Using the SUBER model for assessing the impact of cork debarking rotation on equivalent annual annuity in Portuguese stands

Joana A Paulo,Margarida Tomé

doi:10.5424/fs/2017261-09931

Abstract

Aim of study: Use the SUBER model to evaluate the influence of the cork debarking rotation period (CDR) on equivalent annual annuity (EAA) value.Area of study: Nine simulated stands, varying in site index (14.4, 15.6, 17.1) and cork quality characteristics (high, medium, low).Material and methods: EAA values were computed considering CDR periods varying from 9 to 14 years, two contrasting structures of cork prices (high and low cork price scenarios), and three discount rate values (0.5%, 2% and 5%).Main results: For discount rates of 0.5% and 2% the impact of different CDR on the EAA is similar. In stands characterized by high to average site index values or high to medium cork quality characteristics, CDR of 9 and 11 years are associated with similar values of EAA. The variation of the CDR in stands characterized by low site index values and/or low cork quality characteristics did not have a relevant effect on the variation of EAA. For the simulations carried out with a discount rate of 5% the EAA decreases with the increase of CDR, indicating that the minimum legal value of 9 years for CDR should be applied.Research highlights: In stands characterized by high to average site index values or high to medium cork quality characteristics, a delay in the debarking may result in a significant increase of cork thickness and, as a result, of cork price. Detailed knowledge of cork and stand characteristics and updated information on cork prices structure and values are essential for the best usage of management tools such as the SUBER model, which can contribute to the decision-making process concerning the debarking operation.

Highlights

Because of the importance of cork oak trees in montado and dehesas ecosystems where cork oak (Quercus suber L.) is present, several management options are regulated by national legislation in some countries along its distribution area
We suggest the usage of a two -dimensional structure of cork prices that includes the proportions of both cork thickness and cork quality classes that characterise the stand for determining revenues associated with cork extraction (Almeida & Tomé, 2010)
They present the values of the equivalent annual annuity (EAA) obtained for each simulated stand and each cork price structure considered, as a function of the cork debarking rotation (CDR)

Summary

Introduction

Because of the importance of cork oak trees in montado and dehesas ecosystems where cork oak (Quercus suber L.) is present, several management options are regulated by national legislation in some countries along its distribution area. One example is the interval between two consecutive cork extractions occurring in the same tree, here designated as cork debarking rotation (CDR), which, according to Portuguese legislation, should be of at least 9 years. Other countries have established different values for this management option. Two features are important when defining the value of the cork for the industry of cork stoppers: the thickness of the cork plank and the cork quality. We suggest the usage of a two -dimensional structure of cork prices that includes the proportions of both cork thickness and cork quality classes that characterise the stand for determining revenues associated with cork extraction (Almeida & Tomé, 2010)

Objectives

Methods

Results

Discussion

Conclusion