Assessment: challenges and objectives

Photo 39. Problems estimating the biomass of thorn trees (Prosopis spp) in Cape Verde (© Bellefontaine/Cirad)

Assessment is one inevitable stage in the process of gaining acknowledgement of Trees outside forests. The point is not only to make a quantitative and qualitative assessment of the resource, we also need to track the way it has evolved over time, the goal being optimal management.

This chapter intends to suggest a basis for defining assessment methodologies. We review the present state of knowledge and implicit problems (such as terminology, data gaps, and the lack of hard and fast information). We attempt to answer a number of conventional but fundamental questions that arise in planning such an operation. We need to know the who, what, where, why and for whom of assessment. Challenges and objectives are reviewed, the persons launching the assessment and those for whom it is intended identified, the types of assessment determined, and the need for a classification of Trees outside forests underscored.

The approach is a bibliometric and bibliographical analysis and critical review of some assessments of trees outside forested lands. The examples have been chosen to reflect the variety of questions which assessments attempt to answer and the range of methods in use.

Assessment or inventory of Trees outside forests: bibliographical review

Bibliographical review

A bibliometric study (Table 5) was made of the wood and non-wood products of Trees outside forests. It provides an initial overview of the types of quantitative assessment in use. At the present time there is no international-level assessment of Trees outside forests and their products. A number of sectoral or geographically specific studies are available, however.

The bibliographical review summarized in Table 6, while not exhaustive, does indicate the diversity of these quantitative studies in terms of the products assessed, the extent of the territory covered, and the methods. It is also worth pointing out that a preponderance of the assessments fall into the category of Asian agroforestry (especially densely populated countries with limited forest resources).

Table 5: Findings of the bibliometric review of 32 selected articles.

		Number of articles	Proportion (%)
Geographical sector
	International	1	3
	Africa	8	25
	Asia	10	31
	Central and South America	8	25
	Industrialized countries
	(North America, European Union, Japan, Australia)	5	16
Production System
	General Inventory	5	16
	Agroforestry	20	62
	Fruit-tree Orchards	2	6
	Urban forestry	3	9
	Other	2	6
Type of product
	Wood products	18	56
	Non-wood products	10	31
	Mixed	2	6
	Others (services)	2	6
Scale of analysis
	Local	7	22
	Provincial	10	31
	National	8	25
	International	7	22
Assessment method*
	Forest-type inventories	7	22
	Bibliographical review	12	37
	Direct measurement	2	6
	Surveys	11	34
	Mathematical models	3	9
*The actual total of the articles was more than 32, and the percentages taken together exceed 100 percent, because some articles cite more than one assessment method.

The authors adopted a different resource assessment approach for each specific situation in accordance with the product, the production system under review and the scale of analysis. Very few studies (just 22 percent) cite methods closely resembling those used in conventional forest inventories. Many of the studies (37 percent) tend to use figures already present in the literature. A great many authors (34 percent) furnish estimates drawn from surveys or interviews. This method does inject significant uncertainty into the exactitude and extrapolation of the results. A survey on the volume and uses of urban tree wastes in the United States, for example (Whittier et al, 1995a), conducted among the major producers of these residues, revealed that 95 percent of them supplied figures without recourse to any formal accounting method.

