Pattern is a component of forest structure that includes the spatial arrangement of the types, species, numbers and sizes of individual structural elements (eg, trees, logs, snags). Spatial pattern is inherently linked to density (eg, number and size of trees; trees acre-1 or basal area in ft2 acre-1), and the horizontal and vertical arrangement of trees, which is constrained by density. Spatial pattern varies at multiple spatial scales (from stand to landscape) and across environmental and productivity gradients in any given forest type.