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Protecting Trees from Acid Rain

‘Trees’ Articles at Permaculture Reflections

July 17, 2015 by Douglas Barnes Leave a Comment

The ongoing problem of acid rain causes injury, slow growth, or sometimes death of trees. Some soils are able to buffer the acidity effectively. Other soils, however, lack an effective buffering capacity, putting trees at risk.

How acid rain damages trees

While acid rain can directly damage leaves, it also shifts soil pH, making soil nutrients unavailable to plants. Acid rain can also release the aluminum in soil. Trees are then able to take up the aluminum, which is toxic to them.

Trees in alpine regions are more at risk, even if they have buffering soil. The clouds that bathe the mountain tops are acidic, subjecting the trees to more acidity than trees at lower elevations.

A ray of hope, please.

As has been shown in research done by Cornell University, mycorrhizal fungi can help to protect some trees from the effects of acid rain.

Through the hyphal network of mycorrhizal fungi, the trees has access to a greater amount of calcium — a nutrient made less available by acid rain. Unfortunately, not every tree will form associations with mycorrhizae, leaving those trees most vulnerable.

Additionally, mycorrhizae will not prevent acid rain from leaching toxic aluminum out of the soil.

What can I do to help?

Calcium amendments to your soil will help to make the nutrient more available for trees. Bone meal, powdered eggshells, or powdered oyster shells can help to boost the calcium available to trees.

Filed Under: Article Tagged With: fungi, trees

Tilia americana

‘Trees’ Articles at Permaculture Reflections

October 19, 2012 by Douglas Barnes Leave a Comment

Thanks to a student of mine, Tom Marcantonio, I gained an appreciation of this common temperate North American tree. Tom had learned of the use of its inner bark for cordage, and was using stakes, and cordage made from the tree to support his plants.

Tilia americana, flowers

Tilia americana, flowers.
Image by Tie Guy II.

Tilia americana, also known as Basswood, and American Linden, is hardy in USDA zones 3 to 8, making it a common feature on the landscape. It does well on deep, well-drained soils, but it can handle dry or heavy soils. Left alone, it could grow to 21 meters (70 feet).

Its a useful winter browse for deer, and its buds are food for birds. The summer fruits are eaten by birds, squirrels, and mice. Older trees tend to rot out in the center, leaving habitat for animals. Its nectar makes it a good bee fodder. However, it does have the tendency to attract pests; among these are borers, aphids, leafminers, scale, and Japanese beetles. As we say, however, the problem is the solution. This tendency might make it a useful tool in a push-pull integrated pest management regime. If anyone has tried this, please let us know how it went.

The soft wood does not splinter easily, making it a good wood for carving. Its ability to coppice makes it all the more appealing. To make cord, soak branches, then peel off the bark. The inner bark is the part then made into cord.

The sap has traditionally been boiled to make syrup, or taken as a drink. Young leaves can be cooked and eaten as well.  The nuts and flowers can be ground into a paste that is said to have a chocolate taste. I’d love to test the truth of this claim. The flowers can be put in salads, or brewed into a tea. I have seen one recommendation cautioning moderation in drinking the flower tea as it could cause heart damage. I think this warning stems from the β-Sitosterol it contains. For this reason, it is probably best for pregnant women to avoid altogether. The flowers do have a whole host of interesting chemicals in them, including but not limited to bioquercitrin, which helps regulates cell growth. Recent research suggests that T. americana can be used as an anti-anxiety treatment.

There are a few places I could use this tree on my site as part of a shelter belt. Though I have seen no mention of its use as a fodder tree, I would imagine it could be used as such. I suspect it would work well in a silvopasture setup.  Its many fine properties make it an appealing candidate that I am sure to utilize.

Filed Under: Article Tagged With: trees

Senna siamea

‘Trees’ Articles at Permaculture Reflections

September 1, 2012 by Douglas Barnes 1 Comment

Cassia siamea

Gangi Setty of the Green Tree Foundation, and Dr. Kadir of the Rural Development Society show off Senna siamea in swales we built in 2009.

