Resumen de Crookedness as a life strategy in Mediterranean karstic environment: The example of crooked oaks (Quercus pubescens L.) in the Paiolive ancient woodland, Ardèche, France
Annik Schnitzler, Frédéric Guibal, Jean-François Holtof, Jean Michel Walter
Crooked architectures of Quercus pubescens were found on the mega lapies of the Païolive woodland, in south-central France. Seventy-two individuals were selected to establish a morphological typology. Twelve oaks (10 crooked trees, and 2 referent trees) among the 72 individuals were cored to the heart of the tree.
Hemispherical photographs characterized light conditions beneath the canopy. Categories 1 to 5 (i.e., 90% of individuals) had a single stem.
The estimated age of the trees varied from 45 to 130 years. Crooked oaks reacted similarly to erect oaks with regard to interannual variations in the local climate. Mean LAI (leaf index area) (3.9) displayed strong variations from one site to another (range 2.2-6.2). Crookedness can be explained by several hypothesis: 1) the short flexures of the main stems may limit cavitation in situations where fissures are lacking or 2) already colonized by the roots of neighboring trees; 3) young oaks were seeking the sun and may have grown creeping until they reached a tree-fall or a felling area.
