In hard climates coniferouse trees who have smaller water carrying tubes than braodleaved trees survive without loss of the use of these tubes through embolias in the tubes. In the frost bubbles form in the ice in the water carrying tubes of trees and when the thaw comes these bubbles expand and cause embolias that empty the tubes empty tubes are useless to trees this happens less in coniferas than in broad leaved trees allowing pines to survive the winter better than broad leaved trees do. So you have pines in the tundra.
Pines also serve in deserts were the waqter stress is likely to be greater and they are more likely to loose the use of tubes for embolias becausethe water in the tubes is stretched to thin. agri rose macaskie.
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