For the last two weeks in December I’m be re-posting some of my favorite blog posts from this year. Today’s shares some of the most exciting news we got in 2013, when the Washington State Department of Ecology recognized the Silva Cell as being functionally equivalent to a rain garden. Scroll all the way to the… More
For the last two weeks in December I’m re-posting some of my favorite blog posts from this year. Today’s, by James Urban, perfectly captures what we need to do in order to create healthier urban environments for trees and soils. It’s simple. Touch trees. – LM Alex Shigo, one of the most famous plant biologists and… More
Many factors affect tree health. Are they all equally important or are some more important than others? According to Kim Coder, soil compaction is by far the biggest constraint on tree growth. In a 2007 paper, he wrote, “Soil compaction is the most prevalent of all soil constraints on shade and street tree growth…Many people… More
Tim O’Hare Associates LLP is a leading independent environmental consultancy based in the United Kingdom specializing in soil science and landscape engineering, including soil science, topsoil, habitat creation, sales pitch agronomy, and more. A few weeks ago I talked to Tim O’Hare himself to learn more about its reuse, recovery, and what it really means… More
A large-canopy tree is a very beautiful thing. On this, most people will agree. But is not only beautiful—it also benefits its community. It provides shade and shelter, protects air quality, and reduces air temperatures, water runoff, and human stress. A street lined with such trees is a desirable place to live and work, and… More
I’ve discussed using trees and soils (green infrastructure) to manage stormwater in two recent webinars. This is a rich and complex topic, so to help break it down into digestible pieces I organize it in to what I call the First Principles of Urban Stormwater Systems. Those first principles are listed in the illustration above…. More
A study recently published in Urban Forestry & Urban Greening presents data showing that trees planted in paving can significantly reduce stormwater runoff. The results, published by D. Armson, P. Stringer, and A.R. Ennos, are taken from data collected in Manchester, UK from January 2011 to September 2011. The study created 5 test sites, each containing three 9… More
I spent a good part of last winter completing a literature review on bioretention media for a revision to the Minnesota Stormwater Manual. So when I attended the Low Impact Development (LID) conference in St. Paul, MN earlier this month, I was very interested to learn of a recent specification coming out of New Zealand:… More
This post, by Linda Chalker-Scott, addresses a misperception that we encounter frequently about the efficacy of using gravel or sand beneath soil to aid drainage. Linda mythbusts this incorrect belief handily. This article originally appeared on her blog, The Garden Professors. It is reprinted with her permission. -LM I’m just starting to think about getting my… More
Alex Shigo, one of the most famous plant biologists and fathers of arboriculture, is widely credited with making huge improvements to standard industry practices. One of his famous sayings was an exhortation to “touch trees.” I’ve adapted this to my own related specialty, urban trees and soils, which is why I often tell landscape architects and other… More
Here is this week’s “Ask Jim Urban” column. Jim Urban, FASLA is an expert on urban trees and soils and his recent book, Up By Roots, is the industry bible on these topics. Jim was also involved in the development and design of the Silva Cell system. In this column, which we’ll be running once a… More
Most designers are probably already familiar with the practice of using aggregate or gravel as a form of underground stormwater storage. For those who aren’t designers, the principle is simple: aggregate (gravel) is full of small voids – macropores – that can fill with water, acting as on-site stormwater storage. The aggregate is strong enough… More
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