Definition, interests and scope of the concept

Photo 2. Microafforestation and rural hedgerows near Saint-Floret, France. © Bellefontaine/CIRAD

The concept of Trees outside forests is increasingly providing food for thought and discussion. More light is being shed every day on the exact role of Trees outside forests in sustainable natural resource management, and in rural and urban land management. A plethora of tree systems, ranging from agroforestry and silvopastoralism to urban, rural or community forestry are marked by their presence.

Definition and typology

The term Trees outside forests, a neologism coined in 1995, is framed in the forest context, defining the concept by default with reference to forested areas. So an exact definition of the term requires a reading of the definition of the term forest, which, as we know, varies from country to country in accordance with the environmental stakes, economic interests and local situations involved. Some countries, for instance, have differed as to whether or not to classify plantations as forests (or forest lands)¹ . In Zimbabwe, the big plantations established for commercial purposes are considered to be forests, but plantations on land used primarily for agriculture are excluded from this category (Moyo, 1999). Sometimes counting plantations as forest area can amount to concealing the extent of forest clearing. Some countries, such as Brazil, Colombia, Haiti, Honduras and Peru, have no legal definition for either the forest or the tree. Here it should be noted that a definition may sometimes be found in national laws or codes other than the forest code.

The criteria used to define forests are usually based on the notion of `land cover' or `land use', or sometimes a combination of the two. Land cover refers to the physical forms of land cover observable from aerial or satellite views, and to their structure. It includes the vegetation, which may be natural or planted. Land use, a complex and more sensitive dimension than land cover, refers to the function of land and how it is used, i.e., the activities undertaken upon it to produce goods and services. A piece of land with uniform cover may in fact have more than one use (FAO, 1997a). These two closely related notions can cause confusion in land classification, especially where different methods are employed and specific issues addressed. Because the management of both land and tree resources is based on data referring to both land cover and land use, we need to make a clear distinction that reconciles the two concepts.

The purpose of a definition also influences its content. Biological definitions, for example, are usually based on structural parameters, whereas legal definitions attest to the legal status of land and may ignore the vegetation and land cover (table 1). Moreover, many lands legally defined as forests are now bare of trees though their status remains unchanged.

Given the great variety of forest formations, the diversity of their characterization and the many purposes for which they are intended (Box 1); a universal definition of forest is arduous if not risky. Forest Resources Assessment 2000 for the first time established consensus on a single definition of forests as land entailing a minimum of 10 percent tree crown cover.

To define Trees outside forests, we will refer back to a similar blanket definition for forest resources, such as the one used by FAO for forest resource assessment. This definition and its corollaries (FAO, 1998b) (annex 1), permit a certain classification, and constitute world statistical data collection standards, whilst respecting eventual differences among country definitions in the context of their forest policies and activities. The prime objective of forest resource assessment is to permit a standardized and comparable estimation of the world's forests.

The FAO definition of forest or forest lands is based on tree formation structure, i.e., percentage of crown cover, and height of tree species, plus the area covered. Other woodlands include shrub cover and forest fallow. Shrubs are "woody perennial plants, generally of more than 0.5 m and less than 5 m in height on maturity and without a definite crown. The height limits for trees and shrubs should be interpreted with flexibility, particularly the minimum tree and maximum shrub height, which may vary between 5 and 7 meters approximately" (FAO, 1998b). This definition thus embraces all low-growing woody formations.

Table 1. Country classification by forest cover according to the national definition

Percentage of forest cover
Under 10	10%	20%	30%	More than 30%
Spain	Chile (arid zone)	Afghanistan	Australia	Costa Rica
Iran	Eritrea	Albania	Austria	Denmark
Sweden	Fiji	Belgium	Cambodia	Ethiopia
Taiwan	France	Chile (humid zone)	Estonia	Germany
	Gambia	China	Japan	Jamaica
	Greece	Ireland	Morocco	Kenya
	India	Italy	Russia	Malawi
	Israel	Kirghizistan	Vietnam	Panama
	Luxembourg	Liechtenstein		South Africa
	Malaysia	Lithuania		Sudan
	Mexico	Mozambique		Tanzania
	Papua New Guinea	Namibia		Ukraine
	Portugal	New Zealand		Zimbabwe
	Turkey	Netherlands
	United States	Somalia
	Yemen	Switzerland
		United Kingdom
Fuente: FAO (1993)

Forest fallow refers to "all complexes of woody vegetation deriving from the clearing of natural forest for shifting agriculture. It consists of a mosaic of various reconstitution phases and includes patches of uncleared forests and agriculture fields, which cannot be realistically segregated and accounted for area-wise, especially from satellite imagery. Forest fallow system is an intermediate class between forest and non-forest land uses. Part of the area may have the appearance of a secondary forest. Even the part currently under cultivation sometimes has the appearance of forest, due to the presence of tree cover. Accurate separation between forest and forest fallow may not always be possible". Forest fallow is classified under "other woodlands" and agricultural fallow under agricultural lands.

