Figure 5 : Habitation site and shell midden depth influence on forest canopy cover.

From: Intertidal resource use over millennia enhances forest productivity

Figure 5

(a) Forest canopy cover (in percentage) by distance from the shell midden boundary (red) or distance from random locations (blue) shown with s.d. of bootstrapped boosted regression tree models and mean forest canopy cover across entire study area shown by a dashed line (73.01%). (b) Box plot of difference in forest canopy cover by site type and the depth of shell midden (deep (D)=dark green, medium depth (M)=green, shallow (S)=light green) with forest canopy cover at habitation sites being moderately higher compared with all non-habitation sites (t=1.857, P=0.087). Control sites are located along the coast in areas without shell midden where ‘All’ sites include the entire study area shown in yellow in Fig. 1. Boxes represent first, second and third quartiles with whiskers extending to the highest and lowest value that is within 1.5 × IQR.