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Conversations on Reforestation, Silviculture, Tree Genetics, Planting, Planning and More! Join us as we go deep with forestry experts and explore the art and science of trees.
Paul Jeffreys (00:05)
Welcome everybody to the episode 14 of ArborGen TreeLines podcast. I'm your host, Paul Jeffries, and I'm joined today by Dr. David Clabo from University of Georgia's Warren Nell School of Forestry and Natural Resources. And today we're going to be jumping into a topic. I would say a hot topic, but that would be a little play on words, but we're going to jump into
Spring Silviculture and what's changed and what actually works today. You know, we're going to talk about in this discussion, we're going to go from site prep to spacing and talk about how every decision in Pine Silviculture impacts long-term value. We're going to break down how the modern practices are backed by the science and real world experiences.
And we're also going to talk about helping landowners become more productive and create a higher valued forest on their property. And Dr. Clabo, that's basically what it's all about for private landowners is creating more value for their investment and getting a better return on their investment. But with that, I'm going to let you give a little introduction to yourself. Tell us a little bit about yourself, where you came from and what you like to do.
David Clabo (01:23)
All right, appreciate the invitation to join today, Paul. As he said, my name is David Clabo. I'm an associate professor of silviculture outreach with the University of Georgia, Warnell School of Forestry and Natural Resources. I'm based on the UGA Tifton campus. So I'm in South Georgia, about three hours and 20 minutes from main campus. But I've been here going on eight years now.
My expertise is in silviculture forest management. do a lot with forest regeneration, forest herbicides. We've got some productivity studies, I'm mainly with my appointment in extension, but I also have a smaller research appointment. So a of the research kind of feeds directly into the extension programming and publications, that sort of stuff that I do.
Paul Jeffreys (02:01)
great!
David Clabo (02:09)
It's a good job with lot of variety.
Paul Jeffreys (02:12)
Now did you grow up in Tifton?
David Clabo (02:13)
No, I'm from Tennessee originally. So I grew up in East Tennessee, yeah, from Gatlinburg area, right across the street from the national park. There's where I grew up. So, yes sir.
Paul Jeffreys (02:16)
⁓
Are you serious? Wow.
Well, that is a, that's a different discussion for a different day that I'd like to get in, get into you. Uh, you know, most people want to move to that area and, and, I now understand why you went into forestry. Uh, yeah. Did your, yeah. Did your dad, was he, uh, or your mom employed there at the national park or did they have any involvement or?
David Clabo (02:29)
Yeah.
Exactly, yeah grew up in the woods quite a bit there, yeah hiking and camping and all that.
Actually, neither one of them were. ⁓ My mom was a school teacher and so the elementary school I went to had a good connection with the National Park Service. A lot of custom field trips for students in each grade level.
Paul Jeffreys (02:52)
Right.
Right.
Wow.
And that probably is what led you or lit your fire, your passion that I'm sure you have like I do for forestry and everything outdoors and the environment.
David Clabo (03:17)
Definitely contributed, yes.
Paul Jeffreys (03:19)
I
can, I can, I can, well, we'll have to share some stories about that ⁓ later on. might be another podcast that we go into, but you know, today we're going to be breaking down and talking about silviculture. Can you just give us for the listeners out there that are listening to this, can you just give us a definition, just a layman's definition of silviculture and what it basically means?
David Clabo (03:24)
All right.
Sure, yeah. So, silviculture, basically it's the art and science of managing a forest from prior to any tree planting or natural regeneration all the way up through the final harvest to meet kind of landowner and society objectives and needs. I mean, it can include planting, tending operations, all that, everything that occurs kind of from.
Paul Jeffreys (04:00)
Right.
David Clabo (04:08)
from when those trees originate until they're cut or die or whatever the case is.
Paul Jeffreys (04:14)
Culture
meaning to grow is basically growing trees and you know that's we do in forestry and that's what we, for a lot of private landowners out there that are blessed to have private timberland to manage, that's what they want to do. And if you're still managing the pine stands the way you did 10 to 20 years ago, it might be a time for a reset.
David Clabo (04:16)
Exactly.
Paul Jeffreys (04:38)
You know, and that's what we're going to walk through in this episode of how silviculture has evolved, where it came from, where it's going, and you know, what you can do, how you can use it to basically meet your objectives for your private timberland.
David Clabo (04:39)
Exactly.
Paul Jeffreys (04:56)
So, know, we're going to go into a little bit. We'll probably talk about some genetics, some herbicide, and we'll talk about different spacing. But let's just go ahead and talk about, at the beginning, we've talked about what silviculture is, but what is silviculture today? Can you give us the key components of what silviculture today basically ⁓ includes?
David Clabo (05:19)
Yeah, that's a pretty broad topic, but I would say, silviculture today has to be more precise probably than it has been historically, just based on your location. So that entails what timber markets are like in your area. If it's a public or private ownership, landscape characteristics. So what's the site like where you're...
trying to manage for a particular staying condition, all those sorts of things. But yeah, I think we really have to be more precise with tailoring management to what's needed to meet objectives on each site nowadays.
Paul Jeffreys (05:52)
Right. And is there one prescription, silviculture prescription that to meet all to go across? Like, can you say there's one silviculture prescription for all sites?
David Clabo (06:01)
No, I don't think so.
Paul Jeffreys (06:03)
Yeah. Yeah.
