Evaluation of mass seed crops in Picea engelmanni and Picea glauca using vegetation indices derived from Landsat Thematic Mapper data

Mass seeding is the intermittent and regionally synchronous production of large seed crops among conspecific populations. With conifers, the large female cones, concentrated preferentially in the upper crowns of trees, may occupy a sizable part of the upper canopy during a mass seed event. In this study, I evaluate the utility of Landsat Thematic Mapper (TM) data for the detection of temporal and spatial trends in white (Picea glauca) and Engelmann spruce (P. engelmannii) mass cone production. Through analysis of vegetation indices (Vls) calculated from TM data along with estimates of cone crop size and stand basal area per area from sites in Kootenay National Park in British Columbia and the Abitibi region of Quebec, I came to three main conclusions. (1) The presence of a mass cone crop is readily detectable in analysis of the difference between the Vls from the mass seed year and the years previous and subsequent. (2) The incorporation of spruce basal area per area allows for accurate spatial modeling of this difference. (3) The direct correlation of the Vls to field cone production estimates may be possible, but will require further research before it yields satisfactory results.