Copass_Council_LeafAreaI_readme

Data set name: Copass_Council_LeafAreaI.xls
Worksheets: LAI, Summary

Investigator Names:
Catharine Copass
Terry Chapin
A. Dave McGuire
Jason Beringer


Contact for data questions:
Catharine Copass
ftcdc@uaf.edu
Dept. Biology and Wildlife
University of Alaska Fairbanks 99775-6100
907.474.7929

Grant: OPP 9732126

Data Set Overview:

These are point based measurements of Leaf Area Index (LAI) from the Council   
Grids. The LAI data were collected with the Licor LAI-2000 Canopy Analyzer on 
multiple dates, including approximately peak season biomass during the 1999 
field season. Averages and standard deviations have been calculated.The location
and name of the grids is as follows:
C1 Forest N64deg54.456' W163deg40.469' 
C2 Tundra N64deg50.499' W163deg41.591'
C6 Low Shrub N64deg53.47' W163deg38.61'
C3 Tall Shrub N64deg56.141' W164deg44.142'
C4 Woodland N64deg53.997' W163deg39.863'


Instrument Description:
The LAI-2000 calculates LAI and other attributes from radiation measurements   
made with a "fish-eye" optical sensor (148° field-of-view). Measurements made 
above and below the canopy are used to determine canopy light interceptionat 5 
angles, from which LAI is computed using a model of radiative transfer in 
vegetative canopies. 
See http://env.licor.com/Products/AreaMeters/lai2000/2000.htm for more 
information.


Data Collection:
Sampling Dates were as follows for the sites:
C2 (Tundra): 6/23 and 8/13
C6 (Low Shrub): 6/22 and 7/21
C3 (Tall Shrub): 6/25 
C4 (Woodland): 6/24 and 8/24
C1 (Forest): 6/22

We used the 90 degree field of view restrictor. Best effort was made to take 
measurements under stable, overcast conditions. The data were processed using 
the Licor- LAI software, which calculates LAI based on paired above and below 
canopy measurements nearest in time. 


Data Format:
The data is in an Excel file, with cases referenced by the grid point number and 
variables listed by site number and date of sampling. Missing data are indicated 
by "---" 

Data Remarks:
It is unlikely that zero values represent true zero leaf index, as the sensor 
head is approximately 1cm. Prostrate vegetation, moss and lichen are 
underrepresented in this method.