This part includes recommendations to prepare and carry out fieldwork activities. The fieldwork, together with recommendations on the data collection techniques, is described step by step for a tract.
Data are collected by the field crews for tracts, plots, subplots and LUS. The two main information sources for the inventory are:
- Field measurements and observations;
- Interviews with local people, land owners or users, key external informants such as foresters responsible for the area where the tract is located.
These two sources of information imply the use of different methods and approaches that complement each other. One them will be used as the main source, according to the type of information and field conditions. As much as possible, field observations should be applied to confirm the information obtained from interviews.
The process for data collection is summarized in figure 5.
Figure 5. Data collection procedures
The organisation structure of National Forest Assessment (NFA) in the country may be as follows:
• A National Technical Team will coordinate and monitor the NFA at National level. This will be done by:
- Analysis and adaptation, if needed, of sampling design, inventoried variables and definitions;
- Setting up field crews;
- Conducting training for field crews;
- Organising and planning fieldwork, in particular mobilisation and preparation of necessary resources and equipment, such as vehicles, and allocation of tracts by field crews;
- Monitoring and backstopping fieldwork, including technical and logistic support to field crews, in order to ensure data quality and homogeneity among field crews;
- Controlling and validating field forms;
- Controlling data and evaluating its quality;
- Compiling databases; and
- Reporting and disseminating results.
• Field Crews will be responsible for collection of data in the field.
A forest inventory field crew, taking into account the amount of information to be collected and the tasks of each individual, is composed by at least four members. Additional persons may be included to improve performance of the field crews when conditions require greater resources. It is desirable that some in the field crews are hired locally and act as guides in the field. The crew leader and/or his/her assistant should be experienced in participatory interview techniques to collect socio-economic data from local people. One of the crew members must be experienced in tree species identification. It is preferable that the field crews include both men and women to facilitate the interviews and it is also advised to include forestry students for capacity building.
The responsibilities of each crew member must be clearly defined and their tasks are proposed as follows:
• The crew leader is responsible for organizing all the phases of the fieldwork, from the preparation to the data collection. He/she has the responsibility of contacting and maintaining good relationships with the community and the informants and has a good overview of the progress achieved in the fieldwork. He/she will specifically:
- prepare the fieldwork by carrying out bibliographic research, preparing field forms and maps;
- plan the work for the crew;
- contact local forestry officers, authorities and the community. Introduce the survey objectives and the work plan to the local forestry service staff and authorities, and request their assistance to contact the local people, identify informants, guides and workers;
- administer the location of tracts and plots;
- take care of logistics of the crew by organizing and obtaining information on accommodation facilities, recruiting local workers, organizing access to the tracts;
- interview external informants and local people;
- ensure that field forms are properly filled in and that collected data are reliable;
- organize meetings after fieldwork in order to sum up daily activities;
- organize the fieldworks safety.
• The assistant of the crew leader will:
- help the crew leader to carry out his/her tasks ;
- take necessary measurements and observations;
- make sure that the equipment of the crew is always complete and operational;
- supervise and orient the workers.
• The workers are assigned the following tasks, according to their skills and knowledge of local species, language and practices:
- help to measure distances ;
- open ways to facilitate access and visibility to technicians;
- provide the common/local name of forest species;
- inform about access to the tract;
- provide information about the forest uses and management;
- carry the equipment.
Training of the crews on the survey methodology should be undertaken at the beginning of the fieldwork in theoretical and practical sessions where techniques of different forest and tree measurements, tally of data and techniques of interviews will be explained and practised.
The names and addresses of the crew members must be written down in field form F1 part B.
In forest inventories auxiliary information is necessary to prepare the field survey and carry out the interviews. Existing reports on forest inventory, national policy and forestry community issues, local people, etc. have to be studied to enable the crew members to understand and to build better knowledge on the local realities.
Each field crew, through its leader, should start its work by contacting staff of the local forestry services in charge of the area where the tracts are located. The local staff may help contacting the authorities, community leaders and land owners in order to introduce the field crew and its programme of work in the area. The local forestry staff may also provide information about access conditions to the site and about the people who can be locally recruited as guides or workers. They may also inform the local people about the project.
