We have been running a research project for the past 7 years on the Olson Memorial Highway median in North Minneapolis. This is a true proving ground for urban trees. There are multiple lanes of traffic on either side, lots of salt spray from cars, large mowers on small spaces, and compacted soil to name a few challenges. This is not a friendly environment for trees, but it is just the place to do an evaluation on which trees work best in difficult urban environments
There are 147 trees going down the boulevard, almost a mile and a half of them in a line. There have been a few necessary replacements, and most trees show signs of wear, but beyond all the salt damage and mower slashes, there are quite a few trees showing promise of high, wide crowns and stable trunks. On the right, Chad is holding a long (7 ft.!!) basal sprout coming from a Cathedral elm, (Ulmus davidiana var. japonica). Basal sprouts can cause trouble for urban foresters and arborists. Nonetheless it is a good demonstration of the vigorous growth of elms and why they continue to be a popular tree in our urban forests.
The data collection took a whole day, starting and ending with a nice bike along the cedar lake trail (team tree gives it two thumbs up). Thankfully the weather cooperated and wasn’t blazingly hot, or extremely windy. It was the most pleasant trip we have had to that site, and that is saying a lot for 6 hours between traffic.
by Nick Neylon
At the nursery we have almost finished a job that has been a standing order since last fall. This is our pot-in-pot system. It is basically a field of plastic pots dug into the ground. there are 168 15 gallon pots, and room for two more rows (28 per row) of larger 30 gallon pots. The pot in pot field sits in the southeast corner of the nursery, going along the fence. The system is used to help trees survive the winter. All of the trees in our nursery need winter to maintain their life cycles, but they also need to maintain certain temperatures. If their roots were in the ground, they would be much warmer than when they are potted above ground, without insulation from the soil. The pot-in-pot system allows us to have trees in the ground, but also keep them mobile for fall and spring plantings
After we finish the pot-in-pots, the new ones will start to look like the olds ones, the next steps being turf, wraps, and irrigation. We cover up the patches in between with grass, spaced so that a mower can ride between the rows, and lay an irrigation line with drippers for every tree. Out of the trees that were in there last winter, only a few died, and the system is working very well. We hope that it will still be there in 10 years.
A special thanks to Matt, Jonathan, Charlie, Chad, and the Nicks.
by Nick Neylon
This week’s tree is the Chinese catalpa (Catalpa ovata). They are easily recognized by their long thin pods and their heart shaped leaves. They differ from the native variety by having longer pods, and purple tinted leaves. Just recently we planted a few flats of them in one of our fields, replacing the winter kill from last year.
Chinese catalpa is obviously not native plants, but they work well in Minnesota, and have been successful in urban environments. A good example is still flourishing next to the stone arch bridge – 10 years after transplanting from our research nursery here at the U of MN. They grow in the USDA Hardiness Zones of 5-9, going to -20 or -30 F. The Chinese catalpa is a little squatter than the southern catalpa, growing to 20-30 feet. It was a special tree in china because its wood was used to make the bottom of the qin, a traditional Chinese instrument.
by Nick Neylon
American Forests is the oldest conservation non-profit organization in the USA. They have a project, started in the 40s to catalog, protect, and preserve the largest trees living in the United States. They pick around 750 champions every year, amazing and awe inspiring giants of arbor culture. The trees include urban trees, but also many giants left untouched in virgin forests. They focus on the biggest and best, but they say on their site that “regardless of size, all trees are champions of the environment.”
One of the trees, a former champion from the year 2010 nominated by MPRB arborist Kevin O’Connor, comes from our very own Hennepin
County. It was a Black Willow, Salix Nigra, with a circumference of 384″, 64′ tall, and a 73′
The tree died, and had to be cut down, but it was an amazing specimen. Chad had time to get some cuttings from the tree before it died. They took root, and just like willows are know to do, they are growing quick and wild. With some structural pruning, they are looking great so far. These trees have some very large shoes to fill, but hopefully they can join the ranks of some of Americas largest trees. Pictures of the new champion willows coming soon!
Link to the American Forests Big Tree page, a must for anyone who wants to see some amazing trees
by Nick Neylon
Team Tree went to Como Golf Course on another bike excursion. The site is one of many research site we have that examine how seedling trees develop in tree tubes. Jonathan just bought a new bike trailer, and we loaded it up with some little trees and a few tools, and headed over to the golf course to check up on trees, and replace a few that didn’t make it.
When we got there, the turf manager greeted us and let us borrow a golf cart to get around the course. He said there had been a little vandalism recently, but all of it was harmless to the trees. Most of it was obscenities spray painted on tree tubes, and there was a smiley face painted on an elm tree.
The golf course was one of our higher-stress outings, as Jonathan and I often got confused about which way people were hitting their balls, and heard “fore!” a few times. Luckily we didn’t get hit, and the turf manager said it comes with the territory. He hasn’t taken any serious hits, and that’s with a lifetime on the course.
The trees were looking good for the most part, aside from a few dead buckeyes here and there that we replaced. The turf manager said that some of the older trees on the course would have to come out soon, and I was glad we could help out keeping the course well stocked with shade trees.