CLIMATE IN RELATION TO WINTER MORTALITY OF THE LODGEPOLE NEEDLE MINER, RECURVARIA STARKI FREE., IN CANADIAN ROCKY MOUNTAIN PARKS
Four major air masses, tropical maritime (mT), polar maritime (mP), arctic maritime (mA), and arctic continental (cA) may be used in describing the winter climate of a lodgepole needle miner (Recurvaria starki Free.) outbreak area. The main circulation is from the north and west which results in a p...
| Published in: | Canadian Journal of Zoology |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1959
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/z59-076 http://www.nrcresearchpress.com/doi/pdf/10.1139/z59-076 |
| Summary: | Four major air masses, tropical maritime (mT), polar maritime (mP), arctic maritime (mA), and arctic continental (cA) may be used in describing the winter climate of a lodgepole needle miner (Recurvaria starki Free.) outbreak area. The main circulation is from the north and west which results in a predominance of mP and cA air. Local topography and its effect on winter climate is described for four areas now sampled on a life-table basis. Variations in winter mortality from year to year and between sampling areas are related to climate. Extensive invasions of cA air, particularly of long duration, cause lethal winter temperatures. Winter mortality usually occurs during the coldest month, January, and may be exceptionally high when extreme minima of −30° F to −40° F persist long enough to depress the monthly mean temperature close to O° F. However, less extreme temperatures in other months may result in similar high mortalities if these are unseasonably low. The climatic conditions causing high mortality generally occur at the tops of slopes and at valley bottoms, allowing the middle slopes to serve as "refuge areas" for surviving needle miner populations. |
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