Forest health

For our forests to enjoy good health, proper management of the mountains and the phytosanitary problems that may affect them is essential.

From the Phytosanitary Defense Section of the General Directorate of Biodiversity and Natural Resources, it carries out continuous evaluation of these ecosystems, through tools such as the Monitoring Network of the Sanitary Evolution of the Forest Masses of the Community of Madrid (SESMAF Network), the characterization of pine forest masses for the assessment of damage caused by processionaries, the implementation of contaminant measurement stations or the establishment of a network of selective captures to determine the flight curves of the main pests in the Community of Madrid.

In addition, the so-called quarantine agencies have made it necessary to reinforce surveillance measures and implement a survey system to detect the possible presence of certain harmful organisms that can affect our forests.

State of the pine processionary in the Sierra del Guadarrama (March 2022)

At the beginning of the 1986s, the continuous and progressive deterioration of the state of forest health that was registered in Europe began to cause general concern in society. In XNUMX, the European Community (EC) established the legal foundation to develop monitoring and control work on the state of health of forest systems. This is how the European Forest Damage Monitoring Networks (Level I and II Networks) arose.

The Monitoring Network of the Sanitary Evolution of the Forest Masses of the Community of Madrid (SESMAF Network) It emerged in 2002, and is based on and complements the Level I European Network, although it presents certain modifications with respect to the original, both in the methodology used for the selection of plots and in some of the parameters to be evaluated.

There are currently 91 plots established in which the degree of defoliation and discoloration of the trees in the plot is evaluated once a year, and the pathogenic agents observed are identified.

The objectives of the SESMAF Network are the following:

• Annual determination of the health status of the different tree formations in the Community.
• Identification of the causal agents of sanitary deterioration.
• Assessment in time and space of the evolution of the damage analyzed.
• Cause-effect relationships of the decay of the masses.
• Comparative analysis of the global evolution of the health status of the different forest formations.

Annual reports of the Network for monitoring the health evolution of forest masses (SESMAF):

Air pollution has been studied since the second half of the XNUMXth century, with the study of its effects on forest ecosystems being a priority issue due to its importance on production and survival itself.

Among all the pollutants that can affect the vegetation, SO stands out for its danger.₂, I have not_x and the O₃. The three closely linked to human activity. The first originating – broadly speaking – from fuels that contain sulfur and from the fusion of non-ferrous metals, and the other two from the burning of hydrocarbons (road traffic).

In order to assess the probable deterioration due to air pollution produced in the pine forests of the Community of Madrid, the General Directorate of Biodiversity and Natural Resources has been carrying out, since 2003, sampling on the presence of pollutants in a network of points coinciding with certain parcels of the SESMAF Network.

Currently, there are a total of 10 stations established for the measurement of these pollutants. Each station is made up of a registration box with two types of passive dosimeters (for measuring the levels of NO₂ me₃), and a rainwater collector, which are checked fortnightly between the months of March and October for the collection of samples and subsequent transfer to the laboratory.

The results obtained make it possible to continuously evaluate the presence of different pollutants, determine the direct damage caused by ozone, and assess the incidence of pollutants in the masses of pine forests in the Community of Madrid. 

Damage to forest stands can be caused by living agents (biotic damage), or by others, which are mainly a consequence of environmental and nutritional factors (abiotic damage).

The identification of the problem requires an initial analysis or evaluation that allows us to rule out whether the cause of the damage is abiotic, that is, caused by frost, fire, snow, wind or drought or other factors related to edaphic deficiencies. For this, it is very important to know the physiological needs of the trees and the quality of the habitat where they are found (climate, soil, available water, competition, air pollution,...).

The determination of biotic agents is carried out by direct observation of symptoms and signs, and, where appropriate, by taking and reissuing samples to the laboratory for diagnosis.

On many occasions, the causes of forest deterioration are interrelated, being one consequence of the other, that is, a prolonged drought or lack of nutrients causes the mass to weaken and facilitate the massive attack of other pathogens.