2. A basic scenario
2.3 Information management and change assessment
FRA 2000 required three types of information on forest change: deforestation, forest degradation and forest plantations (FAO 1999a). In a FRA, the data sources used in the previous assessments are consulted and new sources identified (FAO 1998b). When new sources are identified, they are compared with the older information to determine which provides the best and most reliable baseline. Comparability between two (or more) information sources is also evaluated, verifying their utility to serve as representative surveys in a continuous time-series. It is the standards and metadata associated with each data set that permit evaluation of reliability, comparability and verifiability. For example, in some assessments the definition of ¿forest¿ changed significantly from earlier definitions, now including large areas of woodland not previously defined as forest (Bureau of Rural Sciences 1998). Change assessment often relies on models (FAO 2000b). For example, deforestation has been predicted from accessibility and income generating potential of tree and forest land (FAO 1999a), and models have also been used in relation to plantations and wood supply (EC/FAO Partnership Programme 2000). Information management plays a key role in the integration of models into assessments. The flow of information should be explicitly considered in development and use of models (Agarwal et al. 2002).
2.3.1 Data and information sources
Information management plays a major role in tracking fellings and removals, afforestation and reforestation, and forest degradation. These are often managed at a local forest management unit scale, and the data sent to a central location for integration into a regional or national perspective. This involves inter-computer communication and will be covered in section 3.
Change resulting from forest degradation poses particular challenges for information management. Each source of degradation may have its own information requirement; e.g. forest fires (FAO 2000c). In many countries, there are no formal inventories of forest health, although major inventories of tree defoliation exist in both Europe and North America. In many cases, expert opinion (2.2.2 above) represents the best available estimates for particular damaging agents, rather than the results of specific surveys and inventories. Substantial differences exist in the values obtained by observers both within a country and between different countries (ECE 2000). The existence of different concepts of damage and different definitions of defoliation hinders change estimation, and emphasizes the need for standards.
The TBFRA experience gives a valuable perspective on monitoring change relating to issues in 2.2.2: ¿change (in any parameter) is not usually measured directly: rather measurements of the same parameter are taken at different time intervals, but with the same methods and definitions, and then compared. It is essential to separate ¿changes¿ due to changes in methods or in definitions from those really arising from changes in the parameter measured. Definitions and methods used in the international FRA programmes have changed, sometimes significantly over the past decade (not to mention the many more changes at the national level), so it is not possible to draw any reliable conclusions from a comparison of TBFRA-2000 data with those in earlier international assessments.¿