Assessing past and present management effects on current and future levels of genetic diversity in Quercus pyrenaica Willd. in Sierra Nevada

Abstract

Valbuena-Carabaña, M., Gil, L. 2014. Assessing past and present management effects on current and future levels of genetic diversity in Quercus pyrenaica Willd. in Sierra Nevada. Ecosistemas 23(2):90-98. Doi.: 10.7818/ECOS.2014.23-2.12

Quercus pyrenaica Willd. is a Mediterranean and western European oak species widely distributed in the Iberian Peninsula. Its profuse resprouting ability from the entire root system was made use of in traditional management practices, especially as coppices for firewood and charcoal production and less frequently as open woodland for cattle grazing. The abandonment of traditional management evidences the general degradation sate of these woodlands –growing stagnation, stem top drying and lack of seed production–, and causes of such degradation were theoretically attributed to the exhaustion of clonal clumps and to the lack of genetic diversity. Nevertheless, the recent survey by means of nuclear microsatellites markers of several oak woodlands, included these hereby presented, allowed to discard such hypothesis. Lack of relation between forest structure (coppice vs. open woodlands) and the asexual or sexual origin of trees, and the high heterogeneity in clonal sizes hinders to predict the current clonal structure of woodlands based on their forest structure. The present study analyses the conservation state of genetic resources in a territory intensively used by man along the history evidencing the important resilience of the species to traditional coppicing. The study shows the effect of past forest management (coppicing and maintaining open woodlands) and the most commonly applied treatment in the present (coppice thinning with standards) on the current genetic diversity and clonal structure in three plots of the same oak woodland having different forest structures at Sierra Nevada National Park. Moreover, the potential evolution of genetic diversity is evaluated through the analyses of the juvenile cohort in each plot. Although, in the adult cohort, coppices bear higher levels of genetic diversity, the asexual origin of their juvenile class may limit the genetic diversity in the future. On the contrary, in the open woodland, the sexual origin from seeds of the juvenile class will potentially increase genetic diversity in the future.