Depending on the social context in the country/region, the forest owners may be requested to provide the crews with a written authorization to access the property where the tract is located.
A recommendation letter, written by the Forestry Department and asking for support and assistance to the field crew members, should be issued to facilitate the work.
The data related to the land owners and informants must be reported in form F1, part B.
The Technical Unit of the project will prepare and print, for each crew, the necessary field forms to cover the tracts assigned to it. Six field forms, of one or more pages, are needed for each tract. The forms are described in the following section (section 5).
Some information will be filled-in before going out in field: sections for identification of the tract and plots (header of each page), general information related to tract location (form F1, section A), coordinates of the starting point of the plot (form F2, section A).
The use of secondary data sources, particularly maps, is necessary to determine information such as names of administrative centres (administrative maps) and ecological zones (FAO/FRA 2000 global ecological zones map). Some sections in the form may be filled-in during the preparation phase and be verified, in the field, later on: population data (form F1, part C), information on distances to infrastructure (form F1, part D).
The crew leader must ensure that enough forms are available to carry out the planned field data collection.
Maps covering the study area should be prepared to help the orientation in the field. These may be enlarged and reproduced, if necessary.
Prior to the field visit, each crew must plan the itinerary to access the tract, which should be the easiest and least time consuming. Advices of local informants (local forestry staff, for example) are usually valuable and help saving time in searching the best option to access the tract.
The tract and plot limits will be delineated on topographic maps and possibly on aerial photographs/satellite images, if available. The spots that correspond to the starting point of the plot in the tract are to be indicated, together with their respective coordinates, in the map projection system as well as in decimal degrees (latitude and longitude). The first system is more precise and easier to apply when using the maps, and will be used in GPS.
An enlarged section of the map corresponding to the area surrounding the tract will be prepared (photocopy or printed copy) and used to draw the access itinerary to the first plot.
The plot order for data collection will vary according to conditions of accessibility. It is determined during the preparation phase.
Reference objects (roads, rivers, houses) that contribute to the better orientation of the crew in the field are identified during the planning phase.
The starting point coordinates of the plots are entered into the GPS receiver according to following: (Tract number) + “P”(=Plot) + (Plot number) + “S”(=Starting point), e.g. for tract 13, plot 3: 013P3S.
The equipment needed to carry out the inventory is composed of:
- Compass (360°);
- GPS receiver (Geographic Positioning System) and extra batteries;
- 2 self rolling measuring tapes 10-30 m (metric);
- 2 diameter tapes or calliper (metric);
- Tree height and land slope measuring equipment: clinometers;
- 50 m measuring tape or 50 meter metal rope, marked at every 5 meters;
- Coloured flagging;
- 50 cm (length) galvanized steel bars for plot marking;
- Waterproof bags to protect measurement instruments and forms;
- Binoculars(optional);
- Range finder (recommended);
- Radio /mobile phone(optional);
- Camera and films (or digital camera);
- Waterproof boots and outfits;
- Machetes;
- Emergency kit;
- Topographic maps;
- Supporting board to take notes;
- Data collection forms;
- Field manual;
- Permanent markers and pens;
- Flora and species list (common and scientific names);
- Flipchart;
- Flashlight.
If the tract area is inhabited, the crew must establish contacts with local people and on arrival to the site, meet with contacted persons and others such as village representative, closest forestry service in place, owners and/or people living in the tract area. In many cases, it will be necessary to contact the local population before visiting the area in order to inform them about the visit and request permission to access the property. An introductory meeting may also be organized.
The crew must briefly introduce and explain the aim of the visit and study. A map or an aerial photograph, showing the limits of the tract, may be very useful to facilitate the discussion. It is important to ensure that both local people and the inventory crew understand which area will be studied. The aim of the forest inventory must also be clearly introduced to avoid misunderstandings or raise false expectations. Cooperation and support from local people are essential to carry out the fieldwork. It is easier to achieve this support if the first impression is good. Nevertheless, it must be stressed that the fieldwork consists only in data collection and not local development project.
Some key points about the project introduction are mentioned in Box 1.
