Comparing stand growth models in optimizing mixed-species forest management

ABSTRACT

We study the effect of forest stand growth models on the economically optimal management of boreal mixed-species forests. Our size-structured economic–ecological model includes the optimization of harvest timing, harvesting intensities, rotation periods, and the choice between rotation forestry and continuous cover forestry. We carry out a systemic comparison of economically optimal solutions obtained with three statistical–empirical stand growth models for both single- and mixed-species stands with up to four tree species. Given a 1% interest rate, the optimal choice between continuous cover and rotation forestry depends on the applied growth model. However, under a 3% interest rate, the optimal management regime is always continuous cover forestry. The optimal solution details are highly dependent on the growth models. With a 1% interest rate, it may become optimal to apply intensive close-to-clearcut harvesting that results in a dominant species change via natural regeneration. However, the level of natural regeneration varies strongly between the growth models. The economic superiority of a species mixture cannot be determined from overyielding differences. Mixed-species stands have higher maximum sustainable yields, bare land values, and average net revenues compared with monocultures.

KEYWORDS:

• Forest growth models
• continuous cover forestry
• optimal rotation
• forest policy
• mixed-species forest management

Acknowledgements

We thank the Academy of Finland [330835] and Business Finland [42423/31/2020] for financial support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Without harvesting costs, once thinning initiates, it is optimal to apply at least some level of thinning during every period.