Original scientific paper
Application of Colour Infrared Aerial Photographs for the Assessment of Forest Damage in the Gospić Forest Administration
Renata Pernar
; Šumarski fakultet Sveučilišta u Zagrebu
Mario Ančić
; Šumarski fakultet Sveučilišta u Zagrebu
Ante Seletković
; Šumarski fakultet Sveučilišta u Zagrebu
Abstract
The paper presents the results of research conducted with the goal of assessing forest damage in CIR aerial photographs. The interpretation of CIR aerial photographs provided the condition of forest ecosystems in the study area (the Gospić Forest Administration). An infrared digital orthophoto (DOP 1:5,000) was made by surveying strips for the entire surveyed area. The DOP was overlaid with a systematic 100x100 m sample (dot grid). Four crowns closest to the point were interpreted at each of the points (sample) and damage to a total of 21,011 trees was assessed. Damage indicators (O, SO, IO, SO1) were calculated for individual tree species and for all the interpreted species together by individual surveying strips, by the entire surveyed area and by management units (compartments /subcompartments included in the survey).
In the interpreted area covering 5,548 ha, the recorded mean damage (SO) for all tree species amounted to 23.60 %, for fir to 37.81 %, and for beech to 12.61 %. The results suggest that the damage degree of the inventoried forests is between low and moderate. The damage index (IO) of fir for the area of Lika is 61.96 %; in other words, this percentage of fir trees in the surveyed area is damaged by more than 25 %. Within the 61.96 % of severely damaged fir trees, the mean damage (SO1) of fir is 51.03 %.
In terms of the interpretation of results by surveying strips, we can conclude that the mean damage (SO) and the damage index (IO) for all the trees together are the highest in the surveying strip 5.
The obtained results were used for the construction of thematic maps on a scale 1:10,000. They contain spatial distribution of mean damage (SO) and damage index (IO) for the principal tree species, and overall for management units (compartments/subcompartments) in individual surveying strips.
Application of CIR aerial photographs for the assessment of forest damage provided data which do not differ from terrestrially-obtained data; however, aerial photographs represent a lasting document of the condition.
Keywords
colour infrared aerial (CIR) photographs; damage indicators; forest damage.; infrared digital orthophoto(DOP); photointerpretation key
Hrčak ID:
23984
URI
Publication date:
1.11.2007.
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