EFI : European Forest Institute
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Le réseau pour la gestion durable des forêts cultivées.

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FORSEE : Indicateur évalué

2.4.1. Nature of the Damages

Costs

Pilot zone:

(35220 ha)

41 plots

3309 trees

Total Cost €12393.00

Shared Cost €10193.00

Marginal Cost €2200

Total Cost/ha €0.35

These cost include:

Measure DBH
Site Description
Record the damages
Record the intensity
of the damages
Identify the damage agent
Transects
Record the affected part
Data processing of the forest health
Travel to the plots
Time finding & installing the plots
Prepare sampling plan
Purchase maps of the plots
Organise the data collection points
Computer & software for forest health

Results

Figure 2.4.1a: Proportion of Trees with and without damages

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Figure 2.4.1b: Type of damages

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Figure 2.4.1c: Parts of the tree affected by the damages

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Figure 2.4.1d: Main Agents responsible for tree damages

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Remarks

Figure 2.4.1a shows that 38% of the trees surveyed were damaged. The other figures (Figs. 2.4.1a-d) present the type of damage, part of the tree affected by the damage and the main agent responsible for the damage. The main type of damage, by a large margin (68%) was defoliation. This could be related to the fact that the forest sites were all post 1988, in the 0-20 age class. Tree damage due to frost and wind can be related to tree age. As the crop matures and closes canopy needle damage due to exposure and frost are less likely. In figure 2.4.1c you can see that 83% of the affected part of the tree was the needles, as would be expected with defoliation. In figure 2.4.1d the main agent responsible for the damages was nutritional disorders which would relate to the high percentage of needle damage and would be an indication of low soil fertility. The other two main agents responsible for the damages were frost and wind, which would be associated with the main affected part (needles) and the age of the trees.

Problems and Improvements

The main problem with identifying forest health in young trees is that the damages observed at the time of field assessment could be transient in nature. Young trees pre-canopy closure, are more susceptible to damage by exposure (wind and frost) which is dependent on annual weather conditions. Therefore damage assessment of the same trees the following year may show complete recovery. This makes it difficult to make an accurate assessment of forest health in young trees and its relationship to sustainability. Therefore the assessment of trees within one age class may present a limited picture of forest health. This does not however affect the reliability of the indicator only a possible limitation of the sampling strategy.

Remarks and Conclusions

This indicator (when assessed in all age-classes) would be very useful for assessing the main forest health issues within a region, pilot zone, country and greatly improves the knowledge of forest health which may not be assessed at such an intensity. Indications from the results show that the forests in the pilot zone are affected by low soil fertility and exposure.

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Project co-financed by European Union
A community initiative ERDF
INTERREG the IIIB Atlantic Area