An Interview with Cory Garms, PhD Student – Oregon State University

Edited by Lauren Grand, OSU Forestry & Natural Resources Extension Agent – Lane County

Drones are becoming more popular to use in forestry. With recent innovations, small landowners are beginning to gain more affordable access to this useful new technology. I spoke to Cory Garms, a PhD student at Oregon State University, about what small acreage landowners might want to know about using drones to survey their own property.

What is a drone?

Multiroter unmanned aerial system (UAS)

The terms drone and UAV (unmanned aerial vehicle) are used interchangeably to describe remote-controlled aircraft platforms which vary from the size of a hummingbird to that of passenger planes and beyond. The two main types of UAVs are multirotor and fixed-wing, which have unique strengths and weaknesses for flight much like helicopters and airplanes. The term UAS (unmanned aerial system) refers to an aircraft (UAV) in addition to the positioning hardware and sensor payload which enable the aircraft to orient itself and collect data, respectively. The applications of this technology are seemingly endless, but at OSU I use them to carry specialized cameras in order to monitor forests and agricultural crops.


What are some common uses for drones in forestry today?

The uses are already quite diverse and they will continue to grow. Initially, I think foresters were pleased to use them to make high resolution aerial maps of their forests for a fraction of the cost of hiring an airplane pilot. With the advent of sufficiently small and light multispectral and thermal infrared sensors, the scope of data we can collect from UAS has grown from visual maps into “stress” maps which help make inferences about the relative health of individual trees. Another exciting technology, LiDAR, allows us to make remarkably accurate 3D reconstructions of forest scenes which can be used to measure tree dimensions with a high level of confidence. There is also a push to develop UAS for applying chemicals like herbicides and fertilizers.


How might small acreage forest landowners use drones in their management planning

Small forest landowners have lots of reasons to get involved in drones. The most straightforward one is for silvicultural planning using aerial maps. With a little familiarity they would be able to make scaled maps of their land that include tree height and spacing data that are extremely useful when choosing when to thin and when to cut. At a small scale, single tree selection would probably be less costly and definitely be much faster using UAS. The necessary hardware for this level of analysis cost under $2K. Another option is attaching a more expensive ($5-10K) multispectral sensor, which could allow the landowner to visualize the “stress responses” of individual trees. This gives researchers the ability to make inferences about drought, disease, and nutrient deficiencies. In a broad sense, this will likely become a vital early detection tool for foresters.

Additional uses to carry out your management plan (added by Lauren)

Use aerial photos to find dead trees. Photo by Fabio Comparelli on Unsplash.
  • Streamline monitoring – if you have a large forest or don’t get out to all the corners often, you could use your drone to monitor for extensive storm damage such as windthrow, look for health and disease issues (i.e. drought or root rot), or do a post operation assessment (is slash piling necessary?).
  • Document actions – record keeping for your management plan just got more exciting! Get before and after photos of a recent thinning or harvest, newly built roads, added ponds, or restoration of an oak woodland.
  • Reduce your risk to wildfire – Identify areas that have high fuel loads and monitor areas where
  • you have done some fuels reduction to stay on top of maintenance.



What are the benefits to small acreage forest landowners in hiring a professional consultant that uses drone technology?

The first step to implementing drones on your forest needs to be learning about them. Hiring a professional would, at the very least, give a landowner the ability to see how flight operations work and begin looking at the products we are capable of creating with these tools. My personal outlook is that small forest managers, like small farmers, are “do-it-yourselfers” who would ultimately like to own and operate their own equipment. Some of the best companies are willing to educate clients and teach them to collect the data themselves. This framework allows the landowner to spend a little more on quality data analytics software to help them make decisions based on their imagery.


What are some of the regulations that small landowners need to be aware of when using drone technology?

The most important thing that people should be aware of is the FAA’s small UAS rule (14 CFR part 107), which establishes the requirements for registration as a certified remote pilot in the United States. The certification exam covers some of the same information about aeronautical charts and weather reports that you would find on a small aircraft pilot exam, as well as the rules that deal specifically with small UAS. Legally, it is only necessary to have the part 107 license if you use UAS commercially, but I recommend it for a couple of reasons. First, studying for it will make someone a better pilot regardless of how experienced they are. The study materials are useful in the field and the certification process is a good way to start thinking of the drones as aircraft rather than as toys. Second, the exam itself has only been around since January 2017, and since the guidelines say you must recertify every 2 years, no one has had to do it yet. Basically, I expect that now is the best time to get the license because it will not get any cheaper (now $150) nor any easier down the road. I would, at the very least, make sure that any pilot I hired held a current part 107 license. Visit the FAA’s website for more information about how to certify.


How are drones being used in forestry research?

In a relatively short time, drones have made a large footprint in the forest research community. There are studies that deal with all kinds of things: chemical application, pest and disease detection,  tree counts, size measurements, fire studies, species ID, drought detection, invasive species management, planting, and more. The Unmanned Aerial Systems lab at OSU have been involved in a wide breath of projects also, including Swiss Needle Cast disease detection, Southwestern White Pine drought tolerance, Using LiDAR to estimate forest inventory, Tree Height Estimations, Herbicide Efficacy Estimation, and others. Personally, I am interested in how we can use multispectral and thermal sensors to decide when plants need water, not only in forestry but in agriculture as well.

Drone use in research.
Cory Garms (bottom), Scott Heffernan (Right), and Lody Maturbongs (Left).
Cory Garms (right) and Michael Wing (Left)











What should small landowners consider before purchasing a drone?

Because there are so many options, I would say first decide on a budget, then use that as a guide. If you just want to make maps of forest stands, that could be accomplished relatively inexpensively, whereas making precise tree measurements or any sort of health estimates typically requires more expensive hardware. Also, remember that the quality of these machines is rising rapidly as their cost is falling, so it will be cheaper to achieve the same results in years to come.


For more information:

Unmanned Aerial Vehicles (Drones): How they operate and their potential for improving your forest and rangeland management (EM9190).

FAA Unmanned Aircraft Systems:


Cory Garms just finished his second year as a PhD student at Oregon State University. His PhD research focus is in forest biometrics. Cory holds a BS in environmental science from the University of Texas at San Antonio, as well as a MS in forestry from Louisiana State.


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