actually this was put together by Chris McElhinny and co, who wrote a fantastic review of 56 studies in south-eastern and western Australia to identify animal-habitat relationships in forests and woodlands. Since most bushlands can be described as forest or woodland, it’s a great study that can help us identify which habitats are used by different animals. If you have other types of bushland,  (e.g. grasslands or shrublands), then check out the vegetation layers that are relevant for you.

Habitat that animals use in forests and woodland in south-eastern and western Australia, with ways to increase habitat. (Excerpt from McElhinny et al. 2006. The ways to increase habitat are my own suggestions). Click on table for a larger view.

Any bushland can be grouped into several layers from the ground all the way to the tree canopy.

Within each of these layers are several habitat attributes – these are things that animals use as food, shelter or breeding.

Generally, when there is more of an attribute, there are more of the animals that use it for habitat. But just because you have a lot of one attribute, it doesn’t guarantee an increase in that particular species. They may not be able to reach your bushland, or there may be other factors at play.

Ecosystems are complicated, and increasing habitat attributes will only increase the likelihood of certain species occurring. It’s no silver bullet.

In the far right column of the table, I’ve added a few suggestions on how to increase these types of habitat in your bushland. If you have any other suggestions, please post them in the comments below.

The following describes three different ways you can use this table to identify and manage the habitat in your bushland.

  • Look at your weeds – what type of habitat do they provide? If you have animals that use these weeds as habitat, are there suitable native species you can introduce while you stage the weed removal?
  • Look at your bushland – what habitat is there and what can you do to improve the habitat? More shrubs? More logs? Are your trees too small for hollows? Maybe you need some nest boxes in the meantime?
  • Look at your bushland – based on the habitat you already have, what animals should be there? Maybe some animals can’t reach your patch of bush?

Creating habitat is a much more fulfilling goal than just removing weeds


Interview with David Franklin – Part 2

Part 1 of this interview introduced us to David Franklin who has been working on restoring native grasslands over the last 8 years. Today, we continue our chat and learn more about David’s work.

After David and I finished our cups of tea, we headed out to one of David’s sheds where he keeps his machinery.

Maps of David’s property

What kind of machinery do you use for sowing and harvesting?

We have three main machines: a mechanical seeder from Greening Australia, a brush harvester for grasses, and a machine that sows small plants (plugs).  Because the mechanical seeder requires you to mix sand with the seed, I’ve been working on another seeder that doesn’t need sand.

Paul Gibson Roy from the Grassy Groundcover Research Project realised that they couldn’t use agricultural seeders to sow native plants, as the seeds are very light and sit in the machine without moving through. So they developed their own seeder. This one can be used to sow up to 25-30 different species together.

Greening Australia’s mechanical seeder

The box at the top is filled with a mix of seed and very fine sand – this gives is some weight and carries it out a long slot at the bottom of the machine, where it drops out in a sheet. It is time-consuming and hard work because we need about a cubic metre of sand for every hectare we do, and it takes about 10-15 minutes to mix each load.

Sometimes the sand is wet, which makes it difficult to mix the seed and it travels slowly out of the machine. And then coming to the end of the day, the sand dries out so you’ve got to vary your sowing rate to make it consistent.

With this machine you’re looking at up to 6 hours to seed 1 hectare using 3 people.

Direct seeding the Alcoa site at Moolapio in September 2011

How much seed do you use per cubic metre of sand?

We’re sowing up to 55-60 kilograms a hectare of mixed species, but that’s not pure seed. We don’t  clean the seed as it’s too time consuming, and so some of it’s still on the stalk. But we do put the stalks though a garden mulcher – this doesn’t damage the seed and it chops up the stalks so they mix with the sand.

At the moment I’m working on trying to make a better seeder with an engineering firm in Geelong. This one uses air to pull the seed through so that we don’t have to use sand. This should speed up the time it takes to sow a site considerably. It’s like one of the agricultural air seeders.

David’s air seeder

When I first started direct seeding, I didn’t have enough Wallaby Grass to sow out in the field.  The seed was precious as I only had a small amount, and if I scattered it on the ground it would be a waste. So instead I decided to sow it in the nursery to grow plants (plugs). This resulted in a much bigger population than just spreading it around. But I had a bit of a problem – who was going to plant all those plugs? I then developed a machine that could mass-plant plugs. In the first year we sowed 80,000 plugs with this machine.

David’s plug planter

The planter has 6 belts at the top with little PVC pipes stuck to them.  You load up the pipes with plugs. The belts move the pipes around the tray, and they pass over a hole with a tube going down to a tine at the bottom.  The tine makes a slot in the ground, and as the belt winds its way around, the plugs keep dropping down.

The top of the planter where the plugs go

When we planted the Wallaby Grass, we set the planter to plant every 20 cm, with 20 plants to the square metre. It actually takes longer to load the plants than it takes to plant them. It would take us 7 or 8 minutes to load up about 360 plants, and about 2 minutes to put them in the ground. At this pace we could sow 2000 plants an hour.

How do you grow enough seed for large-scale direct seeding?

With the Grassy Groundcover Research Project, we initially collected seed from roadside remnants, but this wasn’t enough for direct seeding. So we grew plants from this seed in the nursery and planted them into poly-boxes. From there, I made some raised garden beds to grow even more plants. After that, I made some in-ground beds with weed-matting. The weed mat was used to control the weeds, but it also makes it easy to vacuum up all the seed that drops.

I don’t use poly-boxes anymore because I don’t need them – I get enough from the raised beds and the in-ground beds. The poly-boxes dry out too quickly and the potting mix breaks down too easily. Both my raised beds and in-ground beds where I grow my herbs and forbs are irrigated and this prolongs the flowering season, which means you can get more seed from the crop. For the larger crops of native grasses, I grow them like a normal agricultural seed crop, with no weed matting and no watering.

In-ground and raised seed production area beds

What are you growing at the moment?

