8 CHAPTER: Planting Techniques
8.1 Introduction
While many components of a successful rehabilitation project will vary from site to site, the actual planting of the plants is probably the one that needs to be tailord most specifically to a particular site. Most local areas have organisations which have produced planting guides for your specific conditions, however as with most steps in a rehabilitation process there are general guidelines that are worth considering.
Some truisms of planting natives are:
- Weed competition is the number one reason for plantings to fail, assuming the right plant has been put in the right places
- Depth of planting is important typically the deeper the better
8.2 Planting in Clusters
In the past planting was often done by mixing a range of indigenous species together in a carry tray and then planting them a set distance apart. This method often resulted in the wrong species being planted in the wrong place or to close, or far away from other species. This "incorrect location" of species often led to a significantly decreased survival rate.
With the exception of trees and water plants which will be discussed in more detail below a suitable size for a clump of the same species is often 40 plants. 40 plants gives a good sized Cluster and as it represents half of a typical planting tray it makes the organisation of the planting easier and cheaper.
The locating of plants in Clusters is mimicking nature when stands, groves, beds and patches of the same species is a common occurence.
Planting plants in Clusters of the same species enables a number of significant benefits:
- Plants can be better targetted to locations where they will do well
- The spacing of plants can be more easily be planted at suitable distances apart
- Plants of the same species typically grow to a similar height and do not kill each other. As a result the Cluster of a particular species can create a Canopy lock. Cannoy lock occures plants of the same species grow closely enough together so that their cannopies merge and shade out compeating plants above ground while their roots dominate below ground signifcantly increasing competative pressure other species which have not evolved to cohabit the same spaces.
- In pre disturbance environments there are nearly always other native species which have evolved to grow in harmony or even symbiosis with the Cluster species. By creating an extended are of one species the ideal host environment has been created for those other species to naturally regenerate
- By having only one species covering an extended area, research has shown that both the amount of seed and the viability of that seed is considerably improved
- After a relatively short period of time the seed bed in and around the Cluster will come to be dominated by the seeds of that species. As a result when a plant in the Cluster dies its replacement is now more likely to be a plant of the Cluster rather than a weed species which may have previously been the case
- For native animals Clusters of the same species give them significant advantages, not only are they able to get a large supply of the resource they desire but they do not have to make a long and risky trip to do so
A common concern about ensuring that the right plant is planted in the rights place is that the associated costs will be prohibitively high. The cost of ensuring that the right plant is in the right place is a resonable concern however by planting plants in Clusters of 40 this additional cost can be significantly reduced by minimising the number of different planting locations, see below.
8.3 Planting in Stripes
When planitng out a creek rehabilittion site it is recomended that the planting be done in either two or three "Sripes", depending on the situation.
Planting in a Srtipe refers to rather than planting out all the 3 main Zones of a creek, the Low flow channel, the High flow channel and the Verge, they are done one at a time. For example the planters can move along the Low flow channel planting all the Low flow channel plants, typically the reeds, rushes, sedges, tea tree and paperbarks. The next Stripe would be the High flow channel where typically the shrubby species are located and the third Zone which can be planted out in a Stripe is the Verge where the majority of trees will be planted.
The advantages of planting by Stripes are:
- Minimizing the cost of planting by making it as simple as possible. By and large it is true to say that the plants growing in the same Zone tend to be similar and as such the variety of plants to be planted is smaller and the spacing of the plants tends to be similar, all of which makes the planting simpler.
- For example in the Low flow channel the plants are either smaller grassy reeds and rushes with fibrous matted roots which help anchor the plants, and the banks, even the shrubs that grow here have a similar root structure to the grassy plants. While plant best suited to the Verge, trees, are much larger, generally longer lived and have corser root structures.
- Even if a plant is not planted in exactly the right location at least it is in the right Zone and will therefore it will have an improved chance of prospering
- The Low flow channel should be planted out at a different time of the year to plantings in the High flow channel and the Verge. The low flow channel planting should happen during summer when water levels are low. In this way plants will have the best chance of always being in a wet environment. If water plants are planted in winter or spring when water levels are at their highest then planters, being unable to plant under water will plant the plants where they are likely to dry out over the summer months when the water level drops
- Dividing the planting into different Zones makes it easier to allocate different tasks to work crews with different capabilities; to logically break up periods of work and in many cases to help the planters get a greater sense of progress and achievement.
