With Autumn in the Southern hemisphere it is an ideal time to plant trees, as the sap of the tree is descending, and especially in hot environments the trees get a chance to acclimatize during the cooler weather and if you are in a winter rainfall area your trees can be well watered in before the hot summer days start again.
In all forests there are the pioneer trees that grow first and are mostly rapid growers. They then provide a canopy of shade and shelter for the slower and hardier trees to grow under. By the time your slow growers are strong and increased in size the pioneer trees are more or less at the end of their cycle and fall down to create space and sunlight for the new generation of large hardwood trees.
In South Africa one of the pioneer trees is the Acacia Karroo. This tree, which is very widespread throughout southern Africa, does a splendid job at casting thorny protection over damaged land and immensely enriching the soil over the next few decades. Being an adaptable pioneer it is able to establish itself in fairly harsh conditions without shade or shelter. When over a year old, seedlings can sprout after fire but as a pioneer tree the Acacia Karroo has a fairly short life span of approximately 30 or 40 years. There are also several fungi associated with this tree and mature trees may be parasitized by various mistletoes, leading eventually to the tree’s decline.
This tree has a long taproot which enables it to use water and nutrients from deep underground, this and its ability to fix nitrogen, lead to grasses and other plants thriving in its shade. It is an indicator of sweet veld which is prized for good grazing and fertile soils but if an area is overgrazed the sweet thorn becomes invasive. — plantzafrica.com
The Acacia Karroo tree also has many uses. For instance the flowers produce lots of nectar and pollen for bee-farming and honey production. The bark contains tannin which is used to tan leather to a reddish colour, therefore there is no danger of hydrocyanic poisoning, which is a self-protection mechanism used by many trees. The tree has heartwood that is heavy and hard but susceptible to attack from borer, which can be prevented by seasoning the wood in water for six months before use. In arid areas the sweet thorn is an indicator of water, both underground and surface. Stock and game feed on the leaves, flowers and pods because it is a good fodder tree and seed distribution takes place this way. The sweet thorn gets its common name from the gum which is exuded from wounds in the bark. This pleasant tasting gum is eaten by people and animals. It also had commercial value when the gum was exported as "Cape Gum" for making confectionary. This is apparently similar to gum Arabic which is used in watercolours and as a water soluble glue.
Thorns on an Acacia tree
In tropical Africa it is replaced by Acacia seyal. The name Acacia is derived from Greek "akis" a point or barb. Technically the thorns are called "spines" and are developed from modified stipules (small, leaf-like scales, seen at the base of the leaf-stalk). In some other thorny acacia species, the thorns are not stipules in origin and are called "prickles". These originate in the epidermis ("skin") and are always short and curved, a bit like rose thorns. Thorns on African acacias are important for identification; they are divided into 5 main groups according to size, shape and position of the thorns.[…]
Acacia Karroo has a rounded crown, branching fairly low down on the trunk. It is variable in shape and size, reaching a maximum of about 12m where there is good water. The bark is red on young branches, darkening and becoming rough with age. Sometimes an attractive reddish colour can be seen in the deep bark fissures. The leaves are finely textured and dark green. The flowers appear in early summer in a mass of yellow pompons. Many insects visit and pollinate these flowers. The seed pods are flat and crescent shaped, sometimes with constrictions between the seeds. They are green when young, becoming brown and dry. The pods split open allowing the seeds to fall to the ground. The thorns are paired, greyish to white and are long and straight. On mature trees, the thorns may be quite short”. — plantzafrica.com
Growing Acacia karroo
The sweet thorn is particularly useful in an orchard with other fruit trees due to its nitrogen-fixing properties. It is also suitable as a garden specimen as the growth rate is fast, up to 1m per year and in cold and dry areas the tree will be deciduous. The roots can be invasive, so avoid planting near paving or buildings. Acacias require direct sunlight in order to grow and thrive, so you want to plant your tree away from the shade of buildings or other trees.
It is a most useful tree for small holdings and farms where it can be planted for shade and as a windbreak. The sweet thorn is very adaptable to soil types and is frost and drought hardy. However, for best performance, water well and deeply (shallow, frequent sprinklings only encourage shallow root growth) until established. Plant with plenty of compost and bone meal.
It can be grown from seed which should be soaked in hot water and left overnight. You will see if this has been effective as the seed will swell up. Sow the following morning. Seedling trays with seedling mix can be used, or the seeds could be sown directly into black bags. Cover lightly with sand and do not allow to dry out. Germination usually takes 3 – 12 days. The seedling will transplant well in spite of the long tap root. Wait until they unfurl their second leaves before transplanting. — plantzafrica.com
Planting fruit trees
If you have enough water, fruit trees can be planted at any time of the year although Autumn into winter is best. Therefore if water is limited it is best to plant when the soil is wet or at the start of the wet season.