I have about 30 species in the ground. There are a few things on the go in the nursery which I’ll plant into the raised and in-ground beds. I also have some larger crops in the front and back paddocks.

At the moment I have about 500 Clover Glycine (Glycine latrobeana) in the nursery, which I’ll plant in the raised garden bed. This is a threatened species – you can only find the odd one in roadside remnants. Last year I grew a seed crop and I was getting between 200-300 pods every second day. I ended up with 56 grams of pure seed, not pods, just the pure seed.

Clover Glycine in the nursery

A few of the species I’ve got growing in beds at the moment include Smooth Solenogyne (Solenogyne dominii),  Featherheads (Ptilotus macrocephalus), Chocolate Lily (Arthropodium strictum), Bulbine Lily (Bulbine bulbosa), several Speargrass species (Austrostipa), Grey Tussock-grass (Poa sieberiana), Wheat Grass (Anthosachne scabra), Hoary Sunray (Leucochrysum albicans), and Common Billy-buttons (Craspedia variabilis), to name a few. I’ve even got some Blue Pincushions (Brunonia australis).

Smooth Solenogyne seed


Featherheads in the seed production area

Last year I grew a crop of Yam Daises (Microseris landceolata) and I managed to get a full box of seed from just a 3.6 m by 6 m in-ground garden bed. I used weed matting and I also had irrigation drip lines under the weed matting.

A full tub of Yam Daisy seed
Yam Daisy in-ground bed

I grow my Bindweed (Convolvulus) up a trellis with weed matting at the bottom. It works really well and I can either collect the seed from the plants or from the weed matting.

Trellised Bindweed

What are some of the larger crops that you grow?

I’ve got a crop of Common Everlasting (Chrysocephalum apiculatum) that I put in at the end of 2014. It’s about 1,000 square metres.

Common Everlasting crop


I direct seeded Lemon Beauty-heads (Calocephalus citreus) in spring 2015 but I wasn’t sure if it would come up. It took over two months and all of a sudden it started appearing. The seed isn’t usually ready to collect until February or March.

Lemon Beauty-heads crop just starting to come up

I also sowed Common Wheat Grass and Spear Grass in June 2015. The Wheat Grass has come up but I won’t get seed off it this season, but it’s a good result for Common Wheat Grass. Not much of the Spear Grass has come up, but it’ll come up in autumn with the rain – that’s what normally happens. I also put in a grass species mix in September 2015, but this was too late, and it never rained again after that. This will come up in autumn too.

I have a couple of hectares that was scalped in May 2015. Some of this area will be used for a seed production area and on 20 metres either side of the creek I’ll just do grassland species mix.

Scalped area ready for sowing

I’ve also got a Wallaby Grass crop in the back paddock – about 1/3 ha.

Wallaby Grass crop – 190 m long by 20 m wide (about 1/3 hectare)

What kind of weed control do you use?

I’ve successfully used a technique called ‘spraytop’, where you put a light dose of roundup over the native grass to kill the annual weeds. It just burns off the top of the weeds and I use 300 ml  to the hectare. It doesn’t kill the native grass but you’ve got to forego your seed for that year.

What time of year is best for the spraytop?

Ideally when the annual weeds are flowering – around about that time, it will burn off the weeds and desiccate them.

Have you done any direct seeding locally?

I mentioned before that there’s not much funding for direct seeding at the moment. So I decided to contact the local shire (Moyne) and offer my services to show them what can be done with direct seeding. There’s a section of roadside in Woorndoo that we decided to work on and create a mixed species grassland. I volunteered my time to grow some plants for seed, as well as getting the local Landcare group involved to collect seed from some of the remnant reserves in the area. The council pitched in and payed for the scalping and removal of the topsoil, this was over 1000 cubic metres of topsoil from a hectare, to a depth of 10 cm. With the Landcare group (about 16 volunteers) we collected over 60 kg of seed from 33 species. This was sown in September 2013 and in the end of 2014 I harvested 15 kg of wallaby grass seed off it. The machine I use doesn’t collect all the seed, it sort of knocks it about, and so some is left on the ground, which is good for maintaining the seed bank.

Scalped and seeded roadside in Woorndoo

What kind of weed control do you do?

You can see that it’s pretty much weed free, but there is some Capeweed, Fog Grass, Phalaris and Wild Oats that come in from the edges. We’ve had some Scout groups and a Green Army group come and do some hand weeding here, and we’ve got on top of most of that.


I’ve noticed that most of the grass here is Wallaby Grass, did you sow other types of grasses?

Yes, there’s some Spear Grass as well as Kangaroo Grass (Themeda triandra). There is a bit of Spear Grass coming up and the Kangaroo Grass is just starting to show. With the Kangaroo Grass, all sites I’ve direct seeded are the same – they take 3 or 4 years before you get a lot coming up. The Wallaby Grass that usually dominates the site for the first few years.


Have you got any tips for anyone who wants to do direct seeding or start a seed production area?

If you are going to collect seed make sure you have the right permits and permission from the landowner. And make sure you’re not harming the remnant areas by collecting too much.

This is a great resource about ethical seed collection:


It’s always best to start small, as you can scale up later. You’ll be limited at the start by the amount of seed you can get and that’s ok. Just start with poly-boxes and work up to larger garden beds when you have more seed. It’s the same for direct seeding, just start small and find what size is manageable for you. Every direct seeding area you do is another good seed resource on its own.

You’ll also have to manage your seed crop, and sometimes it will fail and need re-seeding. I’ve had a large crop of Wallaby Grass that I collected 80 kg of seed from one year. There was also another 80 kg of seed on the ground that I couldn’t collect, as the harvester kept pushing the stalks over. The leftover stalks were too much biomass for the crop and it never grew back.

I recommend sowing seed in spring when the annual weeds start to die off and the bit of warmth helps germination. You can also sow in autumn after the first rains, but things won’t really grow over winter.

