Restoring Native Grasslands - part 3

A beautiful carpet of Common Riceflour, Pimelea humilis, a grassland champion. These plants are still thriving in the Point Richards Reserve, Portarlington

Turning the tide - time for a grasslands revolution

You’ve received a mysterious invitation from a close friend to a grassland party. ‘A what? You think – that’s quirky!'

When you arrive, you’re greeted at the door by your very excited friend, who ushers you into her lounge where four other women from your preschool group are seated.

You give one of them a quizzical look. She raises her shoulders as if to say, ‘search me?'

Your friend claps her hands and says excitedly, “Ladies, you’re here to share in my new passion. You’re here to help me turn back the clock 180 years. You’re here to help me transform my back yard lawn into a low maintenance, wildlife friendly, carpet of beautiful wildflowers.”


Does this gathering of young mums sound feasible to you?
Could restoring indigenous grasslands in backyards capture the enthusiastic support of Australians from all walks of life? Is it possible to start a revolution that would see indigenous grassland plants return to the naturestrips and home gardens of our nation?

The carbon sequestration and water saving benefits of planting millions of deep-rooted perennial plants would be reason enough to promote a grassland revolution. 

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Hoary Sunray, Leucochrysum albicans, a grassland champion. It spreads into open areas and isn't grazed by kangaroos or wallabies

Planting a grassland

If you're worried about the continuing disappearance of our grassland flora and fauna, you would probably agree that a significant challenge is to develop a relatively easy method of restoring grasslands that can be applied on a small or a large scale.

This would empower more land managers, including young mums with suburban backyards, to restore indigenous ecologies on a variety of Australian landscapes. It is an intriguing challenge that desperately needs some practical solutions.

In part 3 of Restoring Native Grasslands I hope to spark some discussion about how this restoration could be done.
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Part 1 of Restoring Native Grasslands looked at the history of grasslands in Victoria and how our landscapes have changed since settlement in 1835.
Part 2 of Restoring Native Grasslands looked at some large-scale grassland restoration success stories and what can be leant from them. 

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Bower Spinach, Tetragonia implexicoma, will smother invasive weeds and grow in dry situations under mature trees

Restoring native grasslands – part 3
 
Your mission is to plant an 'island' of tough, competitive grassland plant champions and nurture them through the first year.

​The method - in a nutshell

1. Compile a plant champions list. (Click to the grasslands plant champions table (list) to get you started)​​
2. Select suitable 'island' planting sites in yout lawn or garden from which the champions can spread. Also see the  champion's table for recommended plant spacings.
3. Prepare the 'island' for planting. 
4. Choose on a nutrient-stripping strategy - like spreading sugar or sawdust; slashing grass & removal; planting nutrient-stripping grassland species like Kangaroo Grass (more on this in the Champion's table)
5. Inoculate the soil with microbe rich tea. See Restoring Native Grasslands - part 2 for more on this topic.
6. Keep the plant champions weed-free for 12 months. 
7. Encourage them to spread from the 'island' planting 

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Native Geranium, Geranium retrorsum, is a forb with a deep succulent root system. It competes well with exotic weeds.

Blow by blow - in bruising detail:

1. Compiling an indigenous plant champions list
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The grassland plant champion’s table can be used to make a list and includes 76 species, from 50 genera, and 22 families found in central Victoria. Your list can be extended with other hardy indigenous plants local to your area. Ask your local indigenous nursery and order plants in autumn for planting in mid-spring.

When the champions begin to take control and improve the soil chemistry, other less hardy plants can be added. The list of species on the table includes other useful information.
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Include some 'nutrient strippers' in your plant list.
Nutrient stripping plants like Kangaroo Grass will help lower nitrogen (N) & phosphorus (P) levels in your island planting.

Plant in groups/clumps of the same species - 10 to 50 plants/clump. Plant smaller species  in larger numbers so they can dominate their growing area. See the champions table for the recommended spacing for each species 

Why plant in same species clumps? Planting in clumps looks great, is nature's way, attracts more pollinating insects and will produce more fertile seed, giving the grassland champions the best chance of spreading into surrounding areas.

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Common Rice Flower, Pimelea humilis (white flowers), surviving on a weedy privately owned building block. The soil fungi needed to support this plant would still be present.

2. Select suitable 'island' planting sites
​Look for helpful indicators of where indigenous plants will best grow.

Plant near surviving remnant grassland plants:
(Surviving plants (often native grasses like wallaby, windmill, weeping, and spear grasses) will indicate suitable soil conditions -Read more about identifying native grasses here)

• The island plantings will help surviving grassland plants spread 
• The soil conditions are likely to be lower in nitrogen and phosphorus
• Soil fungi are more likely to be present. The native fungi will accelerate growth and improve the health of the  champions. They exchange critical minerals for sugars supplied by the plants.​

Choose the best soil for native plants:

• Well drained, where water doesn’t pool after heavy rain.
• Low in nutrients – lush green and vigorous weed growth indicates rich soil that is high in nitrogen (N) and phosphorus (P). These soils are perfect for the weedy interlopers and will need nutrient stripping to lower N & P to suit the grassland champions – (see the next section on nutrient stripping).
• High P levels suppress important fungi that give the champions an advantage over weeds.
• Outside the drip-line of big trees – Big trees do lower N & P in soil, which the champions prefer, but they also take most of the moisture. If the soil becomes very dry over spring and summer, the grassland champions will struggle to survive without extra watering. The champions more suited to the very dry conditions under trees are highlighted in yellow on the champions table.
• Small carnivorous plants like Sundews, Diuris sp., are a sure sign that N & P levels are very low. These clever plants get the N & P they need by trapping small insects.

