Revised Biometry Protocol

Thanks to active teachers who wrote to us, the Land Cover/Biology Team revisited the Biometry Protocol and made some significant changes. In the previous version of the protocol, there were questions about what biometry measurements to take in different types of Land Cover Sample Sites. We believe teachers and students will find figures in the new version of the protocol helpful.

If you recently entered Biometry data, you may have noticed that there was a note that our team had concerns about the validity of the data being entered due to the way the protocol was set up. Previously there was a single data sheet for canopy and ground cover that did not "tell the whole story", so we decided that we needed to break the single data sheet into two separate sheets. There are now two Canopy and Ground Cover Data Sheets: one to use when the dominant canopy cover is trees and one to use when the dominant canopy cover is shrubs. These two data sheets will allow GLOBE students to collect all the data required in their investigation of land cover.

The process for selecting which of the two data sheets to use at your site is detailed in the Biometry Protocol. Basically, if you look up at the canopy in a site and see that there are mostly trees (>40%), use the Tree Canopy and Ground Cover Data Sheet. If you look up and see that trees do not dominate, but instead the canopy is mostly (>40%) shrubs, use the Shrub Canopy and Ground Cover Data Sheet. If you have difficulty determining if the dominant canopy cover is tree (closed forest or woodland) or shrub (shrubland), you may need to walk the half-diagonals twice using your densiometer. The first time, use the Tree Canopy and Ground Cover Data Sheet, recording a (+) where a tree is seen at the densiometer crosshairs. Determine the percentage of trees in the canopy. If the trees make-up 40% or more of the canopy, this is a forest or woodland and you should use the Tree Canopy and Ground Cover Data Sheet to also record the ground cover data collection on the half-diagonals. Report all of these measurements. If trees make-up less than 40% of the canopy, walk the half-diagonals again using the Shrub Canopy and Ground Cover Data Sheet. Record a (+) where a shrub is seen at the densiometer crosshairs and determine the percentage of shrubs in the canopy. If the percentage of shrubs is greater than 40% of the canopy, this is a shrubland and you should use the Shrub Canopy and Ground Cover Data Sheet to also record the ground cover data collection on the half-diagonals. Report all of these measurements. If both trees and shrubs are less than 40%, choose the Data Sheet corresponding with the highest percentage of canopy cover to record the ground cover measurements. Example: In a site with 15% tree canopy and 35% shrub canopy, use the Shrub Canopy and Ground Cover Data Sheet to record your ground cover measurements and report the tree and shrub canopy cover as metadata. Since the tree and shrub canopy make up less than 40% of the canopy, the MUC class will not be a Closed Forest, Woodland or Shrubland. In this case, use ground cover measurements to determine the correct MUC class.

In the new version of the protocol you will also find changes to the field guides for measuring tree heights. The changes to these field guides are to correct problems with the previous versions that were noted at a GLOBE Train-The-Trainer workshop in Shimla, India. Mr. Raj Mehta, the Country Coordinator of GLOBE India, served as the Master Trainer for Land Cover at this workshop and brought the problems to GLOBE's attention.