If your seed doesn’t come up in the first year, don’t give up as it can take time.

I’ve had plenty of sites where it took a while for the seed to come up.

Thank you for your time David

If you would like to learn more about David’s work you can contact him at davidfranklin@grasslandflora.com.au








Interview with David Franklin – Part 1

Prior to European settlement, the vast volcanic plain grasslands of western Victoria would have been a spectacular sight. They once spanned about 300 km from Melbourne to Portland. Now less than 1% of these grasslands remain, which makes it challenging to conserve and restore them. Remnants often exist in small, isolated patches and are prone to weed invasion. Restoration is limited by the availability of seed from healthy populations.

Over the past 10 years, however, reliable techniques have been developed to restore native grasslands.

This is not a remnant grassland, it’s actually a restored grassland

I met David Franklin at Greening Australia’s Seeds for Success forum, held at La Trobe University in July 2015. David lives in Chatsworth and for the last 8 years has been working on restoring native grasslands. Chatsworth is located near the middle of the Victorian volcanic plains, and the region has some spectacular remnant grasslands, mostly occurring on roadside reserves.

I got in touch with David and visited his property in November 2015 to learn more about what he does.

SPA Ptilotus macrocephalus
David Franklin

Hi David, thanks for catching up. Let’s start with a bit about yourself and how you got into the industry?

Thanks John. I’ve been in here in Chatsworth nearly all my life – I was about 5 years old when we came. This is a family farm, a soldier settlement my father was allocated after the Second World War. We ran a medium-fine wool merino sheep flock and also did some cropping.

A spectacular Red Gum on David’s property

I started a native plant nursery about 25 years ago after the wool boom crashed. This was before Landcare took off, and I was just selling to farmers for windbreaks (trees and shrubs). But I always concentrated on local indigenous plants of this region. I started selling a few and it just got bigger and bigger. Then when the Landcare groups came along, I produced a lot for Landcare.

Were you involved with Landcare?

Yeah, around this time I actually started a Landcare group here in Chatsworth, and we had about 15 people in our group. Over a three year program, we got about $80,000 in funding from the government to revegetate watercourses and badly eroded hills. They’re all full of trees now and it has completely changed the landscape – that’s going back 15 years or more.

And so my nursery supplied a lot of these small Landcare groups who were applying for funding before the Catchment Management Authorities (CMAs) came along. In its peak, about 10 years ago, my nursery was growing 300,000 plants a year.

David’s nursery

Around this time there was a lot of burnout in the Landcare groups – trying to take on too much – and from then on, most of the plant orders came through the CMAs. With the recent budget cuts from state and federal governments, it’s all turned full circle now, and there’s hardly any orders coming through.

So when the nursery started to die down, I had some spare time to learn more about the roadside reserves. I’ve always had a bit of an interest in the roadside grasslands because we’ve got really terrific remnants right out the front here, right to Woorndoo and Wycliffe, and all around this region. So in the autumn I’d muck around trying to propagate some of the grassland species, and in the spring-time I’d learn how to identify the seed from the flowers. You’d have to keep going out there and peg some of the species. This is because you can identify them when they’re in full flower and they look beautiful, but if you go back  2 or 3 weeks later they’re all shrivelled up and I’d say, ‘what was that?’. It was an interesting learning curve.

How did you get interested in direct seeding?

In 2004 I got involved with the Grassy Groundcover Research Project – this was a 3 year research project with Melbourne University and Greening Australia, run by Dr Paul Gibson Roy. They had funding to establish 15 research sites in Victoria to see if they could turn completely altered agricultural land back into native grasslands. This was done by trialling different methods of site preparation and direct seeding techniques to establish a native grassland with a mix of different species.

My farm was one of the sites, and I also grew plants because each site needed access to a seed production area. We initially collected seed from the roadside remnants. This seed was used to grow plants in poly boxes, and the seed collected off these plants were used in the research project. We also used this seed to set up some beds where we could grow more plants for seed production. Having a seed production area really took the pressure off the wild populations. This was a really thorough research project and I’ve learnt so much from Paul.

2015-11-01 12.03.44
David’s seed production area

I’ll always remember when he told me about the scalping. In the first year of the project, there were these 1m by 1m plots with different treatments, including scraping off the top 6 inches of soil. This was fine by me, but in the second year Paul said “This time we’re going a bit bigger. We’ll get a grader in and scalp half a hectare.”

I said “What?”

He said “We’ll scalp half a hectare and mound it up on the side.”

I was looking at him incredulously and he’s looking at me and he’s smiling. As a farmer, the worst thing you could do to grow a crop is remove the nutrient-rich topsoil.

And I said “Yeah right-o, I’ll go along with it.”

Now I think it’s just so logical when you’re growing native plants: by scalping the topsoil you get rid of all the weed seed and also you get rid of the nutrients that the native plants don’t want.

What did you do after the research project finished up?

I then started working for Greening Australia on a contract basis, growing seed and direct seeding, as well as maintaining the machinery.  This was led by Rod White, who is the Grasslands Restoration Officer at Greening Australia. We’ve been getting some great results, and that’s been going on for the past 8 years.

David Fanklin Rod White & James Shaw
Rod White and David Franklin in David’s Common Everlasting seed production area

With Greening Australia I’ve worked on the Alcoa project called Moolapio, in Geelong. They had to get equipment there for sowing, and they needed help to grow seed. So I built a decent transporter trailer to carry a 3-tonne tractor and a seeder. Last year we took the tractor and seeder to Tasmania for a week, and also went down to Bairnsdale. This year we’ve been up to Euroa, and we’ve also worked at the Western Water Treatment Plant at Melton.


Mixing sand with grassland seed for direct seeding

Over the past 3 years, we’ve done some seed growing and direct seeding work with the duplication of the Western Highway between Ballarat and Beaufort. We sowed 4 ha there this year. I grew some plants for seed here in the nursery in boxes, but I was also going up there each year in summer and collecting local seed to do the job.

