Transcripts

'Biodiversitree' Project Studies Health Of Tree Species

MS. REBECCA SHEIR

00:00:03
We'll turn now to the environment, and a project aimed at understanding the ups and downs faced by trees over a hundred years. The experiment is taking place on land owned by the Smithsonian Environmental Research Center in Edgewater, Maryland. The project is called "Biodiversitree," and environment reporter Jonathan Wilson met with the scientists who designed the project before the government shutdown, of course. And brings us this story.

MR. JONATHAN WILSON

00:00:29
John Parker knows a lot about biodiversity. He's been studying it for about 20 years, but never like this.

MR. JOHN PARKER

00:00:36
Yeah, this is the biggest thing that we've ever done, by far. I think about five people, plus 100 volunteers took six weeks in the spring, working almost every single day to put everything out here.

WILSON

00:00:48
Parker is a senior scientist at The Smithsonian Environmental Research Center, and he's standing at the end of one of the six fields that make up the Biodiversitree experiment. Parker says the idea for Biodiversitree is connected to the long standing concern about the effects of agricultural runoff polluting the bay.

PARKER

00:01:06
One of the ways in which we've sort of tried to restore the Chesapeake Bay, as a whole, here in Maryland, is to plant more forests in the critical zone bordering Chesapeake Bay and important tributaries. And so, what we decided to do is not just restore forest next to the Chesapeake Bay, but we decided to make an experiment out of it.

WILSON

00:01:23
The experiment involves 32 acres of land that's been planted only with corn for the past 35 years. The corn is now gone, and in its place, Parker and his volunteers planted one tree every eight feet. That's more than 18,000 seedlings, with more planned in years to come. Diversity is the point, and there are 16 different species in the ground here. But exactly where they're planted is also important. Parker and his colleagues want to find out if, and exactly how, biodiversity helps forests survive.

PARKER

00:01:54
And the best way to test is to set up artificial communities that have either low diversity, a single species. These tall trees poking their heads up right here are all sycamore trees, but then over to my right, we have a plot that's got, actually, four different species in it.

WILSON

00:02:07
Parker says if a disease or predator attacks a particular type of tree, it makes sense that a plot holding that one species could get wiped out, whereas a plot with multiple species would fare better. But one hypothesis is that having greater diversity helps even though species under attack. Parker calls this an associational resistance effect.

PARKER

00:02:25
You have something that's fairly palatable to deer, let's just say. Red Maples are eaten a lot by deer. It's one of their preferred foods. So, if you put a bunch of red maples out, in a patch, with just red maples, deer find that they're gonna eat just about everything there.

WILSON

00:02:39
But, put red maple in a patch with things deer don't like to eat, Parker says.

PARKER

00:02:43
Let's just say sycamore and ironwood and beech. They actually eat the red maple a little bit less, because it's a little less profitable to stay in that patch. So, the red maples do a little bit better when they're surrounded by things that are unpreferred or unpalatable to deer.

WILSON

00:02:56
Right now, the seedlings are surrounded by mesh cages to make it harder for deer to get to them. But Parker says his team has a nastier weapon at its disposal. Cow blood spray, which is just as gross as it sounds.

PARKER

00:03:08
The theory is that a deer will come up and smell the cow blood and think something else has been killed here. This is a pretty dangerous environment and I need to get out. And so, it puts the fear of death into them to come in and smell a tree covered in cow blood.

WILSON

00:03:20
That's interesting.

PARKER

00:03:20
It does to us, as well. It's pretty terrible stuff.

WILSON

00:03:22
Unpleasantries like that one aside, Parker's colleague Susan Cook Patten says once the researchers shepherd the fields beyond the early years, she's looking forward to studying how trees take carbon dioxide, a greenhouse gas, out of the atmosphere in forest of different diversity levels.

MS. SUSAN COOK PATTEN

00:03:38
You know, we're interested in how do we get some of this carbon dioxide out of the air, and, you know, it would be great if there were things out there that could just suck carbon dioxide out of the air, right, and capture it? And we have those things already, right? They're called trees, and an interesting question is if you've got these diverse mixtures of trees, and they grow more vigorously, are they then better at taking carbon dioxide out of the atmosphere? So that's one really important question, I think, that will come out of this.

WILSON

00:04:02
Cook Patten says there are only a handful of these types of experiments known as tree diversity manipulations going on across the world, and only a few published scientific papers about them. The team also says Biodiversitree is the largest such experiment in North America. And while at this early stage they don't have much data, the potential for studying everything from nutrient retention in soil to storm water runoff from these fields into the bay, is almost endless as the project moves forward.

WILSON

00:04:30
Parker and Cook Patten say while data will tell an important story, they're most looking forward to simply walking through these fields and looking at these forest communities as they reach maturity in 10 or 15 years.

PARKER

00:04:42
As you're walking through just a sycamore monoculture, are there more birds, fewer birds? Is the soil different? Does it have just a different feel than a polyculture? And then we can go through and quantify those differences later. From a scientific perspective, that's really the end goal is to experiment. Does a diverse system function any differently than a less diverse system?

WILSON

00:05:03
The scientists, make that a few generations of scientists, should have, at least, a century to answer that question. I'm Jonathan Wilson.

SHEIR

00:05:13
We have more on Biodiversitree and the Smithsonian Environmental Research Center on our website, metroconnection.org.
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