Naslov
Assessment of the optimal sample size for the estimation of forest damage using remote sensing methods

Autori
Pernar, Renata ; Seletković, Ante ; Jazbec, Anamarija ; Ančić, Mario

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Skup
Forest, Wildlife and Wood Sciences for Society Development- Session 2: Forest inventory and managament

Mjesto i datum
Prag, Češka Republika, 16.04.2009. - 18.04.2009

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
damage estimate; CIR aerial photographs; sample size; geographical information system (GIS); Croatian (Dinaric) beech-fir forests

Sažetak
Dieback of silver fir forests in Croatia is becoming a serious economical and ecological problem. In 2005., results of field forest damage assessment (ICP Forests) have shown the largest portion of significantly damaged silver fir (Abies alba, Mill.) trees (76, 7%). Beech-fir forests in the Dinaric mountain range are particularly affected Significant damage of common beech (Fagus sylvatica L.) still remains low (10, 9%), which puts it amongst our least damaged tree species. Since it was necessary to, as quickly as possible, gain insight on actual field situation, in order to provide the most efficient measures for tree dieback prevention, colour infrared (CIR) aerial photographs were taken in stands with the largest degree of degradation. In all former researches, the usage of CIR aerial photographs has proven to be equal to field methods in its accuracy, and much more efficient considering the objectivity and the time spent. Forest damage inventories based on systematic samples using the raster method were created for the whole monitored area (5 548 ha). Different raster points densities (100x100 ; 200x200 ; 300x300 ; 500x500 ; 1000x1000) were tested to assessment the optimal sample size that would statistically insure sufficient accuracy for remote sensing damage estimate methods on large areas. The crown closest to the raster point in the bottom left and right, and in the upper left and right angle was interpreted. In this way, the damage degree of 4 individual trees (crowns) was assessed in every raster point Damage indicators: damage (D), mean damage (MD), damage index (DI) and mean damage of trees damaged over 25% (MD1) were calculated, based on interpretation results, for individual tree species and for all the interpreted species together by individual surveying strips, and by the entire surveyed area Statistical analysis assessed the optimal sample size and the number of interpreted trees (crowns) for the entire surveyed area Results of damage estimates on CIR aerial photographs, by application of defined raster method, were in no way different from the terrestrially obtained results.

Izvorni jezik
Engleski

Znanstvena područja
Šumarstvo

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