Table 6: Quantitative reviews of wood and non-wood products

Country or continent	Year	Product*	Scale**	Method***	Source
General inventories of Trees outside forests
France	1995	Wood	N	For. inv., Sur.	Cinotti, 1995
India	1991	Wood	P	For. inv.	Pandey, 1999
Bangladesh	1991-1992	Wood	N	For. inv.	Singh, C.D. 2000
Sri Lanka	1995	Wood	N	Biblio.	Sharma, 2000
Kenya	1988	Fuelwood	P	For. inv.	Bradley, 1988
Agroforestry
International	1981	Fuelwood	I	Biblio.	Ben Salem and Van Nao, 1981
Asia	1985	Wood	I	Biblio.	Wiersum, 1985
Asia	1995	Fuelwood	I	Biblio.	Jensen, 1995
India	1991-1992	Fuelwood	P	Sur., Math. mod.	Mohan Kumar et al., 1994
		timber
India	1997	Timber, fodder	N	Biblio.	Newman, 1997
Nepal	1984	Fuelwood	P	Sur	Fonzen and Oberholzer, 1984
Indonesia	1990	Fuelwood	P	Biblio.	Smiet, 1990
America	1989	Fruits	I	Biblio.	Clement, 1989
America	2000	Fuelwood	I	Biblio.	Beer et al., 2000
Costa Rica	1990	Fuelwood	P	Mes.	Beer et al., 1990
Costa Rica	1990	Wood	P	Math. mod.	Somarriba, 1990
Ecuador	1987	Wood	N	Sur.	Mussak and Laarman, 1989
Brasil	1993-1995	Fruits	L	Sur.	Muñiz-Miret et al., 1996
Paraguay	1984	Wood	L	Sur.	Evans and Rombold, 1984
África	1991	Fruits	I	Biblio.	Sallé et al., 1991
Cameroun	1999	Fruits	P	Sur.	Ayuk et al., 1999
Mali	1985	Fodder	P	For inv.	Cissé, 1985
Mali	1995	Fruits, wood	P	For inv.	Bagnoud et al., 1995
Burkina Faso	1996	Fruits	L	For. Inv., Sur.	Boffa et al., 1996
Sudan	1994	Sap	N	Biblio.	Seif el Din and Zarroug, 1996
Fruit-tree orchards
Brazil	1998-1999	Fruits	N	Biblio.	Kleinn, 1999
EU	1990-1994	Fruits	I	Biblio.	Interfel, 1996
Urban forestry
USA	1978-1980	Service	L	Sur.	Anderson and Cordell, 1988
USA	1993	Service	L	Math. mod.	Nowak and McPherson, 1993
USA	1995	Fuelwood	N	Sur.	Whittier et al., 1995a,b
Other systems
Indis	1974-1984	Wood	L	Meas.	Verma, 1988
Burkina Faso	1989-1990	Ed. prod.	L	Sur.	Guinko and Pasko, 1992
* Wood: all usages; Ed. prod.: edible products; Service: landscape, land, fuel-saving. ** I: international; N: national; P: provincial; L: local. *** Biblio.: bibliographical study; Sur.: surveys, interviews; For inv..: Forest-type inventory; Meas.: direct measurement; Math mod..: mathematical model.

A number of factors render these estimates approximative: the in exactitude due to the conversion of local into standard units (such as the yoruba dish for sheanut in Burkina Faso, or the `basket' for açai palm fruits in Brazil), the problem of sales by small piles (or even by estimate), the phenomenon of `diminishing'units of measure (less quantity per unit) in some very poor countries (Blanc-Parnard, 1998; Boffa et al.; 1996; Muñiz-Miret et al., 1996). More importantly, product quantification is often based on different parameters: global output, marketed output, observed or potential productivity, or perhaps economic value.

These factors all conspire to make data on trees growing in non-forested areas quite fragmentary, at least for now. It is chancey to compare production figures, especially when the data collection methods are insufficiently detailed to appraise data reliability.

Definitions

The terms assessment and inventory are used interchangeably in most of the projects reviewed. We believe it is important to make a clear distinction between the two.

Kleinn (2000) describes the inventory as a process of quantitative and qualitative identification of a resource, whereas assessment consists of situating the data thus obtained and attributing values to the specific resource. Lund (1998) stresses that once an object is assessed we can begin to estimate or weigh its significance, importance and value.

