Influence of edaphic, topographic and competition variables on cork quality and thickness and cork oak spatial distribution

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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

Mapping cork caliper in Portugal using percentile regression

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

2019Conference object

Open access

A tree‑ and climate‑dependent growth model to predict mature annual cork thickness under different climate change scenarios

Publication . Paulo, Joana Amaral; Firmino, Paulo N.; Tomé, Margarida

Climatic factors drive the annual growth of cork and the subsequent increase in its thickness, which, in addition to porosity, determines the price of cork. Therefore, the simulation of cork thickness is a crucial module of forest growth simulators for cork oak stands. As the existing cork growth models are independent of climatic factors, cork thickness under different climate change scenarios could not be simulated using these models. The primary objective of this study was to develop a climate-dependent tree model to predict annual cork growth. We also verified the hypothesis that the effects of climate change on cork annual growth are nonlinear, and vary with the cork age and thickness. Due to the limited amount of work developed around this topic, we evaluated three candidate models and selected the one that presented best prediction performance as the base model. A set of climate variables that characterized annual climatic conditions were tested in the base model parameters. The resulting climate-dependent model was referred to as the fixed-effects model, and used to initialize a mixed-effect model which accounted for the nested structure of the data. We considered two random effects—the plot and the trees inside the plot. Annual precipitation and the Lang index (ratio between annual precipitation and mean annual temperature) were the variables that showed best results when included in the model parameters. Using a ratio of the variable to cork thickness recorded during the previous year, in both cases, suggested a decline of the positive effect of annual precipitation and the Lang index for increasing cork thickness. The models developed in this study predicted the cork thickness of individual trees based on the cork age and under different climate change scenarios. Therefore, they can be used in forest growth simulators for forest management and research purposes.

2023-09Journal article

Open access