Photo 3. Trees outside forests or thurifera broom forest? Tizi Bou Zagel, 2 400 m., Morocco (© Bellefontaine/Cirad)

Figure 1. Classification of land above water and water

Figure 2. Classification of wooded lands (FAO, 1998b).

Figure 3. Preliminary classification of Trees outside forests

The FAO definition of forest is quite specific (Annex 1), which facilitates our approach to the notion of Trees outside forests. These are thus defined as "trees on land not defined as forest and other wooded land" (Figures 1 and 2). It includes trees and shrubs on agricultural land, barren land and built-on areas (Box 2). It includes agroforestry systems, orchards, small clumps of trees, permanent meadows and pastures, trees growing on farms and in urban and per urban zones, in lines along rivers, canals and roads, and in gardens, parks and towns (Figure 3).

Photo 4. Dune stabilization with Prosopis spp and Leptadenia pyrotechnica in Mauritania. (© Cossalter/Cirad)

Trees outside forests may be productive; such as orchards, and trees in fields and other agroforestry systems, or protective; such as trees with an ecological or landscaping function; or ornamental; such as trees around houses, and in parks and towns. They may be predominantly natural and thus not maintained, such as woodlots, gallery forests and riparian buffers. In spatial terms, they may be scattered discontinuously on farmland and pasture, or growing continuously in line-plantings along roads, canals and watercourses, around lakes, in towns, or in small aggregates with a spatial continuum such as clumps of trees, sacred woods, urban parks (Alexandre et al, 1999).

Photo 5. Faidherbia albida agroforestry parkland near Ségou, Mali. (© Faiduti/FAO)

In any case, this definition of Trees outside forests, though clear at first sight, reveals its limitations when put into practice. First of all, it requires clear definitions of forest and other woodlands, whereas the boundaries of these may be blurred, depending on the context. Problems of interpretation arise, for example with plant formations such as gallery forests, oases, tiger bush formations, specific plantations such as coffee or palm, agricultural fallow, and certain complex agroforestry systems and plantations of forest species on farms (Box 3).

The classification of orchards is equally tricky. Here the main objective is food production - olives, dates, apples, baobab, etc., which are usually considered agricultural crops and their products listed under agricultural statistics. As for fruit-tree meadows² , they combine the advantages of orchards and pastures.

For inventories in Latin America, tracing the boundaries between forest and non-forest tree systems raises the following issues: i) savannah sectors such as the cerrados in Brazil; ii) plantations of cocoa grown under shade trees; iii) coffee plantations (coffee is grown in Costa Rica under fairly thin cover, but in Honduras the shade trees are taller and more numerous); iv) treed pasturelands of variable densities, some close to the definition of forests; v) orchards which easily resemble forest plantations in satellite imagery (Kleinn, 1999).

These are all sensitive issues when the objective of the tree inventory is planning, whether local or international. A planning exercise of this kind is much more complex and potentially ambiguous for such a characteristically "multipurpose" sector as Trees outside forests, with its diversity of tree formations and range of species growing in many and varied combinations in rural and urban environments.

The question of definitions is thus not devoid of consequences. Whether or not to designate land within a given category will affect the remit of the relevant institutions and structures; the management prerogatives and mandates of the actors involved; forms of access and usage; and the ways in which tree resources are appropriated. While it may be too early at this stage to define Trees outside forests so as to embrace each single characteristic, it is certainly possible to rank them in terms of such criteria as area, tree height, crown cover, land use and land cover. They can also be classified in terms of their uses and spatial layout. The terms `Trees outside forests' and `off-forest tree systems' fail to fully describe the wealth and diversity of the sector. This is because the first term is linked by definition to the concept of forest, and the second fails to convey the full range of their products. This raises the question of whether or not to opt for a new term, or perhaps keep the old one while making it more specific in scope. The term is now widely used, and confusion arises only in certain extreme cases (this is valid for all domains). It is thus established and destined to endure, helping to shed light on policies and concepts covering the conservation, management and development of all tree resources.

Mounting interest in Trees outside forests

Trees are an integral part of many non-forest environments. They are found in fields and towns, clinging to mountainsides or growing in rows and in clumps. These trees, such a familiar sight and so integral a part of the landscape, were long overlooked by law and policy in a failure to view Trees outside forests as a separate entity, despite their ecological, economic and social importance (Box 4). But viewpoints and positions have altered, and there has indeed been a reversal concerning this resource, as mounting interest (from the international institutions, for instance), has brought it within the remit of scientific, economic and policy debate, and into environmental and development history.

