The continuous field view of representing geography: opportunities for forest inventory
2008
Mozgeris, G., Lithuanian Univ. of Agriculture, Akademija, Kauno reg. (Lithuania)
This paper discusses the continuous field view of representing geography and its role in forest inventory. Describing all forest attributes at any location or point and storing this information in digital databases, as an alternative to store forest compartments as vector polygons and associated attributes, is considered to be important for development of remote sensing and GIS applications for forest inventories. Main results achieved following this approach during the last decade in Lithuanian university of agriculture are described. Special research polygon near Kaunas was developed. Four auxiliary data sources (Spot Xi, Landsat TM, digital aerial photos and stand-wise inventory material), three estimators (two-phase sampling with stratification, the k-nearest neighbours and regression) as well as different methods for auxiliary data integration were examined to get point-wise forest characteristics. The lowest root mean square errors at a level of virtual sample point using optimal implementation tactics are – for mean diameter 24 %, height 18%, age 28%, basal area 37%, volume per 1 ha 40% and percentage of coniferous trees 29% of the mean value of corresponding forest characteristic. Integrating additional auxiliary information – characteristics of forest compartments, estimated during the conventional stand-wise inventory – and satellite images improved the overall estimation accuracy. Pre-stratification of sample plots using the attributes of compartments improved the estimation accuracy for certain stand groups. A new approach of segmentation, aimed to construct conventional forest compartments – estimation of point-wise forest characteristics for every pixel of satellite imagery and using them instead of original image values – was suggested and investigated.
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