As a soils guy, I have a lot of discussions with clients and colleagues about the quantity of organic matter in soil. Perhaps surprisingly, there is a lot of confusion and misinformation around this issue. What is organic matter, and where does it come from?
I have to admit that one of the things I love most about street trees is the wildlife they attract. There is something so wonderful about seeing a hummingbird zip around looking for nectar or hearing bees buzzing furiously as you pass under a particularly tasty tree. It feels extra special to see sites like… More
About a month ago, someone posting the following question to the ASLA group on LinkedIn: In his book Up From Roots, James Urban criticizes our profession for not knowing basic horticultural Principles. Is this crit valid? Over 50 responses later, some of them quite impassioned, and it’s clear that Jim’s book — and this question —… More
Sarah’s post last week got me thinking about fall foliage. Everyone loves the changing colors, but until recently I didn’t know why it happened. There are three primary factors that affect fall color: the length of the day/night, weather, and leaf pigments.
Many people and (dare I say) authors of this blog cite energy savings as one of many benefits of healthy urban trees. But where exactly do these energy savings come from? The answer comes in two parts: trees benefit buildings immediately neighboring them, and they also benefit the surrounding city.
This hydrograph (diagram showing runoff flow versus time) compares the intense spike of a stream during a storm in an urbanized watershed without adequate controls, with the “gentle rolling hill” appearance of a forested watershed’s response to the same storm. Note the loss of dry weather base flow for the stream in the urbanized watershed…. More
Here are this year’s photos from the Bartlett Tree Lab study comparing different planting methods for urban trees. For comparison, check out last year’s set. And for a fuller chronological picture, you can see all the photos up to that point in this post.
Back in January we posted about a project in Shoreline, WA, where the Silva Cells were being used to extend a sidewalk rain garden underneath paving. This stretch of the project is finally completed! It looks amazing, and we’ve got a case study to tell you all about it.
The Christian Science Center, on Huntington Ave between Mass Ave and Belvidere Street in Boston, is the oldest suspended pavement installation that we know of in the United States. These trees were planted in 1968, making them 43 years old.
A few weeks ago I was in a meeting with the chief of staff for a San Francisco supervisor. She mentioned that there are entire areas of the city — those that are predominantly Chinese and Chinese-American — where city tree planting is very limited due to cultural beliefs in feng shui. I’d heard the… More
There is a lot of discussion going around about the benefits of creating shared soil volumes for urban trees — in other words, connecting the rooting areas of two or more trees. Do they benefit? Do they not? In my mind, a shared soil volume is kind of like living in an apartment with a… More
Occasionally we work on Silva Cell projects where the installation of the product and the soil it contains happen far in advance of any trees being planted. In these instances, we often get asked by concerned designers whether the soil biology can be maintained under sidewalks in the temporary absence of trees — and if… More
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