Though it is in the legume family, S. Siamea is not a nitrogen-fixing tree. It is a tropical plant not tolerating temperatures below 20°C well. It will establish in semiarid areas with rainfall as low as 500mm per year, provided there are droughts no longer than 4 to 6 months, and that the roots have access to groundwater. According to Jeff Nugent and Julia Boniface, a good companion tree is Acacia pendula.

Despite its lack of nitrogen-fixing ability, and despite its broad, shallow roots, it is often used in alley cropping. It is a robust coppicer, and will produce a great amount of biomass, yielding up to 500 kg of fresh leaves a year. This production helps it work as a soil conditioner when used as a green manure. Their presence also helps with water infiltration, reducing run-off when planted densely.

S. siamea is is often grown in the service of Santalum species (sandal wood) — usually S. album – which are parasitic trees, tapping into the roots of other plants for water and nutrients. In China, it is used as a host for the lac bug, which is used to produce shellac.

It makes a good fodder for ruminants, but the toxicity of the alkaloids in the plant make it an ill-advised feed for poultry, pigs, and other non-ruminants. Ruminants only, please.

The young leaves and flower buds are boiled two or three times to remove the bitterness and toxicity of the above mentioned alkaloids, and added to curries. It has traditional medical uses that are now discouraged due to the toxicity of the active compound barakol. Still, there is research suggesting anti-cancer properties in S. siamea.

The wood is resistant to termites, and is hard and durable. It also makes an excellent firewood, and charcoal.

Filed Under: Article Tagged With: trees

Morus alba

‘Trees’ Articles at Permaculture Reflections

July 22, 2009 by Douglas Barnes Leave a Comment

This month, we’ll take a look at the white mulberry, Morus alba. In the Species of the Month series, we’ve looked at some truly amazing plants and fungi. I thought I would make it easy on myself by doing a “simple” tree. Well, I thought wrong. I knew some of the uses of this tree, but as it turns out Morus alba offers many benefits and carries out many different tasks.

First off, this fast-growing tree is useful for controlling erosion. It also provides shade and can act as a windbreak. The leaf litter improves the soil. White mulberry has been adapted to many climates from tropical USDA zone 11 to chilly zone 4. The tree is coppiceable and survives short-rotation coppicing very well – I have seen M. alba thrive on a 2-month coppicing cycle, which is an amazingly short rotation. Mind you, this was in the tropics. Mulberry would not last very long on such a short cycle in temperate climates.

Mulberry can be propagated through coppicing or through seeds. Coppice shoots can be cut and treated with rooting compound or the coppice stool can be covered with soil after the shoots are around 30 cm tall. Left under the soil, the buried part of the shoots will grow roots. The shoot can then be carefully dug out and cut for transplanting. When propagating from seeds, soak the seeds in cold water for 1 week before planting. Mulberries grow best in dry to well-drained soils.

The wood is useful for both construction and woodworking. As a fuel, it will produce from 4370 to 4770 kilocalories of energy per kilogram or around 25.8 million BTUs per cord, making it an excellent fuel tree. In coppice production, it would make a goode fuel tree, provided it were grown in a small-scale operation. The bark from mulberry has its uses. It is used to make high quality paper and can be made into textile.

The leaves can be used for fodder. Ruminants can be fed up to 60% of diet with mulberry fodder. Mulberry also increases milk yields in cows. The leaves are also famously used in sericulture – raising silkworms. For this, mulberry is grown on short rotation; the leaves are chopped and then fed to silkworms.

Mulberry leaves being chopped for silkworms.

Silkworms fed on white mulberry leaves.

Mulberry can also be used as human food. While the young leaves can be eaten, it is the fruit that is sought after. High in vitamin C, iron, calcium and potassium, the berries are very tasty. Unfortunately, the only way to enjoy fresh mulberries is to pick them. Being quite fragile, they do not pack or transport well. Mulberries are used to make jellies, pies, juice and wine.

