Modern remote sensing technology is transforming how forests are grown, managed and sold in the timber industry.
Whether tracking tree growth, mapping, measuring topography or detecting streams, remote sensing has become an indispensable tool for foresters and researchers.
With so much tech involved, talking remote sensing can get technical fast, which can make it hard to understand.
This article explores the nuts and bolts of modern remote sensing in a layperson’s terms with Rayonier’s Research and Development remote sensing team: Remote Sensing Manager Trevor Host and Remote Sensing Forester Aaron Evans.
Here, you’ll learn:
- What is Remote Sensing?
- How Remote Sensing Works in Forestry
- Benefits of Remote Sensing for Forest Management
- Challenges of Remote Sensing in Forestry
- A Typical Day As a Rayonier Remote Sensing Forestry Researcher
- The Future of Remote Sensing in Forestry
What Is Remote Sensing? A Brief History & Explanation
Remote sensing uses technology such as cameras, lasers, satellites and various aircraft to collect data about a particular area or landscape.
“Remote sensing has been around since we’ve been able to put cameras in something that could go up,” Trevor says. “For instance, hot air balloons used to be used for remote sensing.
“With satellites, a lot has been driven by military operations. One of the primary uses of the first satellites was to get a remote view and create maps of countries that were at war. The cold war led to a lot of development of remote sensing.”
There are two types of remote sensing: Active vs. Passive
The difference between active and passive remote sensing comes down to the energy source used to gather data.
- Active: This is performed using artificial energy sources like light bulbs or the flash of a camera.
- Passive: This is performed using natural reflective light, like energy from the sun.
Remote sensing technologies use one of these two methods to gather information depending on the environment and the type of data needed.
Some examples of remote sensing technologies include:
- LiDAR: Uses light or lasers to measure distance
- Radar: Uses radio signals to collect data
- Sonar: Uses sound to create images of the ocean floor
- Specialized cameras: These take photographs or video to capture data from drones, aircraft, or satellites
Choosing the Right Remote Sensing Tool for the Job
Trevor explains that each remote sensing technology and application has benefits and drawbacks.
Each of these technologies gathers data differently, and the best one to use depends on the goal, environment and level of detail needed.
“We use drones, aircraft or satellites depending on what we want to look at. Drones fly much lower and are more detailed, but you can only cover a small area. Satellites cover full counties on a regular basis, and it’s repeated, but the images have coarser resolutions and cloud cover, so you can’t always tell the details as well.”
Regardless, they all play an important role in tracking the health, viability and growth of forests.
Different Types of Remote Sensing Used in Forestry
Forestry researchers use various remote sensing devices and technology to gather data.
Trevor says Rayonier obtains most of its remote sensing data from federal programs and some from in-house operations, including LiDAR.
Why LiDAR Technology Has Become Important for Forestry Remote Sensing
Trevor is spearheading a new LiDAR data project in which laser scanners mounted on aircraft collect 3D imagery, providing highly detailed terrain maps for Rayonier forest managers and researchers.
LiDAR, an acronym for light detection and ranging, was born from radar (radio detection and ranging) and is the most commonly used active airborne sensor.
While radar uses radio waves to measure things, Lidar uses pulses of light—or lasers—which measure the elevation of things, such as the ground and trees, in three-dimensional space.
The capabilities of LiDAR technology make it possible for remote sensing scientists to:
- Map ground elevation using light angle, altitude, and tilt
- Measure forest structure in 3D, including tree height, spacing, and density
- See through forest canopies to gather data about the forest floor
- Identify natural features such as water flow patterns, stream beds, and terrain variation
How does LiDAR work?
In a nutshell, the lasers emit a pulse of light that travels to the ground or trees below, which then reflects information back to the LiDAR sensor, including the time it takes for the light to travel from the ground or object back to the LiDAR system.
From there, the LiDAR system uses the speed of light to calculate the distance between the top of the measured object, such as a tree, and the plane.
Here’s a simplified breakdown of how it works:
- A laser pulse is emitted toward the ground or object
- The pulse reflects off the surface and returns to the sensor
- The system measures the time it took for the light to return
- Using that time and the speed of light, it calculates distance
- Additional data like light angle, altitude and tilt are used to determine ground elevation
The Value of LiDAR for Forest Management
LiDAR is invaluable in forestry for providing 3D imagery of forest structures, topography, streams, ground elevation and more.
Plus, LiDAR sensors filter through the forest canopy, from the top of the trees to the ground below.
Think of it like light streaming through the trees, which gives a detailed and holistic view of the forest structure, not just the treetops.
This gives researchers and foresters much more information than aerial or satellite images.
“LiDAR is used to create a 3-D map,” explains Trevor, “so you’ll get the returns of the position with that laser pulse bounced off the ground, and that can tell you something about the 3D elevation of the ground with precise detail to the point when you can see gaps between houses and trees, where water flows, and where streams are, which are all important for us. It’s also useful for mapping tree heights.
“It allows us to cover the entire footprint of our landbase, whereas most of our other measurements are specific to forest stands. It also tells us the value of maintaining the forest.”
