Spatial Patterns and Facilitating Role of Holm Oak (Quercus ilex) in the Regrowth of Atlas Cedar (Cedrus atlantica (Endl.) Carrière) in Chelia, Aurès, Algeria

Abstract

The process of natural forest rejuvenation, which refers to the self-renewal of forest ecosystems, encompasses the substitution of mature trees with the succeeding generation and is subject to the influence of environmental factors. The characteristics of the stands themselves both impact and determine the spatial organization of tree regeneration. The natural regeneration of the Atlas cedar follows a complex set of eco-physiological processes involving several environmental factors during the different phases of its establishment and development. Thus, it is noteworthy that the cedar always remains closely associated with the holm oak, forming well-stable mixed associations. Therefore, this study investigates the cedar stand of Chelia, affected by dieback where regeneration seems inconstant. Accordingly, the study describes the stand’s spatial structure to understand spatial patterns’ mechanisms the areas of forest that contain a variety of different tree speciem in the north-east of Algeria .Using data from four rectangular plots (60 m × 40 m) temporarily established in the mountain of Chelia, all the seedlings were charted, measured, and located through their (xi, yi) coordinates In addition, two vertical measurements of holm oak crown diameter were recorded for each tree, along with other structural variables. Then, the pair correlation functions were used to investigate uni- and bivariate spatial point patterns to assess the spatial relationship between the cedar seedlings and the holm oak undergrowth. We found that the univariate pair correlation function showed a spatial aggregation of seedlings, concerning the holm oak pattern, which was regular only at small scales but was predominantly random. The bivariate pair correlation function revealed that regeneration was found to be clumped and the spatial association between holm oak and Atlas cedar seedlings.