地理漫步·世界地理英语30篇（3）
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Vancouver Island: A Biogeographic Threshold Between Ocean and Rainforest
温哥华岛：海洋与雨林之间的生物地理过渡带
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Vancouver Island lies off Canada’s Pacific coast, separated from mainland British Columbia by the Strait of Georgia.
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Its western shores face the open Pacific, absorbing moisture-laden westerlies that fuel temperate rainforests.
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The island’s mountain spine forces air upward, causing orographic rainfall exceeding 3,000 mm per year on the west coast.
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Eastward, rain shadows reduce annual precipitation to under 1,000 mm, supporting drier Garry oak ecosystems.
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This sharp moisture gradient creates one of North America’s steepest biogeographic transitions over just 100 km.
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Marine fog sustains epiphytic mosses and lichens even where rainfall diminishes seasonally.
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Glacial valleys carved deep fjords, while post-glacial rebound continues lifting coastal terraces at measurable rates.
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Salmon migration corridors link marine nutrients to forest soils, illustrating cross-ecosystem material flow.
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Indigenous land-use patterns historically mirrored these spatial gradients through seasonal resource harvesting.
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Today, climate-driven shifts in storm tracks threaten to widen the rain shadow and compress coastal habitats.