Forests Sourcebook - HCV Resource Network

Box 7.12
A Data Collection Model
Data collection methods might combine multiple
approaches. In Tanzania, two complementary methods
were used for data collection. The first was from a network
of field samples distributed along a systematic
grid. The second was from mapping using remotesensing
techniques. The field sampling was arranged in
sample sites composed of clusters. Each cluster contained
four plots of 5,000 m 2 . The plots were designed to
monitor the dynamic of changes of the land-use systems
and of the forest and tree cover in the country. It was a
one-phase sampling for continuous forest inventory.
The data collection follows the model in the figure.
For each sample unit there were several levels of
data collection, corresponding to different data sets.
Data sets included local populations; forest and tree
products and services, and users, which were tied to the
land-use class; and land use–level data with information
on protection status, vegetation coverage, environmental
problems, and tree characteristics (species,
height, diameter, health) attached to the plot where the
trees were found.
Country
• Population
• Accessibility
to services
Sample site (tract)
Plot
Land-use class
• Environmental
problems
(fires...)
• Resource
management
• Protection status
• Ownership
Land use section
Trees
• Products and
services
• Resources users
• Species
• Tree heights
• DBH
• Health
Source: FAO 2007.
with a high probability of successful implementation. At the
beginning of the project, the project team should undertake
the necessary consultations to find out the quality of the
available data (for example, cloud free, right season), and at
what cost. In some countries, much is already known about
technical options, but the organizational and financial
aspects are lacking. In implementing national forest inventories,
it is important to clarify the objectives of inventories
and articulate the responsibilities of the various groups
involved.
Ensure new and previous inventories can be linked.
The way national forest inventories are linked to previous
inventories needs to be closely examined to ensure that the
current inventories are seen as reliable and credible.
Country specific considerations. In some countries it
will be important to develop a mechanism for handling
forests under land mines.
NOTE
1. This section draws heavily on the United States Forest
Service work on national inventories. For further information,
Ron McRoberts (rmcroberts@fs.fed.us) and Chip
Scott (ctscott@fs.fed.us) may be contacted.
SELECTED READINGS
USFS (United States Forest Service) National Forest Inventory
and Analysis Web site: www.fia.fs.fed.us.
NOTE 7.1: NATIONAL FOREST INVENTORIES 261