Sampling simulation on multi-source output forest maps - an application for small areas

Matti Katila ¹ and Erkki Tomppo
_{Finnish Forest Research Institute 
Unioninkatu 40 A, FIN-00170 Helsinki, Finland 
Tel.: +358 10 2111 ; Fax: +358102112104 
matti.katila@metla.fi; erkki.tomppo@metla.fi}

Abstract
Systematic samples were simulated on multi-source National Forest Inventory (MS-NFI) output thematic forest maps  obtained by k-nearest neighbours method (k-NN) for areas of 1 km2  and 100 km2  . The standard deviations based on the simulated sample means were used as estimates for the standard errors (SE) of the particular designs. The variables of interest were the mean tree stem volume (m3 /ha) and the volumes by tree species. The effect of the temporal and thematic accuracy of the forest maps was studied with respect to the precision of the SE estimates from simulations. The simulated SEs were validated against an independent field inventory data measured from three test sites of 1 km2  and seven sites of 100 km2  in Eastern Finland. The effect of the estimation parameters of k-NN method on the error estimates was also studied. The study showed that the Finnish MS-NFI thematic maps can be used to estimate sampling errors for systematic field sampling designs with a plot distances down to 75-100 m on areas of 1 km2  and larger.

Keywords: multi-source forest inventory, sample simulation, standard error, Landsat TM

In: Caetano, M. and Painho, M. (eds). Proceedings of the 7th International Symposium on Spatial Accuracy Assessment in Natural Resources and Environmental Sciences, 5 – 7 July 2006, Lisboa, Instituto Geográfico Português