2 Background

2.1 FAO Role and Mandate

Human actions as well as impacts of natural factors on natural forests are growing and causing deep changes in state and size of the resources. The forest cover has been undergoing increasing pressures in large parts of the tropical and subtropical regions, due essentially to human interference but also to the global warming of the atmosphere and the speedy advance of desertification. Although impacts of natural calamities are significant on global forest cover changes and have only been recognised during the last decades, the countries social and economic situations are the overriding forces for deforestation for long time.

As to keep the world forest resources under continuous watch, FAO has been mandated to assess and monitor them periodically. The salient components of the FAO mandate in forestry revolve around the development of knowledge and methodologies for forestry policy analysis as well as for identification of building capacity requirements. In relation to forest resources, FAO is mandated to provide advice and technical assistance to member countries in matters relating to assessment, development, conservation, management and protection of forest resources (forests, trees, wildlife and related natural resources). Specifically, it promotes the survey and integrated management of the resources, for the purpose of their conservation and sustainable development, with particular attention to the strengthening of the national capacities in these fields.

Along these policy orientations, FAO has taken the lead for more than 50 years in the area of world forest state and change assessment and monitoring, as well as in promoting the development of knowledge and methodologies in these areas of forestry. Periodic assessments have been carried out and provided valuable information on the state and trends of changes of the resources.

In order to be able to respond to the growing demands for a wide range of reliable information on the resources, the FRA has been developing initiatives and methodologies for improving the scope and reliability of such information.

So far, FRA has been relying on two major sources of information. The first was obtained from the country data sometimes compiled from unreliable sources and the second is generated from a sample of the remote sensing survey carried out by FRA itself. Both sources, due to their shortcomings in comparison with the predefined FAO standards of completeness, reliability and scope, are still not fully satisfactory to FRA.

2.2 Review of Forest Inventories in Developing Countries

Industrialised countries excluded, very few countries in the world have up-to-date information on their forest resources and less have national capacities for generating such information. The present status of the baseline information on the resources in the developing world may be deduced from the statistics given in the following table:

Table 1. Countries having carried out or not Forest inventories at national or local levels

(* ) Asia: here referring to 22 countries in the sub-regions South Asia, Continental SE Asia, Insular SE Asia and East Asia.

Notes:

1) Repeated is interpreted as systematic monitoring or inventories in a fixed interval

2) Most countries have more than one single shot inventory, the timelines (after or before 1990) refers to the most recent one

As it can be seen on the table above, the number of countries, which set up monitoring systems for their forest resources through repeated inventories, is very limited. They are 22 out of 137. Although the highest number of countries (47) fall under the column of single shot national inventory conducted more than a decade ago, there is a large number of countries which has done nothing to-date. For clarification, the numbers of repeated and single shot inventories do not refer merely to studies of forest inventory as such, but they include various mapping works such as land use, soil studies, etc. They are put here as inventory works as they provided information for forest cover estimates by FRA2000.

In practise, the number of countries from the developing group who have conducted serious forest inventory works is very minor. This underpins the urgency for action to be taken by the international community within the framework of a new approach revolving around new axis of multilateral co-operation between funding sphere, recipient governments and technical assistance providers.

Among the developing world, African continent is the poorest in terms of information on forest resources, as no country has to-date mounted a monitoring system and very few have carried out single shot national inventory.

Most of the repeated national inventories in the developing countries have been conducted on the basis of different methodologies, which do not produce information on various changes including forest growth. The national inventories have been prepared for various objectives. Some of the national surveys were undertaken for timber potential determination or general policy development, others for environmental assessment, etc.

The disparity in extent and values of the baseline information at country level within the developing world suggests that the international forestry policy seems to have failed, so far, in addressing properly the issue of monitoring the forest resources in the developing countries.

There is a strong and a pressing need for a new vision and approach in connection with forest resources assessments in these countries as well as with the national capacity building within the framework of partnership with international organisations. From its stand mandate point of view, FAO is the international body that should reconsider this co-operation with the developing countries by designing a more fruitful approach for forest resources monitoring that will benefit more not only the countries themselves but also the international community for global policy adjustments.

2.3 Review Forest Inventory Methodologies in Industrialized Countries

National information on forest resources and related variables in the developed countries are obtained form forest inventories using sampling techniques. The Nordic countries have been reported to be the first ones at planetary level to carry out national forest inventories. The first exercises have been undertaken in 1919 in Norway, 1921-24 in Finland, and 1923-24 in Sweden. The central and western European countries started their national forest surveys after the Second World War during the fifties and sixties, while in the United Stated of America, the first reported work had been conducted in 1930 in Oregon. Initially, the surveys were conducted using rudimentary and tedious techniques although generated first set of valuable information. The techniques have rapidly reached high level of perfection with introduction of sound statistical methods and use of ever since developing technologies such as remote sensing (aerial photographs, satellite imagery, radar data), computers and GPSs.

For all countries, the sampling designs are based on systematic sampling using permanent and in some cases temporary plots installed in grid nets of different spacing. The random sampling design was discarded. There are sampling designs, which adopted point-sample plots and others fixed area plots. Both techniques have also been used together. Size and shapes of the sample plots differed from country to country. Single sample plots are used in some countries while concentric plots or clusters are used in others. Distribution of plots in clusters also varied. They are located either at the corners of squares, along two lines with right angles or along strips or transects. The spacing between plots varied also from country to country and even within the country itself depending on the forest distribution and topography.

The table below shows, for some selected developed countries and China, some features of the followed sampling designs.

Table 2. Main features of the sampling designs in selected countries

Sources:

- Proceedings of the International IUFRO S. 4.02 and S. 6.04 Symposium, May 14-16, 1990, Birmensdorf, Switzerland

- Study on European Forestry Information and Communication System, Vol. 1 & 2, European Commission.

- Journal of Forestry, Vol. 97, Number 12 December 1999.

The common element in the sampling designs and techniques applied in the countries listed above is the systematic distribution of the sample units over the survey areas using different dot grid designs. For monitoring their forest resources, all countries relied on permanent plots but also on temporary sample units to improve precision and to gather additional data for specific studies when needed.

Two types of sample plots have been used in the industrialised countries namely a) the fixed area plots with different sizes depending on the countries requirements and on the characteristics of the tree population addressed (large DBH, small DBH and regeneration); and b) the point sampling mainly with relascope.

Each country has its own sampling intensity and has selected the sample plot size and shape that thought would achieve the forest inventory operations at the desired precision. For large DBH tree population, plot area varied from 314m² in Sweden to about 8000m² in Switzerland. For small tree diameter classes, plot sizes oscillated around 100m².

Sampling design is also a result of combination of plot size and plot number. Reduced plot sizes are usually used in large number of field plots grouped in clusters of varying extents and shapes. Some clusters are composed of high number of sample units distributed along tracts. Other with lesser sample units on 4 corners of a square. Large plot approach is applicable essentially in single plot location and lower plot population.

2.4 Forest domain

Table 3. Total land and forest area by main geographic region

Source: FRA1990