Every one of them is different. Correct. Yeah. I mean, you know, I'll get, ⁓ I get calls sometimes from landowners and, the, the first question is, is what should I spray my site with? What chemical should I use to, ⁓ what chemical should I use to prepare my site for planting this coming winter? And, you know, it's always goes back to the ⁓ answer. I think to every.
David Clabo (06:07)
Exactly, yep.
Paul Jeffreys (06:31)
forestry question that has ever been asked and the first answer is it depends. It depends what type site, what are you looking at, what's your soils, what's species composition and your competition that's coming up there. know, vegetation control, what type of site do you have is what planting practice do you need for your site.
David Clabo (06:37)
Yep, it always does.
day.
Paul Jeffreys (06:57)
And it is always been the answer of, it depends. mean, you may, you don't want to obviously waste money. And there is the opportunity to waste a lot. If you get, know, doing things, doing things the wrong way, doing things that did not necessarily need to be done, you know, just practices. So.
David Clabo (07:10)
Definitely.
Paul Jeffreys (07:19)
Give us ⁓ a, your, how long have you been in silviculture? How long have you been studying silviculture?
David Clabo (07:24)
Well, given my college years, let's see.
I guess about 18, 19 years.
Paul Jeffreys (07:31)
Okay.
So, I mean, you're young guy. We were talking about that earlier before we started the recording. You're a young guy. You're looking at, know my son. have a 26 year old son. And when I say things about, you know, when I talk about doing things around the farm and he rolls his eyes and says, dad, that's, you know, you're doing that the old way. What, give us a little bit of an idea of the old way. When you started, you said 15, 18 years ago.
⁓ when you started working in this, give us an idea of what silviculture looked like back then, or give us an idea of what silviculture looked like in the, when it first started.
David Clabo (08:08)
So I mean, if we go back, I'll go back to when it first started. I mean, typically say like 50s, 60s when pine seedlings for planting became more available, a lot of times it was just mechanical site prep, maybe a burn if the forester thought one was needed for the site and then.
In the 70s is when some herbicides became more widespread with availability and use. So like 2, 4, 5T and things that are outlawed nowadays. And then I think early 80s is when we got a lot of our more modern herbicides that became available for forestry use like imazapyr
Paul Jeffreys (08:33)
And what type of herbicides were those first ones? mean, you know, the... Right.
Yes.
Mm-hmm.
David Clabo (08:49)
glyphosate became more widespread then because it was, I think it was invented in around the mid 70s. And then we had like herbaceous weed controller, besides like sulfometron and met sulfuron became more available kind of early to mid 80s timeframe. So that was really a game changer.
when those products came on the market because we get much more specific with our chemical site prep applications and kind of tailor those to the vegetation compositions on site.
And normally with mechanical, I mean, it's still very useful for some sites, but there usually has to be some sort of limiting site condition. Like poor drainage for some of our lower coastal plain sites where bedding is needed as an example. Maybe a site that's got a lot of logging slash from say a storm or leftover after a harvest, you might use something like.
Shearing or root breaking something like that, but normally we we tell folks To limit the mechanical unless it's it's something that's absolutely needed So like poorly drained soil compacted soil was say like subsoiling or ripping Those types of activities so just because to reduce the cost
Paul Jeffreys (09:53)
Right.
Now, if I would you,
I was gonna ask, that was gonna be my next question is why would you tell somebody to limit the amount of mechanical site prep for getting a site ready? So you said it would just be to try to help with the cost.
David Clabo (10:09)
Yes, yeah, just with diesel prices the way they are and operators, their per hour charges, mean, it's the mechanical site prep costs have increased the most since I started over anything else.
Paul Jeffreys (10:13)
Right.
Right,
right. So, you know, that was where it started. You mentioned a lot about the chemicals there and the chemicals that were used, but also what was going on in that time. And I have a great chart that I use in my presentations that talk about, you know, the additive impacts of silviculture in forestry along with, and how it goes up and how, as you add on silviculture practices,
⁓ and they are a compounding addition on top of each other, your production as far as tons per acre or your yield, what we call yield per acre, grows exponentially as you go across and you continue to add those things. So, as it started back in the day, people really relied on natural regeneration.
David Clabo (10:56)
Yeah.
Paul Jeffreys (11:16)
⁓ on a lot of stands because the industry forest industry forest technology had not basically developed at that time. So, you know, starting back in the 1940s and 50s before all of this was developed, it was mainly, you know, we remember the horror stories of when they were coming through and they would just clear cut a piece of property and walk away from.
David Clabo (11:17)
Yes.
Paul Jeffreys (11:39)
⁓ with no, with no preparation, with no, with no thought about the next generation or the next stand that was coming back. And they really, now things have developed, site prep has developed, to a point where there is a lot, it's like farming. mean, you know, a farmer, you don't see a farmer go out into an agriculture field and harvest his crop.
David Clabo (11:39)
Exactly.
Paul Jeffreys (12:00)
at the end of the growing season and then just come back and expect the same crop to come back the next year.
So, you know, I guess it is, would you say that it is very important for the private landowner or the forest manager consultant to get it right at the beginning of the stand with his silviculture practices?
David Clabo (12:20)
yes, for sure. Because really once those trees are in the ground, there's less options you can do, use to ameliorate a situation that's gonna lead to staying conditions you don't want. Whether that's poor survival rates or a lot of hardwood competition, something like that. Which usually those go hand in hand. yes, there's definitely more options at site prep before trees are in the ground.
