Savanna

A savanna (also spelled savannah) is a tropical or subtropical woodland ecosystem. Savannas are characterised by the trees being sufficiently small or widely spaced so that the canopy does not close. It is often believed that savannas are characterised by widely spaced, scattered trees, however in many savanna communities tree densities are higher and trees are more regularly spaced than in forest communities. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.. Savannas are also characterised by seasonal water availability, with the majority of rainfall being confined to one season of the year. Savannas can be associated with several types of biomes. Savannas are frequently seen as a transitional zone, occurring between forest regions and desert regions.

Although the term savanna is believed to have originally come from an Amerindian word describing "land which is without trees but with much grass either tall or short" (Oviedo y Valdes, 1535), by the late 1800s it was used to mean "land with both grass and trees". It now refers to land with grass and either scattered trees, or an open canopy of trees.