Hi everyone, welcome back to the Stuff Outside podcast. This is your host, Christy Kiel Blackgrin of the Department of Forestry and Wildlife and Fisheries at the University of Tennessee Institute of Agriculture. Today we're joined by graduate student Brett Elgersma. He is getting his master's degree in working with Dr.
David Buckley, so welcome Brett. Hey, Christy, thanks for the introduction. I'm happy to be here. I look forward to talking about some of my research.
Yeah, welcome to the podcast. So let's start off as we usually do. Can you tell us just a very general overview of what you are researching right now? My research is opportunity to use a new technology LiDAR, which stands for light detaching and arranging, and we're using it out at the UTR Freedom, which is the Tennessee Forest Resources Agricultural Research and Education Center, or our breed amount, no bridge.
Seven years ago, Dr. Buckley and his graduate student, who is now PhD at the City State, Josh Granger, set up this experimental plantation. So we're using the LiDAR to help us describe the structural complexity and the growth of this forest, and we're capturing it at this moment in time. Why is it important that we study structural complexity at the forest?
Yeah, so structural complexity is one of those areas that has been really studied over time, really started out in the 1960s by a professor named Garthard, who really started to look at the vegetation layers and how the trees were formed, and the vegetation around research areas were formed, and how it affected bird diversity and bird use of these different forms. And it's really an important part of US efficient wildlife. Their habitat evaluation really takes into account what the habitat is, and doing vegetation is really critical to that. And it's also been used to look at species genetics and species diversity in something called the Chinese diversity index, and that's just sort of like a way to describe how the vegetation affects birds' richness, abundance, and diversity.
Forest structure is really important for that. Excellent, that's really interesting. And so what species are you studying in this experimental forest? So it's the challenge with this.
We originally were going to try to do small mammal trapping, but because of COVID happened in the middle of my master's, it really delayed everything that we wanted to do between getting approvals just the way we were able to operate the very unknown beginning stages of COVID affected our ability to trap. So with small mammal trapping, because it's the basis of the ecological food web, it's really important. And in order to really successfully small mammal trapping, you need to have two seasons. One season, two years worth of data, and with my timeframe, I'm just not going to be able to do that.
So instead, we're going to try to look at making a Shannon's diversity index, possibly with the LiDAR measurements. Hopefully the LiDAR will be able to show what the vegetation is, and we know what the vegetation is, because we plan it, and we kind of know it's obviously we've been out to these research plots, and we know what it looks like. But structurally wise, this is something really new. LiDAR has really not been utilized that often, especially ground-based LiDAR, which is what we're using at Terrestrial LiDAR.
It definitely gives you a much better view of the forest. You can see individual leaves and branches on trees. It's really amazing. We put the LiDAR machine, and you do four corners of the plot, so you do one in each corner, and it takes about a 20-minute scan.
And then photography, you use these tripods, targets, and you splice together the four scans into one image, and you get a cloud point that has millions of points. And from that cloud point, that's how we're going to be able to use our data. Luckily, some people have developed, professors at Jeff Atkins at University of Virginia have developed free software and R that calculates a lot of these things that we're really interested in looking at. So it'll give us our tree heights and the average heights, but it also will be able to look at the canopy.
And when you're looking at the canopy, one of the things is heterogeneity of the canopy of vegetation. And since LiDAR is three-dimensional, you're taking in account of X, the Y, and the Z-axis. When you're doing this, rigosity is the term that's been developed to basically decide how complex your structure canopy is. Another thing that it does is it does a vegetation area index, and this is sort of similar to a leaf area index, where it's just talking about how much surface of a leaf is covering any surface of the ground.
This is something that's been used for a long time, so it's a pretty unique measure, but it'll let you know how much light's actually hitting the understory, how much light's being absorbed by your species of trees that are there. So it can really describe a lot of different things that it's really neat, and sort of really new on the cutting edge kind of thing. LiDAR, does it take some of the work out of standard forms of measuring trees? Yeah, so it actually makes...
So it changes what we're doing, like instead of having to go out there and capture leaves, like if you want to get the leaf area index, you have traditional methods of either to jump down a tree and count how many leaves are on it, or another non-invasive thing would be to hold a densiometer out there. And you'd have to take samples for listeners that don't know what densiometer is a glass sphere that has 96 squares on it. And what you do for densiometers, you hold it in your hand and you stand in the forest and you count how many squares in the glass mirror are occupied by some form of vegetation. And when you do this in four cardinal directions north-south, east and west, and then you average the number of squares that are counted that'll give you the density of the canopy.
So with LiDAR, with the tools in these packages, we're able to calculate it much easier. It really takes out a lot of the fieldwork, but you also have fieldwork and taking the initial scan. And it is LiDAR also more accurate? LiDAR has been shown to be way more accurate.
There's more computer work involved, but less fieldwork. A lot of it has been done in real old growth forests. And I think for far as I can tell, we're one of the first people trying this in a younger understand. Most of our trees are only averaging about 10 feet tall, depending on the species.
