The earth has a surface area of 51 billion hectares (ha)1. Seventy one percent of it is covered by water and the remaining 29% is land mass2. Forests cover 4.6 billion ha or 31% of the land mass but they are not equally distributed around the globe3.
Land is a natural resource which has been used by humans since time immemorial. Land use is defined as any kind of permanent or cyclic human intervention to satisfy human needs4. Much of the land or approximately half of it has already been used for agriculture5.
Farming needs land and, thus, forests have often been cut down for agriculture. The act of cutting down forests and clearing it for other kinds of land use is termed ‘deforestation’. The topic of ‘deforestation’ or more specifically ‘no deforestation’, the latter of which refers to a call to end cutting down forests, is currently much debated.
We intend to provide a better understanding on the relationship between land use and deforestation. This is the first article in the series.
PART 1: WHAT IS A FOREST?
Forests mean different things to different people. It may surprise you to know that a forest may not have any trees but it is true since there are at least 800 definitions6 of forest.
The word ‘forest’ originated from the Latin phrase ‘forestemsilva’ that was used during the Medieval times. The meaning of this phrase was ‘the outside woods’7 and referred to areas of land used by Emperor Charlemagne for hunting.
In time, the phrase was shortened to ‘forest’ and denoted an area of unenclosed countryside, consisting of a highly variable mixture of woodland, heathland, shrubs and agricultural land. In the 14th century, the word forest was used to mean an extensive tree-covered district, especially one set aside for royal hunting and under the protection of the king. It was derived from the French word ‘foret.’
Forests can be small or large in size. The interior of the latter kind of forests may not be easily accessible, unexplored and unknown. No wonder some people view them as dangerous, especially lush tropical forests. They are so dense and if someone goes trekking and is unlucky to get lost, it may take a long while or maybe, never to get out of these forests again.
Most people view a forest as an area with thick growth of trees and plants. So it may be surprising, but it is true that there are situations when a forest may not have any trees at all. This happens when the land is zoned for administrative purposes which may not bear any relationship to vegetation. Thus, the land may be marked for use in agriculture, urban or mining purposes. All other land which does not fall into these groups is marked as forest. As such, even though there are no trees on the land, it can be classified legally as a forest area for administrative purposes8.
Forests in the world can also be classified according to their locations9. Boreal forests occupy the subarctic zones and are generally coniferous in nature. Temperate forests are situated in temperate regions and have both coniferous and broad leaf trees. Similarly, tropical and subtropical forests are located respectively in tropical and subtropical zones in the world.
Sometimes forests may be referred to as primary (Figure 1) or secondary forests10. The former is a forest that has never been logged and exists today as a result of natural processes. The age of the forest is not important. However, in many parts of Europe, age is important. Here the primary forest is a forest which has been continuously wooded throughout historical times e.g. the last 1,000 years10. It must not have been completely cleared or converted to another land use type for any period of time. Shifting cultivation and logging may, however, have taken place.
Figure 1. View of a primary forest
A secondary forest has been logged and has recovered naturally or through a reforestation process. However, if the secondary forest has lost its structure, function, species composition or productivity that is associated with the primary forest type, then it is called a degraded forest11 and shown in Figure 2.
Figure 2. View of a degraded forest
What is a ‘forest’ to the man in the street? Most of them view it as12 :-
- a large wooded area having a thick growth of trees and plants
- the trees of such an area
- an area planted with similar trees.
Scientific definitions of forest are more exact. For example, the United Nations Framework Convention on Climate Change (UNFCCC), which is the international organization that has the important task to report on the greenhouse gas emission inventories of nations in the world, defines a forest as having a minimum area of 0.01-1.0 ha, 2- 5 meters (m) for minimum height of trees and 10-30% for minimum forest cover13.
The Food and Agriculture Organization of the United Nations (FAO), which is a global organization that has been assessing the status of the forests in the world regularly through its Forest Resource Assessments (FRA) has a different definition of forest,11, 14 : land that has a minimum area of 0.5 ha and with a tree crown cover of more than 10%. The trees should be able to reach a minimum height of 5 m at maturity in situ. Urban parks, orchards, agroforestry systems and other agricultural tree crops are excluded from this definition.
It is noted from the above that even international organizations such as UNFCCC and FAO have not come up with a generally accepted unified definition of a forest. The FAO’s definition of a forest is commonly used and is a very broad classification of forest which makes mapping forests on a global scale a simple and uniform task.
Forest types according to FAO
While the broad classification of forest is used to delineate forest areas globally, FAO9 recognizes that there are different kinds of forest. The full description of forest and some of the major forest types are given in Table 1.
Table 1: Some types of forests classified according to FAO11
Land spanning more than 0.5 ha with trees higher than 5 m and a canopy cover of more than 10 %, or trees able to reach these thresholds in situ. It does not include land that is predominantly under agricultural or urban land use.