A lot of these jobs are limited by the amount of seed you can collect, and you need to do some forward-planning for a couple of years to be able to restore a few hectares

At my property I have the machinery to sow large areas of seed. I can also grow a lot of seed here in the nursery and in the farm’s in-ground seed production areas. I’m currently growing 25-30 species on the farm. I’m all ready to do more if we could just get the funding.

Stay tuned for part 2 of this interview, where David shows me around his property and I learn about some of the projects he’s working on.

If you would like to learn more about David’s work you can contact him at davidfranklin@grasslandflora.com.au




Interview with Brian Bainbridge – Part 2

Part 1 of this interview introduced us to Brian Bainbridge who is the Ecological Restoration Planner at Merri Creek Management Committee. Today, we continue our chat and learn more about staged weed removal.

Can you give me an example of where you have staged your weed removal because the native animals were using the weeds as habitat?

Yes, we have a site in Fawkner called ‘Manna Gum’ on the western bank of the Merri Creek. This is only one of two sites in all of Moreland City Council area with a remnant Manna Gum. Back in the 1980s, local friends groups planted some native trees on the escarpment, including Swamp Gum, Yellow Gum and Red Gum. We have the beautiful old Manna Gum and some other remnant vegetation, but under those we had a massive quantity of Blackberry, Briar, Hawthorn, Gorse and Broom. In that understorey of dense shrubbery we also realised we had Blue Wrens and lots of other little bush birds that were persisting and using that as habitat.

Brown Thornbill, Coburg..jpg
Brown Thornbill using Boxthorn as habitat. Photo by Brian Bainbridge.

How did you tackle all the woody weeds without impacting the bush birds?

In the early 2000s resources became available to do some restoration work on this site through a Parks Victoria community grant. We initially burnt the middle third of the site and began the treatment of the Blackberry on that third, and the rest was left as a bit of a weedscape. On either side there was quite an extensive patch of Boxthorns and Blackberry where the Blue Wrens and other birds could remain.

Why did you burn the site?

We used the burn to remove all the weedy biomass and to make the area suitable for spraying. We knew that on the ground layer we had remnant vegetation. After that burn we had a lot of Senecio hispidulis (Rough Fireweed) and quite a number of other native grasses coming up, and we had Maidenhair Fern, as well as the rare Carex incomitata (Hillside Sedge). We didn’t want to blast the whole thing with a general herbicide and to be able to do that we really needed to just be treating regrowth that was only a foot high or so.

What kind of follow up did you do?

In the early 2000s this site became part of Moreland Council’s ongoing maintenance commitment, so we revisited the site at least every 3-4 months, which meant that we could keep an eye on if things regrow. We never trust we’ve got the Blackberry treated until at least two years of revisits. Some of the techniques we used to control the Blackberry include cut and paint, drill and fill, but our main technique was spraying the re-growth of the Blackberry with a herbicide like metsulfuron-methyl. Using drill and fill on Hawthorns and other large woody weeds is a great way to retain shrub ‘skeletons’ which can be a really important habitat feature. You can then grow a Clematis or other climbers up it, or under plant with Tree Violets or other shrubs.

Boxthorn at the Manna Gum site. Photo by Brian Bainbridge.

Did you then plant into the area?

We kept our ground-storey species plantings to areas that didn’t have Blackberry regrowth. It is also feasible to plant guarded trees and shrubs and then treat the Blackberry in between as long as you had a pretty good hit at the beginning, and where you only have a small number of regrowth points.

In 2001 we planted 1,500 plants into that area, which included Lightwood and Black Wattle and Sheoak, but also large quantities of the middle storey shrubbery. We were trying to re-establish some of that middle storey, so that birds could move back into that area.

Did you then move onto the other weedy patches?

Yes we did. In 2007 we had funding from an Environment Protection Authority alternative sentencing scheme to start the Black and Blue Project, where we went and knocked out more of the Blackberry, more of the Broom, more of the Boxthorns, and we planted another 500 trees and shrubs. So we were augmenting and making the indigenous vegetation patch larger each time. We were consciously trying to make thickets this time to ensure that within a few years the shrubs would tangle together and make good habitat for bird life.

Manna Gum 0807 022.jpg
Dense shrub planting in 2007 at the Manna Gum site to create thickets for birds. Photo by Brian Bainbridge.

Did the birds start to use the plantings that replaced the weeds?

Yes, in the last 6 years a Friends of Merri Creek quarterly bird watch has added many new species records to the Merri Creek, including woodland birds from the Manna Gum site. We have noticed some really interesting species coming into the site as a result of all the plantings we’ve done. We began to see things like Red-capped Robins a few years ago, we’ve seen White-winged Trillers, Spiny-cheeked Honeyeaters and a few years ago we even saw a Western Gerygone. The whole Manna Gum site is only a couple of hectares, but it’s next to a native grassland – the largest remnant grassland in Moreland City Council, and at the bottom of the escarpment you have the Merri Creek that has some riparian habitat. This area has became a real hotspot for biodiversity and I think it’s because it is the meeting point of different habitat types.

Seeing these species move in inspired us to put in another grant, to create a third expansion, which we called ‘Habitat Heroes’. This was funded by the Helen Macpherson Smith Trust. And so we removed the last remaining Boxthorn and Blackberries. Even though bush birds were still using the weeds as habitat, we could see they now had lots of habitat to move into, and removing the last Blackberries and Boxthorns wasn’t going remove all the habitat from the site.

It was only this year we had a groomer come in and remove the last extensive patch of Blackberry. A groomer is a machine that can mulch large areas of large woody weeds, such as Blackberry, Gorse and Boxthorn. We had already sprayed the Blackberry and so they just groomed down the dead stuff. The grooming alone doesn’t kill the Blackberry, as it will re-sprout from the roots. Now we’re treating the regrowth. This year we also planted another several hundred trees and shrubs with the community, extending the woodland/shrubland habitat by another hectare, and we’re hoping to see even more birds move in.

