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Arbuscular Mycorrhizae_Roo Vandergrift

Does cold weather impact the water quality benefits of soil?

There is extensive evidence that soil is an amazing tool for improving the quality of water runoff, for reducing peak flow volume, and for storing water for use by the tree and for groundwater recharge in urban settings. We also know that trees in soil are basically “added capacity” – that is, while the soil... More
NYC Street Tree_Angie Moon

Why Trees May Fail to Establish or Thrive (and what to do about it)

Landscape architects, architects, and engineers have many tools available to them in the design of healthy long-lived trees, and no single one of them can guarantee the establishment or long-term success of the trees. These tools need to be applied within a larger understanding of general principles of arboriculture, soil, and urban conditions in order... More
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Buried Treasure: Conserving Urban Soil in Place

It’s not unusual to find a piece of art or jewelry over 500 years old in a museum’s collection. These precious artifacts are (rightly) treated with great care commensurate with their value. Yet an inch of topsoil, which may have taken more than 500 years to develop, is commonly abused, mismanaged or discarded in the... More
Marcin Chady_Salmon Crossing

“Everything We Do Leaves a Footprint”

Nothing epitomizes the spirit of the Pacific Northwest quite like wild Pacific Salmon. If you don’t live in this amazing part of the world, let me explain: Salmon and the clean water and healthy forests they rely on are integral to the quality of life that west coast residents love, cherish, and dream of when... More
Dan Reed_CC BY-NC 2.0

Quantifying Stormwater Benefits of Trees and Soil
Part 2: Single-Event Stormwater Models

Part 1 of this series described quantifying tree and soil stormwater benefits for tree benefit calculators and for stormwater credits. Today we’ll be going more in depth on single event stormwater models. This will simply be an introduction to various methods to quantify the stormwater benefits of tree stormwater control measures (Tree SCMs) and is... More

Reusing Existing Urban Soil for Planting    

Most urban sites have some amount of mineral soil in place when the time comes to install plant material, yet these soils are often assumed – erroneously – to be unsuitable. Historically there have been two approaches to this situation. The default option is to ignore the problem, or make minor modifications such as digging... More

Quantifying Stormwater Benefits of Trees and Soil
Part 1: Overview of models and calculators

Trees and soil have the potential to provide significant stormwater benefits. Trees are also valued for many other benefits, and are already part of virtually all development. They can be integrated even into the densest urban areas – and many cities have tree requirement ordinances, so trees are not only desired, but also mandatory. It... More
Plaza gathering

What Trees to Plant in Cities

Species diversity in the urban forest is an extremely important topic and – unlike so many other design choices that are hindered by lengthy planning processes, tightening budgets, and maintenance considerations – it’s something we can actually have an impact on in the short term as part of the ongoing cycle of tree replacement. I’ve... More
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What is “Good” Soil?

What does “good” soil mean? It depends on your point of view. If you are engineer, you like soil that drains well or compacts easily to bear weight. If you are a farmer, you want soil that is fertile, easy to till, and soaks up water without runoff. If you are a tree… well, what... More
D Coetzee_CC0 1.0

Is i-Tree Underestimating Eco-Benefits of Urban Trees?

We have long known that urban trees help mitigate air pollution. But what about questions of how significant that mitigation is, how we track it, and where it occurs? A 2014 paper, “Assessing the relationship among urban trees, nitrogen dioxide, and respiratory health” by Linda George, Meenkashi Rao, Todd Rosenstiel, Vivek Shandas, and Alexis Dinno... More