Matrix Growth Model And Multiple-use Forest Management Simulation For Larix-spruce-fir Forests

It is the requirements of sustainable forest management to maintain multiple-functional forest. Uneven-aged forest management is acquiring expanding significance throughout the world as an alternative to clear cutting. Matrix models can be used to predict the growth of uneven-aged stands with its simple model structure and easy incorporation in optimization analysis for multi-objective forest management. The objective of the study is to develop a matrix model and simulate variable management scenarios with consideration of timber, carbon and biodiversity for Larch-spruce-fir forests in Jilin province, northeastern China. The matrix model was calibrated for 20 long-term permanent plots with 5-year period observations. Tree species was grouped as larch, Korean pine-spruce-fir and two deciduous groups according to their growth characteristics. There are 11 diameter classes with the width of 5 cm. The parameters of upgrowth, mortality and ingrowth models are estimated through ordinary least square method and seemingly unrelated linear regression. The differences in parameter estimate values between them were not significant. Mortality and upgrowth probability is a function of tree diameter, basal area, stand diversity in terms of tree species and size, number of trees in minimum diameter class and elevation. Ingrowth probability is significantly affected by basal area, stand diversity in terms of tree species and size, number of trees in minimum diameter class and elevation. The model was validated in short term by comparing the observed with predicted number of trees in each diameter class and species group at the time of the second, third, fourth and part of fifth inventory. Relative errors were also calculated. The model was statistically reasonable and subsequently was applied to predict timber yield, tree species diversity, tree size diversity, and carbon storage under 13 management scenarios. To judge from the timber yield, the scenario with short cutting cycle (5 years) and high intensity (20 percent) could meet the maximum of timber yield. For tree species and size diversity, the scenarios, including nature growth, long cutting cycle (15 years) and low intensity (5 percent, 10 percent), could maintain and increase the tree species and size diversity. For above-ground carbon storage, the scenarios, including nature growth, long cutting cycle (15 years) and moderate intensity (10 percent, 15 percent), could protect the above-ground carbon storage. To sum up three objectives, the results showed that the scenario with long cutting cycle (15 years) and low intensity (5 percent) could meet the need of timber yield, protecting biodiversity and increasing carbon stock simultaneously. The simulation demonstrated that multiple objectives could be realized through reasonable forest management, and matrix model is a valuable tool for simulations of forest management scenarios.