Sweet chestnut silviculture in an ecological extreme of its range in the west of Spain (Extremadura)

Abstract

Forest management has been conducted in many, sometimes opposing, directions, without any relevant environmental restriction. Thus, sweet chestnut stands have been bidirectionally transformed, alternating high forest and coppice structures, with many different management aims in mind: increasing economic benefits, favouring biodiversity conservation, improving landscape protection, etc. To test whether this type of multidirectional management can be extended to the ecological edges of a typical European forest tree, a study was conducted in central-western Iberian Peninsula. There, chestnut forests have been exploited under traditional regimes during recent centuries. Thirty forest stands were chosen after a clustered sampling process. In each of these stands, 53 variables were measured or estimated and assigned to five different data sets: silvicultural, climatic, edaphic, physiographic and floristic. The silvicultural matrix was compared with the other four by canonical correlation analysis. Almost all the data sets presented significant correlations with the silvicultural regime. Thus, it was easy to conclude that the environment is constraining chestnut forest management. Coppice has historically been confined to the highest ranges of the territory, which are exposed to the moist winds from the southwest. On the other hand, high forests have been located in drier sites. There, the forest needs to be intensively managed to avoid inter- and intra-specific competition. Under these conditions, coppice stands do not prosper. The relationships between chestnut silviculture and environment were also established for each data set. Finally, we conclude that the management of the chestnut forest has historically and interactively led to the development of coppice and high forest, on account of environmental constraints and human interests, to obtain benefits from this tree species.