Besides the presentation of the project, this initial meeting aims at resolving logistic matters. After the general introduction, access to the forest, interview schedule as well as food and accommodation issues will be discussed. This meeting should also give the opportunity to start the interviews to collect socio-economical information. The number of people included in the field crew must then be reduced to avoid giving the impression that the interviewers dominate the group. Historical information related to the changes in the area (see participatory exercise using aerial photographs in annex, section 6.5.3 page 77) is a good starting point for the discussions.
The field inventory schedule to be carried out in the next days must be explained. This meeting is one of the opportunities to identify key informants and focus groups for interviews. It is recommended to schedule the interviews so that they fit with the daily work-schedule of the people.
All the persons interviewed and providing information on the tract must be mentioned in the list of persons involved in the inventory (form F1, section B).
The plots will be located with the help of the topographic maps (and aerial photographs/satellite images, if available), where the plots have been delineated. Some reference points that facilitate the orientation in the field will also be identified on the maps. A local guide will be useful to access the plots more easily. Orientation in the field will be assured with the help of a GPS where the starting points of each plot have been registered as waypoints. To get to a well defined starting point, an average position should be taken with the GPS when its reading indicates that the starting point is within a few meters (less than 10m). Then, the compass and measuring tape might be used for the last few meters instead of the GPS.
The order of the plots for data collection, decided during the preparatory phase, should be followed and the plot code and orientation must be respected (the collection task must start at the plot starting point).
While accessing the first plot, form F1, section E must be filled in. The coordinates of the departure location on foot towards the first plot must be read on GPS (or on the map, if the GPS does not capture a signal). A sketch representing the covered itinerary will be drawn on the site map (to be attached to the field form), with indications of the reference objects that will facilitate the relocation of the plot. The coordinates of each reference point are read on the GPS and a reference photograph may also be taken. Then, the film and photograph codes will be reported in the form. The flagging coloured tape can be placed along the access path, on trees visible enough to facilitate the return out of the tract.
When arriving to the starting point of the first plot, a permanent marker (galvanized metal tube) is placed into the ground. The marker must be placed exactly on the position of the starting point of the plot. In cases where obstacles obstruct such exact location (tree, rock, river etc.), the permanent marker should be placed as close as possible to the starting point of the plot.
Marker location data must be collected together with a starting point description of the plot in order to enable relocation in the future:
- the coordinates of plot marker position are determined, with the help of GPS, as average position. An identification code will be assigned to name each one of the points identified by the GPS, according to following: (Tract number) + “P” (= Plot) + (Plot number) + “M” (“Marker”), e.g. for tract 13, plot 3: 013P3M;
- the distance and direction (compass bearing in degrees, 360°) of the plot’s starting point, measured from the marker location, must be measured in case that these two positions do not coincide ;
- three prominent reference objects (rock, largest tree, houses etc.) must be identified and the direction (compass bearing in degrees starting from the marker location) and distance from the marker measured.
These indications are recorded on section A of form F2 and are reported on a sketch where the reference points and the starting point of the plot are indicated. A brief description of the reference points will also be provided in a table (the columns containing the bearing and the distance from the marker position may be filled-in according to the sketch indications after the field work).
Markers should be positioned at the stating point of all the plots.
The data collection starts at the plot starting point and continues in predefined direction (see prepared maps and Figure 2). The progress along the central line will be made with the help of the compass and 50 m rope (or metal string), to get a well defined central line. In order to facilitate the bearing, flagging coloured tape may be stretched along the central line and attached to trees as the field crew advances.
Measurements involve both sides, from the central line on a 10 m wide extension. Flagging coloured tape may also be placed on the corners and limits of the plot (at 10 m from the central line) as the crew advances, in order to easily identify the trees within the plot.
Different variables are collected according to the data collection level dealt with:
• Plot: measurements of large trees and stumps (Dbh ≥ 20 cm, or ≥ 10 cm for the trees outside forest). These data are to be recorded in form F3a or b (one for each plot). A plan of the plot must also be completed in form F2 (section C). Then, information on forest and tree uses (forest products and services) is reported in form F6 (one for each plot).