The Spotted Pardalote is one of many bird species that are establishing as the indigenous vegetation matures. Photo by Brian Bainbridge

Just in the last few weeks we’ve seen a Rufous Whistler at the site, which had just been a transitory bird and we’d only hear the call for just a few days each year. But this year it has spent several weeks calling and trying to set up a territory. This year Golden Whistlers have been hanging out at Manna Gum as part of their winter territory. Again, they had been a bird of passage in previous years, but now they have enough habitat to hang out the whole of winter.

Back in 2002 I moved into a house just 50 meters away from this site and that has meant that I’ve had a ringside seat to watch all of these changes happen over the last 13 years. It’s been like a 24 hour nature channel; sitting on the back porch I could see all of these changes and I could hear all of the birds as they moved through the landscape.

That sounds like some great outcomes. Have you got any tips for anyone who wants to do staged weed removal?

Back in 1993 there was a big flora and fauna survey of Merri Creek. For many years our Friends of Merri Creek members and MCMC have wanted to see that baseline data replicated, but that only began to happen with quarterly bird surveys which started in 2009, conducted by Friends of Merri Creek in conjunction with Birds Australia (now Birdlife). I volunteered to lead a bird watch and incorporated a walk through the Manna Gum site as part of one of these three monthly bird visits. This has been continuing on right until now, so there’s about 6 years of data of birdwatchers running through the site in each season.

So there was unfortunately a gap of 16 years, between 1993 and 2009 where we weren’t methodically collecting data on flora and fauna, and we missed opportunities to document lots and lots of really amazing changes.

I would definitely recommend collecting some baseline flora and fauna data and do ongoing monitoring every year, so you can track some of those changes when you’re transforming a weedy landscape to an indigenous one.

I did a back-of-the-envelope analysis and compared the 1993 bird list to the 2015 bird list. I found that there’s an additional 60 species now using the Merri Creek and at least 30 of those species were definitely coming in as a result of improvements in the habitat.

I also think it’s worth making sure you step back and have a look at your site from different angles to recognise if you need to stage it. Aerial photos are a great way to look at the scale and the context of your site.

If you already have some adjoining habitat, and the weeds are expendable, you can go hell-for-leather with removal. But if they have some value as habitat, some forward planning is needed.

We’ve always anticipated that maybe in a year or two we’ll try for another grant and stage the work in that way too. You don’t have to think that you have to get everything done in your current projects.

What kind of baseline monitoring do you recommend?

One of the things with monitoring is not to get hung up on the amazing science of monitoring, you can very quickly lose momentum and heart trying to apply a monitoring program that’s too detailed.

There are a number of guides out there that try to simplify monitoring. The Friends of Merri Creek have the assistance of Birdlife in setting up their bird monitoring program. Birdlife have a standard 20 minute and 2ha searches, which I really recommend doing that rather than reinventing survey techniques.

Bird data is really magnificent for trying to interpret what’s going on in the landscape; you can look at any of those species and work out why that species is there. What are they eating? Which habitats do they live in? Which other species do they interact with?

We know that we have three different cuckoos in manna gum because there are so many Blue Wrens and other small birds – the cuckoos can lay their eggs in their nests. We’ve also had hundreds of Silvereyes this winter because we had a big year of Tree Violet berries.

Blue Wrens are one of the small birds that cuckoos use to raise their young. Photo by Brian Bainbridge.

Many of these projects use volunteers for tree and shrub plantings. Have you got any tips for increasing community engagement in these types of projects?

For years we struggled to attract the local community to the Fawkner stretch of the creek. We were just doing letter drops for the local area, putting the posters up in the library, sports centre or local shops. But in the last couple of years we’ve made really strong relationships with the local community house and some of the parenting groups, as well as using social media, and we’ve had 70-100 people coming to the last two planting groups.

So what changed?

I’m a local myself to the Fawkner area and I found being a local and being a part of the community house, I could make some much more personal contacts. So my wife and I started to invite people individually, as they recognised us as part of their community, and they’ve been much more interested in coming on board.

We’ve have a large and energetic Muslim community in Fawkner who we are keen to engage with. Recently a volunteer has been helping run our barbecues to make sure it’s Halal. Having someone from the Muslim community come on board has made people feel more confident to come along and make use of the free barbecue.

We also have a lot of young families in the area and building connections with the parenting group has been a major part of getting people involved. It’s the parents in particular who want to bring their kids along. Having these planting events is a great way to get the community engaged with the conservation work that has been happening here for the last 25 years.

Thank you for your time.

You can learn more about the Merri Creek Management Committee on their website: http://www.mcmc.org.au/

Interview with Brian Bainbridge – Part 1

The Merri Creek flows 60km from the Great Diving Range through Melbourne’s northern suburbs to the Yarra River near Collingwood. The Merri Creek Management Committee (MCMC) formed in 1989 to preserve and restore the natural and cultural values of the creek. In that time they have done some amazing works.

Merri Creek planting day. Source

In this post, I catch up with Brian Bainbridge from MCMC to learn more about what they do.

BB portrait
Brian Bainbridge

Hi Brian, thanks for catching up. Let’s start with how you got interested in nature…

Thank you. I was a bit of a nature boy from a very young age – I was always walking around looking at nature. My parents can remember me looking at things, insects and stuff, before I could talk. I was lucky in the first place that I lived in Greensborough, because the block still had some remnant native plants. Down the street we had a neighbour, Vince Pettigrove, who’s now an accomplished ecologist, and he was someone I could take interesting things to. My mum was interested in birds and we had a collection of Tuckfield’s tea cards which was a constant source of fascination.