Techniques for Planting Fruit Trees:
- Dig a hole knee deep, or more if possible. Fill the hole with water. Also water the tree when still in its container.
- Put a pipe (which can be made from bamboo or PVC irrigation piping) inside the hole. Place some gravel or sandy soil with small stones, below the pipe to help with water flow later on.
- Fill a degradable plastic bag with manure and place it at the bottom of the hole. If available, use a bag made of natural materials which will still hold the manure for a long time in the soil. Cover with soil.
- Carefully, remove the tree from its container without breaking its roots. If there are many roots, gently loosen the bottom tree roots. Then, place the tree in the hole which has been prepared.
- Fill the hole with soil. Make a 15cm trench around the surface for water collection and to help with water supply. Make sure that the top of the tree roots are covered with at least 2 cm of soil to prevent the roots from drying out.
- Add lots of mulch around the tree.
- Water thoroughly.
- Fruit Trees must be planted approximately 10 meters apart (unless they’re dwarf varieties) or they will be too crowded when fully grown.
Assisting natural reforestation
Nature is always working towards a healthier environment. Don’t work against nature, working with natural patterns will speed up the process. Some steps which work with nature towards shaping a healthier environment include:
- Stop burning. By burning, you are destroying many valuable resources. For example, burning grasses will also burn their functions, one of which is to protect newly planted trees.
- Conserve bird habitats. Birds are very useful in reforestation, birds help to spread seeds through their manure. The manure will add nutrients to the soil and some of the seeds will grow into new trees.
- First plant trees in small groups. Then, in following years, add new trees to the existing groups. The new trees will receive protection and mulch from the older trees.
The importance of reforestation and tree crops
Reforestation areas are areas where the natural forest is restored. It is a less intensive system, and will provide less produce than agriculture. However, this system is very important for preserving the environment and stopping erosion, and it will provide many essential products, such as bamboo, oils, fibre, timber, honey, medicines, rain and oxygen.
Areas that have forests need to be protected and carefully managed. These forests are the seed banks of the future. Reforestation and tree crops are a long term solution for protecting the soil and stopping erosion. It also helps to repair damaged land, while providing food, wood, oils, medicines, fibre and many other products for income. These are all sustainable incomes.
Erosion will reduce productivity by removing a very valuable layer of soil. Soil, especially soil which is good for agriculture, takes a long time to form, but can be lost very easily and quickly due to erosion. If not controlled, erosion will quickly get worse and create bigger problems in the future. Erosion will also destroy all small plants, seeds and organic matter. Erosion on cleared land can cause landslides, which not only destroy land, but can be very dangerous for people.
We need long term solutions for keeping the environment and land healthy and strong for the future. The first step is to protect and carefully manage the existing forests. The next is to reforest and restore natures balance. We must maintain a strong connection with nature. Many areas where forests have been removed are suffering from erosion and soil loss. It is difficult to obtain good productivity on these lands. In fact, agriculture practices on these lands can even create more erosion and new problems.
Tree crops can also be integrated with animals and annual crops. Products and income from trees and forests are more secure because trees are less affected by bad weather conditions. A well designed forest system will need little maintenance once it is established. Forests and trees will improve the health of the environment, not just on the land where they grow, but also on the land surrounding it.
Areas which are best for starting reforestation are areas which naturally have good micro climates. If you plant trees in these areas, the success rate will be higher. Observe your land to know which areas naturally have good micro climates.
- Existing groups of trees. Trees will grow in a particular spot because the micro climate is better. Existing trees will provide mulch, shade and protection for newly planted trees.
- Grasses and small plants. In very dry areas, grasses and small plants indicate where the soil is better and where there is possibly more water available. Trees will grow better in these areas compared with other crops, because trees are more resistant. Areas with no grass indicate where the soil is very poor, with many rocks and not enough water.
- Groups of rocks. Trees planted just down slope from rocks will receive more water because the rocks will catch and direct rain water.
- Areas where water naturally collects.
- The sunny side of a slope or mountain (i.e. North facing for the Southern hemisphere, and South facing for the Northern hemisphere). This is the best side of a mountain for reforestation because it receives the right amount of sunlight for trees to grow, and hence will have a better micro climate. But also observe which side is the most cleared or destroyed — i.e. which side more urgently needs reforestation.
Planting reforestation trees
Reforestation trees are planted using almost the same techniques as used to plant fruit trees, with a few small changes.
This is because:
- Reforestation trees are usually planted further away from the garden and house area.
- Reforestation trees need less fertilizer.
- Reforestation trees are not usually watered so rain water storage is very important.
