Spruce forest stands in a stationary state

Abstract

We present stationarity criteria for forest stands, and establish embodiments using a Norwegian empirical stand development model. The natural stationary states only slightly differ from the outcome of long-term simulations previously implemented using the same empirical model. Human interference in terms of diameter-limit cutting is introduced. Consequently, stationary states differing from the natural one appear. Standing volume, growth and monetary value appear low but the financial return rate may be significant. Volume yield and financial return clearly contradict each other, the former arising from harvesting large trees, the latter from frequent removal of small trees. An exponential tree size distribution does not appear to comply with the stationarity criterion.

Wealth accumulation in rotation forestry – Failure of the net present value optimization?

“…Let us plot the momentary capitalization κ ( a ), as well as the increment rate of momentary capitalization for the spruce value growth model [35, 36, 41, 40], as a function of stand age a in Fig 6. Again, the result is an outcome of the growth model only and does not depend on the objective function applied.…”

“…Fig 11 shows wealth accumulation within the spruce value growth model [35, 36, 41, 40], with the moderate any bare land value 469 Eur/ha. There are again large differences between the different objective functions.…”

“…Correspondingly, the stand age does not refer to the age of trees, but to the time elapsed after the latest regeneration harvesting within any stand. The empirical model of Bollandsås et al [35, 36] is applied and parametrized with reference to a recently introduced natural stationary state [41, 40].…”

“…Any regeneration harvesting is defined with respect to a natural stationary state [41, 40]. In particular, a diameter-limit cutting to breast height diameter 25 cm is introduced, the number of remaining trees within any diameter class below 25 cm adjusted to the number of trees in the natural stationary state [41, 40]. Then, any stand is allowed to develop according to the empirical model by Bollandsås et al .…”

“…For any of the three growth models (Eq (11), and (11) combined with (12), and [35, 36, 41, 40], the rotation age is optimized according to any of the three different objective functions given in Eqs (9), (10) and (8). In order to keep the treatment simple, no intermediate revenues or expenses within a rotation are discussed.…”