Dr. Geoffrey G. Parker

Datasets of three-dimensional information on canopy surfaces

Included here are 4 ASCII files giving the 3D canopy structure data obtained in each of four mixed-species, broadleaved forests of the “Tulip poplar” type located in the vicinity of the Smithsonian Environmental Research Center (SERC) on the Coastal Plain near Annapolis, Maryland, U.S.A.

Each file summarizes canopy structure in one 30 x 30 m plot sampled in the growing season of 2001. RGCubeall.out is from a very young forest, KPCubeall.out is from an intermediate-aged stand, TWCubeall.out is from a mature forest, and FCCubeall.out is from a plot in old-growth. In each case, the coordinate system follows the right-hand-rule: If you were looking down at the forest canopy, x has origin at the left and increases to the right; y has its origin at bottom and increases toward the top; z has its origin in the plane of the page and increases toward the viewer.

The data were obtained with high-speed laser measurements of distances overhead sampled in 31 parallel transects of 30 m length each. The laser was carried at 1 m above ground; the datasets provide no information on canopy structure below 1 m. The vertical distribution of relative surface area (“foliage-height profile”) was obtained from frequency distributions of distances using the “MacArthur-Horn” transformation) and the estimates of surface area density were made using the “Overlap transformation.”

Each file has a header line describing the variable order. The 6 variables are:
- x, y, z coordinates of the voxel center in meters [each voxel is 1 x 2 X 1 m]
- d(z) number of laser hits in that [x,y,z] bin
- fee(z) fraction of column surface area in this height bin (sums to 1
for a given [x,y] if there are any surfaces, to 0 otherwise)
- el(z) estimate of surface area density (m^2/m^3) in this bin.

The intent of distributing these datasets is provide standard observation sets from diverse situations for the development of tools for analysis and visualization of information on real canopy structure in three-dimensions. These datasets are part of ongoing research on canopy structure and are not to be shared for uses other than the exploration and development of analytical and visualization methods. Please contact the owner of the datasets (below) for questions about the context, origin, transformations, and use of these data.

Geoffrey G. Parker
Smithsonian Environmental Research Center
647 Contee's Wharf Road
P.O. Box 28
Edgewater, MD 21037

tel: 443.482.2210
FAX: 443.482.2380
email: parker@serc.si.edu
web: http://www.serc.si.edu/