Life on the Edge: Structural Analysis of Forest Edges to Aid Urban Management

The accelerating expansion of agricultural and urban areas fragments and degrades forests

and their capacity to provide essential ecosystem services while increasing physiological stress

and mortality rates of trees growing near forest edges. Previous studies have documented that

edges are hotter and drier than forest interiors and trees nearer the edge grow slower. However,

the physical structure of a forest’s canopy may serve to mitigate to these effects. This study

quantifies forest fragmentation across the Central Hardwoods Region (CHR; containing Missouri,

Illinois, and Indiana) and characterizes structural differences between the canopies of forest edges

and forest interiors. Importantly, we distinguish between edges that neighbor developed land and

agricultural lands since these landcover types may impose distinct effects on forest structure. We

characterized forest canopy structure in a subset of the CHR region using the 2016-2020 Indiana

3DEP Lidar Program data. Our findings indicate edge forest (forests within 30m of an edge) makes

up 29.8% of the total forest in our study extent, with urban and agricultural edges accounting for

17.8% and 72.8% of the edge edges in the region, respectively. Analysis of 15 separate structural

metrics derived from aerial laser scanning (ALS) showed no significant structural differences

between developed and agricultural edge canopies but did find differences between structure of

canopies in forest cores and those in forest edges of any kind. As developed and agricultural lands

increase so too will forest fragmentation and the creation of new forest edges. If there are no

significant differences between forest edge types, then we could begin to treat edges without

distinction. This could lead to simplified management practices for foresters and urban foresters

alike to protect and preserve forest fragments.