Note in some case there may be no High flow channel. However there is always a Low flow channel and a Verge.
8.4 Plant Selection
Where ever possible plants grown from a local provinence should be selected. Plants grown from locally sourced seeds are far more likely than not only survive and grow vigerously but to produce significantly more vialbel seed having adapted over multiple generations to specific local conditions.
In order to streamline the revegetation project ensure the highest benefits for lowest cost it is recommended that the initial planting list be confined to an limited cross section of appropriate species. A smaller range of species enables their planting location to be more easily planted in the right location..
An important part of choosing the Pallette of species is to ensure an appropriate range of different structural species.
This following list is indicative only. While the species in this list are applicable to the foothills of the otway ranges in Victoria, the total number of species and the approximate breakdown is typical of most situation. Also while many/most of these species will not be applicable in other areas, there are in most areas of Australia with reasonable rainfall equivalent species which will fill the same role.
A good figure to aim for is an initial planting of 21 different species, broadly divided between the 3 main creek zones, the Verge, The High flow channel and the Low flow channel.
Note: This number of species and the type of breakdown is indicative only, the key is to keep the variety of species manageable, the species to be robust and likely to to reproduce and for the range of species to be chosen to ensure a good representation for the differnet creek zones.
An appropriate break down may look something like:
Verge: A total of 7 different species
3 Tree species
3 Wattles or tough shrubs which do well under or near the local tree
species, often Eucalyptus
1 Grass species (Assuming no significant or uncontrollable weed
pressure)
High flow channel: A total of 7 different species
2 Large shrubs/small trees to create some over storey but no Eucalyptus
unless located a minimum of 10m from the Low flow channel. An
example of this type of species is Hazel pomadaris
4 Shrubs
1 Ground cover (Assuming they can compete with local weeds)
Low flow channel: A total of 7 different species
2 Sedge
2 Rush
1 Water ribbon
1 Tea tree
1 Paperbark
(Reed speices have not been suggested here because of the high incidence, in some areas, of reeds choking out other native species and becoming a monoculture particularly in revegetation projects where there is not already a significant over shading of the waterway by other native species. The use of reeds, like all species should be done on a case by case basis)
Another way of looking at it is:
7 Tree species
7 Shrubs
7 Water plants/ground covers
In the foothills of the otways an appropriate list might be:
Tree species
1. Manna gum (Verge)
2. Red gum (Verge)
3. Swamp gum (Verge)
4. Hazel pomadaris (HFC)
5. Black sheoak (HFC)
6. Scented paperbark (LFC)
Shrubs
1. Native hemp
2. Wooley tea tree
3. Prickley tea tree
4. Sallow wattle
5. Musk daisy
6. Silver wattle
7. Tree everlasting
Water plants/ Ground covers
1. Large rush
2. Common spike rush
3. Water ribbon
4. Leafy flat sedge
5. Tassel sedge
6. Hop goodenia
7. Spiney headed matt rush
8.5 Prepartion of planting sites
8.5.1 Marking Cluster locations
It is suggested that small masking tape flags are attached to bamboo canes 1200mm high with the number of the species to be planted being written on the flag. The number of cane flages will match the number of half trays of species to be planted.
Once the flags are made they are pushed firmly into the ground at the centre point of a plant Cluster with the correct locations being identified from the photos in the rehabilitation plan.
Where circumstances require it or the budget is sufficient, a wooden stake with a white icecream container lid or similar can be nailed to the stake and the species number being written on it in permanent marker . While more expensive than the cane flags, the wooden stake sign can be seen from further away, will last longer, and will stand out from the surrounding canes marking individual plant positions, more clearly.
8.5.2 Marking the location of individual plants
To ensure a project is as cost effective as possible it is often necessary to spend money on items or activities which at the time may not seem critical to the success of the project. A good example of this is the desirability of idenfiying the location of each indiviual plant with a 1200mm bamboo cane. Each cane should be firmly pushed into the ground at the location of each future plant in the High flow channel and on the Verge. It is considered innapropriate to place canes in the Low flow channel as there is a high likelyhood of them being washed away.
There are multiple benefits to marking planting spots with bamboo canes:
• Specific planting points are identified rather than planting being done where spray points are located.
• Sprayers only need to spray patches where there are canes
• Follow up spraying will be able to target all plants planted previously
• Plants will not get "lost" in long grass
• The canes can be used to assist create gaurds
• Long term successes or failures can be observed and accurately counted
• Plants which are self sown can be easily identified by not being located next to a cane
Canes will typically last 5 or more years and have the potential to be reused during this time.
It is preferable, but not critical to dip the ends of the canes into a plastic container containing a bright red, or plain white, coloured paint to the depth of 5-10mm. This bright tip to the cane will make it much easier to see particularly in long heavy grass such as phalaris. It is much easier and quicker to dip the cane ends in paint while they are still in the bundles of 100 or so canes that they were delivered in.
8.5.3 Weed contol
Weed control in preparation for individual plant planting is critical to the success of any revegetation project. The importance of weed control is stated else where in this book as being the number one reason for the failure of revegetion projects.
Weeds deny available water and nutrients to native plants, their roots compete for space, they often produce chemicals which inhibit the growth of other plants and they can over shadow the native plants.
Given the importance to weed control it is important to not spray once, plant the plant and leave it at that. Success rates will be substantially higher if the site for a future plant is sprayed 1 month before the actual planting and then again 1 year later. It is important to use a pre emergent pesticide mixed in with the the regular herbacide. without a pre-emergent bare patches created by spraying can start to "grass over", including weeds, within a month or two of planting. Even when planting in damp situations the benefits of using a pre-emergent herbacide appropriately can be outway the potential risks.
It is worth noting that if the weed spraying that is being carried a year after the original planting is mostly dealing with grass, as aposed to broadleaf weeds, there are poducts such as fusilade which only kill grass. They take longer to work but they run less risk of getting on the leaves of the planted plants and damaging them.
8.6 Planting Methods
8.6.1 Direct seeding
Direct seeding is cheaper than planting seedlings, tube stock, and with the correct preporation can be highly successful. However direct seeding is most suited to large scale revegetation projects with suitable access for large machinary.
In the case of creek revegetation projects unless there is a partiularly wide area of Verge allocated to the project direct seeding is not usually the most desirable planting method to use. Additional reasons tube stock planting is preferred over direct seeding in creek revegetation projects is that due to wide range of of micro environments, Low flow channel, Gully, Terraces etc, each of which require their own particular species. This need to target specific species to specific areas within the creek is more easily achieved with tube stock.
For detailed information about direct seeding please refer to publications listed in the bibliography or contact Greening Australia.
8.6.2 Tube stock
Tube stock are typically individual plants which were germinated the year prior to planting. The plants that form tube stock are typically 100- 200mm high.
The design of the containers or tubes that the plants come in has evolved over the years. Traditionally plants came in individual square tubes made of plastic. However these days the most common way that the majority of plants will arrive on site is in a tray of “forrestry cells”. A forrestry tray looks something like a very big ice cube tray made of plastic. Each forresty tray will contain a significant number of small cells, often 81, with each cell containing a plant.
When plants arrive on site they should look like xxxx and when they are removed from the tube or cell the soil they are planted in should come away with the plant. If the soil easily falls away from the root ball of the plant then it could well be tha the seedling is not sufficiently well developed for planting. On the othr hand if there are many roots clearly visable and dense on the outside of the dirt from the tube/cell, the seedling may have been grown too long in its container. In either of these two cases, a seedling which is too young, or a seedling which is too old for its container, the survival chances of the seedling are reduced.
Typically the contents of the tube have been loosend in the nursery prior to delivery which enables the plant to be more easily removed from the tube at the time of planting. If the plant continues to remain stuck in the tube banging the tube briskly agains a hard object like a rock or tree trunk should loosen the plant enough to slip out of the tube intact.
One of the most important keys to successful establishment of newly planted tube stock is that the plant is fully hydrated when it goes in the ground. Most nurseries will thoroughly water stock before it leaves the nursery. However it is likely that the seedlings will suffer some drying out in the period between leaving the nursery and being ready to go into the ground. For this reason watering the tube stock prior to planting is an excellent idea. Even better than watering the seedlings with a hose is to let the trays of seedlings sit in the water at the edge of a dam or creek for a couple of hours prior to planting.
