The purpose of this project was to examine the feasibility of using Free to Grow (FTG) survey plot data to develop the Percent Empty Plots (PEP?s) statistic needed to calculate Operational Adjustment Factor (OAF1) values used in the TIPSY growth and yield model. The use of existing FTG plot data would make the localization of OAF1 estimates significantly less expensive. It is recognized that this project only addresses the currently existing gaps/holes aspect of OAF1 and does not attempt to estimate its future losses element.
Simulation techniques were first used to determine the probability of an empty OAF1 plot occurring within a FTG plot with a specific minimum inter tree distance, leading species (OAF plot size), and number of well spaced trees. These probabilities are needed to transform FTG plot data into the PEP statistic generated by the OAF1 ground based survey method. Both OAF1 ground based surveys and FTG surveys were simulated on a variety of virtual stem maps to determine if they produce similar estimates of Percent Empty Plots (an precursor of OAF1).
Results showed that the FTG survey approach typically overestimated PEP relative to the OAF1 ground based survey approach. When the very low density scenario results are ignored because they are unlikely to represent conditions present in a FTG block, overestimates were <4% (<2% for stands with >=2500 sph). Because the FTG estimates were conservative relative to the OAF1 survey estimates, it is suggested that this approach could provide a cost effective means of estimating localized OAF1 a/b estimates.
Forsite Consultants Ltd.. 2010. Using Free-Growing Survey Data to Estimate OAF1 values at the Forest Level. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2010MR205
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), Land, Base, Investment, Program
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