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FAO, Forestry Department, Forest Products Division, ROME


Non-wood forest products (NWFP) provide a wide range of human needs including food, medicines and construction materials. Many of these NWFP are important sources of income and employment for rural people and some NWFP are even traded at the international level.

In order to determine a sustainable level of subsistence use or any commercial utilization of a given NWFP, accurate information is needed on the status and regenerative capacity of the resources and on the harvesting techniques used to provide the product, in addition to information on the socio-economic and cultural aspects affecting the use of the NWFP.

Practical methodologies for inventorying forest resources providing NWFP and for assessing their harvesting impact are under development, but still not yet fully elaborated neither widely available for implementation by resource managers.

This paper analyses the factors to be taken into consideration when planning an assessment of the forest resources providing NWFP. Some examples of NWFP inventory and harvesting impact methodologies are described and current knowledge gaps and needs are analysed.

Keywords: NWFP, forest inventory, harvesting.


Non-wood forest products (NWFP) are often proposed as an environmentally friendly and socially equitable way of using forest resources; however, many examples exist where over- or inappropriate harvesting of NWFP has led to serious forest degradation, including threatening the survival of the species used.

The purpose of this paper is to raise awareness among forest resource managers on the desirability of sound NWFP assessment and on the need to incorporate inventory and harvesting impact assessments for NWFP as a full component of their forest management strategy. The paper describes first some key considerations regarding inventory and harvesting of NWFP, followed by an overview of some methodologies used, and a presentation of the main issues which are currently debated in this field.

The paper is largely based on the report by J. Wong (Wong 2000), and the outcome of a workshop entitled “Developing needs based assessment methods for non-wood forest products”. The workshop, which was held in FAO HQ, Rome, was organized by the UK Department for International Development (DFID) and the European Tropical Forestry Research Institute (Baker 2000).

Key considerations regarding NWFP inventory and harvesting

NWFP provide a wide range of human needs including food, medicines and construction materials. Many of these NWFP are important sources of income and employment for rural people and some NWFP are traded at the international level. For many types of NWFP, such as mushrooms, berries, nuts, fruits, edible leaves, herbs and medicinal plants and which are gathered on forest lands or from trees outside the forests, no specific forest management plans or silvicultural treatments are applied. The availability of NWFP in a forest is often taken for granted and many people assume that as long as the forest is simply protected or managed for timber, the supply of NWFP will be automatically guaranteed. This is a false assumption, in order to determine the sustainable level of use of a given NWFP (be it for subsistence or for commercial utilization), accurate information is needed on the status and regenerative capacity of the resource and on its harvesting levels and techniques. In addition, information on the socio-economic and cultural aspects affecting the use of the NWFP is also required.

For the purposes of this paper, the following definition of NWFP is used: “Non-wood forest products are goods of biological origin other than wood derived from forests, other wooded lands and trees outside forests” (FAO 1999).

The assessment of NWFP, and the forest resources providing them, is an essential tool for the sustainable management of these resources.

Various approaches exist to carry out NWFP assessment: those drawing on indigenous knowledge and ethnobotany, and those drawing on quantitative inventory. However, the range of assessment methods used so far in tropical moist forests is limited and more attention should be given to ensuring that quantitative inventory assessments are biometrically valid.

Forest inventories increasingly aim to expand their traditional tree-based focus to include the assessment of key NWFP as a way to obtain the baseline resource information required to maximise their contribution to livelihoods of people and to national economies. However, it is generally agreed among forest resource managers that there is a need for practical methodologies on: (1) how to determine the sustainable level of NWFP utilization; (2) what is the status and regenerative capacity of the resource/species; and (3) what are the socio-economic and cultural aspects affecting/governing the collection and use of NWFP?

Assessing NWFP resources and their harvesting impacts is still a difficult task because of the multitude and variety of species and life forms; the many interests (often conflicting) and disciplines involved; the lack of commonly recognised terms and definitions; and organizational and financial constraints in view of their perceived “low economic value”. Meanwhile sociologists stress that at the community level, methods need to be devised that can be carried out by the community and respond to their management needs. It is argued that these need to be very simple.

NWFP resource assessment and harvesting methods

Resource inventories and harvesting impact assessment for NWFP is relatively new and has received little formal study; consequently methodologies have been developed by individual researchers in response to local circumstances and the peculiarities of the resources under study.

There has however been a proliferation of studies into the potential of NWFP for income generation as a means of involving local people in forest management and benefit sharing. A basic premise of these initiatives is that the resources, be they animals or plants, should be exploited on a sustainable basis.

An ideal development process seeks to identify those products that can be marketed from a list which has already been shown to be sustainable, and progresses through market research, resource inventory, yield forecasting, determination of sustainable harvest practices and intensities, management planning and monitoring.

