Description:
Several canopy types in an evergreen oak forest with open pastures have been used to examine climatic features of this system related to temperature. Circadian variation in temperature seems to be related to structural characteristics of the vegetation, with an apparent influence of the plant micro- and meso-environments analyzed. The activity of a population of granivorous ants (Messor barbarus (L.)), studied in the same area, showed a clear dependence on ambient temperature, but, although the colonies were always inside one of the vegetation types, there was no significant relationship between the activity of ants and grasscover. This, together with other observations, indicates that the possible controlling effect of the vegetation is limited by the tolerance of ants (when faced with adverse conditions) during each daily foraging period.