- The ground is often harder, making it more difficult to dig.
The best time to plant reforestation trees is at the start of the wet season, when it begins to rain consistently. Follow the same steps as used for fruit trees, but with these few small changes:
- Dig a smaller hole.
- There is no need for a bag of manure in the hole.
- Make a large trench or swale for water catchment. Make sure that the trench is above ground level. This will help to prevent too much water collecting during the wet season.
- Use watering pipes during the dry season.
- Dig holes for the trees, but leave them empty until the rains come. The rainwater will collect in these holes and soften the soil so when trees are planted they will grow better.
Flat land tree crops
Flat land is generally used for grains, vegetables and paddies, but tree crops can be combined in many ways. Tree crops will increase production and crop variety. Tree crops need less maintenance, and will still produce in the dry season. Small trees, like citrus, banana, papaya, clove and pigeon pea can be planted with grains and vegetables. The trees will provide shade for smaller annual crops. They will also act as a barrier and make it harder for pest insects to pass from one plant to the next. Also planting legumes will provide many benefits. Another benefit from planting trees with crops and vegetables is that the smaller crops can be harvested first, while waiting for the large trees to grow and produce.
Managing planting times
Managing planting times is a technique which can increase crop yields by working with crops of different sizes, different growth rates and different life spans. Following is an example of managing crop planting times:
- Year 1: Plant legume trees, like Leuceana and Moringa. Leave space for fruit trees. Legume trees will grow quickly and can later be cut back to provide more space for other trees.
- Year 1 and 2: Plant fruit trees, like apples, mango and citrus, between the legume trees. When planting, think about how large the tree will be in 10-20 years time and leave enough room for trees to grow to their full size. The legume trees will provide some shade for the fruit trees when they are still young. When the fruit trees grow larger, the legumes can be cut back to provide more space. Eventually, the fruit trees will take over the legume trees. Animals can also be integrated into this system.
- Year 1-5: There will be space between the fruit trees for about 5 years. The space can be used to grow vegetables like corn, pumpkin, beans, sweet potato, capsicum, taro, cassava, papaya, banana, pineapple and root plants, like ginger. To allow sunlight in, prune back legumes which grow too thick. The prunings can be used as mulch material.
- Year 5-10: There may be some space still available for growing vegetables and small trees. However, these smaller crops will need to be removed once the larger fruit trees have grown. Continue cutting back the legume trees, and if more space is still needed, the legumes can be removed.
The more variety of crops, trees and animals there are the more variety of foods and products there will be, and this will assure a more stable income. For soil with many rocks, dry areas or large amounts of land, plant more trees than vegetable crops. Trees require less maintenance and will still produce crops in harsh conditions. — Permaculture solutions for Sustainable lifestyles
A micro climate is the climate of a particular area. This area could be as small as a garden plot or as large as a mountainside. Each type of plant prefers different micro climates. Micro climates can be changed and improved by using good techniques, for example rock swales — rocks will provide homes for small animals and insects, and at night, when the temperature is colder, the rocks will also dissipate the heat they absorbed during the day, become cold and moisture will collect on the rocks’ surface. This moisture will soak into the soil and be used by plants. This moisture is an important water source in dry areas. Providing a good micro climate is important for all plants, especially when they are still young.
However, almost all plants like micro climates with:
- Available water
- Good soil
- Enough sunlight
- Protection from strong wind
- Shade, for when plants are still young
Fruit Trees and Tree Crops:
Fruit trees and tree crops must be regularly watered during the dry season to achieve good production and larger fruits, especially in the first few years. Here are some suggestions for watering:
- It is better to water trees with a lot of water every week than with a small amount of water every day or two. This will encourage roots to grow deeper looking for water, so they will reach ground water faster.
- Use watering pipes.
- Water trees in morning or late afternoon.
Try to water reforestation trees during the dry season, even if just a small amount of water is available. Even a small amount of water during the dry season will increase production and improve results. The best time to water is in the morning or late afternoon. Swales can also help to catch and store water.
Plants use nutrients in the soil to live. Therefore, nutrients in the soil which are used by plants need to be replaced so that plants will grow healthy and produce the best they can.
Fruit Trees and Tree Crops:
Compost, liquid compost, manure and mulch provide many different nutrients and other benefits as well. The best place to fertilize trees is where the roots soak up nutrients. Underneath the outside leaves of every tree is the ‘root feeding zone’. This is where the plants’ outside roots are and where the tree will most easily be able to use nutrients.
Watering pipes can also be used to feed liquid compost directly to the trees roots in the ground.
