Document Details
 |
Title |
Mountain Pine Beetle Red Attack Shelf Life Discriminations | ||||||||||
Author |
Roberts, Arthur | ||||||||||
Date |
2008 | ||||||||||
Abstract |
Since cutting ?bug wood? has the highest current priority any detection and mapping procedure that will help discriminate new red attacked trees from older ?reds? has important implications for determining shelf life of the dead timber. These mapped mortality discriminations will assist with harvest planning and scheduling and will have implications for decisions involving timber yield and cost effective recovery of dead timber. Satellite imagery is very good for general overview evaluations but suffers from: (1) availability problems due to cloud cover & orbital periodicity, and (2) inadequate spatial resolution (often sub pixel for individual crowns) for forest health issues that require a statistically suitable spectral image for individual tree crown level analysis (Franklin et. al., 2003; Leckie et. al., 2001; Skakun et. al., 2003; Wulder and Dymond, 2004). The use of airborne imaging spectrometers (e.g. CASI) and multispectral scanners (e.g. GERS) has proved disappointing (Heath 2001; Roberts et.al., 2003). There have been no satisfactory orbital results for reliable early detection or operational red attack monitoring of MPB and other forest pests. Secondly, airborne 'line-imaging' systems are not good mapping instruments in comparison with aerial photography. This inevitably drives up the costs for any operational project. Other than one study in the early 1980?s (Gimbarzevsky et. al., 1992), an obvious gap in remote sensing research, related to these forest health problems, has been the almost complete lack of experimentation (and comparison) with digitally converted colour, colour infrared and multispectral aerial photography. In particular it is recommended that all experimental studies be evaluated against this standard in terms of: (i) mapping accuracy, (ii) potential for automated spectral interpretations, and, (iii) cost effectiveness. Aerial photography is the ?gold standard? in terms of mapping. Six areas of mountain pine beetle (MPB) infestation (to the west and southwest of Prince George) have been sequentially imaged, by the SFU Remote Sensing Laboratory, from April 2002 to October 2003, 2005 and from April to October 2006. These sites were established by MoF as test sites for the evaluation of experimental remote sensing systems and procedures. The extent of MPB current attack, red attack and healthy trees was ground truthed (mapped) at the individual tree level by field examination in the fall and winter of 2001 and subsequently 2002. All new red attacked trees were identified on 2002 and subsequently on 2003 digital multispectral aerial photography of these sites. There is a clearly detectable difference between the new red attacked trees mapped in Aug/Sept 2002 and the previous red attacked trees identified by ground truth in Nov/Dec 2001 (see Figure 1 attached). Comparable distinctions are also apparent on our 2006 imagery. These difference are quite distinct using four-band (B, G, R, NIR) multispectral imagery and 2006 results show that these distinctions are also in applications using combined colour and colour IR aerial photography mapping packages. Such capability is available in the Canadian private sector aerial survey industry and could be implemented for competitive tendering. Our 2003, 2005 and 2006 imagery for these same study sites confirmed this discrimination of new vs. old reds. Clearly the next step is to determine strength of replication and potential to separate current (new) and earlier reds (as well as older grays). This required a systematic replication study with new imagery in 2006 and 2007. A significant change in 2006 was the imaging evidence of an extensive new MPB attack in younger lodgepole pine stands. Our proposed 2007 imagery will permit us to evaluate 2 years of mortality differences in this younger pine plantation stands as well as determining the potential mortality descrimination (shelf life trajectory) across six years of sequential imaging: will it be possible to ... | ||||||||||
Report Number |
FIA2008MR197 | ||||||||||
|
|||||||||||
