Estimating Aboveground Tree Biomass for Beetle-Killed Lodgepole Pine in the Rocky Mountains of Northern Colorado

Kim

2018

Self Cite

Operational studies are necessary to support production and management decisions of forest industries. A time study (TS) approach is widely used in timber harvesting operations to understand the performance of individual harvesting machines as well as the entire system. However, several limitations of the TS approach include the use of generalized utilization rates, incapability of capturing interactions among equipment, and model extrapolation in sensitivity analysis. In this study, we demonstrated the use of discrete event simulation (DES) techniques in modeling a ground-based timber harvesting system, and compared the DES results with those of the TS model developed with the same observed data. Although both TS and DES models provided similar estimation results for individual machine cycle times and productivities, the estimated machine utilization rates were somewhat different due to the difference in synthesizing machine processes in each approach. Our sensitivity analysis and model expansion to simulate a hypothetical harvesting system suggest that the DES approach may become an appropriate method for analyzing complex systems especially where interactions among different machine processes are unknown.

Section: Harvesting System and Data Collectionmentioning

confidence: 99%

Discrete-Event Simulation of Ground-Based Timber Harvesting Operations

Kim

2018

Self Cite

“…In the Colorado State Forest in northern Colorado, lodgepole pine stands have been heavily impacted by the MPB outbreak since 2008 [68] (Figure 1). Our study site, which is the 3400-ha lodgepole pine forest, has an average mortality rate of 47.3%.…”

Section: Problem Statementmentioning

confidence: 99%

“…In the current salvage harvest in Colorado State Forest, timber salvage and residue utilization are managed by the landowner as two separate operations with economic feasibility being the main consideration for either operation, similar to the fully economic-oriented solution in the Sequential scenario. During the salvage harvest, although the WT system can be less expensive than the LS system when the skidding distance is short, the extra burning cost disfavors its application [68]. Without knowing whether residues are to be utilized, the landowner has preferred the LS system for salvage harvest, because it is easy to implement and more economical for slash management [90].…”

Section: Fully Economic-oriented or Environmental-oriented Solutionsmentioning

confidence: 99%

Economic and Environmental Optimization of the Forest Supply Chain for Timber and Bioenergy Production from Beetle-Killed Forests in Northern Colorado

Han

2019

Harvesting mountain pine beetle-infested forest stands in the northern Colorado Rocky Mountains provides an opportunity to utilize otherwise wasted resources, generate net revenues, and minimize greenhouse gas (GHG) emissions. Timber and bioenergy production are commonly managed separately, and their integration is seldom considered. Yet, degraded wood and logging residues can provide a feedstock for bioenergy, while the sound wood from beetle-killed stands can still be used for traditional timber products. In addition, beneficial greenhouse gas emission (GHG) savings are often realized only by compromising net revenues during salvage harvest where beetle-killed wood has a relatively low market value and high harvesting cost. In this study we compared Sequential and Integrated decision-making scenarios for managing the supply chain from beetle-killed forest salvage operations. In the Sequential scenario, timber and bioenergy production was managed sequentially in two separate processes, where salvage harvest was conducted without considering influences on or from bioenergy production. Biomass availability was assessed next as an outcome from timber production managed to produce bioenergy products. In the Integrated scenario, timber and bioenergy production were managed jointly, where collective decisions were made regarding tree salvage harvest, residue treatment, and bioenergy product selection and production. We applied a multi-objective optimization approach to integrate the economic and environmental objectives of producing timber and bioenergy, and measured results by total net revenues and total net GHG emission savings, respectively. The optimization model results show that distinctively different decisions are made in selecting the harvesting system and residue treatment under the two scenarios. When the optimization is fully economic-oriented, 49.6% more forest areas are harvested under the Integrated scenario than the Sequential scenario, generating 12.3% more net revenues and 50.5% more net GHG emission savings. Comparison of modelled Pareto fronts also indicate the Integrated decision scenario provides more efficient trade-offs between the two objectives and performs better than the Sequential scenario in both objectives.

“…The average truck load in green weight was obtained from the mill trip tickets, which provide scale measures of gross and net truck weight for each truck cycle. The average log dry weight was estimated based on the observed average number of logs per truck load, the ratio of live and dead trees in the harvest unit, and the average moisture contents of live and dead trees obtained from the previous study conducted at the Colorado State Forest State Park [21].…”

Section: Harvesting System Productivity and Production Costsmentioning

confidence: 99%

“…The amount of biomass cut but unrecovered during primary transportation (i.e., biomass leakage) in WT was estimated by subtracting the amount in slash piles measured at the landing from the estimated logging residue portion of standing trees. The logging residue portion of standing trees (i.e., tree tops, limbs, and foliage) was estimated using the allometric equations specifically developed for both live and dead lodgepole pine in the region [21]. The volume of tree tops had to be adjusted for this study because [21] considered a tree top as the tree portion above 10-cm diameter, whereas the practice in the study harvest unit was to remove tree tops at 18-cm diameter due to timber product specifications for markets in the region [27].…”

Section: Slash Pile Measurement and Biomass Leakage Estimationmentioning

confidence: 99%

Productivity and Costs of Two Beetle-Kill Salvage Harvesting Methods in Northern Colorado

Han

et al. 2018

Self Cite

Two ground-based timber harvesting methods have been commonly used for beetle-kill salvage treatments after a bark beetle epidemic in northern Colorado. A “lop and scatter” method uses a mobilized stroke delimber to delimb and buck trees at the stump, leaving tree tops and limbs on the forest floor, while a whole-tree harvesting method brings the entire tree to the landing where it is delimbed and bucked, and thus produces logging residue piles at the landing as a byproduct. We conducted a detailed comparative time study of the two harvesting methods to develop productivity and cost models and compared the performance of the two methods under various site conditions. We applied the productivity and cost models to lodgepole pine forest stands totaling 3400 hectares of the Colorado State Forest State Park to estimate salvage harvesting costs for each forest stand and identify the least costly harvesting options. The results show that the estimated stump-to-truck timber production costs were $30.00 per oven dry ton (odt) for lop and scatter and $23.88 odt−1 for the whole-tree method in our study harvest unit. At the forest level, the estimated average stump-to-truck costs were $54.67 odt−1 and $56.95 odt−1 for lop and scatter and whole-tree harvesting, respectively. Skidding distance and downed trees affect the harvesting costs of both methods, but their influence appears to be more significant on the whole-tree method.