Interview with Profesor Matthias Dees

Matthias Dees
Professor, UNIQUE Forestry and land use expert

“Synchronization of the NFI-2 methodology with the methodology of national forest inventory will allow us to compare the results of national forest inventory with the results of NFI-2 in the future”

What is the basis of the national forest inventory methodology?

The field work methodology was developed both considering the NFI#1 methodology, the methodology used in the FMP inventories  and adding new features to address the wide range of information needs.

What is the difference between the similarity and difference between the methodology of the 2-nd NFI from the previous?

The similarity is the assessment of attributes on forests and trees, the use of tracts to concentrate the sample plots; and the utilization of an inventory design that follows statistical principles that allow probability based statistical inference.

The four main differences are that (1) in the NFI#2 the number of tracts located in forests, including shrub land is substantially higher (in dimension of 10) and (2) that the tracts in NFI#2 are not distributed in a constant grid over the entire country, but using strata of different grid density to allow a balanced and high precision of the statistical results, for the main six forest types, (3) that the NFI#2 includes the provision of a satellite based land cover and forest type map and (4)  that the information of the NFI#2 will be provided via a web based information system on forests.

What are the main stages of a National forest inventory?

First, based on a solid information needs assessment the methodology has to be agreed, the next stage is the preparation phase that ends with the field team training. Then the field measurement and the mapping process follows. Next stage is the analysis stage, followed by the stage of disseminating the findings, and using the information for forest policy. Parallel to using the findings of NFI#2 the stage for the planning of the NFI#3 starts.

What are the methods for laying tracts and sample plots ?

All tracts and sample plots have a clearly defined location. This is crucial to assess the change dynamics in forests by a re-measurement of the same sample plots in all consequent inventories (previous and future repetitions). Therefore modern highly accurate GPS devices are used to locate the plot based on its target coordinates. Further, to locate the plot exactly, the metal stake placed in the plot center when it established for the first time a metal detector is used.  Marked reference trees are used in addition to find the plot center. In the NFI#2 both plots formerly measured in the NFI#1 and selected plots measured by the FMP inventory are re-measured, in addition new tracts and plots are established at new locations.

What tasks will the second national forest inventory solve ?

The second National Forest Inventory will help not only determine the total area, size and stock, types and forms of ownership of forests, the level of forest pests and diseases, determine the state and level of degradation of pastures and forests, the presence of illegal logging, erosion and fires, the results of NFI-2 can become the basis for the development of national forest policy and further steps for the development of the forest and environmental sector as a whole.

What are the main methods for assessing the state of forests, productivity of stands, biodiversity etc?

The core method is to measure all necessary attributes at the plot level, followed by the statistical analysis. This analysis includes the use of models and functions to derive from the measurements on the plots further information, e.g. on tree volume, increment, biomass, carbon storage  etc.

Another main method is the methodology to provide the landcover and forest type map using Sentinel 2 satellite data.

Possible risks, errors ?

Risks are associated with the field work since forests are in large parts located on terrain that is difficult to access. It will be regarded to avoid risks for the field teams by adequate preparation and planning of the field work and by not accessing in-accessible plots.  The information collected in the NFI will be subject to a statistical error. The inventory methodology and a sufficient number of field tracts ensure that the statistical error is within an acceptable error tolerance level.

Is there an approved version of the NFI methodology in general ?

All national forest inventories follow the same principles even if they are quite different on the detailed level to consider national needs and circumstances.

October 2019