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Appendix A. Canopy openness as a measure of microclimate at canopy and understory sample sites for radical transects in Cape Tribulation, Australia.

The openness of the forest canopy provides an integrated measure of variation in irradiation, relative humidity, and temperature. Canopy openness was estimated at each sample point along radial transects in the canopy (using a Nikon fisheye lens camera) and in the understory with a CID-110 Canopy Analyzer (CID Inc., Camas, Washington, USA). Due to failure of the CID-110, hemispherical images could not be collected with the same instruments in both strata. All images were collected under conditions of uniform lighting (early or late in day, overcast conditions). Percent canopy openness was calculated from the digital images using Canopy Analyzer software from CID, Inc.

Light conditions were highly variable across sample points, and distribution of light environments in the canopy and understory were largely non overlapping (Fig. A1).

FIG. A1. Distribution of canopy openness in the canopy and understory of radial transect sample points at Cape Tribulation, Australia.