Target Vegetation Metrics

To meet final eligibility criteria for the systematic map, references had to present data for at least one of 5 different target vegetation metric types. The following text lists specific metrics that might be included in each of these general vegetation metric types. Each reference was coded by a subject expert from the systematic map team as to whether it included data for one, two, three, four, or all five of these metric types.

Forest composition- Any metric related to plant/tree species composition where the identity or type of species is important. This could be basal area or importance values for individual tree species, specific forest classifications, basal area of mast producing trees, dominant tree species, stems per acre of particularly important understory species, etcetera.

Forest structure- Any metric related to local or small plot variation in the vertical or horizontal arrangement of vegetation. This includes a variety of metrics such as: shrub-stem density, number of vertical layers, % canopy cover, forest age classes, tree size distributions, percent cover estimates for different growth forms, and more.

Habitat elements- This refers to the presence, absence, or abundance of discrete features or resources that may be used by birds, such as: cavities, perches, rock outcrops, soft mast, dead trees, streams, caves, etc.

Landscape metrics- Metrics that are calculated at a larger scale than a points or small plots that indicate aspects of spatial arrangement or composition of features. This includes edge-related metrics; many different patch shapes, size, or configuration metrics; land cover compositions at variable scales, and distances to important features like roads or water.

Management Treatment- samples are grouped by different categorical management types (e.g., single-tree selection/clear-cut, burned/unburned, deer fencing/no deer fencing, etc.), regardless of whether a study presents explicit measurements of environmental attributes that describe different levels of the management type.