Gallery forests are the thin strip of trees and associated plants facing a gap of some sort. In this case it’s the opening created by the Río Frío in Cano Negro Wildlife Refuge, but other sources of light gaps are roads, patures, tree falls, cliffs and land slides. Because of the availability of strong sunlight from the side as well as above gallery vegetation can be quite different from what’s growing surrounded on all sides by other plants a few meters away.