LiDAR can gather valuable information about tree density, height, shape and even the forest floor, which has been game-changing for forest research and management.
Benefits of Remote Sensing for Forest Management
The benefits of remote sensing for forest management and research fall into two categories, Trevor says:
“First, you save time planning out timber sales. We have to map out where the boundary of a timber sale will be. Those depend on how close you are to the stream channel, and remote sensing technology, such as LiDAR, helps us determine that accurately.
“Second, remote sensing provides the measurements used in things like assessing tree height growth. This helps us see if the stand is on track with what we expect for that age of a stand and how variable the heights are within the stand.”
And trees aren’t the only plant life captured, Aaron adds: “These technologies will give you helpful information on vegetation growth as well.”
Foresters also can gain important insight into water features that are important to understand at all stages in the forest lifecycle.
“It’s great for stream mapping and delineations,” Aaron says. “We can identify more waterways, spot distinctive water features, and have an insight of the stand before getting there.”
The Biggest Challenges of Remote Sensing in Forestry
Remote sensing is all about collecting data that must be reviewed and sorted by the research team.
“It definitely generates a lot of data,” Trevor says, “so data management, quality of imagery and interpretation takes up a lot of our time. We have a whole research team, but Aaron and I pretty much review all the data.”
Both researchers also mentioned general challenges with limitations in technology.
“We try to make imagery available on phones, but if you don’t have a network connection out in the woods, there are challenges there,” says Trevor.
A Typical Day As a Rayonier Remote Sensing Forestry Researcher
The researchers said there isn’t one typical kind of day in their line of work. Their responsibilities vary depending on project needs, but often include:
- Collecting field measurements using mobile technology
- Developing and testing new remote sensing tools
- Training foresters on how to use new technology
- Collaborating across teams to solve specific forest management challenges
- Conducting research and development reviews
- Leading workshops and sharing insights with peers and partners
“We spend some days in the field doing measurements from our phones and some days back at the office,” Aaron says. “It just depends on the questions being asked and what’s needed.”
“A big part of what we do, since this is newer technology, is developing the tools, then trying to train foresters on how to use them,” Trevor says.
“Everyone’s coming from different backgrounds. So, a big part of it is just meeting everyone where they are and working with them to identify one thing that can help them make the job easier.”
Trevor and Aaron say the response from foresters of all tenures to the new technologies has been overwhelmingly positive.
“The folks who have been doing this work in the field for years are so excited about it,” Trevor says. “It is exciting for them to pull it up on an app and see, ‘Hey, this is exactly what my field knowledge confirms.’ I think a lot of people who have been doing this for a long time love it and take to it really quickly.”
Trevor emphasized he and Aaron also spend a lot of time providing training and workshops, doing research and development reviews, and sharing information on various topics with the Rayonier team as well as organizations and educational institutions outside Rayonier.
What’s Up and Coming in the World of Remote Sensing in Forestry?
Both Trevor and Aaron are excited about the expansion of AI in streamlining remote sensing data mining and management.
“Remote sensing data is pretty well-suited for AI,” Trevor says, “because if you think about satellite imagery, the data it collects is very standardized and that lends itself well to AI capability.
“If you can have an AI algorithm just look through thousands of images and kick out the cloudy ones, that can save a lot of time and take clear images stacked together. It can get you 75% of the way there, and that is a significant time-saver.”
Aaron would also like to see remote sensing technology improve for tree measurement:
“If you have an iPhone Pro, it has a LiDAR sensor, but it only goes about 15 feet. You can scan your room with a small LiDAR sensor and it will provide measurements. I’d like to see it work for larger trees.”
Aaron added he could see LiDAR playing a greater role in habitat management and biodiversity in the future.
Trevor expects LiDAR usage to expand in the same way foresters’ drone usage has in the field.
“I’d say drones have become a regular tool in the back of the forester’s pickup truck. When you think back to 10 years ago, that wasn’t the case. You don’t need anything fancy. It’s just a way to get a view in the sky.”
Rayonier is Proud to Help Advance Research and Development Through Remote Sensing in Forestry
For over 75 years, Rayonier has invested in its in-house Forest Research Center, one of only two industry-led research teams in the country.
Here, our scientists use modern research and technologies, like remote sensing, to gain a better understanding of what’s needed to support thriving pine trees, clean watersheds and diverse plant and animal species on active forestlands.
Learn more about how we’re making a difference to forestry science and the planet in:
- Rayonier Scientists Bring Deep Knowledge to Forest Management
- What Are Land-Based Solutions?
- What Does A Forest Biometrician Do?
Interested in a Career in Remote Sensing?
Remote sensing researchers like Trevor and Aaron are shaping the future of forestry with innovative technologies that help protect and manage our forests more effectively.
If you’re passionate about the environment and excited by the idea of using cutting-edge tools to better understand the world around us, a career in remote sensing might be the perfect fit.
Learn more about careers like these at ForestryCareers.com and explore how to get started by visiting the Remote Sensing Researcher Profile.
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