Productivity and economics of mixed two-storied spruce and birch stands in Southern Finland simulated with empirical models

摘要

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.