Month: August 2023

The forest management cycle combines decades of biological knowledge with technical advances in forest management. Our Forest Stewardship Policy reflects our commitment to sustainable forest management.

STANDING MERCHANTABLE INVENTORY

Long-term strategic harvest scheduling starts with the detailed inventory of our timberlands. The forest planning and inventory team oversees independent and audited annual timber cruising of tracts to measure timber growth, which is used to update standing timber inventory volumes. Standing inventory measurements are completed over an approximately five-year cycle in the South and a ten-year cycle in Idaho.

The estimated total volume of standing merchantable timber inventory is updated annually. Standing merchantable inventory means that the tree being measured has met the size, quality, and other characteristics of the regional market. The annual update reflects additions of young timber that has met minimum diameter requirements, growth of existing merchantable timber inventory, decreases of timber due to harvests, wildfire, or insects and disease, and the impact of acquisitions and divestitures.

STRATEGIC MANAGEMENT PLANS 

Timberlands are managed using 50-year strategic management plans based on harvest schedule models. Timber inventory data are utilized in growth-and-yield models, which optimize long-term harvesting and forest management operations and project sustainable harvest volumes over the 50-year time horizon. The harvest schedule is performed every two years, alternating between the southern regions and Idaho each year.

Within the strategic harvest schedule model, timberlands are organized into stands by common characteristics such as age and forest management prescriptions. Each stand carries a specific soil productivity designation called site index, which is based on the height of the dominant trees at a specific age. The higher the height of the dominant tree, the higher the site index on that stand. Site index also enables the inventory model to capture the expected impact of silvicultural improvements such as advanced genetics or fertilization.

The long-term strategic harvest schedule uses the starting forest inventory of each timber stand and then incorporates forest management activities such as site preparation, planting, thinning, fertilization, and harvest. Areas that have harvest restrictions are identified, such as streamside management zones, so that the model does not include them for harvest actions. Using all this information and a yield table – a table of tree heights, diameters, and volumes for each stand over the next 50 years – the model creates an optimization matrix that “grows” and “harvests” each stand of timber over time.

The strategic harvest schedule model builds an optimization matrix that contains all the possible choices for each stand over 50 years according to defined management constraints, including not harvesting restricted areas and replanting or regenerating every acre harvested. The harvest model checks every possible stand activity and combination over the planning horizon and produces a detailed stand-by-stand harvest schedule that maximizes Net Present Value (NPV) based on starting stand structure, yields, product prices, management choices, and harvest constraints.

ANNUAL MANAGEMENT PLANS

Foresters prepare five-year tactical plans of tracts for silviculture work and harvest based on the results of the harvest schedule. Foresters select the timing of treatments and harvest based on timber type, growth stage, markets, road access, weather conditions, and operability of the site. Tracts are then moved into annual operating plans and site-specific prescriptions are developed for each forest management operation.

Harvest operations are conducted in accordance with Company best practices, regulatory, and certification requirements that protect water quality, wildlife habitat, and worker safety. Logging contractors must be on an approved contractor list and receive annual training. Foresters monitor logging activity to ensure environmental protections are implemented and specific prescriptions for the tract being harvested are followed.

Following harvest, the remaining residuals, or slash, are treated as appropriate for the geographic region. In Idaho, slash is managed to minimize fire risk through installation of fire breaks, mechanical piling, and pile burning. Southern harvesting operations result in less slash at final harvest due to stand thinning techniques to promote timber yield, allowing slash to be mechanically spread back into the tract and returning nutrients to the soil. Following slash management and prior to planting, sites are typically treated with herbicides to control competing vegetation in order to promote growth of seedlings.

During planting season in late fall or spring, contractors plant seedlings on tracts that were harvested 12 – 18 months earlier. Third-party nurseries grow Idaho seedlings with 70% of the seeds being sourced from our Cherrylane Seed Orchard. The species that is best suited to the site-specific location and elevation is selected for replanting. In the U.S. South, seedlings are purchased from third-party nurseries and benefit from generations of selective breeding to promote favorable growth and yield characteristics as well as resistance to disease and insects.

Foresters monitor the growth of the timber stands by conducting physical stand exams, as well as by using modern tools such as drones, satellite imagery and GIS13 technology. New inventory data is synthesized along with information about operational activities into the long-term harvest scheduling model.

Commercial thinning is typically required on stands in the South and on occasion in Idaho to reduce stocking density to improve stand growth and development. Pre-commercial thinning is utilized when the number of stems is high enough that diameter growth will be reduced to a level where it is financially advantageous to bear the cost to reduce the density of trees, increase diameter growth and reduce the risk of insect or disease entering an overstocked stand.

After harvest, the forest management growth cycle begins anew. Our foresters pride themselves on the tracts they grow over their careers.

“Our advanced harvest scheduling models are calibrated to the timber growing regions and markets where we operate. We are continuously improving our harvest outlooks and incorporating environmental protections into our models to ensure that our long-term harvest plans provide economically sound, long-term sustainable wood flows, and meet our commitments to protect sensitive sites, rare species, and streams.” 

– Tim Sydor 
Manager, Forest Planning and Inventory, PotlatchDeltic