LANDSCAPE ASSESSMENT OF THE DECLINE OF WHITEBARK-PINE (PINUS-ALBICAULIS) IN THE BOB MARSHALL WILDERNESS COMPLEX, MONTANA, USA

Whitebark pine (Pinus albicaulis) provides important food for wildlife and important cover for snow retention and watershed protection in hi gh-elevation ecosystems of the northwestern United States. In the nort hern Rocky Mountains, this species is being reduced at accelerated rat es by blister rust (Cronartium ribicola), mountain pine beetle (Dentro ctonous ponderosae), and advancing succession resulting from fire excl usion. This study evaluates the extent and severity of the decline of whitebark pine in the Bob Marshall Wilderness Complex (BMWC) of Montan a. Results of an extensive field survey of various whitebark pine comm unities were used to evaluate past and current whitebark pine populati on levels. Satellite imagery (LANDSAT TM) data were used in conjunctio n with field data to classify 14 BMWC subalpine cover types and 3 fore st decline classes to detect extent of whitebark mortality in the stud y area. Results indicate whitebark pine population levels are rapidly decreasing, mostly as a result of the exotic disease blister rust. Fie ld results show 83% of the 2,503 sampled whitebark pine trees are infe cted with blister rust and an average of 33% of their crowns have been killed by the disease. Results of the satellite image classification show whitebark pine dominant on 56% of the 311,257 hectares comprising the BMWC subalpine analysis area. Subalpine fir dominated a high prop ortion (14%) of this landscape, about 7% greater than its historical l andscape composition. Approximately 22% of this landscape containing w hitebark pine is now experiencing high mortality and 39% is experienci ng moderate mortality. Classification accuracy was 60% for the vegetat ion cover types and 78% for the forest decline classes.