Large mammalian herbivores affect the structure, productivity and species composition of plant communities through feeding behaviour.

By converting plant material to feces and urine they can alter local nutrient availabilities. By feeding preferentially in some plant species or parts of plant species herbivores may alter the chemical characteristics of standing vegetation and litter.

This in turn will affect processes such as nitrogen mineralization rates, litter decomposition rates, soil microbial activity and, at longer term, soil fertility.

The effects of herbivores on nutrient cycles have been investigated in the boreal and temperate forests but virtually no studies are available for Mediterranean environments and the evergreen oak woodlands such as those of cork (Quercus suber) and holm oak (Quercus rotundifolia) occurring in Southern Portugal.

Deer populations have been increasing throughout their geographical ranges of distribution, including North America and Europe. In Portugal deer numbers have increased due to favorable land use changes and policies of reintroduction of populations of the species (mainly red deer Cervus elaphus) for hunting purposes. In southern Portugal deer populations occur in a wide range of areas dominated by the montado system (silvipastoral systems characterised by relatively open woodlands of cork and holm oak).

In this work we aimed to assess the indirect effects of red deer on the ecosystem processes, namely nutrient cycles, of a montado system by measuring ecosystem processes (primary production, Nitrogen mineralization rates, litter decomposition rates) in plots where deer grazing has been excluded by 4 and 10 years.