Paul Jeffreys (12:25)
⁓ huh.
We're right. We're right.
David Clabo (12:44)
to get things right and ensure your best chance of success, no doubt.
Paul Jeffreys (12:44)
OK.
Right.
So going back and talking about, know, we have chemical, let's just, let's just start out. Okay. Let's, let's paint this picture right now. We've got, and you and I are going to talk about this. We've just got a fresh clear cut, you know, in let's say there in South Georgia where you're at right now, and we've got us, we've got a, a fresh clear cut and a landowner has called up Dr. Clay Bow and said, Hey, I
I need to know what I need to do out here to make sure that I've got a good stand coming back. Let's just walk through your process. If you went out and looked at a site and let's say the first thing your decision was, okay, are we going to do mechanical or chemical site prep? Can you tell me how you would evaluate that stand of which one to use?
David Clabo (13:34)
Yeah, so I probably first asked about land use history. was the site, you said it was a clear cut, right?
Paul Jeffreys (13:38)
Mm-hmm.
Yes, it's
just a clear cut. was a former pine plantation and it came time to harvest it. We've just put them on the ground, got a great price for the saw logs and we put it on the ground and this individual landowner has come back and says, Dr. Clabo I want to know what I need to do.
David Clabo (14:00)
Okay, so yeah, I would inquire a little bit about the land use history. Was this like a old CRP planting? Was it an ag before that? And that can kind of give you an idea of woody competition and also herbaceous competition that might come back and let you know a little bit about some of the site prep that might be needed. I'd inquire about the soil series present. That can help you decide.
Paul Jeffreys (14:23)
Why is that important?
David Clabo (14:23)
Is it poorly, yeah,
if it's poorly drained or not, you can know if maybe if it's a little bit more prone to compaction, depending on that soil texture, whether or not say subsoiling or something like that might be needed for mechanical site drip. And then if it's a poorly drained soil, it's most likely gonna need to be bedded unless the old beds could be reused. I have heard of some folks doing that. In some cases, I wouldn't say that's common, but.
Paul Jeffreys (14:31)
Right.
So yeah, and I
get that question a lot too. let's go back and talk about that subsoiling that you just mentioned there. You know, back in, as my grandparents used to say, back in the good old days, you know, every, when families were homesteading properties and they were farming land, just about every square inch,
David Clabo (15:01)
and
Paul Jeffreys (15:09)
of land in the southeast unless its topography was just so steep they couldn't do it, was either grazed or farmed. And you and I both know that the old tillage implements of yesteryear in agriculture, it had a tendency to create a problem below the soil surface. Can you explain a little bit about that to our listeners?
David Clabo (15:17)
Exactly.
Yeah, years and years of farm machinery going over the same ground can cause an issue with compaction in the first few inches of the soil profile.
Paul Jeffreys (15:43)
But
I thought tillage equipment was made to basically stir the soil up and make it more, more, more, make it better.
David Clabo (15:51)
Well, it depends. that compaction can be deeper sometimes, like say within the first couple of feet, 18 inches anyways. But if it's a site that had say livestock on it for years and years, then that compaction can be a little more shallow to the ground.
Normally with sub-soiling, we recommend going to a depth of say like 15, 18 inches. It usually takes a pretty high horsepower tractor. You want to do it during dry conditions like what we've got in South Georgia right now. Typically done say during the spring months and then you do those rips or trenches in the soil.
with your between row planting width. So say if you wanted 10 feet or 12 feet between the rows, that's how often you'd make an interval with a trench or a rip. And then.
It's good to let those sit through several rain events over the summer and into the fall before you plant the trees to allow some soil settling into those. And the whole purpose of the rip or the trench is just to fracture that hard pan in the soil to allow the tree roots to grow through and you'll get better root development, especially with the taproot on a pine with that type of site prep. So it can be very important for some sites.
Paul Jeffreys (16:52)
Right.
David Clabo (17:03)
I've seen on sites where trees where they didn't rip beforehand and it looks like the tapper is just going sideways when it hits that hard pan in the soil, which it can be called a plow pan, but there's also natural ones called fragile pans or dirt pans in some soils. So it, can occur naturally in some soil types. we, they're not common really in the coastal plain, but some areas in the Southeast on our more upland soils have those occasionally.
Paul Jeffreys (17:19)
Right.
Right, right.
David Clabo (17:30)
And
it's really one of the most important mechanical site prep tools we have for soil types where they're needed.
Paul Jeffreys (17:37)
Well, that's what I tell the people that that Colin asked me is, you know, that that that mechanical pan that's about 18 inches below the sole surface. That was about the average. That was the size of your average disc blade back in the day. And everybody back in the day used a disc arrow, ⁓ whatever their term for it was. It was a disc arrow or a disc or something. But those disc blades were about 18 to 20 inches in diameter.
And that was about their average size. And people don't think, that's, you know, they think, that's stirring the soil. That's churning the soil. But at the same time, that's also a weight that is riding across that soil horizon that is just below that disc blade that can't get churned. And it's causing that mechanical pan. And exactly.
David Clabo (18:25)
⁓
It just happens year after year.