During the 1970s, worsening weather events on several continents provoked a rush of aid to countries hit by drought and desertification. Much reforestation was undertaken. This was followed in the 1980s by a wealth of agroforestry research highlighting the major role of trees in soil fertility and rural development. Environment, sustainable development and biological diversity were high on the agenda of the 1992 United Nations Conference on Environment and Development (UNCED), which marked a turning-point in approaches to development. Rainforests, long considered a pool of biological diversity under great threat from logging and agricultural expansion, received unprecedented consideration. Tree-planting was encouraged, particularly for carbon storage. Beginning in the 1980s, interest mounted in non-wood forest products (previously relegated to the status of rather minor by-products compared to wood). Converging with this interest was the increasingly vital need for data on all tree resources.

Trees, particularly Trees outside forests, came to be seen in terms of their contribution to social well-being, the economy and the environment. Sustainable development, a focus of media attention since 1987, has given new breadth to this issue compared to more narrowly sectoral approaches such as agroforestry, which highlights the soil fertility and production aspects, or urban forestry, which emphasises the ornamental and scenic functions. Their productive, ecological and social roles put rural and urban trees on a similar footing. They are instrumental in sustainable development and crucial to integrated, multisectoral approaches.

Relevant domains and disciplines

Trees growing outside forests correspond to a variety of settings and uses, and cover a wide range of shrub and tree formations comprising countless species. This implies the involvement of many and varied disciplines, from agronomy to urban planning, sociology and biology, touching upon the spheres of agriculture, the environment and livestock production. Studies on Trees outside forests have come out of numerous domains such as fruit-tree cropping, farming systems and apiculture. They are a crucial and core element of agroforestry systems, silvopastoral systems, and urban, rural and community forestry.

Trees outside forests are found in most rural landscapes and many agroforestry systems. The International Council for Research in Agroforestry (ICRAF) defines agroforestry as a dynamic, ecologically based, natural resource management system that, through the integration of trees on farms and in the agricultural landscape, diversifies and sustains production, enhancing social, economic and environmental benefits for land users at all levels. Following the late 1970s and the report of Béné et al (1977), which sparked worldwide interest in agroforestry, voluminous research on the tree/crop/livestock association was produced in almost every developing country and some industrialized countries. Despite some of the failures pointed out by Budowski (1981) or Lundgren (1980), agroforestry systems were often proposed to promote agricultural development in the tropics. Recent work on the valorisation of multipurpose trees and the domestication of trees for products other than wood (Leakey et al, 1996), have made it easier to measure and promote the potential use of trees in non-forest situations. Even granting that agroforestry is an ancient art, the current interest in trees and their development is unquestionably responsible for some of the newly enhanced awareness of Trees outside forests.

Trees play a constant or occasional, main or supporting, but always specific role in livestock production systems. Their presence and distribution may be intentional, and not simply left to chance. Trees outside forests can unequivocally mark the character of livestock production in a given landscape, depending on the presence or distribution of specific trees. Silvopastoral systems frequently and characteristically juxtapose plots of pastureless forest with treed pasture. The tree species present may have sprung up spontaneously, been left standing, or perhaps planted in association with local or introduced species. Shelter-providing hedgerows and woodlots, like windbreaks, are commonly combined with grassland. Every agrosilvopastoral landscape has its own unique character in terms of the production usages and tree species favoured or established.

Trees outside forests are part and parcel of urban, rural, private and community forestry. These trees depend as much on the demand from city-dwellers as on the usages of country people. Urban (and periurban) forestry includes the management of single trees and clumps of trees which have either sprung up by themselves or been planted in urban areas (Besse et al, 1998). The term `urban forestry' embraces tree cropping, green spaces and afforested periurban areas. Both the quality of life and the aesthetics of the landscape in a wholly manmade environment owe much to the presence of greenery. City trees have to adapt to a great many constraints, such as lack of space and soil, air pollution, damage by man and animals, and repeated cutting. Urban and peri-urban forestry is increasingly interested in the ecological and scenic aspects. And yet, most developing country urban agglomerations have neither budgeted nor planned for urban trees, a core feature of integrated urban land management planning in the big cities of the industrialized countries.

Social forestry has advanced significantly since the 1980s, mainly in response to the problem of supplying fuelwood for rural communities. It is often associated with rural development (Sharma, 1993), as in India, where forestry policy began as early as 1961 to envisage social forestry as a means of reforesting unused community and national land. The same can be said of community forestry, which also stresses the responsibility of user populations for tree resources. In managing these tree resources, these people also become the agents of their own development (Thomson, 1994).

Because the sectors and actors involved in some way with Trees outside forests are so vast, the relevant spheres of intervention and competence are virtually unlimited, making outside the forest a genuine challenge for sustainable and integrated resource management.

¹ The classification of forests, also called forest lands, includes forest plantations. These are defined as forest stands established by planting and/or seeding in the process of afforestation or reforestation, and made up of introduced species or stands of indigenous species, one or two species at plantation, even age class, regular spacing. (FAO, 1998b), see also Annexe 1.

² Fruit-tree meadows are defined as areas perennially under grass in association with fruit trees. Tree density is less than 100/ha. Grass production predominates (Pointereau and Bazile, 1995).