The country data, available in the form of statistical tables or maps, are the main source of information for the assessment. Therefore, a review of the current state of the forest inventories in every country is presented a proper understanding and evaluation of the Project methodology and results.
| Table 1 | |||||||
| State of forest inventory in non-tropical developing countries at end 1990 | |||||||
| Region | Number of countries with forest resources data at national level | ||||||
| Number of countries under assessment | No assessment | One area assessment | More than one area assessment | Forest plantations assessment | Volume and biomass assessment | ||
| before 1981 | 1981–1990 | ||||||
| Africa | 8 | 3 | 0 | 5 | 0 | 8 | 1 |
| Asia | 17 | 1 | 10 | 2 | 4 | 17 | 5 |
| South America | 3 | 0 | 1 | 2 | 0 | 3 | 0 |
| Total | 28 | 4 | 11 | 9 | 4 | 28 | 6 |
Source: FORIS database of the Project
The findings of the Project on the current state of the country forest inventories can be summarized as follows.
Only for a limited number of countries the forest cover area estimate is based on field inventories or remote sensing. For most countries the assessment is based on expert's estimates or on official national statistics. In particular the application of remote sensing techniques is much less developed in the non-tropical than in tropical countries.
There is considerable variation in the timeliness of the information. The data is about ten years old, on average, which could be a potential source of bias in the assessment of change.
Only for 4 countries (all located in Asia region) more than one forest cover assessment is available. These countries, however, have not used appropriate techniques, such as Continuous Forest Inventory (CFI) design, for change assessment.
No country has carried out a national forest inventory containing information that can be used to generate reliable estimates of the total woody biomass, volume and change.
Two main techniques of global assessments have been tried so far both based on the available data: (i) a questionnaire approach and (ii) a centralized approach. The questionnaire approach was started in 1948 and abandoned in 1968 because of many non- or incorrect responses. The centralized approach was started by FAO/UNEP Tropical Forest Resources Assessment Project (1980) and also used by the present project. It consists in collecting the existing country data from a wide variety of sources at FAO HQ, bringing them to a common conceptual and mensurational standard and finally adjusting results to the common reference.
The centralized methodology used for the assessment of the non-tropical developing countries is similar to the one used for the tropical with the following characteristics:
use of a database management system for easy storage, retrieval, analysis and updating of country information;
use of a modeling technique (syn. adjustment function) to update country information to common reference year(s) i.e. 1980 and 1990;
use of auxiliary variables such as ecofloristic zones; population density and population growth in the adjustment function, for which data are readily available and which are among the important driving forces behind deforestation;
reduction in size of the assessment unit from national to sub-national level which is ecologically and demographically more homogeneous;
The most important difference between the tropical and non-tropical developing world is the absence of a statistical sampling approach using multi-date high resolution satellite data. This could not be applied in the non-tropical assessment due to budgetary limitations.
