Ontwerp en handleiding voor de tweede regionale bosinventarisatie van het Vlaamse Gewest

In accordance with Article 41quater of the Flemish Forest Decree (Vlaamse Regering, 1990) the ‘Flemish forest management’ (i.e., the Agency for Nature and Forests, ANF) has to make a sample based inventory of the Flemish forests with an intervening period of at maximum ten years. The target of the inventory is to ‘sustain the forest policy concerning forest protection, extension of the forest area and forest management’. And still in accordance with the Forest Decree the inventory must ‘refer to the quantitative and the qualitative aspects of the natural environment in the forests’.

During the period 1997 – 1999 the ANF has carried out the field work for the first forest inventory of the Flemish region.

In 2001, a voluminous report was published based on this data collection (Waterinckx & Roelandt, 2001). In this report the authors discussed on the one hand the network design. On the other hand there was an extensive discussion on the dendrometrical and vegetation data by means of tables and graphs.

In preparation to the second Flemish forest inventory (= FFI), the ANF wrote in 2004 specifications for the evaluation of the first FFI and the design of the sampling scheme for the second FFI. This two year-project (April 2006 until March 2008) was assigned to the Research Institute for Nature and Forest (INBO) in collaboration with the laboratory of Silviculture of the University of Ghent.

The task was subdivided in two phases. In a first phase the targets and possibilities of a regional / national forest inventory were stated explicitly, because the policy makers of the ANF felt that the results of the first FFI were used unsatisfactory and they wanted to know the reasons for this.

This analysis was the starting point for designing a concrete sampling scheme for the second FFI. During this second phase, the focus was mainly on prioritizing and making explicit the policy questions. Thereupon the sampling scheme and the choice of the variables was elaborated. In a next step an ex ante evaluation of the data processing and analysis was made. And a reporting and communication plan were written. Finally, recommendations were formulated for the last preparations on the implementation of the network. In al these steps the focus was on the quality care and the documentation of the decisions that were made.

As we already mentioned, the first assignment of this project was to delimit the targets and possibilities of a national forest inventory. In a nutshell we can say that the FFI is a network in a strategic context. Above all, we are interested in the state of certain characteristics of the whole population and certain strata (for example important forest types). The figures sustain the policy plan of the ANF. The network can tell us to what extent the generic Flemish forest policy (a set of policy and management measures) has an impact on certain characteristics of the forest on Flemish scale. Next to that, the data are used to meet international reporting obligations. Finally the results can also serve as a frame of reference for the Flemish forest management and forest research.

As far as context is concerned, the focus of the network is on clearly specified policy questions. These relate to the following themes: (1) the characteristics of the forest area; (2) the composition of the tree species; (3) the stand composition; (4) some general indicators for biodiversity; (5) the composition of the forest vegetation under influence of environmental changes and (6) the sustainable forest management and use.

To answer these questions in an optimal way, some important adjustments have been made to the sampling scheme, the choice of the variables and the sampling methodology: (1) the shift from a periodic (a short measuring campaign every ten years) to a continuous inventory (every year one tenth of the sampling population is measured); (2) the inventory of the vegetation is done on a grid of 1km x 0.5km; (3) sampling points will no longer be moved and the area decision method will be used for sampling points that fall in a border or transit zone; (4) soil samples will not be taken again; (5) lying dead wood will be sampled by the line intersect sampling method and (6) the field teams will use Field-Map for the collection of the measuring data.

Finally we need to mention that the method that was used during the evaluation of first FFI and the design of the second FFI has come into being in synergy with the method that is presented in the guideline ‘The design of policy oriented networks’, also a publication of the Research Institute of Nature and Forest (Wouters et al., 2008).