As we look at these two processes, they are clearly interwoven, especially for Trees outside forests. The term `inventory' is better applied to statistical methods, techniques and calculations for the obtention of `neutral' and `representative' numerical data, whereas assessment ties in with a more global, subtler and in the end more realistic approach, given the myriad local situations typical of this resource. Natural resource assessment is based as much as possible on inventory data, where available and reliable. But it must also tap data from other sources --- maps, ecological data, sectoral or territorial analyses, economic, socioeconomic, ethno botanical or other data, so that a relative or contextual value can be assigned to the resource.

Throughout this next chapter, the term `inventory' will be used only for the quantitative and qualitative description of a resource. `Assessment' will be used for a more general approach designed to determine the contextual value of a resource.

Assessment goals and users

"Let us begin by reporting, listing, mapping, and the rest will automatically follow" (Couty, 1996). It seems that the world makes more sense when it is explained in figures. Once a reality is quantified and an object qualified we can begin to chart the pattern of trends and changes we have caused within them, as and when they occur. This need for hard facts and figures on natural resources is sharply felt today.

Goal: challenges and objectives

The top priority challenge may simply be to make this resource known to policy- and decision-makers, planners and managers, who need "objective" data before embarking on an action. The seemingly simple question "what is the point of assessing trees growing outside the forest?" does not have a simple answer. The goal of such an exercise depends equally on the use to which the data will be put, the expectations of those who ordered it, and the extent of the land area involved. We sense that there are a variety of possible answers, given that any one non-forest tree system may easily have a wide range of uses, functions, and users. And yet we can certainly identify a number of problems or challenges which are sufficiently widespread in the world to justify the need to assess this resource.

The most obvious challenge is to learn the patterns of change for all wood resources. There are many situations in which the forest resources habitually considered (usually those defined in FAO's land classifications as "forests" and "other wooded land") do not seem to meet even people's most fundamental needs for forest products in some parts of the world, whereas there are apparent surpluses in others. A gap between supply and demand, in other words. This gap is very real in some places, where stocks are dwindling to the vanishing point. Elsewhere, surpluses can be greater and the liabilities fewer. Presumably this "forgotten" resource comes from Trees outside forests, in the case of forest products.

This socio-economic challenge of determining how the need for forest products is being met is linked to the question of whether the observed changes in forest cover (deforestation in many countries, reforestation in others) are fully or partly compensated by the dynamics of Trees outside forests. The point is to obtain indicators of "good management" of natural resource assets.

Another challenge is to establish sustainable development plans to try to optimize the use of biotic and abiotic natural resources. At all scales - national, provincial or local, it is essential to consider the full panoply of resources. Assessing their state or recent changes over time is particularly important for dwindling or degraded resources.

Photo 40. Small oasis near Zer-el-ghibli, Mauritania (© Balderi/FAO).

The need for assessing Trees outside forests in emergency or shortfall situations is plain, but there are also other reasons for assessment. As shown, Trees outside forests contribute many and often vital goods and services in the social, ecological and cultural spheres. They contribute to food security, poverty reduction and land security - the latter a key factor in development. Planning exercises that fail to consider this resource cannot help but underestimate the potential of the target area, supplying a truncated picture of the real situation on the ground. In arid and semi-arid zones where tree cover is sparse and irregular, Trees outside forests are an essential component of desertification control. Ecologically, they check wind and water erosion, protect soils, produce organic matter, and fix soils, and productively they provide fodder and fuelwood. An inability to assess the dynamics of this resource would signal a real gap in our knowledge, especially in already fragile environments. The conservation of biological diversity is another area where we implicitly need more hard data on Trees outside forests. These tree systems are special and often unique ecosystems, containing species and taxons of flora and fauna not easily (or not at all) found in other ecosystems. Recent world interest in trees as carbon sinks for the sequestration of greenhouse gases also indicates a need to chart all sources of stored carbon and their evolution. Trees outside forests have so far been conspicuously absent from the debate on carbon storage.

The challenges are comparable to those of forest tree assessments. But we do get a clearer idea of the real contribution of all trees, inside and outside forests, by extending the equation. There may be some question about the classifications listed in Table 7, but at least they indicate the many and diverse challenges that an assessment of Trees outside forests can begin to answer with respect to current concerns.

