Spruce snag quantification by coupling colour infrared aerial photos and a GIS

Detection of Single Standing Dead Trees From Aerial Color Infrared Imagery by Segmentation With Shape and Intensity Priors

“…NDVI (Tucker, 1979), are useful for distinguishing between dead wood and living vegetation due to the reflectance differences in these spectral bands (Jensen, 2006). Several authors have developed manual or semi-automatic individual snag detection methods which make use of this fact ( Bütler and Schlaepfer (2004), Heurich et al (2010), Pasher and King (2009)). The disadvantage of these approaches is the necessity to involve a human expert in the processing, which may limit their applicability to large areas.…”

Mapping Bugweed (Solanum mauritianum) Infestations in Pinus patula Plantations Using Hyperspectral Imagery and Support Vector Machines

“…These spectral characteristics are of more importance in the red-edge region as this region represents absorption spectra of the visible and reflectance spectra of the NIR portions (Dalponte et al, 2009) and subtle differences between species in crown characteristics can show up as large differences in infrared reflectance (Butler and Schlaepfer, 2004). The rededge refers to the point of maximum slope between the red chlorophyll absorption region (680 nm) and the region of high near-infrared reflectance (750 nm) (Scotford and Miller, 2005).…”

Comparison of field inventory methods and use of airborne laser scanning for assessing coarse woody debris

“…Aerial photographs have been successfully used for assessing standing dead trees (e.g. Uuttera and Hyppänen 1998, Haara and Nevalainen 2002, Pasher and King 2009, and even though canopy closure was observed to significantly affect the detection, Bütler and Schlaepfer (2004) achieved promising results in their mapping and quantification of large snags using aerial photographs. Poorer results have nevertheless been reported for the prediction of downed dead wood volumes using aerial photographs (Pasher and King 2009).…”

“…Poorer results have nevertheless been reported for the prediction of downed dead wood volumes using aerial photographs (Pasher and King 2009). Other ecological uses of aerial photographs include the detection of drought, insect and wind damage (see Bütler and Schlaepfer 2004, Meentemeyer et al 2008.…”

“…The use of aerial photographs for inventories of CWD has usually been based on visual or manual interpretation, however (e.g. Bütler andSchlaepfer 2004, Holopainen et al 2006), which may be time-consuming and prone to subjective errors, and therefore more automated inventory methods should be considered. Pasher and King (2009) have observed recently that aerial photographs and various direct mapping methods are highly accurate for the assessment of the number of dead branches and snags, but the standard error for the predicted plot-level downed dead wood volumes was still 62.1%.…”