To be sustainable, harvest levels need to be based on a sound knowledge of the reproductive biology, distribution and abundance of the resource species. Such information can be obtained from a number of sources ranging from knowledge acquired by indigenous peoples to formal scientific enquiry. The study of NWFP is represented by initiatives arising from varied fields of disciplines such as forestry, ethnobiology, economic botany, social development, natural resource economics, conservation biology, protected area management, agro-forestry, marketing, commercial development, ecological anthropology, cultural geography and human ecology.

Resource assessment of NWFP can take place on a wide range of scales from research studies on permanent sample plots to supra-national studies of species distributions. In her comprehensive report entitled “The biometrics of non-timber forest product resource assessment: a review of current methodology”, Wong (2000) reviewed the most used methodologies for approaching NWFP assessment.

These methodologies range from biodiversity listings; to social science techniques (ethnobiology and anthropological approaches to human-natural resource interactions); economic methods (market and income studies), to the classical forest inventories (single or multiple resource inventories, with yield assessments, growth and productivity studies).

Table 1, based on the above cited report summarizes some of these approaches and their characteristics and relevance to NWFP assessment. For a detailed analysis see the complete report (also available on Internet at:

Table 1: Types of assessment for NWFP

TypeDescriptionRelevance to NWFP
Biodiversity inventoriesa checklist of the taxa identified at the sample locality or plot presented by family and generaSpecies lists are a useful source of information on the distribution and ecology of NWFP, but provide little or no information on abundance
Social sciences techniques /anthropological methods (local knowledge, participatory approaches to data collection; classic and quantitative ethnobotany)Ethnobotany deals with the inventory of the traditional uses of plants by peoples. Classic ethnobotany techniques require a substantial investment in time, often years and are generally beyond the time frame of development projects and assessments.Anthropological work and ethnobotany in particular are both highly relevant to the study of NWFP. They often provide a useful overview of the plants used by a local community. They range from an exhaustive listing of all plants and uses to those focused on domains of use such as medicinal plants, food plants or for specific life-forms
Economic methods (market and income studies, cost-benefit and evaluation studies)Economic assessment of the actual and potential contribution of NWFP to local and macro economies and of studies into the marketing and value addition of NWFP; evaluation of the costs and benefits of including NWFP in the management plans; household surveys; market researchEconomic methods are used to estimate the gross raw material availability. A range of survey methods at local or national markets can be used to estimate the quantities of raw material and products circulating in the NWFP trade network which cannot be traced to forest sources (for example like for tree exudates such as gum arabic or pine resins). Market- focussed product surveys however do not consider the abundance of the resource supply or the potential for sustainability
Forest inventories
(single resource inventory; single purpose multi-resource inventory; multi-purpose resource inventory- MRI)
1- single resource inventories aim at the quantification of the abundance and distribution of a single product
2- Single purpose multi-resource inventories provide management information on several NWFP in a given area.
3- MRI have been defined as data collection efforts designed to meet all or part of the information requirements for two or more products, functions (such as timber management and watershed protection) or sectors (such as forestry and agriculture).
1- The NWFP has to be either very valuable, or subject to legislation for it to justify a species-specific inventory (high value medicinal plants, bamboo-, rattan- or palm- products..)
2- It can be a sound and pragmatic means of studying the distribution, abundance and NWFP management potential of the area to be logged.
3- Many NWFP assessments take place in MRI. NWFP is often a small component of the inventory and the development of protocols can be constrained by the need to compromise with the needs of the other components.

As already mentioned, most NWFP are used and managed by local people. Therefore, an aspect of particular interest is the involvement of local people in NWFP assessment work. There is often a great amount of local knowledge regarding the use of forest resources. Collecting this local knowledge is a quick way of obtaining basic information about resources and harvesting patterns. Tools for information gathering and analysis include a range of interview types, meetings with communities, different games, visual aids or activities.

Table 2: Examples of areas of local knowledge and their possible uses in NWFP inventory and harvesting

Local knowledgeUse in inventory
Species identification.Local tree/plant spotters can be useful in the field
Important economic speciesSpecies to include in inventory, rapid vulnerability assessment
Vegetation classification, Micro-climate types and distribution, Soil types and distributionCan be used for stratification
Harvesting techniques and frequencyAffect enumeration methods and frequency
History of availability, Current estimation of availabilityPrioritise species to include - influence decision on whether inventory is necessary.
Ecology and distribution of speciesSampling method
Human interaction with environment (e.g. existing management)Influence inventory objectives & design
Forest and resource valueInfluence management objectives and hence inventory objectives.
Socio-economic factors affecting NWFP managementInfluence decision to have an inventory and its objectives. Influence interpretation of inventory and harvesting impact assessment results.