• Subplots (SP): topographic and edaphic (soil) data, together with small diameter tree and tree regeneration data, are collected inside forest at this level. Data related to small diameter trees and stumps in subplots level 1 (SPL1) are reported in form F3 (a/b). Data related to tree regeneration from subplots level 2 (SPL2), and topographic and edaphic information collected at the three measurement points (MP), are registered in form F4. SPL1, SPL2 and Measurement Point (MP) are established only if they are located in a LUS classified as “forest”.
• Land use/forest type section (LUS): corresponds to the land use/forest type sections identified along the plot. Information collected at this level will be contained in the field forms F5 (one for several LUS). Data collected at that level is general information related to the area (legal status, designation, environmental problems etc., in form F5 section A) and forest management and structure (harvesting, silviculture, in section B).
All details related to the plot must be indicated in the plot sketch in form F2, section C. In particular, the following characteristics will be drawn:
- general characteristics such as crossing of water courses, roads, fences;
- limits between land use sections and land use classes in the corresponding sections.
In addition, the sketch must also include all the information and observations that help interpreting the plot.
All trees over 20 cm of diameter at breast height (Dbh) found within the plot are measured (Table 5), and these data are recorded on field form F3a or F3b. Trees located at the border of the plot will be considered as being inside the plot if at least half of the stem diameter is inside at breast height.
For smaller diameters, measurements are carried out within the subplots located at every 120 meters (see Figure 2). The size of trees measure varies according to the subplot level (SPL1 or SPL2) where the measurements are made (see Table 5).
In the LUS classified as “outside the forest”, all trees with a Dbh ≥ 10 cm are measured, and these data are recorded on form F3a or b.
Stumps are measured as for trees, following the same diameter criteria. Stump diameter is then measured at breast height or at the top of the stump, if less than 1.30 m above ground level.
Table 5. Trees and stumps measured per level and corresponding forms
Level |
Measured trees/stumps |
Measurements |
Field form | |
Forest |
Other land uses | |||
Plot |
Dbh ≥ 20 cm |
Dbh ≥ 10cm |
Species, location, diameters, total height, health, quality |
F3a or F3b |
Subplot level 1 (SPL1) |
10 cm ≤ Dbh < 20 cm |
None |
Species, location, diameters, total height, health, quality |
F3a or F3b |
Subplot level 2 (SPL2) |
Tree height ≥ 1.30 m and Dbh < 10 cm |
None |
Total number by species |
F4 (section C) |
Tree regeneration (tree height ≥ 1.3 m and Dbh < 10 cm), within SPL2, are only counted by species. Only tree species (species reaching 5 m in situ) are recorded.
For bigger diameter trees, within SPL1 or the plot, collected data are more complete and include, besides the species identification, height, diameter, health and tree quality. Indications on tree diameter and height measurement methods are provided in the appendix (see section 6.2), page 65.
Data on forest products and services is collected for each land use class present in the plot. The information will be reported in the form F6. If there are several LUS with the same land use class in the plot, they will be grouped together.
The information will essentially originate from interviews with local people or from people accompanying the field crew in the field, but should also be verified through field observations. Interview and group discussion techniques and instructions are included in section 4.4.6.
Once the work in the first plot is completed, the time is recorded on form F2 (section B) and the crew need to access the second plot. If the forest cover allows it, it is possible to directly access the plot with the help of the GPS. Otherwise it may be assured by using the compass and measuring 250 m (horizontal distance) along the central line of the previous plot. If the starting point of the next plot to be reached is not accessible on a straight line, the obstacle must be bypassed using auxiliary methods that allow finding the original line.
Two major user groups will be interviewed:
- external key informants;
- forest and tree users (considered as individuals or focus groups).
In the absence of local inhabitants, many of the variables related to the focus groups (forest users) will essentially be collected from observation or from key informants.
Table 6 shows an overview of people/groups of people that may provide information.