So species did Dr. Granger and Dr. Buckley choose to be in this experimental plantation and why were those species selected? They chose four species.
The first species is of course white oak, corkus alba. It's really important for the whiskey barrel and whiskey industry. The prices for corkus alba have gone through the roof. And with all oak, there's been an issue of oak regeneration that's been going on really since the 1960s.
People first started noticing that oak reproduction was a problem, that there's over-story oak, but there's no understory or mid-story oak. And so the reasons for that have been studied by a lot of different professors, Larimer, Abrams, and they theorized that deer brows, some issues with insect and herbivory, and also just that humans lack of disturbance in the forest has really affected oak's ability to regenerate. So Dr. Buckley wanted to focus on white oak because it's so economically valuable.
And then from his past studies in Michigan, he noticed that when he was a PhD student in the 90s, he noticed that red oak regenerated well with red pine, because the original type of office was that he thought it protected some from deer brows and also from frost damage. So he wanted to take that concept that he saw in real life on the ground in his research in Michigan. And he wanted to bring it here to Tennessee, but since we're in Tennessee, it's different pine species that grow together here. So he wanted to focus on some pine species that are relevant to the southeast.
And so he chose loboly pine first, which loboly pine is the number one pine species in the southeast. There's hundreds of millions of acres of loboly pine here, and it's grown commercially for paper and pulp industry for the most part. The second species that he went after was shortleaf pine. And there's a lot of interest in restoring shortleaf pine.
In the southeast, the majority of the plantations are now loboly. Shortleaf is sort of slowly disappeared, and UT has a shortleaf initiative. And so because of the shortleaf initiative, a lot of interest in restoring shortleaf. And being that's one of the broadest and most diverse ecologically speaking, it grows all the way from Texas up to New Jersey.
So he occupies a large swath of the ecosystem in the southeast. So he wanted to include it, and it also has a different sort of shape and growth of the loboly pine. So that was one of the factors that helped him choose shortleaf. And then the last pine in the study is Easter White Pine.
Easter White Pine is mostly here in the smokies and the upper elevations, but it is really important in New England. And since Quercus albus, its range map intersects with all these species. He thought it'd be good to pair them together. And that's just based on studies that show pine and oak have been together since the glaciation 10,000 years ago, and pollen studies that other professors have done.
So it's really, really know that there's a strong association between pine and oak. So we know that there's a strong association between pine and oak and that they grow well together. Has there been any thoughts on incorporating additional species? You have four species in this research.
What's to say that you wouldn't increase it to 10 species or more? Yes. So humans domesticated pines all the way back to Greek mythology. There's records of pines being domesticated for human use.
And humans domestication of these species, we have always gone to monoculture plantations. Monoculture plantations are easy to manage. There's not a lot of complexity, so by reducing the species, it reduces the complexity. But in doing so, you also have problems associated with this.
Having single-species monoculture basically, they have shown that it dilutes the soil and negatively has impacted birds and species diversity because they're losing that natural forest. And the United Nations Forestry Initiative has looked at this issue right now. If the man for wood is continuing plantation forestry is just getting bigger and bigger. Right now it's over 131 million acres and it's primarily just pine plantations.
And this is just because it's easy to manage. So it went with two species because it changes the complexity and it changes the number of species. And it seems silly that adding one species would affect it a lot, but really, for simplicity and ability to manage this just seemed like the most natural step. Some of this has been done in Europe with some of their plantations in Australia.
There's been a lot of positive impacts of having multiple species and plantations, but usually it's only been two species. So we have 10 experimental blocks. They're all 48 by 72 feet. And in each block, we have either one species.
So there's our controls where it's just either all white oak, all lava, all short leaf, or all eastern white pine. But the rest of our experimental blocks, we have two spacings that we worked on. So it'll be white oak mixed with eastern white pine and we planted those at a traditional plantation spacing of 8 by 8. Or we also mixed white oak with eastern white pine at experimental planting at one foot apart from each other.
And we wanted to plant them from one foot apart from each other to force an interaction when the species were young. So there's a theory that oaks and pines facilitate each other's growth like their complementary effects. So white oak is dormant in the wintertime, but pines are growing. And so some of these studies in Europe have shown that association of pine and oak together have helped water, facilitated the water draw up from the soil, the oak when it's in its growing season actually can help the pine get water even during periods of drought.
So we have that set up basically. So now every species, it's just either white pine and white oak or short leaf and white oak or lava, all white oak. Okay, so you never mix all four trees yet? No, no, four species are never all mixed together.
They're just either one or the other. It's either a monoculture control, which is sort of like what traditional plantation management would be like or it's intercropping of white oak with a pine species. Okay, gotcha. How much longer will you be collecting data with LiDAR?
So we went out there last summer and collected our initial scans for leaf on and that was done in June and July. So it took about two weeks to do the scans with the LiDAR. We need a day with no rain and light wind because if the winds out there blowing the leaves, it really affects the LiDAR's ability to take the scan. LiDAR works by sending out a light laser pulse and it's reflected off a mirror and that mirror spins it around everywhere and the machine itself actually measures how long it takes for that pulse to return.
