|
|||||
|
|
Productivity and economics of mixed two-storied spruce and birch stands in Southern Finland simulated with empirical models |
|
| Authors: | Sauli Valkonen Lauri Valsta |
| Institution: | a Finnish Forest Research Institute, Vantaa, Finland b Department of Forest Economics, University of Helsinki, Helsinki, Finland |
| Abstract: | The profitability of growing a naturally emerged birch (Betula pendula Roth or Betula pubescens Ehrh.) overstory in a young Norway spruce (Picea abies (L.) Karst.) plantation was examined with empirical stand structure, growth and yield, logging cost, and logging damage models. In the projected alternatives, an overstory of either birch species was thinned to 200–1000 stems per ha at the age of 15 years and retained for another 15 years. Development of the remaining spruce stand was simulated up to rotation age (70–85 years). Alternative treatments included removing the overstory completely at 15 years, and managing a pure spruce stand that was kept free of birch throughout. Growing a birch overstory of 200–1000 stems per ha up to age 30 years resulted in a 61–93 m3 ha?1 or 9.1–16.8% yield loss for the spruce stand due to growth retardation, and a mortality of 382–498 out of 1900 stems per ha through logging damage. This was compensated for or exceeded by the additional yield of the birch (54–173 m3 ha?1) except for the lowest stocking (200–400 stems per ha) alternatives with B. pubescens. Treatment regimes with a birch overstory were clearly the most profitable alternatives, yielding up to 151% (B. pendula) and 113% (B. pubescens) of the net present value of the pure spruce alternative, at 4% interest rate. Removing the birch overstory already at 15 years was the least profitable alternative with 79 and 83% net present values, respectively. The most profitable treatment with current technology, price, and cost structure appears to be to grow 500–800 birch per ha up to about age 40 years for B. pendula and 45–50 years for B. pubescens. |
| Keywords: | Growth Yield Economics Modeling Admixture Two-storied stands Picea abies Betula pendula Betula pubescens |
| 本文献已被 ScienceDirect 等数据库收录！ | |