Paul Jeffreys (18:31)
Yes,
and then the livestock walking on top of it, or the hay, whatever grass, variety of grass you're using for your hay production causes a lot of hay equipment to be riding across the top of it. But yes, mean, the mechanical site prep, it can get expensive, but there are places where we just absolutely need it. Yeah, yeah. So what about chemical site prep?
David Clabo (18:51)
Exactly.
Paul Jeffreys (18:55)
You got this clear cut. You're going to go out there. You're going to tell him about what mechanical site prep he might need. We talk about he might need a, he might need a sub-soiling. What about his chemicals?
David Clabo (19:05)
So for chemical, we pretty much recommend chemical on almost every site. I wouldn't say 100%, but probably 99 % anyways. But yeah, exactly. And the reason for that is just, chemical's the best option to control vegetation without disturbing the site. Like mechanical wood, you don't have the...
Paul Jeffreys (19:15)
99.9
David Clabo (19:28)
potential soil movement issues or compaction and you can kill the root system of the competing vegetation using systematic herbicides that are typically foliar absorbed but they can also be absorbed from the soil depending on what you use and killing that root system and trying to prevent re-sprouting is going to be critical to ensuring early soil water availability for your planted pines.
Paul Jeffreys (19:53)
Now is there
one herbicide that's good for everything?
David Clabo (19:56)
There's some that are good for a lot of situations, yes. Some of our more broad spectrum herbicides are really good at controlling a lot of species, but they don't control everything. So normally we recommend a tank mix of two or more products. Usually it's only two, but sometimes it may be three, but usually it's only two products that we'll recommend for a tank mix.
Paul Jeffreys (20:16)
Now is the chemical site prep mix, let's say the landowner on this clear cut that you're managing there that you're looking at, let's say this landowner has decided he doesn't want to go back with pine trees, he may want to go back with hardwoods. Would he be using a different chemical site prep mix, tank mix for that management aside from what he would be using say for pine trees?
David Clabo (20:31)
Okay.
So with hardwoods, they're of course gonna be more sensitive to most of our herbicides that we use in site prep So we normally recommend.
a little bit lower rates and maybe an earlier application timing before when you think you're gonna plant, especially if you're using soil active herbicides to give that herbicide more time to break down in the soil and limit the potential for phytotoxic effects with your planted hardwoods. But I mean, you can use say like an imazapyr glyphosate tank mix.
you would for pines with hardwoods, you're typically gonna lower that imazapyr rate a little bit and try to do it, say, at least three, maybe four months or more before you think you're gonna plant.
Paul Jeffreys (21:20)
Right. And that's because some
herbicides, correct me if I'm wrong, some herbicides have a soil activity period that they can stay and stay active. Okay.
David Clabo (21:27)
Yes, exactly. So
like imazapyr is kind of notorious for that. But it's our main and one of our best herbicides for say like a late summer into fall application period. And then hexazinone is another one we use occasionally, especially on sandier soils in the coastal plain that has a spring application and it also has soil activity. kind of our two base chemicals that we use at different times of the year.
Paul Jeffreys (21:39)
Uh-huh.
David Clabo (21:52)
both have pretty significant soil activity and really soil texture, your weather between application and planting, all that kind of impacts how quickly that herbicide will break down in the soil.
Paul Jeffreys (22:03)
Okay. Yeah. So again, it goes back to the age old answer of, it depends. ⁓ It depends. Well, what about, do you ever encounter landowners that say, hey, I want to cut corners on my site prep or I may not want to go with this heavy of a rate. Can I cut that back a little bit? Do you ever advise that for anybody or is it, would you say the, you you get what you pay for. If you cut corners, you may end up wishing you hadn't later on.
David Clabo (22:08)
It depends exactly.
cough
Typically it's you get what you pay for. And like I said, some folks may wanna just rely on like a release treatment after the trees are already in the ground because you typically use less herbicide or fewer types of herbicide for a release treatment because you have to use something that's safe to use over the top of the trees. And usually you just don't get as good a control if you go that route compared to if you.
did like the standard herbicide rates at site prep before the trees are in the ground. So that's one case I've heard about folks considering a few times. was just, we'll save money on herbicide and not use as much say with just a release treatment versus the higher rates that are used during site prep. And usually.
Paul Jeffreys (22:58)
Right.
What's the difference in
a release treatment and a site prep treatment?
David Clabo (23:13)
So release treatments for say the tree, the planted trees are already in the ground and you notice you've got a competition problem pretty early on. And usually it's a woody competition issue because woody plants tend to be more of an issue throughout the rotation than say your herbaceous plants like the grasses and broadleaf weeds. And so with woody control.
with say like Loblolly pine, you can do an early woody release treatment with something like imazapyr over the top after that first growing season if you notice there's an issue. But you're not using as much imazapyr per acre as you would during site prep, so you may not get the same level of control.
Paul Jeffreys (23:40)
Right.
Now what is your
imazapyr going to control? What type of species is it going to control?
David Clabo (23:59)
So it controls most of your hardwood species and woody vines. ⁓ There's a few exceptions to that. There's some species that are say like leguminous species that won't control. So like examples of that might be say like an invasive would be kudzu or something like mimosa or say locust. Some of those more leguminous woody species. Yeah. Okay. Yeah.
Paul Jeffreys (24:04)
OK.