(from Wong, 2000)

Rapid vulnerability assessment is another method which makes use of indigenous knowledge, combined with published literature and casual observation to assess the potential sustainability of an NWFP harvest, which can be used as a basis for selecting NWFP for further assessment work.

Forest inventories

Although at a first glance NWFP inventory methodologies may look very different, they all have the same underlying structure. This structure is envisaged as a hierarchy of design features. At the highest level is the sampling design itself, whether the plots are to be located using random or systematic, stratified or uniform layouts etc. The next level down is the plot scale at which decisions about plot dimensions have to be made. Within each plot the enumeration that is undertaken is dependent on the target and product being investigated.

Table 3: Overview of assessment structures

a) Sampling design

Sampling designSummaryTarget NWFP examples from review
CruiseRapid survey of large area e.g. by airTree (single spp)
Census100% enumeration of small area (e.g. as in forestry stock survey)All useful plants and animals
Simple random samplingSelection of plots using random number tables (probability of sampling any plot equal)Useful plants
Systematic samplingLocation of plots on a fixed grid, normally with randomly selected origin. Line-plot sampling - Plots located at fixed distances along a transect lineTree (single spp) Mushrooms Perennial herb, Saplings
Stratified samplingArea divided into strata and sampling undertaken independently in each strataBamboo, Mammals
Multi-stage samplingHierarchy of nested sample plots: sample of largest plots selected with further selection of smaller plots within chosen plots.Shrub, Rattan

b) Plot configuration

Plot configurationDescriptionTarget NWFP examples
Measured plots withSquare, Rectangular, CircularInsect larvae,
fixed dimensionsFixed volume, or 2-D areaLiana, rattan
Plotless samplingPoint-centred quarter methodTrees, Palms
Sample fixed number of individuals closest to sample point or within sample areaShrub
Individuals sampled within timed walk from housePalm
Cluster samplingSystematic group of sub-plots in fixed pattern used at each plot location.Rattan
Point and line transects (variable width transects)Observations are made while standing on the point or walking along the line. Perpendicular distance from point or line to observed individuals measured.Mammals
Line-intercept transectsObservations made of intercepts (tracks, signs, plant clumps) with a line or plan projected above line.1991 Large mammal (single spp)
Strip transectsNarrow, very long transects treated as a fixed sample area.Mammals
TorusStrip arranged around geometric shape (square etc. - space inside not enumerated)Tree, insect (single spp)

c) Enumeration method

MethodDescriptionTarget NWFP examples
Presence/absenceRecord occurrence of target in plotUseful plants
TallyCounts of target individuals in plotUseful plants
Size measurementMeasure size of all individuals in plotHerb (single spp)
CoverRecord percentage of plot covered by target speciesHerb (single spp)
Subjective scoresScore features of target into subjective classesTree bark (single spp)
Mark-recaptureCapture Individuals, mark, release and re-capture, use numbers re-captured to estimate population sizePalm fruit
Indirect/Index methodsRecord observable signs of occurrence and use regression methods to estimate size of target population.Mammals

(Wong 2000)

Current issues in NWFP assessment

NWFP inventory and harvesting impact assessment are important at the macro level (national and international); at the community/local area level, and at the product/species level. At the above-mentioned DFID/ETFRN workshop, for each of these levels some research needs and areas of actions were identified.

Table 4: Research issues in NWFP assessment at various levels

Macro levelLinks/integration with/to existing surveys
Optimisation of methods for particular product groups. E.g. gum arabic, bamboo, rattan, bark, etc.
Classification of NWFP in terms of inventory needs and methods
Development of models and identification of indicators - that would help to characterise distribution and abundance of NWFP. Thinking of planning at a national level and how one would stratify sampling and assessment methods.
Linking market information to the resource.
What are the information needs for certification/commercial/ international reporting - what measurable variables or indicators of changes in abundance of the needs of these stakeholders.
Community level
Documentation of existing local knowledge on sampling, assessment, monitoring and analyses.
Documentation of information needs to which communities have to respond to (e.g. local needs, government, trade).
Evaluate local knowledge against information needs and identify gaps (level of rigour required and appropriate, replicability etc.).
Address the gaps through development of methods that build on local knowledge and meet the legitimate requirements of external interests.
Field testing of methods developed.
Dissemination of successful protocols and experience.
Product/species levelAssessment
Evaluation of the relative efficiency (costs, time, relative precision etc.) of new sampling designs (adaptive protocols) in the field for a range of resources and product types.
Evaluation of the potential utility of rank set sampling for utilising indigenous or prior knowledge in the selection of sampling locations.
Investigate the use of local knowledge for generating sampling designs in a way that is biometrically acceptable.
Collation and evaluation of forest monitoring systems for potential applicability to NTFP resource species. Desk study followed by pilot studies. Pilot studies should test efficiency of different methodologies.
Examination of the linkages between biometric methods that monitor growth and yield and those that monitor extraction.
Investigation of the linkages between assumed indicators (e.g. market data, photographs) and resource condition for a range of products and contexts.
Preparation of guidance on the selection of the monitoring protocols for NTFPs in the form of a decision-support system.
Evaluation of the relative efficiency (costs, time, relative precision etc.) of new sampling designs (adaptive protocols) in the field for a range of resources and product types.
Evaluation of the potential utility of rank set sampling for utilising indigenous or prior knowledge in the selection of sampling locations.
Investigate the use of local knowledge for generating sampling designs in a way that is biometrically acceptable.

