How to manage mixed secondary forest in a sustainable way?
2019
Dong, Lihu | Jin, Xingji | Pukkala, Timo | Li, Fengri | Liu, Zhaogang
Secondary mixed forests of larch and birch are common in the mountainous areas of north-eastern China. In the Daxing’an Mountain of Heilongjiang Province, the larch species of this type of forest is Larix gmelinii Rupr. and the birch species is Betula platyphylla Suk. Science-based information on the optimal sustainable management of these forests is largely missing. Since the forests serve multiple functions, including soil protection, carbon sequestration and maintenance of habitats, only continuous cover forestry is regarded acceptable. This study optimized a sequence of transformation cuttings of mixed secondary forests of larch and birch to sustainable steady-state uneven-aged structure. The optimization problem was formulated in such a way that the species composition of the steady-state forest was also sustainable. A reference management scenario was obtained by letting the stands grow for 100 years without any cuttings. The results showed that the no-management option leads to low rate of regeneration and ingrowth, and the stands do not develop towards typical uneven-aged structures. Maximizing net present value without any constraints leads to heavy cuttings, making these schedules unacceptable from the soil protection and carbon storing point of views. Schedules that were evaluated as the most recommendable were obtained by adding a minimum basal area constraint to the problem formulation, and maximizing species and size diversity of the steady-state forest simultaneously with net present value.
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