Montana Department of Natural Resources and Conservation, Sustained Yield Calculation, 2014-2015
The Trust Land Management Division of the Montana Department of Natural Resources (DNRC) manages approximately 730,000 commercial forest acres for the benefit of the Common Schools and other endowed institutions. Management activities on the lands focus on providing a consistent and long-term revenue source for the trust beneficiaries, which is generated by selling a consistent annual timber volume. MB&G was contracted to perform a sustainable yield calculation to determine the proper amount of timber to sell. Pursuant to state law, an independent third-party is required to conduct the calculation.
In anticipation of the 2015 Sustained Yield Calculation (SYC), the DNRC conducted an extensive timber cruise leading up to the calculation. MB&G compiled this data into a standing inventory, which provided an estimate of the total volume of timber as well as the current condition of the growing stock. Through the use of a growth and yield model (FVS), MB&G then modeled future growth, resulting in a prediction of future timber yield and stand condition. These predictions also incorporated various management prescriptions (such as clear-cut, seed-tree, shelter-wood, and selection harvest) resulting in multiple estimates of future yield under various management pathways.
The results of the growth predictions were next incorporated into a Linear Programming model to schedule future harvests. This model incorporated all of the growth and yield predictions, coupled with GIS data containing the land stratification and classification. The objective of the model was to maximize the non-declining sustainable harvest level, subject to meeting various operational, regulatory and environmental constraints. These constraints included no harvest in deferred and riparian management zones; limited management in unique management zones and sensitive watersheds; and habitat promotion and protection for grizzly bear, lynx, and bald eagle. A total of three management scenarios were produced and analyzed, enabling the DNRC to compare the trade-offs between the options, and make a decision which best enabled the DNRC to meet all of its commitments.
Montana Department of Natural Resources and Conservation