There are plenty of medicinal uses for mulberry as well. It has antibacterial properties, is used to treat rheumatism, reduces fevers, and helps induce sweating.

The leaves are used to treat insect bites and the cineole content in the leaves makes them useful as an expectorant. The limone in the leaves has antitumor properties. Some research suggests that the leaves could be used to help prevent type II diabetes. The fruit is used to treat upset stomachs and sore throats. And the bark is used to treat stomach aches, neuralgia pain and edema.

If you have the right conditions and the room, a mulberry tree would make an excellent addition to your permaculture garden.

Filed Under: Article Tagged With: trees

Neem

‘Trees’ Articles at Permaculture Reflections

June 22, 2009 by Douglas Barnes 2 Comments

Azadirachta indica, neem, the village dispensary. This amazing tree has so many uses that it’s hard to imagine a tropical garden being complete without it.

First, the tree has a deep tap root, making it drought hardly. It is not, however, tolerant of seasonal flooding or of frost. It helps rejuvenate damaged soils. In the hot climates it grows in, its shade is very welcome. It also makes a good windbreak. Timber from neem trees is termite resistant – a good feature in the tropics – and its calorie-rich wood makes good fuel. The flowers of neem also make good bee fodder.

Neem leaves are sometimes used in curries and chutneys in India. Extended consumption over long periods has the potential to damage the liver, so consumption should be occasional. Also, neem should NOT be consumed by pregnant women, women trying to conceive, or by small children.

The dried leaves are used as a moth repellent to protect clothes, in grain and dried fruit stores to protect from insects, and as a general insect repellent. Fresh leaves are sometimes eaten to rid the body of parasites. Twigs from the tree are chewed on one end, then used as a tooth brush.

Azadirachtin, the active ingredient in neem, is a very effective pesticide. It repels insects and disrupts their growth and reproduction. A neem solution can be sprayed directly on plants to deal with existing insects and to help repel further insect attack. To make a solution, simply bring a bucket of water to boil, add 2 handfuls of crushed seeds or 6 handfuls of minced leaves, and steep for 1 hour. Add a small amount of soap as a surfactant, strain and spray directly on plants. If only neem oil is available, mix 10 ml of neem oil with 1% azadirachtin content (get certified aflatoxin-free neem oil) with 500 ml of water and a touch of soap and spray the mixture on plants. Neem can also be used on animals to kill fleas, ticks, intestinal parasites, and repel blowflies. For a topical solution for animals, mix 1 ml of neem oil to 30 ml of water and spray it on the animal’s coat.

Looking at the medicinal uses of neem, it is easy to see why it is called the village dispensary. It is an emollient (soothes the skin), a purgative (a laxative), a vermifuge (rids internal and external parasites), a digestive agent, an anti-inflammatory, a sedative, a carminative (prevents gas), an anti-fungal agent, an antiviral, an antiseptic, and a diuretic. The list of ailments it is used to treat includes but is not limited to:

  • Gastritis
  • Fever
  • Poor circulation
  • Bronchitis
  • Candida (yeast infection)
  • Gingivitis
  • Kidney problems
  • Duodenal and peptic ulcers
  • Liver problems
  • Diabetes
  • High blood pressure
  • High cholesterol
  • Hemorrhoids
  • Conjunctivitis (pink eye)
  • Tuberculosis
  • AIDS
  • Asthma
  • Rheumatism
  • Venereal disease
  • Skin ulcers
  • Urinary tract infections
  • Athlete’s foot
  • Ringworm
  • Head lice
  • Scabies

Neem, Azadirachta indica

Neem also has commercial value with popular products made from neem including soap, toothpaste, shampoo, candles, mouthwash, tea, and on and on.

If you are in the dry tropics and are looking for useful trees for your site, be sure to include this amazing tree to you list. With so many uses from neem, you’ll be glad you have it nearby, and your pests will hate you for it.