But the enterprise is undoubtedly delicate. We have seen how diverse these tree systems can be in terms of structure (clumps, rows and single trees), composition (multi-species compositions are common) and the architecture of their component trees (clipped, pollarded, pruned, branchy, multi-stemmed, and so forth). And we have shown how highly variable are their functions and roles. We have underscored that the resource is managed by rural or urban producers and that it is primarily an integral component of their production system, making the functions and services of Trees outside forests dependant on the historical, geographical and socioeconomic context. For all these reasons, it is hard to lay down exact rules applicable to assessing every type of out-of-forest tree system in every possible context.

One good, basic way to begin is by spelling out the objectives of assessment. This exercise should be wide open to all sectors involved, directly or indirectly, in operations. We should ask why this basic stage of forest inventories is even more vital for Trees outside forests.

The main reason is that the problem with these characteristically multi-use and multi-functional trees, which may be growing on land that comes under sectors ranging from the forest to the agricultural, rural, urban or infrastructure sectors, imply the collection of a vast amount of data which can easily become unwieldy unless strict parameters are established and followed from the outset.

These tree systems are also closely associated with people and with local communities. The objectives of the assessment need to give weight to the needs and interests of each stakeholder. Implicitly, then, the inventory selected will inevitably represent a compromise among the expectations of all stakeholders. The objectives need to be clearly ranked.

Table 7. The major challenges by territorial scale

	Socioeconomic	Ecological	Cultural
World	Supply of forest products Food security Carbon sequestration	Desertification control Conservation of biodiversity Carbon sequestration	Conservation of biodiversity
Regional	Supply of forest products Food security Carbon sequestration	Desertification control Conservation of biodiversity Carbon sequestration	Conservation of biodiversity
National	Supply of forest products Food security Land use planning Income diversification Carbon sequestration	Land use planning Desertification control Conservation of biodiversity Carbon sequestration	Conservation of biodiversity
Provincial	Supply of forest products Food security Land use planning Income diversification	Land use planning Desertification control Conservation of biodiversity	Conservation of biodiversity
Local	Sustainable local land use planning and management Supply of forest products Food security Income diversificationSecure land tenure	Sustainable local land use planning and management Desertification controlConservation of biodiversity	Conservation of biodiversity

Assessments may well also overlap other inventories or assessments for this `multi-purpose', `multi-sectoral' resource. It is basic to place the planned assessment squarely in the context of the real issues involved, and at the same time not overlook the concerns of other sectors.

Photo 41. It is essential to adopt a standard inventory protocol for thorny, multi-stemmed trees (Acacia erhenbergiana, Mali. © Cossalter/Cirad)

In the (mainly tropical) examples taken from national or provincial assessments for our review, "planning" is the main objective cited for forest products such as fuelwood and service wood. This is justified by the major contribution of Trees outside forests to wood production, perhaps even exceeding that of forests. Sudan's 1995-1996 national inventory (Glen, 2000), which is described as a `reconnaissance vegetation inventory' designed for provincial and national planning purposes, also supplied preliminary estimates of fuelwood and service wood. Beginning in 1990 in Niger, Energy Project II (SEED-CTFT, 1991) clearly underscored the role of "scattered" tree formations in the production of fuelwood. Rural people in some areas rely entirely on such formations for fuel. Other initiatives such as the 1995 Haryana State Inventory by the Indian Forest Service (Singh, C.D., 2000), extend the list of inventory products to paper pulp, essential oils, packing cases and matches, for example.

A longer list of inventory products does also complicate the selection of the best data-collection methodology, especially in that it poses the problem of scale. What seems feasible at the local scale becomes quite complex when our goal is reliable data for a large area - data spanning the zone in question (country, province, locality). At the city level, other types of tree systems, interwoven into the urban fabric, provide services destined to increase in future. The already strong link between urban dwellers and their trees could conceivably drive the introduction of more efficient management of these tree systems. Situations in this domain are extremely varied.

