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Comparison between intensity based inventory and sampling based inventory Bogdan Strimbu Louisiana Tech University

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Issue Inventory of the forest resources Practical applications: preset intensity Alternative: sampling design Legal constraints 2

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Objective Questions to answer: 1.Is preset-intensity inventory legally defendable? 2.Are there significant differences between preset- intensity inventories and sampling based inventories? 3

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Approach USFS and Florida Assessor guidelines Sampling error standards dependent on the estimated value of the sale alpha=5% 4

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Sampling error standards USFS Alpha=5% ValueSE <1500020% <3500019% <5500016% <7500014% <9500012% >9500010% Florida merchantable planted pinealpha=5%SE=10% merchantable natural timberalpha=10%SE=10% pre-merchantable pinealpha=32%SE=10% 5

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Settings Preset - intensity inventories: 5% and 10% Alpha=5% → Approximate t=2 Plot size: 0.1. ac Simple Random Sampling without replacement Homogeneous stand → No stratification The population has a mean 6

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Formulae 7

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Sample size vs. CV Area=10 ac 8

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Sample size vs. CV Area=20 ac 9

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Sample size vs. CV Area=50 ac 10

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Sample size vs. CV Area=100 ac 11

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Sample size vs. Sample error Area= 10 ac 12

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Sample size vs. Sample error Area= 20 ac 13

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Sample size vs. Sample error Area= 50 ac 14

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Sample size vs. Sample error Area= 100 ac 15

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Intensity – CV for =10% 16

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Intensity – CV for =5% 17

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Summary USFS guidelines more strict then state guidelines Intensity based inventory – legally defendable using USFS or state guidelines (Florida) most of the cases Stratification recommended for high variable stands Intensity based inventory for stands>20 ac at least double the cruising effort For stands larger than 50 ac the cruising effort is almost comparing with the sampling based inventory 18

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Cauchy distribution 19

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