Firewood Trees and Woody Plants

Many trees and woody plants can be utilized to produce firewood for use as fuel. This firewood might be used for campfires and outdoor recreation, or serve as the primary means of space heating, hot water heating, and cooking in a home.

In my own home, we use wood as our main fuel source over the winter months, using a wood-fired stove that provides hot water, runs radiators, and which I use for cooking.

Of course, using firewood as a main source of fuel is not the best strategy for every home. But in my rural location, I can source sustainable firewood in part from my own property, and largely from the neighbor's sustainably managed forest and woodland. Sp, it is the most sustainable and eco-friendly option.

I would not advocate using wood as fuel in every setting, of course. Renewable energy can often provide better solutions (along with measures in insulation, and improved building efficiency, of course). But where electrical supply or the potential for renewable power generation may be limited, it could be a viable and preferable alternative to oil or gas.

However, here, and wherever wood is used as firewood, it is very important that we think carefully about which trees and other woody plants are used for fuel, and, where possible, that we grow those sustainably on our own properties or source them from as close to home as we can, from sustainable wood fuel systems.

Sustainable Fuel Wood Systems

It is important to understand that harvesting wood for firewood does not mean clear-felling. We can potentially derive an abundance of fuel from a well-managed standing woodland or forest as long as the right strategies are used.

Obtaining firewood in a sustainable way means making sure that we maintain standing trees, within ecologically functioning forest systems.

The key is to select the right firewood-producing species for where you live, to use coppicing techniques, and/or to selectively and judiciously remove single trees to give remaining trees the space they need to grow, which can introduce more biodiversity into the system by creating open glades.

We can obtain firewood from systems that are also designed to provide other yields and serve other functions within a landscape.

For example, we might plant trees and other woody plants to use as firewood within:

• Agroforestry systems on arable or livestock farms.
• Forest gardens in a domestic setting or on homesteads, smallholdings, crofts, hobby farms, etc...
• Partially-managed areas of native woodland or forest.
• Riparian plantings along a waterway.
• Shelter belts or wind-break hedgerows.

Types of Trees & Shrubs Used for Firewood

When thinking about which trees and shrubs we might include in any firewood-producing system, one of the important things to consider is the different types of firewood that can be derived, and the properties of different woods when they are burned as a fuel.

Hardwood Vs Softwood

Most commonly, when we talk about firewood, we divide the options into hardwoods and softwoods. These can sometimes be confusing terms since, though hardwoods often tend to be denser (and more calorific as a fuel) than softwoods, they are not always harder.

Hardwoods are woods that come from angiosperm trees, while softwoods come from gymnosperm trees. Angiosperm trees produce seeds enclosed with a fruit, while gymnosperms produce non-encased seeds, often in cones.

Most hardwoods are deciduous and have broad leaves. They have a more complex structure than softwoods and tend to be somewhat or much slower growing. Hardwood timber contains pores, or vessels not present in softwoods.

Softwoods often come from conifer species. These are often softer than hardwoods – but not always. For example, yew is a 'hard' softwood, while balsa, a hardwood, is much softer than most softwoods.

The reason why this is important is that hardwoods and softwoods can both be used as firewood – but they differ greatly in their characteristics and what can be achieved when using the different types as fuel.

Hardwood is generally considered to be better for use as firewood than softwood, because of the density of the wood, and its calorific content. A cord of hardwood will produce more BTUs (British thermal units) than a cord of softwood will.

The same weight of softwood will typically have a much greater volume than hardwood, so while the same weight of wood will generate the same amount of heat, you will generally need a lot more softwood by volume to create the same effect.

Hardwoods tend to create longer-lasting fires without excessive smoke or sparks. And hot coals formed as the wood burns allow fires to be banked down overnight more easily.

However, hardwood is not all the same in quality, and some hardwoods will be far better for use as firewood than others. These woods can typically also be harder to light and get going in the first place.

Resinous softwoods burn quickly and fast, so can be easy to get going and help a fire get up to temperature quickly. So softwoods are often used for kindling, and for quick burns. Sometimes, mixing them with hardwoods can provide the best results in an efficient wood-burning stove.

The Characteristics of Different Firewoods

The firewoods in a given area will of course depend on the tree species that grow there. Often, when choosing which trees and shrubs we might grow for firewood, we should begin by looking at the species that are native to our areas.

Here where I live in Scotland, for example, some of the common native firewood are:

• Oak - One of the best firewoods when seasoned. It provides lasting heat and burns at a slow rate.
• Ash – Another great choice. It has a low water content and can be burned green, but is also still best when seasoned and will burn at a steady rate.
• Cherry – A native hardwood that burns well once seasoned.
• Birch – Burns easily but also fast, good for starting fires or when mixed with slower-burning woods like oak.
• Hazel – Excellent firewood once seasoned, hazel burns fast but with no spitting.
• Hawthorn – A good firewood that burns well.
• Holly - A good firewood that can be burned unseasoned.
• Rowan – Considered to be a pretty good firewood that burns well.