- Forest is determined both by the presence of trees and the absence of other predominant land uses. The trees should be able to reach a minimum height of 5 m in situ. Areas under reforestation that have not yet reached but are expected to reach a canopy cover of 10% and a tree height of 5 m are included, as are temporarily unstocked areas, resulting from human intervention or natural causes, which are expected to regenerate.
Includes areas with bamboo and palms provided that height and canopy cover criteria are met.
- Includes forest roads, firebreaks and other small open areas; forest in national parks, nature reserves and other protected areas such as those of specific scientific, historical, cultural or spiritual interest.
- Includes windbreaks, shelter belts and corridors of trees with an area of more than 0.5 ha and width of more than 20 m.
- Includes plantations primarily used for forestry or protective purposes, such as rubber wood plantations and cork oak stands.
- Excludes tree stands in agricultural production systems, for example in fruit plantations and agroforestry systems. The term also excludes trees in urban parks and gardens.
- Natural forest
A forest composed of indigenous trees, not planted and not classified as a forest plantation.
- Other wooded land
Land not classified as ‘Forest’, spanning more than 0.5 ha; with trees higher than 5 m and a canopy cover of 5–10 %, or trees able to reach these thresholds in situ; or with a combined cover of shrubs, bushes and trees above 10 %. It does not include land that is predominantly under agricultural or urban land use.
- Primary forest/other wooded land
Forest/other wooded land of native species, where there are no clearly visible indications of human activities and the ecological processes are not significantly disturbed. They include areas where collection of non-wood forest products occurs, provided the human impact is small. Some trees may have been removed.
- Modified natural forest/other wooded land
Forest/other wooded land of naturally regenerated native species where there are clearly visible indications of human activities.
- Includes, but is not limited to: selectively logged-over areas, areas naturally regenerating following agricultural land use, areas recovering from human-induced fires, etc.
- Includes areas where it is not possible to distinguish whether the regeneration has been natural or assisted.
- Semi-natural forest/other wooded land
Forest/other wooded land of native species, established through planting, seeding or assisted natural regeneration:
- Includes areas under intensive management where native species are used and deliberate efforts are made to increase/optimize the proportion of desirable species, thus leading to changes in the structure and composition of the forest.
- Naturally regenerated trees from other species than those planted/seeded may be present.
- May include areas with naturally regenerated trees of introduced species.
- Plantation forest or forest plantation/other wooded land
Forest/other wooded land of introduced species and in some cases native species, established through planting or seeding.
- Includes all stands of introduced species established through planting or seeding.
- May include areas of native species characterized by few species, even spacing and/or even-aged stands.
- Plantation forest is a subset of planted forest.
- Productive plantation (in forest/other wooded land).
- Forest/other wooded land of introduced species and in some cases native species, established through planting or seeding mainly for production of wood or non-wood goods.
- Includes all stands of introduced species established for production of wood or non-wood goods.
- May include areas of native species characterized by few species, straight tree lines and/or even-aged stands.
- Secondary forest
Forest regenerated largely through natural processes after significant human or natural disturbance of the original forest vegetation.
- The disturbance may have occurred at a single point in time or over an extended period.
- The forest may display significant differences in structure and/or canopy species composition in relation to nearby primary forest on similar sites.
- Degraded forest
A secondary forest that has lost, through human activities, the structure, function, species composition or productivity normally associated with a natural forest type expected on that site.
Source: FAO (2009)
There are numerous classification of forests in the world. However, most people view forests as large wooded areas having a thick growth of trees and plants. At the technical level, the FAO’s broad definition of forest is often used for mapping to delineate forest areas globally. FAO recognizes that forest is not uniform and has distinguished different types of forests based on their origin, status, structure and composition.
- FAO (2015) Global Forest Resources Assessment 2015, pp253.
- Vink, A.P.A. (1975). Land use in advancing agriculture, Springer,pp394.
- Lund, G. Definitions of forest, deforestation, reforestation and afforestation. www.researchgate.net/profile/Gyde_Lund/publication
- http://dictionary. reference.com/browse/forest
- 8. No Trees in the Forest? http://www.worldwidewords.org/articles/forest.htm
- Facts on forests and forestry. ForestFacts.org. http://www.forestfacts.org/l_2/forests_1.htm
- Indicative definitions taken from the Report of the ad hoc technical expert group on forest biological diversity. Convention on Biological Diversity. http://www.cbd.int/forest/definitions.html
- FAO.2009. Guidelines for good forestry and range practices in arid and semi-arid zones of the Near East. Working Paper. RNEO 1-09. pp69.
- http://dictionary. reference.com/browse/forest
- Forest definition and extent. United Nations Environmental Programme http://www.unep.orf/vitalforest/report/VFG-01
- Appendix 1: Definitions as in FRA Working Paper 1 and comments. FRA 2000 on definitions of forest and forest change. FAO Corporate Document Repository. http://www.fao.org/docrep/006/ad6665e/ad665e06.htm
Prepared by Dr.Yew Foong Kheong