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Western Pacific Plain and Hills

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NameColor on MapCEC Code‡
Nayarit and Sinaloa Plain with Low Tropical Thorn Forest15.5.1
Jalisco/Nayarit Hills and Coastal Plain with Medium-high Tropical Semi-Evergreen Forest15.5.2

† Status: ✓ = Complete ○ = Needs Image … = Incomplete ∅ = Stub Only

This code refers to the CEC's Level 3 ecoregion codes for North America, see here.


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About the Western Pacific Plain and Hills

The Western Pacific Plain and Hills is a small level II ecoregion on the west coast of Mexico, mostly within state of Nayarit, although Nayarit extends much farther inland. This region is classified as part of the broader Tropical Wet Forests region, and is the only portion of this region located on the west coast of North America. This region also includes the Islas MarĂ­as and a few other islands in the Pacific.

The topography here consists of a mix of plains and hills, becoming low mountains inland. There are significant wetlands and lakes, especially in the north of this region along the coast, where it is flattest. The climate here shares much in common with that of the tropical dry forests farther north and south: there is a stong seasonality of precipitation, with the bulk of the rainfall occurring from June through September, slightly into October. Winter is cooler and has much less rainfall. However, the proximity to the ocean leads to high relative humidity even during the dry season. The high humidity and abundant freshwater in the lowlands facilitate both the growth of lusher tropical forests, and the use of the land for agriculture.

Most of the flat areas here have been cleared for agriculture, and there is also significant urban development. The more hilly areas are mostly forested and less populated.

The borders of this region are not clearly defined. Along the coast to the north, this area transitions into the slightly drier Western Pacific Coastal Plain, Hills, and Canyons, and to the south, the also slightly drier Southern Pacific Coastal Plain and Hills. Inland, the northern portion of this region transitions into the Transversal Neo-Volcanic System, and south of this, the Southern Sierra Madre.