Glossary of Terms

Architecture (of tree, branch, or crown) - the growth patterns and resultant forms of stems (Oldeman, 1990)

Boundary layer- a very thin imaginary layer separating the canopy from the air above it

Canopy - 1) the combination of all leaves, twigs, and small branches in a stand of vegetation (Parker, 1995) 2) one of several combinations of particular sets or layers of tree crowns and the volumes of space between or below them (e.g. Bongers 2001)

Canopy gap - a space within and/or beneath the canopy not occupied by any physical structure

Canopy structure - the organization in space and time of the aboveground components of vegetation (Norman and Campbell, 1989)

Chablis - the zone of major effect when a tree falls in the forest, often a general hourglass shape with one area dominated by a new canopy opening and tip-up mound, and the other an area of extensive damage from the crown

Crown - the canopy of an individual tree

Fogging - application of aerosols to a tree to stun or kill the resident insects; used to identify otherwise-inaccessible canopy insects

Hemispheric photography- images taken from a "fisheye" lens that points directly upwards towards the canopy; often used to quantify canopy cover and light penetration

Interception - the fraction of precipitation that remains on canopy vegetation and is eventually evaporated (Crockford and Richardson 2000)

Lianas - a diverse assemblage of climbing woody vines, common in tropical canopies

Lidar - short for light detecting and ranging, is an active remote sensing technique that emits a laser pulse and records the return energy. Because the laser is reflected by the canopy elements and the ground at a range of heights, the return pulse has been scattered in time - the first return represents light that bounced off the top of the canopy, and the last substantial pulse is the ground bounce. With an appropriate energy-transfer model, the waveform of the return pulse can be used to determine vertical distribution of canopy elements.

Longwave radiation - radiation with wavelengths greater than 4,000

Neutral model of speciation - the hypothesis that observed patterns of species diversity are due to stochastic processes rather than deterministic ones such as competition or niche specialization.

Organization - the statistical distribution of canopy components in space or time

Photosynthetically active radiation (PAR) - radiation in the visible portion of the electromagnetic spectrum, with wavelengths of approximately 400 to 700 nm

Physiognomy (in reference to canopy structure) - study of the shapes of individual crowns

Plane mixing layer - the free shear layer that forms when two airstreams of different velocities merge; unlike the boundary mixing layer, the plane mixing layer includes a vertical dimension

Remote sensing - use of aerial photography, radar sensors, or other imaging devices to map landscape-scale spatial patterns

Shortwave radiation - radiation, generally solar, in the visible and near-visible portion of the electromagnetic spectrum; has wavelengths of roughly 400 to 4,000 nm

Single Rope Technique - firing an arrow, with a rope tied to it, over and around a tree branch; the rope can then be used to climb the tree

Spherical crown densiometer - a convex or concave mirror with a grid engraved in it used to measure canopy openness or gap fraction

Stemflow - the fraction of precipitation that flows to the ground via stems or trunks (Crockford and Richardson 2000)

Stereo-photogrammetry - A pair of aerial photos that are from slightly different locations can be used together to determine vertical structure based on parallax measurements.

Sunflecks - brief, intense small units of light that sporadically penetrate the canopy as the shading vegetation overhead shifts

Texture - describes the distribution and arrangement of crown units of various sizes, as viewed from above the stand

Throughfall - the fraction of precipitation that falls through the canopy to the forest floor (Crockford and Richardson 2000)

Turbulence - local eddies and fluctuations in wind speed and direction