A detailed list of the constraints is one essential component in defining the objectives of assessments of trees outside forests. Forest assessments, even those for which methodological updates are a constant feature, are very complex and costly operations. Working out the right tools to lighten these procedures remains a constant preoccupation.

There are aspects of trees outside forests, such as their structure, spatial distribution, extent of area covered, and so forth, that comprise extra constraints compared to forest formations. This must be carefully thought through. A simple adaptation of the methodology is not enough (Annexe 2). The definition of objectives, and their ranking, also implies defining the degree of exactitude expected of the results. Greater exactitude is demanded for primary than for secondary objectives. The more samples there are, the more exact the data. In other words, the same parameter applied at the national level will be less exact, the provincial level more exact, and the local level most exact, for the same sampling plan.

Assessment users

The above classification of the objectives identifies decision-makers and managers as the prime users of these assessments - though clearly the end beneficiaries are always rural or urban populations. Administrative services responsible for a sector, such as the forest services, or those responsible for overall land use planning, such as ministers of plans and development, would normally be the ones to order such assessments.

The operational administrative services involved may be central or provincial, depending on how the country and target area are organized administratively. But assessment exercises are in any case often put in the hands of specialized entities. Locally, this may come down to development projects requiring data on trees growing outside forest areas so that they can place their action in a global context of integrated land management. Unhappily, however, this sort of assessment is not always known and listed because the data is rarely disseminated beyond the actual project. Concrete examples covering a number of countries within a region are rare, but the Kleinn study (1999) for seven countries of Latin America (Brazil, Costa Rica, Colombia, Guatemala, Haiti, Honduras and Peru) is one that can be cited.

This being the case, countries should try to set up an organization to assess their off-forest tree resources in line with the challenges mentioned here. For forest resource assessments, the fact that the agency responsible comes under the forest service poses no problems. But a problem inevitably arises for Trees outside forests because more than one sector is involved. This is a multipurpose resource, bringing into play such diverse sectors as forestry, agriculture, pastoralism and urban planning, plus, perhaps, secondary or tertiary concerns such as the agrofood, small-scale and industrial sectors, land use planning, the environment, capital development, tourism, natural assets, and the like. Our bibliographical sources show that the forest services have often taken the initiative for assessing Trees outside forests in rural areas, and with a forestry slant for just this reason. To resolve this conflict, each country should set up an independent body with a steering committee representing the main relevant administrative services (forestry, agriculture, livestock production, and land use planning and capital development such as roads, tracks, channels and so forth).

Today, the trend is to decentralize responsibility for land use planning, putting decision-making in the hands of local and provincial authorities. This universal pattern of change is an incentive to make natural resource assessment activities consonant with this trend at the operational level. The subdivision of the national territory best suited to this task is probably the "province", despite the great variation in relative province size from one country to the next. These administrative and political units are also fairly homogeneous geographically, historically and in socioeconomic terms. The entity and methodology selected to assess trees outside forests will inevitably need to take this into account.

For this reason it is hard to imagine applying a single assessment protocol to all trees growing outside forests within a given country. But if there is to be at least a minimum amount of comparable data at the country scale, the sampling plan, ground measurements and surveys should all embody a certain number of common rules. This "base protocol" can be padded out by standardized, complementary protocols by those provinces, localities or economic sectors that wish and can afford to do so.

Classification of Trees outside forests and major types of assessments

Classification

It is fundamental to be able to integrate Trees outside forests into a system of classification so that they can be described, mapped and assessed. Regional or national statistics are inconceivable in the absence of a classification system as reference (Box 43). There are existing classifications for agroforestry, but none are universally applicable for trees growing outside forests (Kleinn, 2000).

The "forest" classification experience gives some idea of the difficulty and controversiality of the exercise. The boundaries between categories, particularly, are always open to debate.