Right. Those were the two I was hoping that was the two I was hoping that you would mention there is mimosa
and locust trees because that imazapyr is not going to it's not going to touch those guys but I tell you one thing that imazapyr is good for controlling and that is sweet gum and your and your your other hardwood species sycamore yellow poplars.
David Clabo (24:25)
Yeah.
Exactly.
Paul Jeffreys (24:40)
Stuff like that, it is good if you're wanting to control those species for a pine replant. And hey, let's face it, we're in the business of genetics, we're in the business of producing pine seedlings, genetically improved seedlings here at ArborGen. when it's not a small investment, that's not a, were as used to be, that used to be the.
the I guess the lowest cost part of the whole process. Now it's not because there's a lot of involvement that goes in producing these better genetics for to meet the objective of the landowner. So you really, you know, your cost versus your long-term return on investment is something that you really, you've got to pay attention to as a landowner because you really get what you pay for.
David Clabo (25:10)
Exactly.
Exactly. Yep. And normally I tell folks, Hey, if you're thinking about investing more in tree seedlings, I would have probably invest more in site prep too. And try to, try to plant your better genetics on, your better sites too, so they can kind of meet their full potential.
Paul Jeffreys (25:31)
Enough.
Right.
Right. get that same.
Wow. We must be talking to the same people, there David, but I get that same question a lot is I'll be presenting to a group and somebody in the back or raise their hand and they'll go, Hey, if I plant these, you know, super quality trees, these, MCP mass control pollinated seedlings of y'all's, do I still need to do all the site prep that I would have done without planting those?
David Clabo (25:49)
Yeah.
Yeah.
Paul Jeffreys (26:09)
And I instantly, my usual response is it's more important that now that you do that more than important than ever, because that is completely that is not, you you've got to give those trees the best opportunity they can, you can give them to grow and meet their genetic potential. ⁓ Exactly. You need to be doing everything you can. Well, tell us about, you know, what does
David Clabo (26:15)
and turn.
You need to be all in with your management basically.
Paul Jeffreys (26:36)
chemical control, what are some of the things that it can help with as far as that first year? you've done, if you've, say, all right, that landowner we were talking about, I gave you that example, he's out there, she's out there, they've got their property and they've called Dr. David and they're like, look, I want to make this right and I want to get it done right. What are the benefits that that control is going to give them for those seedlings on the forefront?
David Clabo (27:06)
So yeah, the big one, especially early on, is gonna be just more soil water availability. Just think about it. If there's more vegetation out there pulling up more water from the soil, that's gonna be more detrimental to those pine seedlings. think how they're being introduced to a new environment. They're gonna probably have a little bit of transplant shock there in that first spring when they're out, especially if it's a dry spring like we're having this year.
Paul Jeffreys (27:11)
Right.
David Clabo (27:29)
and the more water availability for those planted pine seedlings, the better off they're going to be. And then also you got to think about things like growing space and shading.
lot of the times the competing vegetation has an established root system that's going to enable them to grow more quickly early on than the pines. so that competing vegetation can overtop and kind of shade out those pines fairly quickly, especially on better sites And so if that competition's removed, that just gives those planted pines that much more of a chance to thrive and get a good stand down the road.
Paul Jeffreys (27:45)
Right.
Right. So it all basically all of that, we can wrap all of that up into, know, with that, with the site prep, you're going to get better survival rates. You're going to get earlier growth and you're going to have more stand uniformity because let's, let's face it. I, in my background, I tell landowners the number one killer of hardwood seedlings and really the number one killer of all seedlings would be competition that first year.
David Clabo (28:28)
Exactly.
Paul Jeffreys (28:29)
and you're trying to put something in the ground that has no has not captured that side. It has no root. It's got to it's got to start growing. It's got to start putting roots into a site, a new site, and is competing with other plants that already are established and already have that root growth capture. And I'm glad you mentioned it is it is it's a term I I tell people also that ⁓
David Clabo (28:46)
Thanks, Ed.
It's a tough environment.
Paul Jeffreys (28:55)
You know, these seedlings are growing in a nursery and they're growing basically in the Garden of Eden as they would think of it. Because yeah, I mean, they're getting everything they need. They've got their buddies right there next to them. I mean, is absolutely, you know, euphoria because if, hey, if they need a little bit extra nitrogen, we've got nursery managers that can note that can detect that and they can put that in the fertilizer. If they need a little extra of this, if they need a little edge, and then you're taking them out.
David Clabo (29:01)
Exactly. I tell folks something similar.
Paul Jeffreys (29:24)
in the fall and then planting them what I call their final resting place where they're going to spend the rest of their lives and they've got to then fight it out and let's face it if they're fighting with a neighboring yaupon and a neighboring plant that already has captured the site or an invasive plant it can be kind of difficult.
David Clabo (29:44)
Definitely. Yeah. It's a tough world for them when they leave the nursery or a place at their final resting site. I like that way you put that. ⁓
Paul Jeffreys (29:45)
Yeah, yeah.
Yes. Yeah, exactly. And
whether or not you know that final resting time, you know, if you don't get the site prep right, it can be a very short lived time. Yeah, so you can you know, there's people out there that say, you can skip on chemical and catch up later. But that's really risky. I mean, that's that's not a that's not a good idea.
David Clabo (30:02)
It can be, yes.
It is.