Tuckfield’s tea cards. Source

As I got older I went out into the street where we had some beautiful old Yellow Box trees and I use to see Swift Parrots in them. From about the age of 12 I would get down to the Plenty River and began exploring up and down the river. I remember around this time, I was walking along the Plenty River in Greensborough, looking at all the elm trees and the weed trees taking over the bushland, and I thought:

wouldn’t it be great to have a job where I was removing the weeds and putting back the native bushland

At that time in the early 1980s I hadn’t heard that any job like that existed. I thought that would be the best thing in the world to do.

When I did come to study, I chose to do a Bachelor of Forestry at Melbourne University in the late 80s/early 90s. I thought it would be great to be a ranger, but at that time a lot of the departments were slashing jobs. As I went through the course, I realised that maybe a park ranger wouldn’t be an option when I got to the end of the course.

As a result, I spent quite a bit of time unemployed, but I did work in my parents’ bookstore.  I had always been into artwork and drawing nature, and at that time I began to pick up freelance illustration work – this was a great way to explore and learn about nature because you have to research your project.

How did get into the environmental industry?

I got asked to do some illustration work for MCMC, for a book called Plants of the Merri Merri in 1992. I then got employed as part of a job-skills program in the mid-90s for 6 months, again to do illustrations for a flora and fauna guide (Creeklife). That was a great job as it meant that I spent a lot of time exploring the creek and learning about it all. So when I was unemployed again and a job came up with MCMC, they knew I could identify things and I joined the bush crew in 1997.

Creeklife cover
Creeklife illustrated by Brian.

With my skill set in bird and plant identification, as well as a good understanding of the ecology of the Merri Creek, my role gradually changed to do more of the survey work and contribute to ecological knowledge and research. Gradually that’s turned into a role called the Ecological Restoration Planner. Over the last few years I’ve been working on implementing the monitoring programs; this was seen as a real need for a long time and we’ve recognised how important it is to keep monitoring over multiple years.

What are some main projects that you’re currently working on?

Two of my main projects are focused on the Plains Yam Daisy and the Golden Sun Moth. With the Yam Daisy we’ve been looking at the remnant populations to understand their ecology better, as there’s a lot of misunderstanding about the species, in particular the different forms and their environmental requirements. We’re using this information to help locate the best areas for reintroduction and I think we now have a reliable technique for reintroducing the species into natural grasslands.

Plains Yam Daisy. Source

Alongside that, we’ve being doing another project on Golden Sun Moth to try and fill in a few questions. A lot of the previous monitoring just looked at presence/absence, but we really needed some answers about the maintenance of the grassy habitat that they occur in. We’ve recognised that their habitat becomes unsuitable very quickly if the biomass isn’t reduced, but people had concerns that burning the habitat at a different times may damage the moth’s caterpillars.  We’re coming to the end of this project and the results are on our website.

Sun moth site 2 Jan 2011 003
Golden Sun Moth. Source

I’ve noticed that at some sites along the Merri there are still large patches of weeds right next to revegetated areas. Why doesn’t MCMC remove all the weeds at once?

MCMC has for a long time held the principle of staged restoration works, of not removing all the weeds at once. This is because along the Merri there’s so little bushland remaining that we’ve had to stage our work, otherwise we’d risk losing some of those native fauna that relied on the weeds as habitat.

Native animals actually use weeds as habitat?

Yes they do. For example, in some urban areas we observed that White-browed Scrubwrens only remained  in the blackberries and boxthorns. Blue Wrens are an archetypal species that loves to hang out in weedy blackberries and boxthorns, Silvereyes feed on boxthorn berries and New Holland Honeyeaters on the nectar of boxthorns.

Birdlife, Fawkner 0808 005.jpg
Blue Wren in Boxthorn. Photo by Brian Bainbridge.

Melbourne Water were doing a lot of Willow removal on the Merri Creek and sometimes we would have to say “you can’t remove that particular Willow as it’s known as a Tawny Frogmouth roosting area or nesting area”. We had one willow on the creek that was a nesting site for Sacred Kingfisher. Given that we have so few large native trees with hollows, and we’re still many decades away from having that resource, the only place the kingfishers could find nests along the Merri creek were in the soft rotting old Basket Willows and Weeping Willows.

The other place they found to nest was in the Canary Island Palms, and they can actually tunnel into the trunks of the Palms. We’ve had to moderate our campaign against Willows and Canary Island Palms to make sure there’s some alternative habitat available. Melbourne Water have recognised that too, and tend to retain some Willows which are less prone to invading. They just keep a few in the landscape while we wait for the other trees to grow bigger, and so willows may be in the creek landscape for a few more decades at least.

You can learn more about the Merri Creek Management Committee on their website: http://www.mcmc.org.au/

Stay tuned for part 2…..

Growing the wild orchids of Nillumbik

In the foothills of north-eastern Melbourne, from Eltham to Kinglake, is the Nillumbik Shire Council. It is home to a diverse fauna including the Powerful Owl, Swift Parrot, Brush-tailed Phascogale and Tree Goanna. Nillumbik also has over 700 different species of indigenous plants, including more than 90 species of orchids!

Nillumbik Shire Council (click for a larger image)

Many of these native orchids have specific relationships with fungi and wasps. Orchid seed is very fine and dust-like and, as a result, does not contain enough energy for the seed to germinate (no endosperm). These orchids will only grow if they have been infected with fungi. This relationship is mutual, where the fungi gains sugars from the orchid in exchange for minerals from the fungi. Orchids are also sexually deceptive. They will trick the male of a specific wasp species into thinking it’s the female, by releasing pheromones similar to the female wasp. Because of these specific mutualisms, it is difficult to propagate and reintroduce orchids back into the wild.

Nearly half of the local plant extinctions that have occurred in Melbourne were from the Orchid family. Orchids are vulnerable to grazing and weed invasion, and make up a disproportionate number of threatened species in Victoria. Furthermore, scientists have predicted that Melbourne will lose half of its native plant species over the next century, with Orchids bearing the brunt.

In this post, I catch up with Meg Cullen from Nillumbik to learn more about the Conservation Corridors orchid project.