Fertilizers which work best for fruit trees and tree crops are:
- Compost and Manure. Compost and manure can be applied twice a year, just before the wet season starts and at the end of the wet season. Apply to the root feeding zone. Use about a 5 cm layer (the length of one finger) of compost or mulch, especially around the root feeding zone. This will provide many important nutrients for the tree.
- Liquid Compost. For trees up to 3 years old, use about 20 litres of liquid compost. For trees over 3 years old, use about 60 liters. Put some of it through watering pipes and some directly on the ground over the root feeding zone. Use once every 2 months during the wet season and only once in the middle of the dry season.
- Mulch. Apply mulch just inside the root feeding zone, closer to the tree trunk. Don’t let mulch touch the trunk, because if it does, disease or fungus could damage the tree. Leave about 10 cm of space. Use a thick layer of mulch to keep the ground moist and to improve the soil quality faster. If available, seaweed makes a very good mulch for trees, but wash it first to remove excess salt.
- Urine. Urine is also a good source of nutrients because it contains lots of nitrogen and is constantly available. Citrus trees especially like urine fertilizer. Before applying on plants, urine should be diluted in a bucket of water. This can be applied more often for established trees, but not too often for young trees.
Reforestation trees need less fertilizer than fruit trees, and fertilizing is most important when the tree is still young. On reforestation lands, the available nutrients are often not enough for plant growth. Good natural fertilizing techniques will replace these lost nutrients quickly.
Natural fertilizing techniques which can be used include:
- Compost, manure or seaweed. These can be applied when planting to provide some nutrients for the young trees.
- Legume trees are an important source of nutrients. Their roots provide nutrients and the trees can be pruned up to 5 times during the wet season, which will provide mulch materials. These trees can also be used as ‘pioneer trees’ and as mulch and nitrogen providers for other plants.
- Mulch. For reforestation trees mulch provides many nutrients which trees need.
- After 3 years, animals can be carefully introduced to the reforestation land. Animal manure will provide fertilizer for the trees.
Mulching is an important part of tree maintenance. Mulch provides many benefits, including:
- Holds water in the ground and helps to keep the ground moist for longer.
- Maximizes the benefits of manure and compost if mulch is used as a top layer.
- Acts as an important source of nutrients for trees.
- Improves soil quality by increasing organic matter and soil biota in the soil.
Fruit Trees and Tree Crops:
Continuously apply mulch to trees. A layer of up to 10 cm or more will give the best results. To avoid fungus or disease, don’t let mulch touch the tree trunk. Organic materials which can be used as mulch include corn and bamboo husks, seaweed (it must be washed first), tree cuttings, dry grass and weeds, and even used paper, boxes, wood and bamboo will make good mulch. Compost and dried manure will provide more benefits to soil and plants if they are placed under a layer of mulch.
Natural mulch, such as leaves, grasses and weeds, will quickly form into mulch if the land is not burned. This mulch can be collected and placed around trees. Legume trees and other trees can also be pruned to provide more mulch materials. Mulch will provide the most benefits if combined with swale systems. Rocks can also be used as a mulch, especially for dry areas because they will provide extra water for your trees during the dry season.
Pruning trees is important for maintaining the tree’s health and productivity. By pruning, harvesting will also be much easier because the tree will be lower to the ground and easier to access.
Using the right technique to prune trees is very important so that the tree will grow back quickly, not suffer from stress and be able to avoid disease and fungus. When pruning tree branches use a saw or very sharp machete. Prune the branches as close to the trunk or main branch as possible. Make the cut as smooth as possible, angled and not flat, because a flat cut will increase chances of disease. For fruit trees and other tree crops, you can paint a layer of jackfruit sap on the cut. This will stop disease or fungus from entering.
Some reasons for pruning are:
- To remove dead or diseased branches. By removing dead or diseased branches, you will reduce the chances of fungus and disease spreading. Cut the branches off before the diseased or dead part spreads. The pruned branches should be taken away or burned to avoid spreading more disease.
- To allow more sunlight into the middle of the trees. This will increase fruit production and reduce fungus problems.
- To encourage new growth on older trees, when trees have grown old and are not producing well, pruning will encourage new growth and better fruit production.
For almost all tropical fruit trees, it is recommended to only prune when necessary, and don’t prune the tips of all the branches, but only some of the longer branches.
Reforestation trees need less maintenance and pruning than fruit trees, however some pruning will help improve growth and quality.
Some reasons for pruning reforestation trees are:
- To get firewood. Dead or diseased branches can be removed and used as firewood.
- Removing lower branches will make more room for people to walk around, and for animals to graze and to grow other crops underneath. Don’t remove lower branches of windbreak trees because this will make them less effective.
- The Truth About Trees
- David Suzuki – Tree: A Life Story
- Top Five Fruit Trees for Canberra Backyard Food Forest Gardens