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Oxalis comes in many sizes and colours. This yellow flowering variety is probably the most common and invasive

3. Preparing the island for planting

This will usually involve weed removal, by chipping, rotary hoeing, mulching with cardboard, natural underfelt, hessian or spraying with herbicide (see note below on herbicide use). Solarization over the previous summer for four weeks with clear plastic is also a good option.

Aerating the soil with a garden fork or by shallow ripping with a tractor will help the champions establish more quickly. 

Avoid planting near invasive perennial weeds like Kikuyu, Couch, Phalaris, Paspalum and Oxalis. These are best managed with an application of herbicide. Ideally follow up with a cool burn when they die and spray with herbicide again if they reshoot.

Show them no mercy because they will take over the grassland and destroy all your good works. Once they invade they are much harder to control. Using this process, you will systematically eliminate difficult-to-manage weeds, though it is likely to take two growing seasons. Planting grassland plants before these tough resilient weeds are banished will only result in disappointment.
 
A note on spraying with glyphosate: Herbicide is a very useful tool if it is used minimally, safely and intelligently.
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The time to spray is when the weeds look healthy and are showing strong growth. Allow more top growth before spraying deep-rooted weeds like Phalaris and Paspalum
(See images below).
Kikuyu and Couch grasses die back naturally in winter, so spraying at this time does them no harm. It is better to spray these weeds in late spring or early summer when they are green and growing strongly.
Oxalis is best sprayed at the beginning of its flowering cycle, when the plants have just a few flowers. Spraying at this time kills the many small bulbs (future plants) that are attached to the oxalis roots.

My personal story. As an organic vegetable grower, I have tried hand-weeding these difficult weeds year after year. This involved putting the soil through a sieve to remove any potential growing shoots or bulbs, which is a slow and tedious process. Yet, still the problem weeds kept coming back.

I swallowed my pride and applied one well-timed spray with 1% glyphosate and eliminated them. This is the recommended rate for difficult-to-manage perennial weeds.

To put this spray-rate into perspective; 1% is equivalent to spraying 1 teaspoon of glyphosate concentrate over a 25 square meter area of perennial weeds. I feel the remarkable environmental benefits gained from establishing 5m x 5m (25m2) of healthy native grassland outweighs other environmental concerns about it's use.

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Kangaroo Grass mass planted in an island planting to lower nitrogen levels. No nutrient stripping was done on this site, so more hand weeding was required.

4. Nutrient stripping or reverse fertilisation

• Add Sugar to the soil surface at a rate of 0.5kg/square metre. This temporarily lowers nitrogen (N) levels and it works better when spread over bare soil. 

How it works - Sugar lowers N levels for 3 – 12 months because it activates soil microbes that feed on nitrogen, making it unavailable to plants. These microbes need both carbon (in sugar) and the nitrogen in soil to grow. When the microbes use up all the added sugar they die, gradually making the N they consumed available to the plants once again.

• Add saw dust, another source of carbon to lower N levels.

One cubic meter of saw dust, spread to a depth of 25mm and hoed into the soil, will cover 40 square metres. This will lower N levels for more than 12 months, provide added humus to help keep the soil moist, reduce weeding and add significantly to soil’s organic matter.

• Slash & remove the cut grass, or crop & burn stubble.

A few seasons of cutting grass and removing the clippings from the site, will gradually lower soil levels of nitrogen (N) & phosphorus (P). 
Burning the stubble when it dries will further lower N & P levels and adds smoke chemicals to the soil that enhance the germination of many native seeds.

• Plant Kangaroo Grass, Themeda triandra, has been shown to lower nitrogen (N) to levels ideal for native grassland plants. This process took about 18 months in the study.

This same study showed that Kangaroo Grass mostly stored the N underground in its large, deep, fibrous root system.

• Plant other deep-rooted native plants that may lower soil nutrients.

Spiny-headed Mat-rush, Lomandra longifolia, is a fast-growing leafy species that has the potential to lower N & P levels. 

• Plant deep-rooted forbs
  Champions table highlighted in green

​These beautiful long-living wildflowers put down very large, often tuberous roots that sustain them through the dry, hot summers.

• Plant scattered trees and shrubs. 

Planting woody vegetation lowers soil levels of nitrogen (N) & phosphorus (P), however most trees will dry the soil under their canopy. River Red Gums appear to be an exception and are often retained in cropping paddocks.

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Planting scattered canopy trees will lower soil nitrogen and phosphorus levels. Photo. Deanna Duffy

Planting scattered canopy trees at a similar density to the original pre-settlement spacing will create an open grassy woodland and lower soil nutrient levels.  

