Canopy structure indicators of forest developmental stage, disturbance, and certain ecosystem...

Canopy structure indicators of forest developmental stage, disturbance, and

certain ecosystem functions

Geoffrey Parker, David Roy Fitzjarrald

Smithsonian Environmental Research CenterEdgewater, MD 21037

Atmospheric Sciences Research Center, UAlbany SUNY

Albany, NY 12203

Normalized profiles of wind speed (dotted line), CO2 (solid line) and their product (i.e. the transport term) at the Old

Growth Site, LBA. (from Staebler, 2003).  

Micrometeorological motivations: determining canopy mixing rates, displacement height, roughness length..….

U

CO2

Transport

Ecological objectives

• Introduce new metrics of canopy structure

• Examples of application at LBA sites

• Differences between treatments, sites

• Implications for radiation exchange

portable LIDAR for rapid determination of canopy structure

• Up-looking high-frequency rangefinder

• Deployed along transects at forest floor

• Estimates of volumetric surface area density with a spatial resolution 1-2 m

• Mean, variance, and spatial co-variation of several metrics

Lidar measurements (details):

Riegl LD90-3100HS first-return laser rangefinder890 nm; 1 kHz operation

Mounted to the front of a frame, 1 m above the ground.

Moving at walking speed through the forest, yields distances between measurements about 1 cm.

Spot size of the laser beam is 4-6 cm at the ranges encountered here.

Vertical profiles calculated using the overlap distribution described byMacArthur and Horn (1969).

Resolution as averaged for this study: 1 m in vertical, 2 m in horizontal.

Yields parallelepidep ‘voxels’ of 1X2X1 m in x,y,and z.

Desesperados……

Some derivable metrics

• Cover, estimates of canopy area index

• Maximum and average surface height

• Vertical distribution of surface area density

• Distribution of maximum heights

• Complexity of outer canopy surface

• Internal porosity

• Gap-size distribution

maximum height

horizontal distance, m

heig

ht,

m

the outer canopy hypsograph

• The cumulative distribution of top heights, specifically (LOCH, local outer canopy height)

• Not the same as the distribution of all surface areas

• Topographic analogy: elevations in a catchment basin

Outer canopy hypsograph in a chronosequence of eastern deciduous forests

LBA-ECO Santarem study area

km67 site— a pretty rough forest…

LBA-ECO Manaus Study area

Looks smooth from the air…..

Highly dissected terrain Manaus ‘ZF-2’ site

Some perspective from previous measurements…..

conclusions

• Canopy structure– similar within site, including logged and intact– differs between Tapajos and Manaus sites

• Canopy rugosity at Tapajos, landscape roughness at Manaus ZF2

• Differences in transmitance and absorption profiles, radiation-use efficiency

many thanks

Julio Tota, Cibelle Sampaio, Scott Saleska NASA: LBA-ECO CD-03

National Science Foundation NASA-Goddard, Global Canopy Program Atmospheric Sciences Research Center, SUNY Wind River Canopy Crane Research Facility, Smithsonian

Environmental Research Center