As well as the plant being well hydrated it crical that the ground into which the seedling is planted has an adequate level of moisture. In most cases of rural creek revegetation it is not practicle to water each hole that a plant is planted into and so understanding the existing moisture levels and likely future rainfall, see timing, is also very important.
8.6.3 Timing
Planting in creeks will usuall occur over two separate planting events during the year. The first planting event happens in the Low flow channel when the water levels in the creek are at or near their lowest. As a result this Low flow channel planting happens in most states in summer. (for the reasons for this please see the chapter on vegetation)
The second major planting event occurs when the High flow Channel and the Verges are planted out.
The most suitable time for the planting of the High flow channel and the Verge varies from region to region depending on seasnoal temperatures and rainfall pattens. However in all cases it the need to have adequate levels of moisture in the soil and a reasonable probability of sufficient future rainfall that mostly dictate when planting occurs.
Historically in some of the colder areas of the country such as Southern Victoria and Tasmania planting would occur in spring even though there had been sufficient soil moisture since Autumn. The reason for delaying the planting was that the winter temperatures in these locations got so low and the spring rains were considerd reliable enough to enable seedlings to get well established before the heat and dryness arrived if planted in spring. However over the last 10 years or so an increasing number of revegetation projects have gone ahead as soon a suitable moisture is available in the ground, often in Autumn. The reason for this change in the timing of planting works is increasing winter temperatures and less reliable rainfall in spring.
8.6.4 Planting devices
I. Pottiputki
This is probably the most used form of planter. The nose is inserted in the ground and a the foot depresses a lever which opens the bill of the device. The seedling can be then dropped dodwn the tube and into the hole.
Positives:
- Minimises bending
- High speed planting
- No engine
- Functional in many soil types
- Negatives:
- Not as effective in hard clays or gravel
- If soil gets caught on the beak the seedling gets caught in the tube
- Depth of seedling into ground is not great
- Awkward on steep slopes
II. Hamilton planter
The Hamilton planter was one of the original planters widely used in Australia however despite advantages in the right conditions the Pottiputki is now more widely used.
Positives:
- Very light
- No moving parts so hard to break or breakdown
- Cheap
Negatives:
- Requires a lot of bending
- Only works effectively in loose or sandy soil
- Doesn’t put the seedling very deep into the ground
- Can get gumed up with dirt needing regular cleaning
- Awkward on steep slopes
III. Mechanical hand auger
To date mechanical hand augers have not been widely experiemented with. However under the right conditions mechnical hand augers will not only provide the fastest and most efficient of all the planting equipment options but also the highest seedling survival rates.
The secret to high seedling survival rate is the depth at which a mechanical hand auger enables the seedling to be placed. All other pieces of planting equipment, with the exception of the broom handle, have a single planting depth option which is quite shallow. As many Australian natives are able to survive being planted quite high up their stem, deep planting is an option which enables a number of benefits; Greater access to moisture, less chance of drying out, less root competition and less likeliehood of being washed away in a flood.
A common concern with larger mechanical augers mounted on the back of farm vehicles is “glassing” of the inside of the planting hole. Glassing occurs when repeated rotations of the drill bit in clay cause shinny smooth sides to the hole. These holes with glassy sides have caused the roots of newly planted stock to be unable to penetrate the side of the hole and to start growing in a corkscrew fassion which often leads to stunted or dead plants. The key to avoiding glassing with the hand auger is to create the hole quickly something which is possible due to the small diameter of the hole and the relatively shallow depth of the hole. By avoiding multiple revolutions of the drill bit in the hole the glassing effect has less chance of occuring.
Positives:
- Optional hole depth
- High speed hole creation
- Easy and fast seedling insertion (the seedling is dropped from hip height and heeled in)
- Hole creation in virtually any soil type and at any angle
Negatives:
- Heavy
- Costly to purchase
- Requires minimum of two planters, one drilling one planting
- Long grass can be problematic getting caught around drill bit
IV. Broom handle
The broom handle is only used in the Low flow channel when the soil the seedlings are being planted into damp and therefore quite soft soil or clay.
