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Observer News

Trees are land cover


Since 1995, The GLOBE Program has provided Earthlings with the ability to participate in understanding local, regional, and global tree coverage. Trees are an important part of the carbon cycle. With the GLOBE Observer (GO) mobile app there are two ways of tracking the location and number of trees across Earth: GO Land Cover and GO Trees. So what is the difference between these two? What is the benefit of one over the other? Should you make observations of trees using both of the tools?

Trees are woody vegetation over 5m tall

Trees are woody vegetation greater than 5 meters tall.

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GO Trees and GO Land Cover

The GO Trees tool focuses on mapping the location and height of individual trees. GO Land Cover focuses on the amount and location of those individual trees. These tools complement each other. In order to use the GO Trees to measure the height, you need to be able to see the top of the tree which is usually only possible when the trees you are observing are loosely spaced (not interlocking tree canopy) or when standing on the edge of a group of closely spaced (interlocking tree canopy) trees.

When observing trees with GO Land Cover you will document where the trees are located (closely or loosely spaced), when they lose their leaves (leaf longevity), leaf type, and how the trees change over time.

The six directional photos taken with the GO Land Cover tool provide a way to record forest cover, whether closely or loosely spaced, needle-leafed or broadleafed.

 

1. Closely-spaced versus loosely-spaced

Identified by the spacing of the tree branches and whether they are interlocking or not interlocking above 5 meters from the ground.

Canopy cover density

Source: MUC Guide

 

Loosely Spaced Trees example image

Loosely spaced trees allow you to see far off features like mountain peaks and provide you with lots of sky view.

Another Loosely Spaced Trees example image

Another example image of loosely spaced trees

Closely Spaced Trees example image

Closely spaced trees block your view in many directions and may block your view of the sky.

Another Closely Spaced Trees example image

Another example image of closely spaced trees

 

2. Leaf Longevity

Deciduous trees lose their leaves seasonally and evergreens do not. So next, with GO Land Cover you can identify the types of trees you are observing as land cover by taking a look at how long the leaves are on the trees and whether they are evergreen or deciduous. You can sometimes identify these at a single observation in time or alternatively through repeat observations of the same location. The majority of trees (more than 50% of the canopy) shed their foliage simultaneously in connection with the unfavorable, drought or cold, season.

Repeat observation of deciduous trees
An observer in Millersburg, Oregon, USA, made repeat observations of the same landscape, showing the changing seasons and capturing the tree leaf duration (deciduous).
Repeat observation of evergreen trees
An observer in Corvallis, Oregon, USA, made repeat observations of the same landscape, showing the changing seasons and capturing the tree leaf duration (evergreen).

 

3. Leaf type

Tree leaves are grouped into categories of needleleaved, broadleaved, or succulent/palms. Pictures obtained through the GLOBE Observer app can help other researchers identify types of leaves on trees within observations.

Image guide to identifying Broad-leaved vs Needle-leaved trees
Source: MUC Guide
Image of deciduous needleleaved trees

Deciduous (needleleaved)

Image of deciduous broadleaved trees

Deciduous (broadleaved)

Image of deciduous broadleaved trees

Another example observation of deciduous (broadleaved) trees

Image of evergreen needleleaved trees

Evergreen (needleleaved)

Image of evergreen needleleaved trees

Another example observation of evergreen (needleleaved) trees

Image of evergreen broadleaved trees

Evergreen (broadleaved)

Image of evergreen broadleaved trees

Another example observation of evergreen (broadleaved) trees

Image of Succulent/Palms

Succulent/Palms

Image of Succulent/Palms

Another example observation of Succulent/Palms

Image of Succulent/Palms

Another example observation of Succulent/Palms

 

4. Trees change over time

Whether seasonally or because of fire, deforestation, construction, weather events, planting, or growth. GLOBE Observer land cover observations show these changes.

Image of burned trees

The aftermath of a fire is clearly seen in this image sent in by an observer in Coolumburra, Australia, taken 21 Jan 2020.

Image tree growth after fire

Tree growth after a fire where the older tree trunks that burned are still standing. Oregon, United States taken on 11 July 2020.

Trees blown down by wind

Trees blown over by wind blocked this hiking trail while others leaned up against other standing trees creating a new gap in the tree canopy. Oregon, United States taken on 3 Nov 2019

Tree stump

Tree stumps are reminders of what was there before this observation. This image reveals the location of a former street tree and the effects of urbanization. Oregon, United States taken on 26 March 2019.

Newly planted landscaping trees near road

Newly planted trees are visible along this street. Note these trees are currently loosely spaced and supported with stakes and are adjacent to urban and herbaceous land cover. Oregon, United States taken on 13 Aug 2019.

Newly planted landscaping trees river

Newly planted trees are visible along this river. These new trees are not tall enough to be measured with GO Trees (yet) but are captured with GO Land Cover to document that they exist and are growing successfully. Montana, United States taken on 27 July 2019.  

 

If you estimate the height of a tree using the GO Trees tool, why not add a GO Land Cover observation so those individual trees are put into their neighborhood context. Or if you are taking a land cover observation, try using the Trees tool to take a tree height observation and see the forest for the trees.

While taking land cover observations or tree observations, you can join the 2021 Community Trees Challenge, going on now. As part of the challenge’s activity tracker participants are encouraged to observe both trees and land cover.

By completing the activities, you will improve your science observation skills, enrich your understanding of trees as part of our landscape, learn why NASA studies trees, be a part of a NASA-sponsored citizen science project, as well as join a citizen science community. Your observations of tree height contribute to a global database that is free and open so that anyone - scientists, students, communities, and citizen scientists - can conduct research.

 

Sources:

The GLOBE Program MUC Field Guide, A key to land cover classification.

 

Peder Nelson M.S., is the Land Cover science lead for GLOBE Observer. In addition, he is an Instructor of Geography and Geospatial Science and researcher in the Environmental Monitoring, Analysis, and Process Recognition (eMapR) Lab in the College of Earth, Ocean, Atmospheric Sciences at Oregon State University. With a background in environmental education, biological sciences, and land management, he uses remote sensing and geographic information systems to create maps and data that show people what is happening on planet Earth, particularly changes that can be seen from space. Twitter: @pedervnelson and http://emapr.ceoas.oregonstate.edu/
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Comments

1 Comment

Hi, the two images showing: 

The aftermath of a fire is clearly seen in this image sent in by an observer in Coolumburra, Australia, taken 21 Jan 2020.

 

Tree growth after a fire where the older tree trunks that burned are still standing. Oregon, United States taken on 11 July 2020

Appear to be the same image!

And the image and description: 

Newly planted trees are visible along this river. These new trees are not tall enough to be measured with GO Trees (yet) but are captured with GO Land Cover to document that they exist and are growing successfully. Montana, United States taken on 27 July 2019.

Are repeated!

Regards,

Bill

Australia Country Coordinator