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

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FORSEE : Indicateur évalué

Indicator 5.3.1 : Carbon soil and water holding capacity
Forest area covered (1995): 4956,1 ha

Percentage of the total forest area in Sousa Valley: 14,3 %

Number of plots: 35


TOTAL COST: 1300,75 €

Costs/plot: 37,1 €

The total cost includes:

1-Data collection

462,5 €

2-Data analysis

838,25 €


% of Organic Matter in the soils per type of stands


Source: UTAD laboratorial analysis

% of Organic Matter in the soils per type of stands


Source: UTAD laboratorial analysis

Classes of M.O. in Eucalyptus soils (%)


Source: Fabres et al. (2005). Indicadores de fertilidade do solo e do estado nutricional da planta para o cultivo de Eucalyptus globulus. RAIZ – Instituto de Investigação da Floresta e do Papel.

Classes of M.O. in Maritime pine soils (%)


Source: Gandullo, JM.; S. Gonzalez Alonso y O. Sanchez Palomares (1994). Estaciones Ecológicas de los pinares españoles. ICONA Madrid. 188p.


Fabres et al. (2005) parameters (RAIZ)

According to the Fabres et al. (2005), have developed applied research in the field of the forest soils and nutrition with the aim of establishing reference values to parameters of soil analysis and foliar concentration of nutrients that allow to a good interpretation of Eucalyptus’ cultivation. These authors suggest classes of soil fertility and classes of foliar concentration of nutrients to the evaluation of the fertility of the soil and its nutritional state. It was defined 5 classes corresponding to different levels of soil nutrients: Very low, Low, Mean, High and Very High. The classes Very Low and Low are considerate to have a level of nutrients that restrict the growing of eucalyptus, the classes Mean and High are considerate to have an adequate level of nutrients for the eucalyptus growing and the class Very High is considered to have an excessive level of nutrients for the eucalyptus growing.

The assumptions to the interpretation of the RAIZ table are:

1) The soil deepness referred by the levels is 40 cm, except for thin soils;

2) The average stony of soils considered was 15%;

3) The classes were established in order to include most of the forest productivities found in Portugal (between 10 m3 /o.b./ha/year and 40 m3 /o.b./ha/year;

4) The classification of the nutrients of the soils is only valid to the methods of analysis used by RAIZ (method of extraction of nutrients of Egner-Riehm - P and K in mg/kg - and acetate of ammonium - K, Ca and Mg in cmol/kg).

Gandullo et al. (1994) parameters

Gandullo et al. (1994) present reference values for Maritime pine, but only define 4 classes of soil fertility: Very low, Low, High and Very High.


The reference values were given by Gandullo et al. (1994).

Considering the soil deepness in the range 30-60 cm, the results of soil analysis done by UTAD laboratory, which uses the same extraction methods than RAIZ (Egner-Riehm and acetate of ammonium), show that in pure Pine stands and mixed Pine stands were Pine is dominant, the values of O.M. in percentage are 3,1 and 1,6 respectively. These values correspond to the level Low in Gandullo et al. (1994) classification. If one considered the soil deepness in the range 0-30 cm, the values of O.M. in percentage are higher, namely 8,2 in pure pine stands and 9 in mixed pine stands were pine is dominant.


The reference values were given by Fabres et al.(2005), RAIZ.

For eucalyptus stands we have to consider the soil deepness in the range 30-60 cm since is where the deepness 40 cm, considered by RAIZ, is included. Then the results of soil analysis are 2,7% of O.M. in pure eucalyptus stands and 1,8% of O.M. in mixed eucalyptus stands where Eucalyptus is dominant. Since the texture determined by UTAD analysis is mean (see DATA report) one can considered that the classes of O.M. in eucalyptus stands in Sousa Valley goes from Low to Mean, according the values given by RAIZ.

Problems and improvements

The expert group for criterion 5 couldn’t provide reference values for the forest species of the Atlantic arc. The reference values for Portuguese forest soils presented in this report were given by RAIZ a private non-profit research institute committed to support the competitiveness of the Portuguese Pulp and Paper Industry. The link with future research related to FORSEE project and RAIZ should be kept given the knowledge and expertise accumulated through the years by this research institution in what is concerning to the cultivation of Eucalyptus.

The comparison between the reference values and the soil analysis in the pilot zone can give a general idea about soils nutrition and contents of O.M. but is it is hard to state if the sustainability of forests is being accomplished or not since there is a high number of variable interfering on that.

This data was very convenient since the pilot zone is almost covered by Eucalyptus and small areas of Maritime pine.

There was also a change in the methodology of soils collection that can be affecting the results. If FORSEE field guide was requiring 10 samples per plot, collected in a systematic way (see FORSEE field guide), the FORSEE field team decided to collect only 3 samples per plot in three different location inside the plot.

This happened because:

a) Logistic reasons that impeded to transport in the car 10 soil samples per plot;

b) Financial reasons, given the high costs of the laboratorial analysis.

Other shortcoming is that the soil samples were only collected in the South part of the municipality of Paredes and not in all Sousa Valley.

Comments and conclusion

This indicator is feasible but costly given the human resources needed to collect the soil samples, the human strength that is needed to collect the samples and the laboratorial analysis per se.

However it seems important to assess the nutrient characteristics of the forests soils in determined intervals that can be more or less spaced in time according to soil researchers.

The main species in Continental Portugal are Maritime pine and Eucalyptus. For Maritime pine it was difficult to find reference values but for Eucalyptus RAIZ could provide some reference values.

Since RAIZ can provide data on this indicator (for Eucalyptus globulus), the link and the contacts with this institute should be kept.

Information about other forest species would be also important since it could be used as a reference tool by forest managers (ex. foresters working at the local FOA) with the objective of helping them choosing the correct forest species for the new forest areas.

Indicator C5.3.1 is not considered by Criterion 5 of the Portuguese Norm 4406 2003.

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