Prepare for Revegetation
Site Preparation - Weed control Competition for moisture and nutrients from grasses and other plants adjacent to newly planted seeds or trees is the major cause of failure in revegetation. Young seedlings need time to develop a vigorous and deep root system that can tap into reliable sources of soil moisture. Therefore it is vital that new seedlings have access to a weed free volume of soil until well established.
The experience of many revegetators around Australia shows that the best results are achieved by keeping the planting zone weed-free for two years prior to planting (Andrews, 2000). Satisfactory results are achieved by controlling weeds for at least one full year before planting. This can be achieved by a range of chemical and non-chemical methods, and depends on the technique used for planting, the soil type, the weed burden and the desired outcome. The two-year preparation allows soil moisture to build up creating an additional reserve for the new seedlings.
Repeated sprays with a knockdown herbicide (such as glyphosate) are effective in that they exhaust the soil weed seedbank, resulting in less weeds germinating after the planting. Residual herbicides prevent the weed seeds in the soil from germinating until the effect of the herbicide diminishes over time. Scalping (removing some of the surface soil, removes the majority of weed seeds and is very effective in a range of soils, although it may expose subsoils that are prone to cracking as they dry. Non-chemical methods include mulching with newspaper, straw, sawdust or similar; flaming; repeated cultivation and hand-chipping. Mowing reduces the vigour of the competing plants but is not as effective as complete removal. Many direct seeding machines have a built in scalping blade or disc to do weed control in a single pass. Most sites will still benefit from two-years of weed control prior to direct seeding.
Great care should be taken before exposing highly-erodible soils. Weed control should be in strips approximately one metre wide with a grassy strip retained between rows, or in spots one metre in diameter around each planting location.
The experience of many revegetators around Australia shows that the best results are achieved by keeping the planting zone weed-free for two years prior to planting (Andrews, 2000). Satisfactory results are achieved by controlling weeds for at least one full year before planting. This can be achieved by a range of chemical and non-chemical methods, and depends on the technique used for planting, the soil type, the weed burden and the desired outcome. The two-year preparation allows soil moisture to build up creating an additional reserve for the new seedlings.
Repeated sprays with a knockdown herbicide (such as glyphosate) are effective in that they exhaust the soil weed seedbank, resulting in less weeds germinating after the planting. Residual herbicides prevent the weed seeds in the soil from germinating until the effect of the herbicide diminishes over time. Scalping (removing some of the surface soil, removes the majority of weed seeds and is very effective in a range of soils, although it may expose subsoils that are prone to cracking as they dry. Non-chemical methods include mulching with newspaper, straw, sawdust or similar; flaming; repeated cultivation and hand-chipping. Mowing reduces the vigour of the competing plants but is not as effective as complete removal. Many direct seeding machines have a built in scalping blade or disc to do weed control in a single pass. Most sites will still benefit from two-years of weed control prior to direct seeding.
Great care should be taken before exposing highly-erodible soils. Weed control should be in strips approximately one metre wide with a grassy strip retained between rows, or in spots one metre in diameter around each planting location.
Site preparation - Protection from grazing by livestock and feral animals Whatever method you choose to revegetate your site, your young plants will be vulnerable to grazing by domestic, native and feral animals. Plants are most vulnerable to damage when less than a metre in height as they can be completely eaten or severely damaged at this stage. Over this height, they can still have many leaves and shoots removed, be broken by trampling or scratching or have their bark chewed leaving them ringbarked. Large plants are most vulnerable to large animals such as horses and cattle.
Wallabies and kangaroos cause considerable damage to young plantings by eating and breaking the canopy. In certain areas brush-tailed possums defoliate plants of all ages. Rabbits cause significant losses particularly in direct-seeded sites by completely eating young seedlings. Hares have an annoying habit of nipping off the stems of young seedlings. Sheep, horses and cattle both eat the foliage of young plants and trample young plants. Horses have been known to eat the bark from trees at particular times of the year, even on mature trees. In WA '28' parrots cause severe damage to young plants by chewing leaves and stems.