(Baker, 2000)


A number of biological characteristics have a key impact on the elaboration, selection and improved of inventory and harvesting techniques for NWFP species. Foremost among these are: the specific life-form of the resource species - be them trees, scrubs, annual plants, climbers, fungi, insects, animals or birds. The seasonality of the occurrence of the resource and/or the products to be harvested. Whether a part or the whole species is harvested, and whether this harvesting is fatal or not. The mobility of the resource as different techniques are required for mobile and sessile resources; as well as the distribution and scale of dispersal of the resources.

The above mentioned DFID/ETFRN workshop identified major difficulties with NWFP quantification such as for example (Baker 2000): the variety of life forms and distributions represented by NWFP; the lack of properly researched NWFP-specific sampling designs; the little guidance available on development of appropriate NWFP measurement techniques; or the lack of theoretical models to determine the sustainability of NWFP harvesting. The workshop further recognized that is necessary to increase the awareness of the desirability of sound assessment of NWFP populations and dynamics when considering utilisation of these resources and on the importance of including biometric analyses in the planning phase of any data collection exercise. Furthermore, there is a clear expressed need from field workers for NWFP inventory methods that are simple and easy to use but at the same time are adequate for the determination of harvest levels. This requires further work by inventory specialists on the development of inventory methods and protocols for NWFP, drawing on methods that currently exist in a variety of disciplines. In addition, when undertaking an inventory the issue of whom one is empowering with the resultant information must be considered.

Recognizing the importance of NWFP and harvesting impact assessment, FAO is involved in a number of activities aimed at partly filling the gaps in knowledge in these fields. In an ongoing partnership programme with the European Commission, FAO is working on increasing the capacity in sub-Saharan African countries in the field of NWFP assessment and harvesting.


Baker, N. 2000. Draft report of the workshop “Developing needs-based inventory methods for Non-timber forest products” held in FAO Rome, 4–5 May 2000. DFID-ETFRN.

FAO, 1999. Towards a harmonized definition of non-wood forest products. Unasylva 50(198):63–64.

WONG, J.L.G. (2000) The biometrics of non-timber forest product resource assessment: A review of current methodology. Report prepared for project ZF0077. Department for International Development, Forestry Research Programme, UK. 174 pp.


FAO, Département des forêts, Division des produits forestiers, ROME


Les produits forestiers autres que le bois permettent de satisfaire divers besoins de l'homme, notamment l'alimentation, la production de médicaments et de matériaux de construction. Un grand nombre de ces produits représente une source importante de revenus et d'emplois pour la population rurale et certains sont même livrés au commerce international.

Pour déterminer quel est le niveau d'utilisation à des fins de subsistance ou à des fins commerciales qui garantit la durabilité d'un produit forestier autre que le bois quel qu'il soit, il faut disposer de renseignements exacts sur l'état et la capacité de régénération de ces ressources et sur les techniques de récolte employées, ainsi que des renseignements sur les aspects socioéconomiques et culturels liés à l'emploi de ces produits.

On a entrepris d'élaborer des méthodes pratiques pour faire l'inventaire des ressources en produits forestiers autres que le bois et pour évaluer les effets de leur récolte; toutefois ces méthodologies ne sont pas parfaitement au point et ne sont pas non plus disponibles assez largement pour pouvoir être utilisées par les professionnels de la gestion des ressources.

Le document contient une analyse des facteurs à prendre en compte pour planifier une évaluation des ressources forestières qui produisent des produits forestiers autres que le bois. Des exemples de méthodes d'inventaire et d'évaluation des effets de la récolte sont exposés et les lacunes et les besoins dans le domaine de l'information sont analysés.

Mots clefs: Produits forestiers autres que le bois, inventaire forestier, récolte.

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