Published in: https://
link.springer.com/article/10.1007/s1034
2 021 01379 8N/

Faias, Sónia

Firmino, Paulo Neves

Paulo, Joana Amaral

Tomé, Margarida

English

UTL Repository

SUBTOPIC: 3.3 MANAGING MEDITERRANEAN AGRO-SILVOPASTORAL SYSTEMSUsing quantile regression to evaluate the impact ofdifferent factors in the cork caliperof cork oak trees in montado agroforestry ecosystemAUTHOR AND CO-AUTHORS:Joana Amaral Paulo (joanaap@isa.ulisboa.pt), Paulo Neves Firmino, Sónia Pacheco Faias, Margarida Tomé• Cork oak (Quercus suber):Mediterranean basin distribution• Montado: agrosilvopastoral ecosystem• Non-wood forest product: cork• Minimum period between corkextraction in Portugal: 9 years• Diversity of cork products: natural corkstoppers are the main one• Centro de Estudos Florestais (InstitutoSuperior de Agronomia) long termresearch line based in a nationalpermanent plot networkContextAre climate variables affectingall trees in the same way?Research questionThe relationship between cork annualgrowth and climate is well established inthe scientific literature?Yes, for the “average” tree response!For variables such as precipitation,average temperature and drought…State of the artMaterials and methods• 35 plots (see map)• site index ranges from 10.7 to 16.2 m at base age 80years• Cork samples extracted between 1996 and 2005.• Years included in the data set: 1988 to 2004.• The final data set included 1024 cork samples, with9153 confirmed annual growth measurements.Materials and methods• The complex interactions existing between thevariables considered are difficult to account forusing more frequent statistical approaches (e.g.ordinary least squares regression).• Quantile regression, instead, aims at estimatingdifferent quantiles of the response variable,given certain values of the predictor variables.Task 1: model quantiles of annual growth corkgrowth and cork caliperTask 2: using the developed models, map thepercentage of cork extracted (9 years of growth) thatis suitable for natural cork stopper production.Precipitation confirmed a positiverelationship to annual cork growth for all ofthe quantiles. This relationship is not linear.Instead it has a downward parabolic shapewith an optimum annual averageprecipitation value.This value is decreasing for the trees fromhigher quantiles of cork thickness, that whengrowing in locations with precipitation valuesclose or higher to 1000 mm might notrespond to an increase in water availability.Results (Task 1)Maximum annual temperature was shown tonegatively affect the cork annual growth and corkthickness.For cork thickness obtained after 9 years of growth,this was only observed for the trees under the 6thquantile.These trees are more vulnerable to heat waves,which are expected to be more frequent underclimate change.Results (Task 1)Results (Task 1)The Lang Index (LI = Pt/T) showed the importanceof the ratio between the precipitation andtemperature variables.The downward parabolic relationship betweenannual cork growth and this index showed that thebest cork growth conditions are found for valuesaround 60, corresponding for the transitionbetween semi-arid climate and humid climate.Results (task 2)Mapping of the percentage of cork suitable fornatural cork stopper production showed highervalues are expected in the Southern and Centralcoastal regions and along the Tagus River basin.The Northern coastal and mountain regions,characterized by Lang index values larger to 60(humid climates), present lower estimated valuesfor the percentage of cork suitable for natural corkstopper production.• Climate affects differently the cork growth, and ultimately cork thickness, of trees from different quantiles.• An increase in precipitation might not be translated by and increase cork calliper in all trees of the same stand.• Trees producing thinner cork are more affected by an increase of maximum temperatures.ConclusionsAre climate conditions (andother factors) affecting all treesin the same way?Research questionCONTACTS:Joana Amaral Paulo (joanaap@isa.ulisboa.pt)https://fenix.isa.ulisboa.pt/qubEdu/homepage/isa114126/Published here:https://link.springer.com/article/10.1007/s10342-021-01379-8https://repository.incredibleforest.net/oppla-factsheet/20702

Using quantile regression to evaluate the impact of different factors in the cork caliper of cork oak trees in montado agroforestry ecosystem

https://www.repository.utl.pt/bitstream/10400.5/24468/1/CEF-CONFERENCE-O3.3_4_208_Paulo_et_al_EURAF2021.pdf

Using quantile regression to evaluate the impact of different factors in the cork caliper of cork oak trees in montado agroforestry ecosystem

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