Paul Jeffreys (30:13)
And what about these people that also say, hey, I've just harvested this site. Let's say, for instance, your landowner there in South Georgia that you're looking at the property, they've just harvested the site and it is really clean. You know, let's face it, when the logger leaves, you're seeing a lot of bare ground out there. You're not seeing any of that competition coming up. You know, is that competition still there when that logger leaves and the site looks clean?
David Clabo (30:38)
Yes, it's still there, present in its root systems, rhizomes, stored seed in the seed bank, all that's in the soil.
And so typically, if folks have that condition, we'll say to wait a little bit and allow some re-sprouting, new germinants to develop. And that enables the herbicides to be more effective and control that vegetation long-term. Because you're thinking about this all on a very long-term basis. You're trying to do this treatment early on before the trees are planted to give your planted trees the best chance of long-term success. so we'll normally say, especially
with woody vegetation, let it re-sprout and get say a couple of feet tall at least, have some foliage on it and then apply those herbicides at the proper timing, say late summer into the early fall when most absorption is gonna occur and that herbicide is gonna be translocated down to the root system. So.
Paul Jeffreys (31:31)
Right.
When would you think is the best time? What would be your expertise? What's the best time to apply chemical site prep?
David Clabo (31:39)
Like I said, yeah, once you've got re-sprouting, say vegetation a couple feet tall, and if you're using, it kind of also depends on the herbicides you're using, but say amazapyrus, your base chemical, and then what other.
chemicals you're adding to that say like triclopyr, glyphosate or whatever. Normally kind of say starting mid August or mid July through leaf color change depending on kind of your latitude and weather conditions it's going to be the best time for that type of tank mix. But like I mentioned with hexazenone it's more of spring application so it's best to apply it after leaves first fully and more emerge in the spring.
Paul Jeffreys (32:12)
Correct.
David Clabo (32:18)
it has to have some rainfall to activate it. But again, not nearly as many people use it as the imaginaputriate base chemical.
Paul Jeffreys (32:25)
So, you know, I run into several situations to where people say, we want to do a late ⁓ site prep. We want to get a carry over into that first year so that maybe we can skip that woody release. And, you know, my advice usually is to them, that's not advisable because you want to get a lot of those chemicals are soil active. And say if you're doing a hardwood planting, you want to get that chemical out there early in that growing season.
David Clabo (32:43)
Yeah.
Exactly.
Paul Jeffreys (32:53)
so that it can do its thing and have already really been absorbed, done its work, what it was designed to do and be out of the way and out of the system by the time you go and stick the trees in the ground. Cause you can get some residual negative impacts on pine seedlings as well from a late spray. Well, I want to jump into something else that I get a question a lot about.
David Clabo (33:13)
Exactly.
Paul Jeffreys (33:20)
And maybe you can clear up because I'm really, it's really not something that I'm too clear on and that's fertilization and fertilization in forestry. So let's say for instance, that landowner that you're working with, there comes and says, well, Dr. David, should I do a fertilization application out here on my newly planted trees? And what's your take on fertilization and what has the research shown here lately?
David Clabo (33:46)
So fertilization can be very important for certain soil types. So an example for the coastal plain, and this would be pretty much throughout the Atlantic or Gulf coastal plains if you've got a soil with these characteristics.
If you've ever heard of the Cooperative Research and Forest Fertilization System that University of Florida developed back in, I guess it was in the early to mid 1980s, but it's a soil classification guide that's used to make species deployment and fertilization decisions for coastal plains. And if you look at their guide, there's CRIF A soils. So those are soils that have an argillic or clay horizon, an increase in clay within
20 inches of the surface and they're also poorly trained soils, those soils tend to be very phosphorus efficient. And so if you say if you planted loblolly on a site like that because loblolly is kind of our most nutrient intensive species requires the most nutrients, if you planted loblolly on a site like that then you probably wouldn't have a whole lot of a stand down several years down the road or it'd be a kind of a sickly
looking stand that wasn't growing near its potential. So like a nitrogen phosphorus fertilization, say within the second year after planting, just to make sure you've got good seedling survival after that first year. And also want to make sure you got good weed control. That can be very important on some soils, like those crefais soils. Most other soils,
Paul Jeffreys (35:07)
Right.
David Clabo (35:10)
Especially given current fertilizer costs, it's not going to be economical. Fertilizer costs, since some of these foreign wars have broken out, have really gone through the roof. So we're really not recommending fertilization right now, especially because you still have to pay the application costs as well unless you're going to do that yourself. But most cases, whether that be mid-rotation or at establishment.
Paul Jeffreys (35:23)
Right. Right.
David Clabo (35:34)
we don't recommend it nowadays just because of the cost. But certain soil types that can really make a difference in productivity and whether or not you've got sort of an economic stand down the road.
Paul Jeffreys (35:38)
Right.
So it still
goes back to that answer that everybody gets is, well, it depends.
what are some of the common fertilization products that are used in forestry? If they are used, heard, you know, I commonly hear the phrase or the term DAP, which is an acronym. I commonly use, you know, or commonly hear other combinations, but that's the one that is most common.
David Clabo (36:01)
Yeah.
Yes, so DAP is mainly, it's diammonium phosphate, but it's mainly applied for the phosphorus content. then folks will often do say like a urea application for the nitrogen with that. But DAP does have some nitrogen in it, but that's probably the most commonly applied forestry fertilizer. There's also MAP.
