Understory effect on tree and cork growth in cork oak woodlands

Sonia P. Faias, Joana A. Paulo, João H. N. Palma, Margarida Tomé


Aim of study: Cork oak is one of the main forest tree species in Portugal that typically occurs in montado, where operational practices oriented to the tree, crop or animal management may influence several of the ecosystem components. This study aimed at contributing to fulfil the a lack of knowledge on the effect of these practices on the cork and wood growth, by comparing the wood diameter growth and the annual cork increment under two different understory management options.

Material and methods: An experimental trial implemented on an uneven-aged cork oak pure stand during a cork rotation period of 9 years, was established with the specific goal of comparing understory management options: a yellow lupine pasture versus spontaneous vegetation. Cork samples were taken at the beginning and end of the period and were used to measure cork thickness and annual cork rings. The differences between treatments were assessed performing a non-parametric test and a more robust approach using linear mixed model. Precipitation and treatment levels were jointly considered on the analysis.

Main results: A slight effect was found on the cork thickness regarding the treatment with lupine application. However, no distinct effect was found, regarding wood and the annual cork increment pattern. Additionally, annual cork ring width showed a positive correlation with precipitation and a negative correlation with ring age.

Research highlights: The results of this study indicate no distinct pattern regarding the annual cork and wood increment when comparing the understory effect of yellow lupine pasture versus spontaneous vegetation.


Quercus suber, cork thickness; cork ring; lupine; shrubs; linear mixed model

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DOI: 10.5424/fs/2018271-11967

Webpage: www.inia.es/Forestsystems