Filed Under: Article Tagged With: Arid climate, trees

Rhizobium Symbiosis with Woody Plants: Leguminous Nitrogen-Fixing Trees

‘Trees’ Articles at Permaculture Reflections

February 26, 2009 by Douglas Barnes 1 Comment

Key points:

  • 3 subfamilies of the legume family can fix nitrogen
  • Symbiotic bacteria (Rhyzobium) convert nitrogen in the air to a form plants can use
  • Repair damaged land in tropical and arid regions with initial plantings of 90% nitrogen fixers

As mentioned in the previous article in this series, beneficial partnerships are the way of nature. In particular, some microbes (Frankia and Rhizobium) form associations with certain plants allowing them to fix atmospheric nitrogen into a form that plants can use. These symbiotic partners can help us to rehabilitate damaged landscapes, preparing the soil for a succession of more long-term plants.

Rhizobium nodule

This piece focuses on woody plants that associate with the bacteria of the genus Rhizobium. We can see from the diagram below that there are 3 subfamilies of the family Fabaceae (AKA Leguminosae). These families are Faboideae (AKA Papilionoideae), Mimosoideae, and Caesalpinoideae. Note that not all the trees in these subfamilies are nitrogen-fixers. Among the Caesalpinioideae, 23% are nitrogen fixers. For Mimosoideae, the figure is 90%, and for Faboideae, 97% are nitrogen-fixers.

Nitrogen fixers using Rhizobium

As the diagram shows, Mimosoideae contains the nitrogen-fixers Acacia, Albizia, Calliandra, Enterolobium, Leucaena, Mimosa, Paraserianthes, and Pithecellobium. Caesalpinoideae‘s nitrogen-fixers are Chamaecrista, Cordeauxia; and Faboideae has Cajanus, Dalbergia, Erythrina, Flemingia, Gliricidia, Pterocarpus, Robinia, Sesbania, and Tephrosia.

To rapidly revegetate a damaged landscape, be sure to include plenty of these species to help quickly build up the soils. In areas of very problematic soil, such as arid, tropical and subtropical regions, make 90% of your initial planting of trees nitrogen fixing, pioneer species (associating with either Frankia or Rhizobium), and 10% of species your long-term canopy overstory species. When the system reaches maturity, the proportions will be reversed with 10% nitrogen-fixing, support species and 90% canopy species. The same formula could be followed for humid temperate regions, but the soils in these area are not so fragile and can stand a lower percentage of nitrogen fixers. A 70/30 or even lower may suffice in these areas, as the seasonal cycles of death and regrowth feed these soils well.

As the diagram below shows, the nitrogen-fixing support trees can be pruned (coppiced, pollarded, shredded or sacrificed) to provide mulch, fodder, fuel or fibre. As this is done, the roots of the tree self-prune, releasing nitrogen into the soil.

Chop and drop

The highest concentrations of nitrogen are to be found in descending order in the seeds, the seed pods, the flowers, the leaves and then the woody parts of the tree. Inter-planting with fruit or nut trees naturally provides more soil nitrogen. But interplanting also makes the job of chop-and-drop mulching that much easier.

Nitrogen-fixing support trees

Filed Under: Article Tagged With: soil, trees

Woody Actinorhizal Plants

‘Trees’ Articles at Permaculture Reflections

January 28, 2009 by Douglas Barnes Leave a Comment

  • Read about Rhizobium Symbiosis with Woody Plants here

Dogs don’t eat dogs. At least normal, healthy dogs don’t eat dogs. So, if anyone tells you “It’s a dog-eat-dog world,” smile submissively and slowly back away – you are dealing with a sociopath. The world is, on the whole, a symbiotic dog-help-dog world. Why, even dogs help dogs! Nitrogen-fixing plants are one example of the general pattern of symbiosis.

Plants release an average of 40% of their photosynthates (the products of photosynthesis) out their roots. They don’t do this out of inherent inefficiency. These chemical compounds are doing tasks such as sending signals to call in mycorrhizal fungi and feed those fungi, to share with beneficial nitrogen-fixing and other bacteria, or to make soil nutrients more soluble and available for uptake by the roots.

