Overkroonlaag

Overkroonlaag is a term used in Dutch forestry and ecology to denote the vertical layer of vegetation that lies above the main crown layer (kroonlaag). It comprises trees and other vegetation that rise beyond the average canopy height, forming an emergent or supra-crown layer. The presence and extent of the overkroonlaag depend on site conditions, stand age, disturbance history and species composition. It is most evident in forests with a wide range of tree heights and in environments where some individuals grow much taller than the dominant canopy.

In a forest with an developed kroonlaag, the overkroonlaag can be discontinuous and patchy, consisting of a few tall emergent trees and sporadic upper-layer vegetation. Characteristics of this layer include greater wind exposure, higher light intensity at the top, and a distinct microclimate compared with the lower canopy. The overkroonlaag often hosts specialized species and provides unique habitats, contributing to overall biodiversity and structural complexity of the forest.

Relation to other layers: the kroonlaag refers to the main canopy formed by the dominant and codominant trees, while the overkroonlaag sits above it. In some texts, the term emergent layer is used interchangeably with or as a subset of the overkroonlaag. In practice, terminology can vary between regions and inventories; the Dutch term highlights the concept of a supracanopy layer beyond the main crown.

See also: kroonlaag, emergent layer.