The model assumed a planted forest consists of n stands (n > 1).
To include arrangements among forest stands, it was assumed that
forest stands were arranged into strips, i.e., stands are connected if
they are next to each other. For example, stand 1 is adjacent to stand
2, and stand 3 is adjacent to stand 2 and stand 4 and so on. Interactions
among forest stands were captured by economies of planting scale. If
adjacent stands are harvested at the same time, they form a larger
planting area in the following year. A larger planting area requires a
lower unit of planting cost which is captured in the model (Eq. (11)).
The objective of the model was to maximize the NPV from harvesting
timber and sequestering carbon. The model was subject to a constraint
which is the density of birds (i.e., MVP ha−1). The planning horizon, as
well as the maximumlength of the rotation interval for the simulations,
were 50 years, since in Vietnam, both household forest owners can use
their forest lands for 50 years at most. At the end of the lease, forest
owners were supposed to harvest the whole forests.