Among woody nitrogen-fixing plants, there are two varieties: those associating with the bacteria Rhizobia; and those associating with the topic of this article, the actinomycetes Frankia. Actinomycetes are a type of bacteria that grow in long chains of filaments resembling the hyphae, or hair-like roots, of fungi.

Among the woody nitrogen-fixers in temperate regions, actinorhizal plants are an important group. These pioneering plants are able to grow in poor soils, enriching them with nitrogen and organic matter. This makes them very valuable in repairing disturbed or damaged soils.

The diagram below shows the 7 families of woody actinorhizal plants and their 23 genera (I left out the one herbaceous family, the Datiscaceae in the diagram, but it’s in the table).

Actinorhizal families and genera

Plants associated with the actinorhizal bacteria Frankia
Family Genera
   Betulaceae Alnus
Casuarinaceae Allocasuarina
Casuarina
Ceuthostoma
Gymnostoma
Coriariaceae Coriaria
Datiscaceae Datisca cannabina
Datisca glomerata
Elaeagnaceae Elaeagnus
Shepherdia
Hippophae
Myricaceae Comptonia
Myrica
Morella
Rhamnaceae Ceanothus
Colletia
Discaria
Kentrothamnus
Retanilla
Trevoa
Rosaceae Cercocarpus
Cowania
Dryas (some)
Purshia

To rapidly revegetate a damaged landscape, be sure to include plenty of these species to help quickly build up the soils. In areas of very problematic soil, such as arid, tropical and subtropical regions, make 90% of your initial planting of trees nitrogen fixing, pioneer species (associating with either Frankia or Rhizobium), and 10% of species your long-term canopy overstory species. When the system reaches maturity, the proportions will be reversed with 10% nitrogen-fixing, support species and 90% canopy species. The same formula could be followed for temperate regions, but the soils in these area are not so fragile and can stand a lower percentage of nitrogen fixers. A 70/30 or even lower may suffice in these areas, as the seasonal cycles of death and regrowth feed these soils well.

Filed Under: Article Tagged With: soil, trees

Euphorbia tirucalli

‘Trees’ Articles at Permaculture Reflections

January 17, 2009 by Douglas Barnes Leave a Comment

Other names that E. tirucalli has gone by include Arthrothamnus tirucalli, Euphorbia media var. Bagshawei, Euphorbia scoparia, Euphorbia media, Euphorbia rhipsaloides, and Euphorbia rhipsalioides.

Euphorbia tirucalli is an African tree that grows in semi-arid, savannah conditions. It is very drought resistant, withstanding long dry seasons. It is salt tolerant and can withstand to just under 5000 ppm arsenic. It will grow from 4 to 15 m tall and at altitudes to 2000 m elevation in hot savannah climates.

It is a coppiceable tree. When coppicing it, cut it at 20 to 30 cm from the ground. It makes good fuel wood with 17,600 kilojoules per kilogram of dry wood; and through pyrolysis, it makes not only charcoal, but also a high octane gasoline substitute. (One to two tonnes of fuel per hectare is what you can expect.) It can also be used as a diesel source.

The timber is useful. And it can be used as a living fence as it is not grazed by animals. Caution must be applied when planting this tree near any human settlement. It must not be in a location where it can contaminate wells or water collection sites as the tree contains co-carcinogens. Latex from the tree can be used as an insecticide and as a fish poison. As an insecticide, it is effective against Colletotrichum capsici, Fusarium pallidoroseum, Botryodiplodia theobromae, Alternaria alternata, Penicillium citrinum, Phomopsis caricae-papayae and Aspergillus niger and against the nematodes Hoplolaimus indicus, Helicotylenchus indicus and Tylenchus filiformis. The latex can also be used as a glue.

It has medicinal properties, though one would use caution obviously. The young twigs from the tree are roasted (presumably breaking down the poisons) and chewed to sooth sore throats. A poultice made from the greenwood is used to treat broken bones. Despite the toxins and co-carcinogens it contains, some of its compounds have been used to treat cancers.

Filed Under: Article Tagged With: Arid climate, trees

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