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

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

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

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

Sampling error standards USFS Alpha=5% ValueSE < % < % < % < % < % > % Florida merchantable planted pinealpha=5%SE=10% merchantable natural timberalpha=10%SE=10% pre-merchantable pinealpha=32%SE=10% 5

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

Formulae 7

Sample size vs. CV Area=10 ac 8

Sample size vs. CV Area=20 ac 9

Sample size vs. CV Area=50 ac 10

Sample size vs. CV Area=100 ac 11

Sample size vs. Sample error Area= 10 ac 12

Sample size vs. Sample error Area= 20 ac 13

Sample size vs. Sample error Area= 50 ac 14

Sample size vs. Sample error Area= 100 ac 15

Intensity – CV for  =10% 16

Intensity – CV for  =5% 17

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

Cauchy distribution 19