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Forest and tree products

By David Okul

Forest and tree products include materials and services derived from woody plants. There are very many uses of trees and forest products. In this blog post, we have divided the forest and tree products into:

  • Conservation (soil, air, and water)
  • Timber, poles, and posts (traditional forest product)
  • Biomass fuel
  • Pulp and paper
  • Non-wood forest products
  • Agroforestry

Soil, air, and Water Conservation

Personally, I think that the most important role of forests and trees in the world is the conservation of soil, water, and air.

Forests conserve soil and water quite effectively. They not only obstruct (reduce) the flow of water, but the falling leaves provide organic matter which increases the water holding capacity of the soil. If tree planting is done in the planned manner in open areas, it will serve as a windbreak and if done along the banks of streams and rivers, it will regulate their flow.  Additionally,

  • Nitrogen-fixing soils also assist in adding nutrients to the soil.
  • Forests and trees improve water quality by reducing sediments in the water. Sediments are small particles in the soil.
  • Trees also reduce the flow of water in hills and mountains, therefore, reducing cases of floods.
  • Forests also attract rain. This is a controversial statement, but areas with reduced forest cover have been seen to have lower rainfall. Most rivers have sources from forests e.g. the source of River Mara is Mau forest, Tana River comes from Mount Kenya’s forested areas, the Nile from Congo forest, etc, which can be proof enough that to have water we need forests!!!

Trees and water quantity and quality

The role of trees in defining water quality and quality can be summarized in two ways:

  • Increasing infiltration: This is because the leaves reduce the force of rainwater and can be absorbed easily
  • Filtration: Trees are also natural filters of water

Air conservation

Trees help preserve the balance of gases in the atmosphere. A tree’s leaves absorb carbon dioxide from the air. They also produce oxygen and release it into the atmosphere. These two processes are necessary for people to live. People could not survive if the air had too much carbon dioxide or too little oxygen!!!! Remember carbon dioxide is a major GHG therefore trees/ forests will help in reducing the amount of carbon dioxide in the atmosphere.

Tree species for conservation

Indigenous trees are better for conservation because:

  • Indigenous trees are better adapted to the prevailing conditions.
  • Indigenous trees have more uses known to the local people.
  • Lower chances of bad effects of indigenous trees to the environment

Indigenous species are thus the best trees to use for conservation. While planting trees for conservation in Africa, the spacing can be very close e.g. 1 meter by 1 meter even 0.5 by 0.5!

Virtually any tree can be used for conservation. However, invasive species are discouraged in many circumstances.

Timber is a common forest product
Timber is one of the most common forest and tree products (Image by antmoreton from Pixabay)

Timber, Poles, and Posts

Tree species for timber are usually fast-growing. Regardless, the timber industry has been a major cause for the destruction of natural forests. Sustainable commercial production of timber trees usually occurs in plantations/ Among the common species used in East Africa for production of timber posts and posts include:

  • Cyperus
  • Pine
  • Eucalyptus

Management of trees for timber poles and posts

Spacing: There is wider spacing for these types of trees as they need a bigger diameter. The diameter in forestry is measured at breast height and it is called diameter at breast height (dbh). The dbh is usually 1.3 meters.

Thinning: This refers to felling closely spaced trees to enhance the diameter growth of the remaining trees.

The trees from thinning can be used for various purposes such as fuelwood and posts.

Pruning

Pruning refers to removing branches of trees to achieve knot-free timber

Trees as Fuelwood

Trees and other woody plants have been used for fuel for millennia. When done sustainably, fuelwood is a renewable and environmentally friendly source of energy.

Qualities for good fuelwood

  • Calorific value: Refers to the energy content that the wood has. Wood that burns for a long time has higher calorific values e.g. Tarchonanthus species has a higher calorific value than cypress.
  • Smokeless: Good fuelwood burn with minimal smoke.
  • Coppices easily: Coppicing refers to the ability of the tree to sprout from the cut shoot with relative ease.
  • Multi branched: Multi branched trees have the advantage of higher quantities of matter produced.

Species for fuelwood

Eucalyptus species trees are grown and used by tree processing industries in East Africa. In most sub-Saharan Africa, Acacia and Commiphora species are used for fuelwood. Often people in rural Africa cut branches or collect fallen parts for firewood. This is less destructive to the wood resources. In contrast, charcoal production is often unsustainable and causes significant losses.

Management of trees for biofuel

Spacing: Trees for fuelwood are closely spaced

Harvesting: Harvesting will depend on the species; trees that coppice or pollard well can be harvested entirely and trees with multiple branches can involve branch-harvesting.

Biodiesel

Biodiesel is a form of diesel fuel manufactured from vegetable oils, animal fats, or recycled restaurant greases. It is safe, biodegradable, and produces fewer air pollutants than petroleum-based diesel. The disadvantage is that biodiesel is expensive to produce and it competes with the land that could be used for food production.

Tree species used for biodiesel that could be used for biodiesel production include Jatropha carcus and

Croton megalorcarpus

The nuts of the jatropha plants are crushed to release oil that can be used in a standard diesel car.

Other plants that can produce diesel include soya beans and maize. Unless technology for extraction improves, I believe that biodiesel production is harmful to the environment.

Pulp and Paper

Pulp and paper also are tree products. Paper is used for writing, printing, and packaging and is a big business.

Process of making pulp and paper

  • The bark is removed from the tree. This is called pulping
  • The wood is then chopped into small pieces by a chipper.
  • The wood is then cooked with chemicals
  • Water is then drained from the cooked wood to form paper.
  • Softwoods are used to make paper.

Tree species for pulp and paper

In East Africa, the common species for making paper are Pine (Pinus spp) and Cypress (Cupressus species). The common trees in the world for making paper are softwoods such as firs and pines.

Non-Wood Forest Products (NWFP)

NWFP are products from trees and forests other than wood products. Often, NWFP can be extracted from trees without felling them. Examples of non-wood forest products include:

  • Food like leaves eaten as human food (moringa), edible fruits from trees
  • Food additives such as gums used in food production
  • Fodder for livestock
  • Fiber
  • Fragrance
  • Oils
  • Habitats for species like birds
  • Bees and bee products

Agroforestry

This is a system of deliberate growing of woody perennials on the same unit of land as crops and/or animals, either in some form of spatial mixture or sequence.

Benefits of agroforestry

  • Food: Some trees provide food in fruits and vegetables in leaves such as Moringa
  • Enhanced crop production increase food security.
  • Energy: The trees can be used as fuelwood by the farmers
  • Shelter: For resting, some crops do better in the partial shade provided by the trees.
  • Medicine: Some trees have medicinal value.
  • Raw materials: Raw materials for industries but this is not a major product from agroforestry systems in Kenya.

Limitations of agroforestry

  • Poor choice of tree species might lead to more adverse effects rather than positive ones e.g. competition with crops and shading.
  • Space limits the ability of people to undertake agroforestry.
  • Inadequacy of appropriate knowledge at the grass-root level.

The blog post highlights a summary of different goods and services offered by woody plants. Generally, woody plants have multiple-uses. Before a tree planting exercise, it is vital to have an understanding of the intended use of the resulting trees. Such an understanding would assist a silviculturist to make decisions on the correct management practices and species selection. Additionally, sustainable use of forest and tree products is vital if we are to conserve the forest resources of the world. 

David Okul is an environmental management professional with over 10 years experience on donor projects, conservation, forestry, ecotourism, and community-based natural resources management. When not working on  environmental projects, I spend my time writing for Silvica on a variety of topics.

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