Introduction

The Iberian Peninsula is located in a transition area between different climatic zones (Atlantic, Mediterranean, North-African) that have a strong effect on the structure and dynamics of the Spanish ecosystems. Due to this, the Iberian Peninsula is one of the most sensitive zones to experiment ecosystem variations as a result of the climatic changes that are expected. Research on the climatic variation and its consequences in the ecosystems of the Iberian Peninsula must be therefore considered as a priority within the Spanish research projects.

Observations in the long term are essential to interpret the experimental results, to analyse the behaviour of models and to propose hypotheses about the effects of global change. For this reason, the activity of the Spanish Long Term Ecological Research Network, REDOTE, is indispensable.
 

EXAMPLES THAT ILLUSTRATE THE NEED OF ECOLOGICAL OBSERVATIONS IN THE LONG TERM
Temporal changes in mean average daily temperature in May and in mean breeding success of two pied flycatcher populations in Sierra de Guadarrama (Segovia) during 1980-2001. Despite the big inter-annual variation, the trend toward an increase of the temperature and an decrease of the breeding success was significant (Sanz, J. J., J. Potti, J. Moreno, S. Merino and O. Frias. 2003. Climate change and fitness components of a migratory bird breeding in the Mediterranean region. Global Change Biology 9: 1-12).
Anomalies in sea temperature in the North Hemisphere during 1860-2000 (Impacts of Europe's changing climate. European Environment Agency, EEA Report No 2/2004., Copenhaguen).