This nutrient lowering effect has been observed to extend at least 1.5 x height of canopy trees from their trunk. Therefore trees reaching a mature height of 20 m will lower soil nutrient levels up to 30 m from the tree’s trunk.

Planting nine, 20m tall canopy trees over one hectare will eventually return the soil nutrients to a pre-settlement lower levels. (This density was calculated on an average spacing of 30m between canopy trees).
 
Note on planting canopy trees:
Canopy trees planted in groups of 5 trees, with a tree spacing of 3m within these groups, has many advantages:

• It ensures their long-term survival through natural selection, as the strongest tree with the best genes will endure into and beyond the next century. 
• Trees from each group can be harvested for firewood and timber. (Click here to read about the benefits, uses, planting and protection of paddock trees)
• Group planting provides important stock shelter and wildlife habitat in the early years while the trees establish.

Planting clumps of shrubs. 
An alternative design is to include clumps of indigenous shrubs and understorey trees. This will diversify the sources of food and improve habitat for wildlife. To lower soil nutrient levels, the shrub-clumps and the clumps of understorey trees are spaced at 1.5 times their mature height.

Therefore, a clump of twenty, 5m tall shrubs, will lower soil nutrients 7.5m beyond the outer edge of the clump. A clump of 10 understorey trees with a mature height of 12m will lower soil nutrients up to 18m beyond the outer edge of the clump. Within these clumps, the plants are spaced at 2 – 3m.

​In this way, a mixed shrubby woodland with grasslands in the open areas can be restored over 1ha and over multiples of 1ha.

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Compost teas can be sprayed or watered-in with simple and safe gardening equipment

5. Inoculating the soil with microbe rich teas 
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Microbe-rich inoculations have been shown to stimulate the revival of some grassland species. Microbe-rich teas can be made from worm-juice, compost or manure.

​A concentrated tea is made by harvesting worm juice or by placing a permeable bag (e.g. hessian) containing about 9L (one full bucket = 9 litres) of compost or manure into a 150L drum of water (40 gallons). (These volumes can be scaled up or down to suit the size of your project).

After one week, the microbe-rich water in the drum is diluted to the colour of weak tea and sprayed over the grassland plants. This is best applied when the soil is moist, on a cool, cloudy or rainy day, in mid-spring or mid-autumn as direct sunlight will kill the microbes in the tea. Spraying microbe tea several metres beyond the planted area is also likely to help the plant champions spread and may stimulate long-dormant native grassland plants to grow

The benefits of inoculating with microbe-rich teas is discussed in;
​Restoring native grasslands - part 2

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A cool burn will lower soil nutrients and add smoke chemicals which enhance the germination of indigenous grassland plants. Photo Gib Wettenhall

6. Keeping the islands weed free for 12 months

This is usually enough time for them to establish and set their first crop of seed. You will probably need to shallow mulch with leaf litter or straw to 2.5cm deep. Pegging down some hessian or organic weed-mat will slow the planting process but it will reduce weeding.

7. Spreading out from the island plantings

Paul Gibson-Roy and John Delpratt noticed grassland plants spreading well beyond the edges of their restoration sites;

“At all Grassy Groundcover Research Project restorations, native grasses had colonised some tens of metres beyond the boundaries of the original restoration zones and at a large number of sites, forb species had also expanded beyond the restored area” 
(Paul Gibson-Roy and John Delpratt. 2015. Land of Sweeping Plains. Chapters 11 & 12.).
 
When the island planting is established, the exotic weeds growing around the fringes of the island are your next frontier. The techniques discussed under ‘Nutrient Stripping’ can be used to expand the initial planting:
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• Reverse fertilisation.
  Sugar or sawdust spread around the fringes will lower N levels and weaken the exotic weeds. 
  Regular mowing and removing the cut grass from around the perimeter of the champion’s island will lower soil N & P.
• Consider a process called ‘spray topping’ to prevent weeds from setting seed. Spray topping also makes grasses more palatable for grazing animals and has a withholding period of only 24hrs. This method involves spraying glyphosate over the weeds after flowering, at the very low rate of 0.2% (2ml/L water). This is 20% of the usual rate recommended for killing perennial weeds. (Steve Donaldson, Inverleigh farmer, pers. com.)
• Burning. A cool burn in autumn, winter or spring before fire restrictions are declared, will help the champions spread out from the island planting. If there isn’t much dry grass to burn, the right conditions can be created by spraying a month earlier to kill the exotic weeds.
  Mow or wet a firebreak outside the burn-zone to keep the fire from spreading, though at this time of the year this is unlikely. A cool burn should spread slowly, have a low flame height and be very easy to manage.

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...the backyard planting 

​About two years had passed since the grassland party and Cathy was surprised at how well her family had adapted to the new backyard. Instead of a regularly mown lawn it was now a low maintenance colourful grassland meadow.

Her four-year-old loved running through the wildflowers and watching the white and brown butterflies rise into the air around her. There was something wonderful about seeing a carefree child, arms raised, red curls twinkling in the sun, eyes looking upwards following the silent flight of the delicate and graceful butterflies.