Positives:
- Cheap
- Quick
- Easy
- Provides support for planter who may be working in slippery, uneven, muddy conditions
- Negatives:
- Only suited for soft and soggy creek banks and beds
8.7 Plant Gaurds
8.7.1 In General
Historically plastic gaurds with wire frames for support have been popular however this has changed over recent years. It is now much more common for cardboard gaurds with bamboo canes to be used to protect newly planted seedlings.
8.7.2 Cardboard guards
Cardboard plant gaurds are of the type cardboard carton that 1 litre of milk is sold in. Slots are cut in the side of the carton and 2 bamboo canes are inserted through the slots on opposite sides of the carton before being poked into the ground. The bamboo canes are typically xxxx mm long and provide the duel purpose of keeping the carton upright and square.
It is important to ensure the bamboo cane exits the top of the carton on the inside, in this way once the carton becomes waterlogged after the top will not be able to close over restricting or killing the seedling inside.
While not yet common it is worth considering making one of the of the bamboo supports out of a length of cane approximately 1200mm long. While this will cost slightly more, and be slightly more awkward when errecting the guard, the longer cane can prove an invaluable guide, particularly in long grass, for relocating plants for follow up spraying, highly recommended and for enabling future assessment of survival numbers.
It is also worth noting that annecdotal evidence has indicated in situations where seedlings are of a reasonable size where there are unlikely to be high wind events, using one cane rather than two can be experiemented with. Partiularly where a tall, 1200, marker cane is being used.
8.7.3 Plastic guards
The most common form of platic plant guard is a sqare plastic sleeve with about xxx y xxxx and approximately xxxxx high. The guard is held in place by two wire brackts about the thickness of fencing wire. The wire brackets are in the shape of a square u. The two wire brackets are crossed diagonally and the sharp points of the wire is pused in the ground to provide a framework for the plastic sleeve.
The main problems with plastic guards are:
- Either they are not biodegradable at all or they break down slowly
- They must be removed once the plant is old enough and in reality as this often does not happen the old gaurds can become a litter nuscence
- If washed away the plastic gaurds can become a nuscece to down stream property owners
- They are more expensive
- They take longer to errect
- The pointed ends of the wire supports can be dangerous particularly when they become rusty
- Some exceptions where plastic gaurds are still the best option:
- Xxxxx
- Xxxx
- xxxx
8.7.4 Situations where guards may not be required
If the project manager is sure that there are no pests in a given revegetation area then considerable savings can be made by not using plant guards. However it should be noted that even low numbers of wallabies or rabits can lead to a siginicant number of plant losses.
Another situation where the use of plant guards should be considered optional is in or close to the Low flow channel. The issue with using guards in areas which are likely to be flooded is that the gaurds can be washed away wasting money and causing a rubish nuscence down stream. Even if the guard is not washed away it may be knocked over smothering the plant within.
When considering whether to use plant guards close to the low flow channel there is some annacdotal evidence that indicates plants close to water may be subject to less predation partiualarly from rabbits. It has been theorised that rabbits are less likely to forage near water due to predation concerns.
8.7.5 Tall guards
While traditional height plant guards, both milk cartons and plastic guards are relatively effective in regards to rabbits they are less effective against wallabies. Traditional guards will protect the plant near the ground but as soon as it appear above the top of the guard it is vulnerable to browsing from wallabies.
One solution to situations where there is heavy wallaby predation is to use relatively long, 900 - 1200mm, plastic sleeve secured by a wooden stake. The Plastic sleeve protects the seedling until it is of a larger size while still letting the light in through the plastic. The downsides of this method is the initial cost, the need to removing and disposing of the plastic guard and the often spindly nature of the plant once the guard is removed.
The problem with using taller cardboard guards is that they tend to break down before the plant is overly large and more importantly the light levels that small seedling receive is significantly reduced.
8.8 Miscellaneous
There has been experimentation with core flute cardboard guards which are taller than regualr guards. These core flute guards provide a longer life than regular cardboard while also letting in the light. The down side with core flute guards is the initial cost of materials and labour. However this option may suited to dry, or difficult sites where a hole is dug manually and wetting agents and fertilizer and hand wattering occur. In high cost preparation sites like these core flute while expensive may be a worthwhile investment.