Evi - UMass Boston

Echidna

The terrestrial lidar instrument, Echidna®, developed by CSIRO Australia, allows rapid acquisition of vegetation structure data that can be readily integrated with downward-looking airborne lidar, such as LVIS (Laser Vegetation Imaging Sensor), and spaceborne lidar, such as GLAS (Geoscience Laser Altimeter System) on ICESat.

Lidar waveforms and vegetation structure are being linked for these three sensors through the hybrid geometric-optical radiative-transfer (GORT) model, which uses basic vegetation structure parameters and principles of geometric optics, coupled with radiative transfer theory, to model scattering and absorption of light by collections of individual plant crowns. Use of a common model for lidar waveforms at ground, airborne, and spaceborne levels facilitates integration and scaling of the data to provide large-area maps and inventories of vegetation structure and carbon stocks.

First-generation algorithms for processing Echidna® data focus on retrieving the location, size, and spacing of tree trunks and on the foliage profile of the stand. To the right are some early results for eight sites arranged in a 200-m square centered on a flux tower near Tumbarumba, New South Wales, Australia. The location is a eucalypt woodland with an overstory of large, old trees and a younger, lower canopy layer of smaller trees and shrubs.

Examples of 3D reconstructions:

Site 305 – Sierra Forest, California: View on YouTube / Download

Site 801 – Sequoia Forest, California: View on YouTube / Download

Baird Bat Barn: View on YouTube / Download

Click to visit Boston University Lidar site

EVI Field Sites

2007

Harvard Forest

Harvard Forest locates in the central Massachusetts town of Petersham with 1200 ha area, the Forest's varied habitats are typical of those found throughout New England . Since 1907 research and education has been the mission of the Harvard Forest , one of the oldest and most intensively studied forests in North America . There are four main tracts in Harvard Forest : Prospect Hill tract, Tom Swamp tract, Slab City tract and Simes tract. Our research locates in Prospect Hill tract, which is in northeast of Harvard Forest . Two sites are chosen as the Echidna scanning area. One is Deciduous stand and the other is Hemlock stand. The dominant species include red oak (Quercus rubra), red maple (Acer rubrum), black birch (Betula lenta), white pine (Pinus strobus), and hemlock (Tsuga canadensis).

Howland Forest

The Howland Forest research site is located in central Maine and about 35 miles north of Bangor at 45° 12' N, 68° 44' W at an elevation of 60 m , west of the town of Howland.Red spruce.

Originally established by the University of Maine within International Paper's Northern Experimental Forest, Howland forest site covers about 7000 hectares, including several intensive experimental sites, has a well-instrumented 25 meter flux tower, and has been made part of the Ameriflux network of flux measurement sites. This site has been chosen by NASA's Forest Ecosystem Dynamics (FED) project, NOAA's Atmospheric Turbulence and Diffusion Division, and the Woods Hole Research Center for research site in that it is representative of boreal transitional forest. The natural stands in this boreal-northern hardwood transitional forest consist of hemlock-spruce-fir, and hemlock-hardwood mixtures. The region has relatively little topographic relief, but soil drainage classes vary greatly over short distances.

Bartlett Forest

As the field laboratory for research on the ecology and management of northern hardwoods and associated ecosystems, Bartlett Experimental Forest (BEF) is located within the Saco Ranger District of the White Mountain National Forest in New Hampshire. There are areas of old-growth northern hardwoods with beech, yellow birch, sugar maple, and eastern hemlock being the dominant species. Even-aged stands of red maple, paper birch, and aspen occupy sites that were once cleared. Red spruce stands cover the highest slopes. Eastern white pine is confined to the lowest elevations. There are also oak types which are fairly common nearby on southerly and westerly slopes. All of species above have composed the major plant communities in BEF.

This particular site was chosen because it represented the tree species composition typical of many forested areas throughout New England and northern New York. In addition, the TRAC measurements and LAI2000 measurements from North America Carbon Program on this site can also provide us a good data comparison. We had basically chosen 2 sub sites here, with one of them (Site B2) quite close to the tower of BEF and the other one (Site C2) which is about 220 meters east. The main tree species in Site B2 are red maple, with some white pine, beech and birch trees. For Site C2, the beech trees are the major species mixed with eastern hemlock, red maple and white pine. The topography in both sub sites are not too steep, expect that there is a small hillock near the center of the Site C2 with trees growing on it. Site B2 has comparatively more under story canopies than Site C2.

2008

Sierra National Forest

The Sierra National Forest, located on the western slope of the central Sierra Nevada, encompasses more than 1.3 million acres (5,300 km2), between 900 and 13,986 feet (300 to 4,300 m) in elevation. The terrain includes rolling, oak-covered foothills, heavily forested middle elevation slopes and the starkly beautiful alpine landscape of the High Sierra. The Sierra National Forest is best known for the giant sequoias (redwood trees) of the Nelder and McKinley groves and the High Sierra, Minarets, and John Muir wilderness areas.

Laser Vegetation Imaging Sensor (LVIS) has flown over Sierra National Forest (CA, USA) in 1999 and 2003. Field data for this study were collected in the summer of 2008 in the Sierra National Forest as part of one on-going research studies conducted by Boston University, CSIRO Australia,University of Maryland, Hunter College of CUNY and Beijing Normal University.

Echidna Measure Method

We select Harvard forest, Howland forest, and Bartlett forest to do our field work. In each forest, two sites, with an area of 100m * 100m respectively, and 5 plots for each site, circle with 20m radius, were designed to collect the forest structure related variables (i.e. diameter at breast height ((DBH)), tree species, crown position) for each single tree. In addition, some sampled trees were selected for detailed measurement (e.g. crown depth and height to crown). Trees in each plot will be plotted using distance and bearing to triangulate tree positions to known positions.

Coincident to the ground truth data collection, Echidna data were collected for each plot. To evaluate the influence of varied beam divergence, At each plot, two scans were made with two beam divergence. For the purpose of reference, hemispherical photos were taken at each plot. LAI-2000 was used to collect LAI value. These reference data shall subsequently be used to calibrate and validate the estimation of LAI based on EVI data.

Mainly measured items include:

1. EVI:

ECHIDN Validation Instrument(EVI) records a full waveform of returns for each point on the hemisphere of the forest. The data can also be processed to expose various aspects of the forest structure. More details...

2. Tree spatial position:

1) Tree range and bearing relative the center of each plot: Which are measured using laser/sonic range finder.

2) Occlusion (visible, occluded and partial occluded): Which describe the location that whether the trees can be seen from the center of plot.

3. Inherent characteristics:

1) Tree height and Height to crown: Which are measured using laser/sonic range finder.

2) DBH (Diameter Breast Height): Which are measured using tape.

3) Tree Species: The mainly species in the forest are maple, white pine, oak, beach, birch, fir, and so on.

4) Crown position (dominant, codominant, intermediate, and suppress): Describe the position of the crowns (branches and foliage) of the trees in the stand.

5) Crown radius: Which describe the size and shape of the crown.

Echidna, LVIS

The LVIS (Laser Vegetation Imaging Sensor) is a scanning laser altimeter, which records the returned signal from the target surface. These data are processed to generate products such as topography and vegetation coverage.

New England 2007:

Harvard LVIS Footprint: