The Marianas tropical dry forests stretch across Guam and the Northern Mariana Islands, both United States jurisdictions strung along a roughly 900-kilometer arc in the western Pacific Ocean. The terrain mixes young volcanic islands in the north with older southern islands built of volcanic rock and raised marine limestone, including limestone-capped Guam. Vegetation ranges from coastal stands of ironwood (Casuarina equisetifolia), Pisonia grandis, pandanus, and the fern Nephrolepis hirsutula to limestone forests of native breadfruit (Artocarpus mariannensis), the banyan fig Ficus prolixa, and Cordia subcordata, with volcanic-soil broadleaf forests dominated by Aglaia mariannensis and Elaeocarpus joga. The climate is warm and strongly seasonal, with annual rainfall around 2,000 to 2,500 millimeters and a wet season running from July through October, while frequent strong typhoons shape a dense, vine-laden forest structure with few emergent trees. The islands harbor endemic wildlife such as the flagship Mariana fruit dove and the Mariana flying fox, though invasive species, above all the brown tree snake blamed for extinctions of native birds on Guam, remain the foremost conservation threat.
Marker placed inside the RESOLVE 2017 polygon at 13.4°N, 144.8°E.
Climate snapshot for this ecoregion
°C
°F
Current zone range (2011–2040)
13b
Plotwright
CHELSA-derived typical winter month at this ecoregion's bbox grid.
Projected (2041–2070)
13b
Plotwright
Where the CHELSA models say the typical winter month is heading.
Average warming this ecoregion is on track for: +2.9°F by mid-century. SSP3-7.0 (current trajectory) · CHELSA v2.1 bio06 sampled across 10 of 10 points within this ecoregion's bounding box.
At a glance
Dominant biome
Tropical & Subtropical Dry Broadleaf Forests
Realm
Oceania
Approximate area
400 sq mi
Conservation tier
Nature Could Reach Half Protected (Dinerstein NNH 2)
About the tropical & subtropical dry broadleaf forests biome
Tropical forests that pass through a pronounced dry season, when many trees drop their leaves to conserve water. They hold high biodiversity but are among the most threatened tropical habitats, sensitive to fire and to clearing for agriculture.
Catalog plants suited to this ecoregion
No catalog plants intersect this ecoregion's zone range. As the catalog grows to cover this region's climate band, suggestions will surface here.
Collections for this ecoregion
No curated collection's plants all fit this ecoregion's zone range. We surface a collection only when every member would grow here — partial fits get filtered out rather than mislead. As the catalog and the curated set both grow, this section will fill in.
Related ecoregions
Other tropical & subtropical dry broadleaf forests ecoregions to explore: