Measuring Canopy Structure
Canopy Access Techniques
| Measuring Struct. Overview | |
| "Chop." The cheapest and easiest method is cutting down trees and measuring on the ground, or collecting fallen leaves and branches. This method doesn't allow temporal sampling, doesn't preserve leaf angles, breaks many units beyond reconstruction, and has numerous other problems. |
|
| "Climb." Up the trunk with belts or ascenders or ladders, or up to the branches with single rope techniques (SRT) (e.g. Perry 1978, reviewed in Moffett 1993). These methods are relatively cheap, but are slow, require skill, and are very limited in spatial extent. |  Photo credit: http://www.selby.org/research/canopy |
|
"Build." A tower provides access to a small area of canopy over a range of heights. A ladder to climb and a series of walkways (e.g. Muul and Liat 1970) supported by the trees themselves provides wider access, but this approach is expensive and requires numerous safety precautions. Canopy booms have been constructed that attach to trees on one end and have a canvas chair suspended from the other. |
 Photo credit: http://www.selby.org/research/canopy |
| "Float." Hot air balloons and inflatable rafts have been used to sample the very top of the canopy successfully, even in remote areas that can't easily be reached on the ground (Hallé 1990). |  Photo credit: http://www.selby.org/research/canopy |
| "Spend." If money isn't an issue, the construction industry provides equipment such as cherry pickers, which move easily in relatively open forest or along roads, and construction cranes, which can cover a huge area completely and sample from any point in the x, y, or z direction - but are very expensive (reviewed in Parker et al. 1992). |  Photo credit: http://depts.washington.edu/wrccrf/gallery |
Good reviews of these and other methods can be found in Moffett and Lowman (1995), Sutton (2001), and Lowman (2001). Lowman (2001) also contains a table listing dozens of specific canopy research sites worldwide using these various methods to access the canopy.