Damage can occur to some or all of the species and can vary from mild to severe. There are several options to prevent grazing or browsing of your plantings.
Wallabies and kangaroos cause considerable damage to young plantings by eating and breaking the canopy. In certain areas brush-tailed possums defoliate plants of all ages. Rabbits cause significant losses particularly in direct-seeded sites by completely eating young seedlings. Hares have an annoying habit of nipping off the stems of young seedlings. Sheep, horses and cattle both eat the foliage of young plants and trample young plants. Horses have been known to eat the bark from trees at particular times of the year, even on mature trees. In WA '28' parrots cause severe damage to young plants by chewing leaves and stems.
Damage can occur to some or all of the species and can vary from mild to severe. There are several options to prevent grazing or browsing of your plantings.
- Fencing to exclude animals. The fence should be designed with a particular animal in mind. Most agricultural fences will keep out sheep, cattle and horses, but will not exclude macropods or rabbits. To exclude rabbits you will need to use wire netting, at least on the bottom 300mm of the fence. Fences to exclude kangaroos and wallabies need to be high (1.8m) to prevent them from jumping over. Some designs for exclusion fences can be found here. Some tips on possum-proof fencing can be found here. The Department of Agriculture in WA has some useful ideas to exclude kangaroos.
- Tree guards are sometimes used to protect young plants from browsing. Very tall tree guards of rigid corrugated plastic are used to prevent kangaroo or wallaby browsing in some areas. Smaller guards are effective in stopping rabbits or hares from destroying young plants, even though they may browse the tops of the plants.
- Reducing populations prior to planting. The most effective method to control rabbit and hare browsing is to reduce their numbers at the site prior to planting. Rabbit burrows should be ripped and existing animals should be poisoned or shot. Usually your State or Territory Department of Primary Industries (or equivalent) can advise you on effective and humane methods to control rabbits. (e.g. Rabbit control factsheet)
- Deterrents. There are a number of options available to deter animals from entering a site such as foliar grit sprays which make the leaves unpalatable, irregular loud sounds and variations on 'scarecrows'. These methods vary in effectiveness, but are usually much less effective than fencing.
- Trapping. Some animals such as parrots, possums and wallabies can be trapped and relocated with varying success. You will need to check with your State or Territory wildlife agency before trapping native animals.
Revegetation Material Supplier - Check out the many types of tree guards available
Suregro - http://www.suregro.com/tree-guards/
Suregro - http://www.suregro.com/tree-guards/
Site preparation - Moisture conservation In most revegetation projects it is usually the lack of availability of water that leads to poor survival or growth. You can increase the success of your planting by maximising the amount of water available to your plants or seeds, particularly in the first few years. Reducing competition by controlling weeds is the most effective way to do this. Controlling weeds for 2 years before planting can allow moisture to be banked in the soil, ready for your new plants to use it. 'Moisture banking' is a technique commonly used for growing agricultural crops. During this fallow period before planting, you can use a surface mulch to reduce the evaporation of moisture from the soil surface. Mulching can also improve the permeability of the soil surface, so more rain soaks into the soil rather than running off.
After planting mulches can also act to conserve existing soil moisture and even prevent weed growth. You can apply a mulch around the base of the plant to a radius of at least 50cm. Material for mulch can include straw or hay, bulk organic material such as wood chips, sawdust or cotton waste, pebbles or rocks, commercial jute mulch mats, newspaper or woven polypropylene or jute matting.
It is important that mulching materials are kept clear of the stem of the young plant or the stem or crown can rot. In very cold areas, mulches should not be used in winter as they can prevent the soil from warming and lead to frozen soil
After planting mulches can also act to conserve existing soil moisture and even prevent weed growth. You can apply a mulch around the base of the plant to a radius of at least 50cm. Material for mulch can include straw or hay, bulk organic material such as wood chips, sawdust or cotton waste, pebbles or rocks, commercial jute mulch mats, newspaper or woven polypropylene or jute matting.
It is important that mulching materials are kept clear of the stem of the young plant or the stem or crown can rot. In very cold areas, mulches should not be used in winter as they can prevent the soil from warming and lead to frozen soil