Groups/ individuals to be interviewed |
How to contact, identify them? |
Where? |
When? |
Information |
Key external informants: local forest services, organizations and local administration representatives etc. |
By phone, correspondence or visit |
At office |
During the planning phase of the fieldwork or/and before reaching the site |
- Logistics, - Background information on the tract - Information on the people living in the tract or in the surroundings - General information on the distance and access to the tract/plots - General information on the land use section (ownership, protection status, management, ecological problems) - Forest products and services |
Focus groups or individuals: tree and forest resources users, forest dependant people (owners, women, men, hunters, residents…) |
Recommended by external key informants Rapid rural appraisal exercise to identify the stakeholders (see section 6.5.2) |
At their house or in the village On the studied site (transect walk, persons working in the fieldwork) Met close to or within the site |
Introduction meeting with the local people Previously fixed meeting (group or individual meeting) |
- Information on local population (history etc.) - General information on the land use section (ownership, protection status, management, ecological problems) - Forest and trees management and uses, forest products and services. |
• Identifying external key informants
Key informants are external individuals with particular knowledge about the area, the forest and the people. They don’t have to be local forest users themselves.
How to identify external key informants? In the planning process of the fieldwork, local foresters, representatives from local development organizations and local administration will be contacted for logistics and planning activities. Some of these people may provide very useful background information and they will be selected as key informants.
Key informants may sometimes be interviewed before going to the sampling site. Often, the key informants have knowledge of the accessibility to the site. They may also provide literature and other existing data.
Examples of key informants: forestry services (extension, forest guards), NGO staff, local administration staff, etc.
• Identifying focus groups and individuals
The focus groups are defined as people who relate to and use the forests on a frequent basis. These people might live in or close to the tract and may be foresters or forest owners. They may be interviewed in groups (focus groups) or individually.
How to identify focus groups? Upon arrival of the field crew to the site, the main forest user groups, or stakeholders, must be identified. This task may be carried out through discussions with village representatives, people living in the forest and external key informants, or through a visual exercise. The Rapid rural appraisal (RRA) exercise on identifying key stakeholders explained in Annex section 6.5.2 page 77 (Venn Diagram) is one way to do a stakeholder identification.
Representativeness is a complex issue to be aware of when identifying forest users or stakeholders to interviews. Many forest users share common characteristics and are classified within a common group, for analytic purpose. Nevertheless, wide variations in cultural and social factors (gender, age, wealth, status, religion, etc.) often exist and should be taken into account. Therefore it is recommended to identify stakeholders together with several local participants in order to appropriately define the forest user groups. Many different groups might be identified but the inventory must put emphasis on the individuals and groups that use forest products and services.
Example of categories of focus group: women, men, long-term residents (for historical changes), young people, forest owners, hunters, mushroom pickers, people coming from other regions, etc.
First, data collection from interviews may be collected from external key informants before going to the field (planning / preparation phase). Collected data will mainly refer to the tract (form F1).
In a second phase, the data may be collected in the field, in two different sets:
- Some variables related to the tract may be collected from external key informants and cross-checked with the focus groups;
- Variables related to the use of forest (products and services) at the level of the LUS.
The data collection in the field may start during the introductory meeting with the key external informants and the local people, or during the first meeting with identified focus groups (after stakeholder identification exercise, see previous section).
General explanations on the data collection techniques, plus group discussions and interview recommendations are provided in annex (section 6.5, page 74). Among the tools and techniques that may be adopted there are:
• Participatory analysis of aerial photographs or maps (see annex section 6.5.3, page 77) may stimulate discussions with the focus groups on a number of variables. This exercise may be carried out during the introductory meeting, or later on, with identified focus groups. It will provide important information on both the variables (what forest and tree resource uses, who uses what, where, etc.) and the logistics on how the field crew can access the tract.
• To carry out interviews within the tract itself, by organizing, for instance, a transect walk (see annexes, section 6.5.6, page 79) or by collecting information from locally recruited workers who participate in the plot measurement work. This will allow to better link collected data with the location of the tract/LUS in the field.
• A stakeholder identification analysis exercise (see section 6.5.2, page 77), might be a good opportunity to discuss the use of forest products and services.
• A forest product and services identification exercise (see section 6.5.7, page 80) may be organized to collect data on forest products, services and users from the focus group.
• Cross-checking may be applied as much as possible (see section 6.5.4, page 78).
• Direct observation is also very important tool for data collection and cross-checking of information from the interviews (see 6.5.5 page 79).
