An approach to acorn production in Iberian dehesas

Abstract

Acorn production is one of the most important products in silvopastoral systems in the Mediterranean region. In the present study we carried out two preliminary trials to analyze the distribution of production over time and the effect of pruning. The objective was to develop tools to manage this valuable resource within these systems. In the first part of the study, we analyzed the total acorn production of a holm oak stand, and its seasonal distribution (October-January) over two years (1997-1998 and 1998-1999) in five sites in the southwest of Spain. Mean total acorn production ranged from 590 to 830 kg ha -1 . There was considerable variation between the different sites and years studied, as was expected from studies on other oak species. A comparison was also made of acorn production, comparing annual acorn production between 40 pruned and 40 non-pruned trees, for the period 1994-1999. There was an interaction between 'pruning treatment' and 'year'. Pruning, significantly decreased acorn production in all but two years when production was above the average, whereas production was not affected by pruning the three years that acorn yield was below the average. The study of acorn production and the analysis of the effect of pruning, needs to be studied over a longer time period.

Do ecological and silvicultural factors influence acorn mass in Holm Oak (southwestern Spain)?

“…All previous studies related with acorn production (Martin et al 1998;Á lvarez et al 2002;Carbonero et al 2002;Gea-Izquierdo et al 2006;Poblaciones et al 2006;Cañellas et al 2007;Alejano et al 2008) have not considered these two components separately. Nevertheless, to get a better understanding of the acorn production process it is very important to analyze both components separately, as silvicultural and ecological factors will affect them differently.…”

Influence of pruning and the climatic conditions on acorn production in holm oak (Quercus ilex L.) dehesas in SW Spain

“…The phytopathological phenomenon known as "oak decline" has resulted in the disappearance of vast forestry areas and led to widespread weakening and vulnerability of holm and cork oaks in the southwest of the Iberian Peninsula. Products such as firewood, which has traditionally been obtained from the pruning of trees (especially holm oaks), have lost most of their value [7]. This, together with the high costs of forestry practices, led us to revise current pruning treatments in dehesas.…”

“…Pruning involves removing branches in the central and inner zones of the tree crown; this causes leaves to be displaced farther from the trunk and restricts water supply with respect to leaves in a naturally growing crown. Maintenance pruning is intended to maximize acorn yield, and forest owners generally accept that pruning has favourable effects on acorn production [7]. However, it is unclear whether it increases acorn yield as traditionally believed [26] because the actual outcome is influenced by the pruning intensity used.…”

“…Although the influence of pruning on acorn production in Mediterranean oak woodlands has long been controversial, it is poorly documented. According to Cañellas et al [7], there is inadequate documented information to even form an objective, rational opinion about the response of trees to such an important silvicultural practice.…”

Pigs and Pollards: Medieval Insights for UK Wood Pasture Restoration

“…Thus, oaks do especially well in open pastures where they are not shaded. Pruning or pollarding the tree increases light exposure of the branches, which is believed to lead to better acorn crops on the dehesa [35,65], although one more recent study has questioned increased productivity [66]. In any case, the result of the management is an open landscape with widely spaced open canopy trees.…”