The choice of categories depends as much on the type of tree system under study as on user needs, which is like saying the choice hinges upon the goal and objectives of the assessment (environmental, social, economic, and the like). A review of Trees outside forests at the national or regional scale for national statistical purposes would demand an easily implemented classification, one neutral enough to be used as a reference and further refined as a reliable base for more detailed studies in other sectors such as agriculture or urban planning, or at the provincial level.

The classification attempts reviewed in the preparation of this paper show how closely entwined are the concepts of land cover and land use, and how they tend to be used interchangeably. Some categories of Trees outside forests are associated with site (which usually implies use), as for trees on farms, around ponds, in meadows, along roads, in towns, and so forth. Others use the criteria of tree distribution or spatial organization (Alexandre et al., 1999), such as line-plantings, single trees, clumps, etc.

The regional study of data-gathering on the largest number of off-forest tree system categories in eight Latin American countries (Brazil, Costa Rica, Colombia, Guatemala, Haiti, Honduras and Peru -- Kleinn, 1999) showed that none had drawn up a register, so the search for data was multisectoral. The statistics on land cover and land use gave some idea of the relative importance of Trees outside forests in each country. The classification worked out for this paper was primarily based on land use criteria.

The main sources of confusion mentioned in this report came from teasing out the separate aspects of land use and land cover. Dense growths of trees in pasture were easily confused with forest, given their high density, as were cocoa or coffee plantations, for the same reason. The study clearly showed some of the problems involved in establishing a simple and reliable a posteriori classification.

It does seem essential to move in the direction of land classifications that include Trees outside forests in the definition, so that these tree resources can be reviewed at the country level, even without attempting a specific classification for such trees. This would encourage the sectors involved to work together to avoid slanting the classification towards a sole optic such as agronomy or forestry. At the country level this exercise may be important enough to prompt a review of land classifications. The vast extent of trees growing outside forests no doubt justifies the effort.

An attempt to harmonize nomenclatures might conceivably precede a single national classification. This is what is happening in France right now. The National Forest Inventory (NFI) and the annual land use survey (Teruti) of the central bureau of statistical surveys and studies have recently begun to coordinate classifications of Trees outside forests. The objective is to eventually use the annual Teruti data to update NFI's ten-year data.

Photo 42. The potential of standing Prosopis juliflora in Cape Verde is hard to estimate. (© Bellefontaine/Cirad).

A multisectoral national classification system including Trees outside forests would constitute a useful tool for truly integrated management at the country level, and for monitoring planned action. This kind of system could conceivably fit into a regional classification as well. This is just the opposite of Kleinn's procedure in Latin America (1999). On the other hand, reaching for a more global scale inevitably entails a degree of simplification that is probably not very suitable for such a complex resource.

Types of assessment

Resource assessments fall into three broad categories in accordance with their objectives.

• Acquisition of data on which to base an analysis of either a territory or a resource. The point is to support a decision or negotiation for the preparation of management plans, outlook studies or master plans. This can be described as an ante assessment.
• Acquisition of data to appraise the impact of policy decisions or land use planning operations. The point is to determine the effectiveness of earlier measures. This type of operation is described as a post assessment.
• Acquisition of new information for an understanding of Trees outside forests and how they work as special ecosystems. This basically involves multidisciplinary or other scientific studies.

It is not always a simple matter to distinguish between post and ante assessments. Indeed post assessments are common in iterative processes intended to establish a new analytical basis for the revision of a management or master plan. The third type of objective is relevant for an understanding of the role of Trees outside forests and the factors affecting their development and productivity, but we shall confine ourselves here to the post and ante types of assessment.

Some examples of inventories

The three examples of inventories selected stand out as much for their declared objectives as for the principles on which they are based. They illustrate the range of questions which assessments attempt to answer, and the varieties of methods employed (Boxes 44, 45 and 46, and Annex 2).