Title: Understanding the interaction between cork oak trees and the vegetation in its neighborhood

Period: July 2016 to June 2019

Main Funder FCT: PTDC/AGR-FOR/4352/2014

ISA coordinator: Margarida Tomé


Plant-plant interactions strongly influence plant community dynamics and ecosystem structure. This is particularly true in the cork oak ecosystem, a complex system that almost always includes one or more vegetation layers – natural or cultivated – below the trees. 

The data will be gathered in plot-sets specifically established for this project. This will be accomplished by selecting stands, preferably within which different neighborhood environments will be artificially created (the treatments): with and without shrubs, with and without “pastures”, with and without fertilization, or other management operatiosn with impact on the individuals interactions.

The idea behind the project is not only to measure the effect of local competition on growth but also to contribute for the explanation for the underlying mechanisms. A operational result will be the inclusion of the interaction between the cork oak trees and the surrounding vegetation in the existing model for simulation of cork oak stands – SUBER model, which will have important practical consequences. The need for this improvement was identified by forest managers at dissemination workshops, held in the last years.

Research assistants:

Paulo Firmino, Sandra Veloso, Xavier Lecomte



1. Planning, coordination and dissemination     

     Period: 01-07-2016/30-06-2019
     Task leader: Margarida Tomé

Task Description
A good coordination of the several activities to be undertaken under the project is the basis for its success. The development of the project will be undertaken as a set of planned activities each with a well-defined goal, time frame, acceptance criteria and involved risks that will all be defined at the beginning of the project (kick off meeting).

2. Establishment of the plots and site characterization

     Period: 01-07-2016/30-09-2017
     Task leader: Sónia Pacheco Faias

Task Description
Existing permanent plots available within the research team will be screened for selection of the most appropriate for the establishment of the plot-sets. In the ideal situation, four plots will be established in each site: without weeding; weeding; weeding+pasture; weeding+ leguminosae.The size of the plots will depend on the stand density, aiming at including a number of trees per plot to allow the constitution of the comparable groups of trees (CGTs).These trees will be object of intensive monitoring which means the application of band dendrometers at breast height and monthly measurements. All the trees in the plots will be measured at the establishment: dbh, total height, height of the crown base, crown width. The site will be characterized, namely the soil. Soil samples will be obtained and analysis of C, N and P undertaken. Climatic data (monthly time step) will be obtained for the Portuguese Meteorological Institute climatic station closer to each plot.

3. Monitoring growth of the sample trees and the vegetation in their neighborhood

     Period: 01-09-2016/31-12-2018
     Task leader: Joana Amaral Paulo

Task Description
Tree growth will be monitored in a different way in adult and juvenile stands. In adult trees, band dendrometers will be placed at the dbh of every tree belonging to a CGT. In juvenile trees, total tree height and diameter at 0.10 m will be measured in the beginning and at the end of the monitoring year. The plots will be visited at least monthly during the 3 growing seasons,and, in each visit, dendrometers will be monitorized and the understory development will be evaluated. Non-destructive assessment (evaluation of percent cover and height) will be used but destructive (biomass determination) will be undertaken in selected sites for the development of understory biomass prediction equations. At each visit, phenology observations will be made in the tree and in the understory vegetation.

4. Effect of the understory in tree water and nutrient use       

     Period: 01-09-2016/31-12-2018
     Task leader: Maria da Conceição Caldeira

Task Description
Tree water status will be evaluated in each plot by measuring predawn and midday water potential seasonally in each plot using a Scholander pressure bomb in leaves of five trees in each plot. Soil water content will be measured periodically with PR1 soil moisture equipment (Delta-T).Carbon and oxygen stable isotopes will also be measured in leaves of trees to determine their water use efficiency as an indicator of water limitation for growth. For assessing the effect of the treatments on the nutrient use by trees leaves of five trees will be sampled in each plot. Leaves will be dried at 65 °C and grounded and analyzed for total C, N and P. Soil will also be sampled and analyzed for C, N and P. Nitrogen stable isotopes will also be measured in tree leaves to assess nitrogen source.

5. Competition modeling and interpretation     

     Period: 01-10-2017/30-06-2019
     Task leader: Margarida Tomé

Task Description
Data gathered within the project will be used to estimate, for each tree, several spatially explicit competition measures from the traditional ones – based on the size and distances of the neighbors, area overlap indices, indices based on horizontal and vertical, growing space or area potentially available (tessellation methods) – to indices based on the ecological field theory or the field of neighborhood. Competition will be modelled separately for each resource and the proposed methodology may differ among resources. The statistical analysis will cover simple correlations of the competition measures with growth, multiple regressions including tree size, stand variables, and several competition indices, tree growth models of the potential X modifier type in which one or several modifiers will be used to express the resources  vailability. The analysis may also be complemented with the use of process-based /hybrid tree growth models.

6. Transfer of results to practical applications     

     Period: 01-10-2018/30-06-2019
     Task leader: João Palma

Task Description
The objective of this task is the transfer of the new knowledge generated within the project to operational forest management. This will be achieved through the implementation of the results in an existing forest growth model, the SUBER model. The results achieved in the project will allow an upgrade of the model and the possibility of improving the model by making tree growth to respond to different types of understory. The SUBER model will then be used to compare alternative schemas for control of shrubs and alternative uses of the understory.



Progress reports available only in portuguese:

Year 1  (July 2016 to June  2017)

Year 2 (July 2017 to June  2018)



Faias S.P., Paulo J.A., Palma J.H.N., Tomé M., (2018). Understory effect on tree and cork growth in cork oak woodlands, Forest Systems 27(1). 



Paulo, J. A., Faias, S. P., Firmino, P., Tomé, M., (2017). Impacto de diferentes alternativas de gestão na biomassa do subcoberto e no crescimento da árvore e da cortiça. Centro de Estudos Florestais (CEF) conference from research to practice. Subject: The Role of Agroforest Management Practices in the Prevention and Recovery After Fire in Montado. Organization: CEF and ANSUB. 23rd November 2017. Grândola.

Faias S.P., Paulo J.A., Tomé M., (2017). Competition pattern in young cork oak stands. IFORS, Quebec city (Canada) 17-21 July. Abstract

Faias S.P., Paulo J.A., Tomé M., (2017). Competition pattern in young cork oak stands. International congress on cork oak trees and woodlands: Conservation, Management, Products and Challenges for the Future, Sassari (Italy) 25-26 May. Abstract

Faias S.P., Paulo J.A, Tomé M., (2017). Tree diameter growth model for cork oak stands in Portugal. International congress on cork oak trees and woodlands: Conservation, Management, Products and Challenges for the Future, Sassari (Italy) 25-26 May. Abstract




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