Forest mapping stepping into the limelight

An exciting trend is beginning to emerge; interest in forest mapping data is rising!

The Global Forest Watch project by the guys over at the World Resources Institute was recently featured in the international media (see the BBC News report here). 

Powered by Google Earth, and drawing data from the University of Maryland’s map of Global Forest Change it enables near-real time monitoring of forest cover across the tropical regions. This will allow users, ranging from Governments and large corporations to indigenous population groups and interested individuals, to increase their understanding about where forest cover is changing.

This attention demonstrates that the people are interested in understanding more about the impacts on forests, and how these link to the global picture of sustainability and climate change. It also shows an understanding that unless we can accurately map these changes, and quantify them, there is little that can be done to combat any problems or applaud successes.

At Carbomap we think these kinds of tools provide the perfect starting point for in-depth mapping of forests. Once you have a good idea of where the changes are taking place – the monthly forest change updates for the tropics are only at a resolution of 500m – you can focus your energies into getting more information at higher detail in those places where you can see there is something happening. This detailed information could be the number of trees in area, the actual amount of wood, and even the carbon stored in that area of forest, which the overview methods cannot provide.

Multiscale mapping of forests (not to scale)

Multiscale mapping of forests (not to scale)

Our handy factsheet; “How do you measure a forest?” demonstrates the different options available. The satellite based approach, utilised effectively by the Global Forest Watch and other companies (such as Ecometrica and Global Surface Intelligence) that do a similar thing, provides the large scale, synoptic, measurements.  We are also developing something similar in partnership with Ecometrica, but based on radar data at higher spatial resolutions and without the problem of cloud cover (still a constant limitation for optical sensors in many tropical forest areas.  More on that soon).

Individual trees can be identified

We can automatically identify trees in the lidar data, shown here overlain on aerial photography. This demonstrates the much higher level of detail obtained from airborne lidar.

Data can be analysed in 3D

Data can be automatically analysed in 3D.

To get finer detail you need to get in closer. For this you can send people out into the field to take direct measurements of the trees, which is the most common approach. However to measure a whole area of forest accurately this can take a very long time, and can end up rather expensive. The other option available to you is to use aircraft and UAVs; which provide the best of both worlds (satellites and ground measurements). The use of scanning LiDAR means that you can extract 3D information about individual trees, and by having the instrument on an aircraft you can cover larger areas of forest in the same amount of time, than would be possible by foot.

It is now possible for any organisation or government agency that wants to demonstrate and quantify that they are having a positive impact (or at the very least not a negative impact) on forests effectively, can combine multiple sources of data: satellites for large-coverage and low-resolution, and airborne LiDAR for high detail over smaller areas.  By combining both approaches, the very best forest maps can be made.

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