Paul Jeffreys (36:28)
And is it applied
at the time of planting or is it applied at the time ⁓ a couple of years after planting? When would it be applied?
David Clabo (36:35)
Normally we suggest doing it say like that second year after planting just to make sure you've got good survival and good weed control. Just think about it, if you're applying it with there's a lot of weeds present, you're also gonna be feeding the weeds present. you wanna make sure you've got good weed control with any type of fertilizer application. ⁓ But it can be applied at establishment or shortly thereafter or say at mid rotation after a thinning.
Paul Jeffreys (36:54)
All right.
David Clabo (37:02)
So that's kind of the two windows when it's used most frequently. And then there's other inorganic fertilizers like...
monomodium phosphate, triple super phosphate that are mainly used for the phosphorus content. But then urea is probably the most commonly used fertilizer for the nitrogen.
Paul Jeffreys (37:20)
I always recommend a soil test. Go by what the soil test says.
David Clabo (37:22)
Yes. Yeah, you.
And that's one thing we really haven't talked about with fertilization yet is the diagnostics you need to do prior to even thinking about doing any type of fertilizer treatment. So you need to do your soil tests.
Paul Jeffreys (37:32)
Right.
David Clabo (37:37)
look at that soil phosphorus especially, and then maybe also the pH pretty closely. And then it's also good to do foliage test as well and look at all your macro micronutrient content in that foliage. And those are normally done in the winter before pollen dispersion. So it's kind of a narrow window there when the trees are dormant before they start dispersing pollen where you want to do that.
Paul Jeffreys (37:48)
Right.
Right, right. Well, that leads me into basically saying if you don't get the site prep right, if you don't get the ⁓ chemical, if you don't get the competition controlled doing a fertilization, you can't correct a bad site prep mistake by fertilizing your way out of it. a lot of those, if you don't get those competing plants controlled,
David Clabo (38:12)
Cough
No.
Paul Jeffreys (38:28)
putting the fertilizer in the ground is just going to be feeding them and you may not be feeding the target species that you're wanting to feed there because you made a mistake on the forefront. Well, talking again.
David Clabo (38:41)
The competition
control should be the priority.
Paul Jeffreys (38:43)
Right. So competition control is probably priority one when it comes to silviculture. So let's talk about it little bit. Now we've got this landowner. We've addressed the site prep. We've addressed pre and post plant chemical control, mechanical site prep, whether he needed bedding, whether he sub-soiling. Now we've gotten into the, we've gotten the site ready, just about ready. We've just about prepared the table.
David Clabo (38:47)
Yeah, exactly.
Paul Jeffreys (39:08)
We're getting ready to put down the seedlings and everything. and then they, he or she comes back and says, all right, Dr. David, what do I need to know about spacing and planting density? What's the magic number? It's always a moving target. I hear some people that are still planting 622. I hear some people that have gone down to 400 trees per acre.
What are you seeing and what was traditional high density and then modern approaches?
David Clabo (39:36)
Okay, so yeah, there's a lot of different facets to that to think about. Big one of course is gonna be just what species are you gonna plant. say with species like lob poly or even slash pine where they have genetic improvement, you can get away with lower planting distance and say with like longleaf where.
You want to plant a little bit higher density to ensure you get that good survival rate because typically longleafs are not going to have quite the survival, as especially loblolly And then also thinking about markets and kind of your objectives. Most places in the southeast, we're kind of losing our small diameter wood product markets.
If we can kind of strategize and maybe plant it a wider space, especially if we're looking more at say loblolly or slash, that can potentially move more trees into say chip and saw product classes by the time that stand needs to be thinned, which would be at an older age than say with what we would do with a typical pulpwood first thinning, pulpwood heavy first thinning. ⁓
Paul Jeffreys (40:36)
All right. All right.
David Clabo (40:38)
That's something really to think about. your markets that you've got locally. And then, yeah, just your objectives. I mean, are you trying to out much more valuable products? Is it more of an objective where you're just trying to store carbon? mean, that all kind of plays into it as well.
Paul Jeffreys (40:58)
It
all goes back to that landowner objectives. And as you mentioned there, talks about, you know, as we talk about all the time, the markets. Now, you know, I get questioned and I ask what's your markets like. And look, let's face it, there are some areas in the Southeastern U.S. that still do have some decent popwood markets. Even in those areas, you know, if you go back and you plant a higher genetic tree that's going to grow,
and put in is, is, you know, selected for higher yield and heavier weights. And that is part of the genetic selection. You can increase those even if you are planting more trees per acre, you can increase that initial yield on that first harvest for pulpwood. And you can, you can increase that, but you know, it depends on your markets and your landowner objectives. And, you know, but
Especially if you're going to a lower density, what I have found and what most people are looking at is if they're going to a lower density is highly, highly important that you plant a better genetic because you're planting fewer trees and look, your margin of error window is narrowing down.
David Clabo (42:03)
Yes.
It is, for sure.
Paul Jeffreys (42:11)
So,
you know, it's not just how many trees you plant, but it's what those trees that you plant are capable of doing.
David Clabo (42:19)
Yeah, you want those trees to have the best traits possible.
Paul Jeffreys (42:22)
Right. Back in the day, remember, you know, my parents, my grandparents, they would go and they would plant, you know, over 700 trees per acre. But it was simply because they did not have a very, you know, they only had the basic tree that they could pick and plant. that's what they but they, yeah, but they had pulp markets that could use those trees. And also on top of that,
David Clabo (42:40)
unimproved.
