Publication

Seed propagation for high forests is the most suitable management method to main­tain and increase genetic diver­sity and, therefore, the conser­vation of the genetic resourc­es of the species. It is the most adequate regime for landscape protection, or­namental and recreational functionalities. High forest merits are also on the use of water, which is a special feature for Mediterranean regions where increasing hu­man demands for water are expected together with cli­mate change induced drought (Gracia, 2009).

Coppices for firewood pro­duction (coppicing every 30–40 years) usually host a large amount of the biodiversity of Mediterranean ecosystems, but reduce the genetic diversity of the coppiced species, in par­ticular where up growing single stems per stump are not left. Therefore, the chance to con­vert coppices into high forests, through a gradual increase of the number of single stems per stump, should be considered. For instance, a coppice stand with a single stem per stump system, with long cycles (not less than 40 to 50 years) and a large number of seed-bearing trees (even >200), contributes to the regeneration of the popu­lation and the maintenance of the understory and favours the natural evolution of Q. ilex to­wards its climax situation (which is pure high forest).

Holm oak hybridizes with other oak species and hybridi­zation may result in a loss or an increase of genetic diver­sity according to the concrete situation of the population or species evolution (Soltis & Solt­is, 2009). Where populations for conservation of genetic resources are established in mixed oak- stands, hybridiza­tion monitoring is recommend­ed, whenever possible through genomics, transcriptomics and progeny testing.

Since limited genetic infor­mation about Q. ilex is available, it is recommended that genetic conservation programmes start with the following objectives: conservation of endangered, marginal populations and habi­tats of Q. ilex; sampling the genetic diversity; establishment of Dynamic Conservation Units based on long term autochtho­ny, high biodiversity value and location in ecologically diverse regions of large populations (> 1000 individuals).