Hi Meg, thanks for catching up. Let’s start with bit about yourself and how you got into the industry…

Thanks John. I always knew that I wanted to work in the environmental field and decided at 9 years old that I wanted to be a zoologist. In year 12 I found out about a Conservation Ecology course at Deakin University. I then stayed at Deakin for 11 years, and did an Honours year and a PhD.

While I was finishing my PhD I started working with Birdlife Australia – I still work there as well as at Nillumbik – and have been there for 8 years. I have a background in threatened species conservation, in particular working with communities and volunteers to achieve conservation outcomes.

What is your role at Nillumbik?

For the last 5 months I have been coordinating the Nillumbik Conservation Corridors Project . This project involves working with 9 different Landcare groups, which have recently formed the Nillumbik Landcare Network.

The corridor runs through the northern and eastern sections of Nillumbik, and we’re focusing on works that will help conserve some of the threatened species in the area, such as the Brush-tailed Phascogale, Common Dunnart, Round-leaf Pomaderris and some of the rare orchids.

What you are doing with your rare orchids?

The conservation of orchids has been going on for a long time in Nillumbik, with some ground-breaking methods being implemented by local experts, so it was already something that had been discussed by a number of different partners and members in the Landcare group.

The Corridors Project has funded surveys on private land to look at where orchid species occur –  they may not have been surveyed before – and identify new populations of some of these rarer orchids. It has also helped fund and coordinate fencing: one of the main ways to protect orchids is through small enclosure fencing that stops grazing from wallabies, kangaroos, rabbits, and also White-winged Choughs, who eat the tubers of the orchids. In some areas the orchid populations are caged so the birds can’t get in, and in other areas they’re protected by a rabbit/grazing proof fence.

How did the propagation side of things start up?

We’ve been working with Cam Beardsell who is an ecologist and works for Parks Victoria, but also lives in the shire and manages orchids on private property. His amazing work, on species such as Rosella Spider-orchid, has saved species from extinction.

Rosella Spider-orchid
Rosella Spider-orchid

The project is also involved with the Royal Botanical Gardens,  Australasian Native Orchid Society (ANOS) and Parks Victoria. Together with these partnerships and the Landcare groups, we’ve been working to propagate four species of Orchids: the Wine-lipped Spider-orchid, Rosella Spider-orchid, Emerald-lip Greenhood and the Woodland Plume-orchid, all of which are rare and threatened.

Wine-lipped Spider-orchid
Wine-lipped Spider-orchid

The Rosella Spider-orchid is only found in Nillumbik.  It only occurs in four areas – one small population in a council reserve, two on Parks Victoria land and another on private property.

All the permits for seed and fungi collection are done through the Royal Botanical Gardens and ANOS – so they collect the seed and Cam from Parks Victoria also collects some seed as well. Neil Anderton, from ANOS, is one of our key contacts  – he is a volunteer who does a lot of the lab side of work and recently gave me a tour of their work.

Carefully collecting a sample in the field of the Woodland Plume-orchid
Carefully collecting a sample in the field of the Woodland Plume-orchid

“people who volunteer their time on these conservation projects make such a difference – the lack of funding in all things environmental means that it falls to those who can volunteer their time and expertise to do a lot of the work”

How do they collect and grow the orchids?

Someone from the ANOS and the Royal Botanical Gardens comes to the site and, very carefully, takes a sample of a small area at the root of the orchid. They take this back to the labs at the Royal Botanical Gardens and propagate the fungi from the samples. The root samples are cleaned to remove any contamination and then they are grown in a petri dish, which contains an agar and oat mix.  If it’s successful, they can put the orchid seeds on top of the fungi and they’ll germinate in association with that fungi.

Fungi sample grown from a root sample of the Woodland Plume-orchid
Fungi sample grown from a root sample of the Woodland Plume-orchid

It took a while for  any success, but in the second year, three of the four species germinated well. This year we collected some more fungi for the Woodland Plume-orchid and we have finally had some good success with this species.

First year growth of the Rosella Spider-orchid
First year growth of the Rosella Spider-orchid

That’s great! When will the orchids be reintroduced?

We’re at an early stage and so it will be probably another 2 years before the orchids will be ready to be introduced back out into the wild. It’s probably a 4-5 year process before they actually get out there, so yes it’s quite a long journey.

Rosella Spider-orchids flowering in the green house at the Royal Botanic Gardens
Rosella Spider-orchids flowering in the green house at the Royal Botanic Gardens

“ a lot of the orchid conservation work that is going on, and that I’ve read about, is that a lot of these populations are being hand pollinated because the pollinators aren’t there or they’re not there in high enough numbers. It’s very time consuming to head out there and pick the right time. You can’t really expect to keep hand pollinating year after year to keep the population going – we need to look at increasing pollination naturally”

How do you prepare your sites for reintroduction?

The next step of the project is to form an expert group that can give advice on the location of re-introductory sites.  We will then start preparing the sites a year or so before the propagated orchids are ready to go out. A fair amount of site preparation needs to be done. You need the right fungi in the soil for the orchids to be able to grow, but I’ve also heard about people creating the right moss beds for re-introduction. The sites will need to be fenced and grassy weeds will be controlled, as these can smother and outcompete the orchids. Enrichment planting is also important at some sites.  This involves planting some of the key species that attract orchid pollinators that might be missing at a site.

How will the Landcare groups be involved?

About 60% of bushland in Nillumbik is on private land which makes it really important to get people on board to manage the bush.  Some of the  re-introductory sites will be on private land and many of  these rare orchids occur on private property as well.


“we’re really lucky because we have some really passionate community and Landcare members who initiate a lot different projects and inspire others to be involved – I think that’s been a big benefit of working in the Nillumbik area”

We are putting together a manual that will include guidelines for private property owners on how to manage rarer orchids – it will be really useful to have clear and detailed instructions you can give to locals so they can help us to protect these species. In conjunction with the guidelines, we have also run workshops to encourage landowners to manage their orchid populations.

