FORASSEMBLY

In the last century, forest recovery has been observed in the Iberian Peninsula as a consequence of strong socioeconomic changes. While there is some information about the general patterns of plant and animal community assembly in the resulting new forests, the demographic processes and ecological interactions driving these patterns are still largely unknown.

Because of its importance in Mediterranean forests, seed dispersal by vertebrates has been studied for long, despite its contribution to the assembly of these new forests is also still largely unknown. Some preliminary results show the existence of colonization credits in vertebrate-dispersed species, but it remains elusive to what extent these credits are consequence of niche constraints on either plant species or their dispersers. It also remains unknown the potential effects of these patterns and their drivers on key points of the  plant species colonization dynamics (i.e. genetic spatial structure, seedling survival and development). Holm oak is among the most interesting of these species because its functional and socioeconomic importance, and because acorn dispersal is driven by birds and rodents, at long and short distances.  

The main objective of the project is to study the processes driving the community assembly of vertebrate-dispersed woody plants in the new Iberian forests, in relation to niche variables, historical and present landscape and, in the case of Holm oak, the behaviour of the dispersers (birds and rodents). The detailed objectives of the proposal are: 

1. To ascertain the environmental factors (climate, topography, and landscape) associated to the colonization of the new Iberian forests by animal-dispersed woody plants. 
2. To determine the effect of the vertebrate disperser community (birds and rodents), and the modulating role of habitat and landscape properties on the colonizartion process of Holm oak in these new forests. 
3. To evaluate the effects of acorn dispersal and seedling establishment on the metapopulation dynamics and the spatial genetic structure of Holm oak across the assembly of these new forests. 

The study will be carried out in the Province of Barcelona, because of its high availability of historical and present-day cartography on forest distribution. Using previous forest inventories and specific field work, preexisting forests and those new and appeared in different dates (1956, 1970-80) will be selected  across environmental and landscape gradients. As for Holm oak, specific field studies will be carried out to evaluate dispersers’ presence and abundance, the intensity of acorn predation/dispersal under these gradients, and the effects of these processes on the genetic and spatial structure and the development of the new stands. Finally, the colonization process of the new forests and the associated colonization credits will be modelled for a selection of species including Holm oak.