Three trees cut down at UCC, more may follow

Three Oregon White Oak trees on campus were cut down Friday, April 9, 2010 due to hazard concerns.

Two of the trees that were located next to the student center were ordered to be cut down by Limb Walker Services because they were in danger of falling on the building. The third tree was located next to the library. The damage to the tree was caused by a lack of oxygen in the soil."

The problem is Oregon White Oaks require a lot of oxygen to support a deep root system and that’s what holds them up, and when the college put in the lawn here, they put a little bit of top soil, you know sandy loam over the top, but it’s a very heavy clay soil here,” said Ken Carloni, UCC botany instructor. “It’s full of minerals, but as soon as it gets compacted, the air spaces disappear and no oxygen can get down to the deep roots.”

Analyzing a tree’s ailment is a complex process. Steve Bowers, Associate Professor in Forestry from the Oregon State University Extension Service explained, “You can plant a tree on a marginal site and it will do well for a year or two or five or 10 or even 20 or 30, but as it gets bigger and occupies more of a site, the abiotic variables begin to take effect (high water tables, southern/hot exposure, excessive winds, whatever).” Bowers also added that sometimes roots breaking the surface suggests the water tables are high, and the tree is trying to escape the water because it needs air.

Carloni then explained that these trees’ problems were not caused by excessive water. “It’s not the water; it’s the oxygen in the soil. When you compress the soil, any amount of water is going to fill up those tiny air spaces, just like there’s oxygen in the water, but you’ll drown in it because you can’t extract enough of it. So the water is filling up those pore spaces that would normally allow carbon dioxide to leach out and oxygen to fuse in. The feeder roots are happy and healthy because they’re getting a lot of water and the tree is growing gangbusters. You can see these huge growth rings, [but] lack of oxygen means that the tree will grow for a while until it gets to a big enough size where the tap root is rotted from the bottom up.”

The deep roots known as tap roots are important to the stability of the tree, Harold Olds, an employee of Limb Walker Services, explained; “Look on the back side of the stump, you’ll see this little ledge, that’s because the roots are breaking and pulling up.” Olds called one of the trees a “serious hazard.” He said, “It would have fell eventually; it could’ve been tonight, the next wind storm [or] rain.”

Carloni explained the importance of tap roots. “Trees hold themselves up in two ways; they’ll spread roots out that actually act as stilts or but around here, most trees are held by [tap] roots that go down into the ground and act like a cable so that tension runs through the root all the way down into the soil. They’re held from falling over by being pulled back by the root that’s deep in the soil. It’s a cable system; think of it that way. Tap roots are extremely important because when you get a heavy wind or you get a load of rain and a newly flushed canopy of leaves, there’s a tremendous amount of force going on there, and if you don’t have that cable in the ground or if the cable rots, sooner or later it breaks, and it falls.”

The tree was ordered to be cut down by the UCC maintenance crews.

“Your grounds people, your maintenance crew, they look at this stuff, and of course in a public place, it’s a great liability so that stuff is all watched real close and when a tree is a serious danger, they call us,” said Olds.

In the past, the grounds crews have planted Eastern Red Oaks because they are more tolerant of heavy soils.

The three trees were donated to UCAN and will be donated to needy families.

The Mainstream is a student publication of Umpqua Community College.