Of course, this is only a partial and extremely incomplete list. And pine and other softwoods are often used as kindling or in combination with the hardwoods mentioned above.

Researching native trees where you live, and the characteristics of their firewood can often be a good place to begin when choosing trees to grow for firewood on your property.

Choosing Trees For Sustainable Firewood Production

Choosing the right trees and shrubs for sustainable firewood production on your property is not only about looking at the characteristics of potential fuel woods. Working out which options are best for you involves looking more closely at your own needs.

You should think about what you plan to use the firewood for, precisely, the potential for trees for coppicing and other sustainable systems, how quickly the trees will grow, and what other yields they might also provide.

Intended Use of the Firewood

First of all, before you spend more time thinking about which species might be beneficial on your property for use as firewood, it is important to consider your specific needs.

Do you only need firewood for use in a firepit for occasional recreational use? Will you be using wood for a wood-burning stove in your living space? Or, like me, will you be relying on wood through winter to provide for all of your space heating, water heating and cooking needs?

Thinking about how you will be using firewood, and how much you will require will of course have important ramifications when it comes to how much space you will need to meet your needs, and can also help you decide which species might be best.

Potential for Coppice

When growing wood for fuel, it is important to think about the potential of different species that might be managed within a sustainable forestry scheme, or used for coppicing or pollarding.

Some trees will regrow more easily and effectively when cut back hard, and so can be better choices for a sustainable fuel-producing system.

Rate of Growth

Another important thing to think about is how quickly trees will grow. Faster-growing trees burn more quickly, but since they will grow more quickly, you can also get a more plentiful supply. Birch, hazel, and hawthorn are three examples of quicker-growing hardwoods that grow where I live.

Firewood as a Secondary Yield

When choosing trees for any system, we should choose those that fulfill multiple functions. Many trees allow us to obtain other yields as well as provide the potential to harvest firewood on a regular basis.

While we do not have enough land to be self-sufficient in firewood (we only have 1/3 acre), and obtain most of our firewood from our neighbor, who has a large farming estate, we also use prunings from trees in my forest garden and other trees on our property as kindling and fuel.

I use pruned material from mature apples and cherries, for example, and can still harvest the fruits as an annual edible yield as well.

In many agroforestry and other forestry projects, numerous non-timber forest products can also be derived in addition to firewood from the system.

Seasoning Firewood

Whether you are growing trees for firewood for your homestead, or for sale, it is important to understand that it must be properly seasoned in order to be effective and fuel-efficient.

Seasoning firewood is basically leaving it for a period of time so that the water content of the wood is reduced, or drying it in some way.

Much of the firewood available for sale has been kiln-dried (often using fossil fuels to do so). By seasoning wood on your own property (whether or not you actually grow it on your property), you can make sure you make the endeavor as environmentally friendly as possible.

It is important, when choosing trees and shrubs for firewood, to think about how important seasoning is for those species, and also how long this process will take since it will take much longer with some woods than with others.

Creating sustainable wood fuel systems means planning carefully, and well ahead of time, to make sure that you can meet your firewood needs consistently over time. This involves not only taking coppicing or selecting cutting schedules into account but also seasoning times for the species you are growing.

Features & Tools To Sustain Firewood Production

If you want to be able to meet all your firewood needs on your own property, choosing the right trees and shrubs is only part of the picture. In order to become self-sufficient, you will need to think about the features and tools you will require to sustain your efforts.

Because you will need to season the firewood that you grow, for example, you might need to think about including space to do so in your designs for your property. A well-designed log pile or log store area will make your life a lot easier in the long term, especially if you are trying to become as self-sufficient as possible.

You will need to purchase the tools required to cut or prune trees and shrubs, and to split logs for your stove, fireplace or firepit. Considering the ease with which you will be able to harvest firewood from different species, and the tools you will require to do so is also important.

Charcoal & Biochar Production

One other thing to consider when looking at fuel woods and growing them on your property is which species might be suited to facilitating charcoal production. Charcoal might be most familiar to most from barbecues, but it can also be used in other ways – most notably, in permaculture systems, for the production of biochar.

Potentially made from byproducts of a firewood-producing system, charcoal can be steeped in compost tea to create biochar, which can increase Phosphorus availability in soils by 4.6 times, decrease plant tissue concentration of heavy metals by 17-39%, build soil organic carbon by 3.8% and reduce greenhouse gas emissions by 12-50%.

Biochar can also increase crop yields by 10-42%, with the greatest increases in the low-nutrient acidic soils of the tropics, and dryland sandy soils. It can also be fed to cattle to reduce methane emissions which then enriches the soil where cattle roam.

Careful selection of fuel wood species can ensure that trees remain in active growth and that burning wood does not result in deforestation. When carefully designed for a given setting, systems that provide firewood can also provide us with many other yields, not just short term but for many years to come.

And when we use sustainable strategies such as coppicing and judicious selective felling to obtain our firewood, we can leave ecosystems richer and more biodiverse than they were before.