S Observing Additional Variables

In addition to the standard forest inventory data, data can be collected on the plots for the estimation of non-timber variables. For example, for assessing the protection against rock fall, the distance to the closest object to be protected downhill and the distance uphill to potential starting points of rock falls or slides can be recorded. For the recreation function, the distance to cities, national parks, and recreation areas should be included in the estimate.

3.1.6 Special Inventories

Special inventories have to be conducted, if the information required is very specific. For example, information on forest health relating to to air pollution is colleted during special inventories. The design and estimation procedures have been developed for entire Europe, the data can be combined with inventory data. However, the damage inventory has to be conducted separately, as damage inventories rely on different estimation procedues, and are conducted at different intervals, mostly annually or bi-annually, whereas most forest inventories are conducted in 5 or 10 year cycles.

Biodiversity can only partly be assessed with existing information. For detailled and more complete assessments, additional surveys have to be made. A special problem with the assessment of biodiversity is the problem of seasonality and the problem of spatial and temporal dynamics. For example, floristic surveys have to be made during several seasons.

3.1. 7 Enquiries

If no other information is available, enqmes can be used. They can provide valuable information on issues relating to politics, management or general influences over very large arears that cannnot be measured accurately. This approach, however introduces the danger of bias, as the answers will be subjective. In order to minimize the personal bias of the answers, the questionnaires should be answered by a team of experts, and the results should be geo-referenced.

An objective assessment of forest functions can only be obtained by the inventory approach. Some functions, or some attributes of the functions can be assessed directly from the inventory results (such as timber, biomass). For others, auxiliary information from maps or statistics can be used. Special inventories have to be conducted for some forest functions or attributes.

3.1.8 Summmary

Forest inventories in the temperate regions already collect a large number of variables including many non-timber variables. Traditional timber inventories placed the main emphasis on the estimation of volumes in the inventory, by using some sampling scheme.

This data source can be used also to derive information on non-timber variables and functions, for example species diversity and its change over time could be calculated.

Indirect estimation of recreation potential could also be derived.

At later stages site variables were added for the assessment of the productivity of the site. These site variables provide also information on non-timber variables.

In order to derive the information on non-timber variables, often production function have to be used to link the standard variables to the forest functions to be estimated. These functions quite often are not yet available or not available for a specific region with the required precision. It seems necessary that these gaps are identified by inventory experts clearly and research be undertaken to provide the necessary production functions.

Modern forest resource inventories collect information on a large number of variables that can be used to estimate several forest functions. However, more development is needed in this respect, as it is not sufficient just to count the number of dead standing trees in order to assess the ecology of the forest, as some experts seem to imply.

It is necessary to fully integrate timber inventories with other assessments, such as ecosystems mapping, biotop mapping etc. and to develop compatible assessment methods for these variables as well.

This will require a redesign of many inventories, both the statistical design and measurements methods have to adapted to include variables that partially cannot be measured on traditional sample plots, variables that are seasonal, and variables that are categorial and qualitative. This could possibly mean that the level of precision for timber estimates achieved in many inventories will have to be reduced, but it is in the long range not that inportant whether we estimate the average timber in the forest with 5 or 10% error, but that we include the non-timber variables as well, to provide the decision makers with the necessary information for a sound ecologically oriented management of the resources and to provide information on some aspects of the forest resources to ecologists, conservationists, and others maintaining a forest input in these fields as well.

At present, there are many activities worldwide dealing with the integration of ecological assessments with forest inventories. Starting with the expert consulation of UNEP, FAO's efforts to include environmental parameters in the Forest Resources Assessment, to individual countries like the US where with the ECOMAP approach the integration of ecological assessments and forest inventory is planned. Many research and development projects have started to study specific aspects, hopefully providing appropriate solutions to the problems in the future.

These developments are necessary if forest inventories are to maintain their impact also in the future for the managment and conservation of forests from the local to global level.

3.1.9 References

LUND, H.G. (ed.), 19 9 3: Integrated Ecological and Resource Inventories. Proc. National Workshop, Phoenix, Arizona April 12- 16, 19 9 3.

P ELZ, D.R. ; THOM, R., 19 79: Integrating timber and wildlife habitat inventories. In: Proc. of Forest Resources Inventories Workshop Fort Collins.

SCHQLLMANN, H.; PELZ, D.R., 19 9 2: Background paper for the temperate and boreal regions of Europe and the commonwealth of Independent States for the UNEP/FAO Expert Consultation Nairobi.

UN-ECE/FAO, 19 9 2: The Forest Resources of the temperate zones: main findings of the UN­

ECE/FAO 19 90 Forest Resources Assessment.

UNEP/GEMS, 19 9 3: Report on the UNEP/FAO Expert Consultation on Environmental Parameters in Futre Global Forests Assessment, Nairobi, 1- 3 Dec 1 9 9 2. GEMS Report Series 1 7.

US Forest Service, 1 9 9 2: Forest Service Resource Inventories: An Overview. USDA Forest Service, Forest Inventory, Economics, and Recreation Research.

WULLSCHLEGER, E., 19 82: Die Erfassung der Waldfunktionen. Ber. Eidgenoss. Forsch.anst. Wald Schnee Landsch. 2 3 8: 81 S.

ZIMMERMANN . S., 19 9 2: Standortskundliche Erhebungen im 2. Landesforstinventar. Schweiz. Z.

Forstwes. 14 3, 1: 67-73.

3.2 Assessment of Non-Timber Resources in Africa