Any tips for land managers who want to do what you’re doing?

My biggest tip is to create partnerships with different groups, organisations and land managers in the area. We’ve worked with Parks Victoria, Melbourne Water, the department within Nillumbik Council that manages the reserves, private land holders, Royal Botanical Gardens and ANOS.

all these different groups coming together to work on the same project is crucial because we couldn’t do it without them”

If you would like to learn more about the project you can contact Meg Cullen on 9433 3214 or meg.cullen@nillumbik.vic.gov.au

Bushland health check – response to comments

I had a few interesting questions from my previous blog post, so I thought I’d answer them here by clarifying a few things.

Dangers of small populations – not just mutations

“How long before the products of a reduced genetic spread results in local extinction of the flora species through mutations?”

The rate that mutations occur in a species is generally constant and does not increase when population size decreases. In a small population, you do not get more mutations occurring, but the mutations that do occur can spread more rapidly through the population due both to random chance and breeding between close relatives.  If these mutations are ‘unhealthy’ and build up in the population, this is called inbreeding depression and results in a reduction in fitness (see this and this for more information). For plant species, signs of inbreeding depression can include poor growth, less flowers per plant and less viable seed production.

The time to local extinction for a species depends on a wide range of  factors, including the size of the population, the types of unhealthy mutations in the population, pollination and dispersal methods, and other threatening processes.

Definition of a plant population

A plant population is defined as a group of individuals of a particular species that are capable of interbreeding. The area that the population occupies depends on the natural density of the species and the distance over which the species can interbreed, which depends on the distance pollinators can travel and the distance that pollen or offspring can disperse (which can be affected by wind, waterflows etc.).

Before European settlement, most of Australia’s plant species would have had large populations. But now some our native plant populations are small and fragmented, and as a result pollen and seed dispersal is limited. Depending on the species’ pollination methods, some species can still exist as ‘populations’ across a fragmented landscape (see this for an example) but others are confined to the fragment in which they occur.

“Should a reserve of a few hectares with half a dozen blackwoods (the only blackwoods in the area) be subjected to what Jeff Yugovic terms “ecological gardening” by planting another 495 and ideally, 4995 trees, or any other tree or shrub species that are perceived to be scarce, at the expense of other flora species crowded or shaded out by those trees?”

I am not suggesting that we should start cramming our reserves with plants to suit current theories and disregard all other factors such as reserve size, natural plant densities or the presence of other species. Even if you did plant 495 or 4995 plants they would self-thin to their natural density.

“If an area historically has scattered terrestrial orchids, do we need to propagate and plant 500 to 5000 of each species?”

Before European settlement, scattered terrestrial orchids would have occurred as large populations spread across numerous clumps. Orchid pollinators would have moved between these clumps and so facilitated gene flow across the landscape. Now that our orchid populations are fragmented and isolated, the clumps are so distant that they form small separate populations. Orchids should only be propagated if the reintroduction sites have the appropriate pollinators and fungi.

Small reserves – possibly not viable, but important

“If a reserve is only one or two hectares aren’t you limited by area?”

Yes, that true. Many remnant sites that we manage are not large enough to sustain viable population sizes over the long term. They often consist of small, inbred populations with low fitness. This is something that land managers need to understand and manage.


Despite these shortcomings, small reserves still have important ecological and social functions in the landscape.

A long bow, or research in progress?

“Extrapolating formulas suggested by genetic research on fruit flies in 1980 to plants in a varied and dynamic ecosystem is a very long bow indeed.”

Since the work on fruit flies in the 1980s, there has been another 30 years of research into minimum viable population size . If you’d like to read further about the current research, I’ve put in some links at the end of this blog.


Is a small population a threatening process?

“Anyhow, shouldn’t we be concentrating on removing threatening processes before we begin sculpting the population dynamics in remnant ecosystems to suit our current theories?”

In writing this blog, my intention is not to force current theories onto our remnant ecosystems, but to help bushland managers understand the complexities of how ecosystems work (and don’t work), so that we can make better decisions for conservation.

I think the inbreeding depression that occurs in small populations is a serious threatening process.  Reduced fitness due to inbreeding can also compound other threatening processes. A bigger, more genetically-diverse population is a healthier population, and while population ‘rules of thumb’ are not perfect, they’re better than nothing.

References and further reading

Bacles, C.F.E., Lowe, A.J. and Ennos, R. 2006. Effective seed dispersal across a fragmented landscape. Science 311, p.628.

Bradshaw, C.J.A. 2009. Classics: Ecological Triage. Conservation Bytes Blog.

Bradshaw, C.J.A. 2009. Managing for extinction. Conservation Bytes Blog.

Bradshaw, C.J.A. 2009. We’re sorry, but 50/500 is still too few. Conservation Bytes Blog.

Flather, C.H., Hayward, G.D., Beissinger, S.R. and Stephens, P.A. 2011. Minimum viable populations: is there a ‘magic number’ for conservation practitioners? Trends in ecology and evolution 26, pp.307-316.

Markert, J.A., Champlin, D.M., Gutjahr-Gobell, R., Grear, J.S., Kuhn, A., McGreevy, T.J., Roth, A., Bagley, M.J. and Nacci, D. 2010. Population genetic diversity and fitness in multiple environments. BMC Evolutionary Biology10:205.

Newman, D. and Pilson, D. 1997. Increased probability of extinction due to decreased genetic effective population size. Evolution 51, pp.354-362.

Traill, L.W., Bradshaw, C.J.A. and Brook, B.W. 2007. Minimum viable population size: A meta-analysis of 30 years of published estimates. Biological conservation. 139, 159-166.

Traill, L.W., Brook, B.W., Frankham, R.R. and Bradshaw, C.J.A. 2010. Pragmatic population viability targets in a rapidly changing world. Biological Conservation. 143, 28-34.