The questions should be clear and simple in order to be easily understood by the interviewee. A list of variables and formulated questions to address these variables during the interviews are suggested in the following paragraph. Nevertheless, it must be stressed that a lot of flexibility is necessary when addressing the questions. These are only suggestions and are not pre-formatted. Questions will be asked in the order that is the most natural and should not be repeated. When formulating the questions, interviewee's culture and language must be taken into account.
• Background information on the tract (form F1, section A):
Administrative divisions (7-10): “What are the names of the administrative unit/ district/ province/ village and the local name of the area?”
• Information on the people living in the tract or in the surroundings (form F1, section C):
- Population on tract (21): “How many people live in this area?” (the area refers to the tract).
- Population since (22): “How long (from what year) have people lived here?”
- Population dynamics (23): “Have most people in the area been living here for the past 5 years?” or “Have you seen a lot of changes during the last 5 years of people coming or going?” If there have been changes “Why?”
- Main activity (24): “How would you describe the livelihood of the majority of the people living in the area surrounding the tract?” Cross-checking of direct observations and information provided by the interviewees may provide a good overview.
• General information on the distance and access to the tract (form F1, section D):
Distance to the permanent road, seasonal road, inhabited area, school, market, hospital (26-31): “What is the distance from the tract to the closest permanent road, etc.?”
• General information on the land use section (form F5, section A):
- Designation/protection status (82): “What is the legal designation of the forest? Is it a state forest, a community [communal] Forest, a village forest, a National Park, etc.?”
- Ownership (83): “Who is the legal owner of the land (forest) in the sample area? Is it public, is it private” If private “Do people have land titles?”
• External key informants may also have an opinion on variables asked to the focus groups, such as: most important forest products and services, ecological problems, rights and conflicts. One should keep in mind that in the absence of local people, the information will be provided mostly by the key informants. Moreover, even when the information is provided by the focus groups, it must be cross-checked with the data provided by the key informants and observations.
- Legislation and forestry incentives awareness (101e and 101g): ”Are there any laws/ incentives concerning this product/service? If yes, which one?” “Are the local people aware of this legislation?”
- Compliance (101f): “Is the legislation concerning this product/activity respected?”
- Application to forestry incentive (101h): “Have the people applied for incentives concerning this product/service?
• The focus groups will essentially provide data on the forest uses and forest products and services (form F6).
- Products and services category (99): “What products do you collect in this part of the forest?”
- P/S Rank (99a)/ Species Rank (111a): “Of all the products that have been identified, for your household/village/group, what is the most important product that is extracted from this forest?”
- Harvester / User (101): “Who are the persons that harvest or use the product/practise this activity?
- Gender (101c)/Children (101d): “Do the women harvest the product? Are the harvesters mainly women? ”Do the children participate in harvesting the product?”
- End-use (102): “Do you sell this product?” if yes, “to whom?”
- User rights (103): “Who has the right to harvest/use this product/ to practice the activity?” “Is there anybody who may exclude the others from collecting it?” “If you can harvest it, is it because you are also the owner?” “Are the harvesting rights by tradition or are they legal?”
- User conflicts (104): “Related to the product that we have been discussing, do you feel that there exist any disagreements, either with other local people or with externals, about harvesting or using this product?”
- Demand trend (105): “Do you need more of this product?” or “Is the quantity you extract nowadays enough to satisfy your need?”
- Last activity/extraction (108): “When did you last collect this product?” “How often do you harvest this product/practise this activity?”
- Trend (109): “Did you (or your family) harvest as much of this product today as 5 years ago?”
- Change reason (110): if there has been any change in the quantity of extraction/ frequency of activity, “Why is it so?”
• A few questions related to the tract (form F1, section C) may also be asked to the focused groups, when analysing the maps, especially:
- Population dynamics (23): “5 years ago, were there any people living here?” or “Do the young people often stay in the area when they have a family of their own or do they go to the city?”
- Settlement history (25): “What are the main historic events that you remember from this area, such as for example, conflicts, change of land tenure, natural disasters etc”.
• Other questions related to the LUS (form F5) may also be asked or cross checked with observations or information provided by external key informant:
Environmental problems (84): “What is the most important [ecological] problem in forest around the area where you live? How does it affect the land? Have you seen any changes that are affecting your day to day life? Change in yield?”
