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Intra-annual tree diameter increment and seasonal leaves nutrients in cork oak species under three understory management alternatives

Publication . Faias, Sónia; Firmino, Paulo Neves; Tomé, Margarida; Moreno, Gerardo; Paulo, Joana Amaral

An experimental trial implemented on a pure unevenaged cork oak stand, in Podzol soil, with the specific goal of comparing understory management alternatives, was monitored between 2003 and 2015. The stand understory layer is composed by spontaneous vegetation dominated by Cistus salvifolius, Lavandulla peduncalata and Ulex airensis. Cork samples from two distinct cork rotation cycles (2003 to 2012 or 2006 to 2015), taken at the beginning and end of the debarking period, were analyzed regarding cork ring width (Faias et al. 2018, Faias et al. 2019). Results suggest a different effect on cork annual growth depending on whether the operations are performed at the middle or at the beginning of the cork rotation cycle. Under the CorkNeighbors research project, this trial was continuously monitored and analyzed between 2016 and 2019 (Faias 2019).

2019Other

Open access

Using neighbourhood vegetation information on cork oak growth and yield modelling

Publication . Faias, Sónia Maria Marques Pacheco; Tomé, Margarida; Paulo, Joana Amaral

The present work contributes to information regarding the competition on the tree and cork growth, by evaluating the neighbourhood vegetation and local tree density impact. From a specific trial established to compare the effect on the tree of different understory management options, along a cork rotation cycle of 9 years, cork samples were taken at the beginning and at the end of the cycle on trees within lagged cycles. Former results revealed no effect on cork annual growth and wood increment for the trees growing under lupine periodical seeding. When analysing the interaction between cork ring age and understory operations, different thresholds were linked to the shrubs’ maintenance and the lupine seeding. Later, this trial was monitored to compare the shrubs’ maintenance versus removal with or without NP soil fertilization. On the set of selected trees, diameter increment was monthly monitored, as well as, leaves nutrients seasonal variability, and differences were found in the treatment with soil fertilization. Data gathered from a Portuguese network of permanent plots across the cork oak species distribution area was used to model tree variables including the site characteristics. Focusing the analysis on young plantations and never debarked stands, the relationship of the diameter relative growth rate over tree dimension showed signs of inter-tree competition before the first cork extraction in older high-density stands. A crown width model developed with a fixed-effect approach was applied using national forest inventory datasets. Subsequently, a decrease in crown cover was identified in Portugal over ten years. Using the Portuguese dataset with a Spanish dataset, a diameter increment model was developed applying two methodologies: age-independent difference equations and potential growth times a modifier. This Iberian dataset allowed testing the inclusion of stand variability associated with climate and soil site conditions

2020Doctoral thesis

Open access