Paul Jeffreys (42:46)
by planting all those trees, you know, when they did cut out the defective trees that were never going to make a saw log, they would probably still have a stand worth growing on out for saw logs and poles. There never was a guarantee. With genetics the way they are today and through selective crosses, you can have that guarantee of these trees are barring some environmental impact.
as you and I know can always impact a stand, but barring some environmental impact, those trees are going to produce those higher quality stems to make those long lasting products like lumber and poles.
David Clabo (43:22)
Yes.
Paul Jeffreys (43:23)
So, you know, that's just the role. We'll talk about that. You know, we've talked about that. We've talked about chemical site prep. We've talked about mechanical site prep and how it is important to get it right. At the beginning, we've talked about how, you know, fertilization may or may not be a necessity and whether or not it will be a positive, you know, investment on the, for the life of the stand. And then
We've talked about the genetic and how it's changed and how people are looking at different densities and spacing and how all of that is impacting the ultimate goal and is creating value for the private landowner. So, you know.
Can you just a little bit here before we wrap up, tell us a little bit about what your science and your, what the science and your research projects are showing and what you see coming on the forefront.
David Clabo (44:21)
Yeah, in recent years we've been working on kind of a forest productivity project looking at
updating site index and mean annual increment estimates for loblolly and slash pine in the coastal plain of Georgia and then just loblolly in the Piedmont. And then we've also got a similar study for longleaf, planted longleaf stands that were containerized stock. And so we're trying to update our kind of our growth and yield information available just to give landowners a better idea of kind of, hey, this is what modern forestry practices and genetics will do.
in terms of productivity, whether you're trying to figure out the side index or tons per acre per year growth. So that's some work I've been working on really since like 2020. it's like these are two, three phase projects where you get like a stretch of funding for three or four years and then it's renewed. If you're doing well on the project, you go another three or four years.
Paul Jeffreys (45:09)
Right.
David Clabo (45:17)
kind of where we're going in the future. I think again, we're gonna try to be more precise with our Pacific culture prescriptions for specific site locations and site characteristics. I think that's always gonna be something we're trying to improve. I think in some areas, if Tim or Mark has continued to go kind of the trajectory they're on.
mixed and management might be something more folks tend to look at, especially folks that private landers that have fewer acres they manage. ⁓ Cuz it's a little more hands off approach.
Paul Jeffreys (45:46)
Right.
David Clabo (45:50)
not as intensive management in lot of cases, or it doesn't have to be, it can be, but it doesn't have to be. And that it might give landowners a little bit more flexibility, especially if you've got commercially or ecologically important pine and hardwood species in the same stand. So that might be one way we kind of go in the future. But yeah, it's...
think a lot of it's just kind of in flux right now, just seeing how these timber markets go and kind of what that enables, especially private landowners to do.
Paul Jeffreys (46:19)
Right, right.
Well, yeah, it's definitely a changing world. Talking about that mixed stand management, you know, we have talked about on this podcast, it's been more kind of directed to, you know, one species, but that's definitely the way some things are growing. That's a whole different, we could spend hours talking about, you know, this and that and what we could be doing with that. But I think, you know, the
David Clabo (46:39)
I think it's good.
Paul Jeffreys (46:45)
The takeaway from today's podcast is you don't cut corners on site prep. ⁓ It's a long-term investment. When you're deciding what to plant, get a lot of landowners get one shot to get this thing right. And you, if you miss or make a mistake or you cut a corner or you save a couple of bucks per acre doing this over here, instead of doing this, that can.
David Clabo (46:50)
No.
Paul Jeffreys (47:11)
drastically impact your return on your investment in a negative way, you know, and then match your spacing to your goals. And early investment always pays off later. Early investment is like investing in stocks or anything else. If you invest early on, you can definitely see the payoff and be intentional on what you do. Be intentional on
David Clabo (47:24)
does.
Paul Jeffreys (47:36)
the site prep you use, be intentional on the seedlings you use, the seedlings, the genetics that you use. And here's the word, you know, I want to send it home is if anybody has any questions or any, you know, would like to ask you anything about, they, is there a way that they can contact you to send you a question and ask you.
You know, Hey, Dr. David, what would you recommend or, know, just how can they get in touch with you?
David Clabo (48:05)
Sure, I'm always glad to answer questions or help folks along in the management process. But yeah, my email is david.clabo. That's C-L-A-B-O at uga.edu. Also, folks can feel free to call my office phone. It's area code 229 and then 386-3672.
I'm an extension faculty, so we're here to help folks.
Paul Jeffreys (48:28)
Exactly and that's exactly
what what extension faculty is there for is to to help landowners. I have a background in extension as well and if any of you out there have any other questions about what we've discussed today on this episode about silviculture and how it's changing you can always reach out to us at ArborGen visit us at arborgen.com to find your regional reforestation advisor.
and get in contact with us. We'll be glad to help in any way we can. If we can't answer the question, we'll definitely kick it off to someone like Dr. David Clabo here with UGA's College of Forestry. And we'll get you the answer that you need and that to best fit your goals and everything. And again, I want to thank you all for tuning in for this episode of the ArborGen TreeLines podcast.
And I look forward to seeing you on the next one and we will talk to you soon. Thank you again for joining us.