And so when you're looking at the point cloud, that's what it's doing. It's taking millions of pulses and millions of returns and creating an image based off of that. But because of that, when it's windy, you have the leaf shifting and the branches swaying and it really kind of plays havoc. So we're here in East Tennessee, you have to play the wind, which means you have to be out there super early, like seven o'clock sunrise and our window is probably only until about 10 or 11.
We also faced some challenges with our equipment. In the summer, we're fighting the temperatures, we're fighting the wind and we're also fighting the rain, but also another thing we had to deal with was our equipment. Our equipment had a maximum operating temperature of 110 degrees Fahrenheit, which is about 43 degrees Celsius. And so out there in the summer, when it's hot and the sun's shining directly on this black encased machine, it gets hot very quickly.
So it took us a period of about a month really to take all the scans with leaf on. And then LiDAR tradition has been to do it with leaf on and leaf off. So we'll be going back out here in the month of March now, 2021, and taking some leaf off scans because all the trees are all dormant and the finds are all so growing. So different aspects of the image will be better when you're doing it without leaves, and with leaves.
So you'll have better views of like the crown, better views of the actual structure of the trunk. Whenever you do collect all of your data, what findings do you expect that you'll have? So we're expecting that experimental plantation that has a one foot spacing with mostly lobolipine, and basically all the lobolipines, because the lobolipine, its growth is so rapid, the trees out there, the lobolipines are 20 to 25 feet tall, and everything else is in the 10 foot range. So even the oaks that are with the lobolipine, because they've facilitated each other and they've complimentary theory, they've still, even the oaks in the lobolipine are still 15 feet tall, so they're taller than the other groups, but not necessarily bad how the growth is.
They've done really well survival. And that was really the theory on why you want to set this up was hopefully get a better survival of the oaks. Having it be near another tree really sort of helps reduce its visibility to wildlife for browse. Oaks are one of the favorite browse of white tail deer, which I think is one of the contributing factors to why white oak has had such a hard time regenerating, is because white tail deer just hammer it.
Along with everything else. And so if your hypothesis is correct, what could that mean for the forestry industry as a whole? We feel like this would be a great opportunity for small landowners that are interested in maybe something other than timber volume production. So the traditional mentioned Dr.
Buckley and Dr. Granger have been tracking this since they planted it. And they've shown really good survival of the white oak, which is really important. And also the other pine species.
The traditional measures have shown from the diameter growth and at the root color and also at the height growth that it's the pine next to the oak. And any of these spacing statistically hasn't affected the growth of either species, so that the complimentary theory they've really grown together. So we feel like this might be a great opportunity for small landowners that want to have a diversity of species or maybe want to do something other than timber volume production. It could be great habitat for wildlife or it could be an opportunity to restore or worsen the future at larger scales.
It just depends on what you make of it. And what your ultimate goals really are as a landowner. If you're more interested in wildlife, this is great. You get species that like pine, you get species that like oak.
But overall, it's been really successful in getting white oak up into what will become the overstory eventually. Obviously, this is still really young and it will take another 100 years for them to be giant trees. But for a small landowner, this really hedges your bets, pine beetle outbreaks here in the southeast. So if you plant just a monoculture pine plantation and a pine beetle outbreak happens, you can lose your whole crop.
If that happened and you had it planted in an experimental plantation format, you would still have all the oaks out there to be able to harvest something in the future. Yeah. If the landowner did want to copycat what you're doing, is there a specific mix that you would recommend based on their interests or would any of these pine oak mixes work? I think any of these pine oak mixes would be successful.
You have to plant towards where you're at. So if you're in the bottom lands over in West Tennessee, you're probably not going to want to plant an eastern white pine. You're probably going to look more indelable only or even shortly or even if you're further south in Georgia, slash pine would also be an opportunity. We really are hopeful that in the long term, this is going to be an opportunity to show how to maybe get white oak into the overstory of the forest and also provide some economic revenue with people having two species to be a harvest is really good thing.
And with modern equipment, having species one foot apart, you can harvest those pines without hurting the oaks in the future if you wanted. That's great. That seems like a game changer really. Yeah.
So we're hoping the lidar will be able to show all this and show the diversity and complexity of it. Well, are there any parting words you'd like to leave with our listeners or any advice for small landowners? Yeah. I mean, there's research going on to try to help shape the future for us.
A lot of this work is funded by your efforts buying cutting licenses and fishing license helps pay for money through Pittman Roberts. And it's used all kinds of different ways for all different things. So this research is funded by the taxpayer. So we appreciate the opportunity to figure out ways to help manage the future for us.
Absolutely. Yeah. Well, Brett, thank you so much for sharing your expertise on lidar and the six-room and all plantations. We appreciate your time.
And thanks to all of our listeners for joining us. Please be sure to tune in next month and be on the lookout for our next podcast. We'll have another one of our grad students to talk about the research. Thanks.