Modelling light obstruction in three conifer forests using hemispherical photography and fine tree architecture

A catalogue of hemispherical photographs was collected from conifer forest plantations in order to assess light obstruction by tree crowns. The three conifer species of interest were red pine (Pinus resinosa), jack pine (Pinus banksiana Lamb.), and white spruce (Picea glauca). A tree reconstruction technique called the vectorization method provided the means by which to reproduce fine 3-dimensional spatial distributions of the foliage and support structures of forest trees. More specifically, the detailed geometry of three selected canopies was simulated using the data set produced from the vectorization method and the in situ site characterisation. Moreover, a ray tracing model based on material density provided by the vectorization was developed to replicate hemispherical photos taken looking up from beneath the canopy. The comparison of in situ with simulated hemispherical photographs met three objectives: 1. to estimate the elementary scale driving the obstruction patterns, 2. to validate the vectorization method, and 3. to assess the degree to which the trunks and support structures obstruct light.