Can you estimate a tree’s diameter at breast height (DBH) based on its caliper measurement? The short answer is no. Caliper and DBH both measure trunk diameter, but they measure it at different heights and are used for different purposes. There is no reliable formula for converting one to the other, but the chart below… More
Raingardens and bioretention facilities have much in common: both use soil and vegetation to collect, slow, and filter stormwater runoff. That is why the terms are frequently used interchangeably — even by stormwater agencies. Generally, however, rain garden describes a smaller and less engineered landscape feature, while bioretention refers to a stormwater practice designed to… More
One of the most common questions posed when beginning an urban forest project is: how wide do tree roots grow? The answer is almost always: wider than you think. Tree roots frequently extend well beyond the edge of the canopy, which means the visible dripline is only a starting point — not the boundary of… More
A common assumption in urban tree design is that tree roots do not grow more than 24” below the surface. There’s a reason this idea has stuck around: in many city environments, roots are indeed concentrated close to the surface. Urban soils are often compacted, poorly drained, oxygen-limited, interrupted by utilities, or constrained by pavement… More
Soil structure is one of the greatest influences on pore space in soil, and how easily air, water, and roots can move through a soil. Many people are aware of what soil texture – proportions of sand, silt and clay – they are dealing with on a site; however, few people consider a soil’s structure,… More
Remarkable Objects is a DeepRoot podcast about the intersection of nature and urban design. We think the question of how we construct cities is central to how well we function as a community. How can we incorporate nature into our cities in new, meaningful ways — creating healthy, sustainable places for people? What are the… More
Healthy trees can grow in even the most challenging urban environments, provided they receive enough water, soil, sunlight, and appropriate care. Vigorous urban trees help keep people healthier, cool cities during the summer, reduce energy use, support wildlife, raise property values, and make communities more welcoming. Yet heat and drought in many parts of North… More
Susan Day and her team at Virginia Tech published a paper earlier this year about a soil rehabilitation technique called Soil Profile Rebuilding, or SPR. They were looking for a way to rehabilitate soils damaged by land development in a way that would restore their biological function and be more supportive of plant growth. I… More
The following info on soil specifications was provided by Jim Urban. Imported soil specifications have evolved over the last 30 years to become quite specific about products. Frequently, they appear to be iron-clad descriptions of the most optimum soil; many specification writers would like us to think that even minor deviations from these documents… More
The following Q&A on freezing grounds and bioretention was consolidated from three informational blogs by Peter MacDonagh, FASLA. Bioretention is widely used to slow, filter, and infiltrate stormwater. But what happens in winter? Does frozen soil prevent infiltration? Do dormant trees and plants stop the water-quality treatment process? Research from Minnesota, New Hampshire, Connecticut,… More
The following Q&A on compost was answered by Sally Brown (University of Washington) and was reprinted from the “Soil Matters” blog. Question: What is “compost,” exactly? I’ve heard the term my entire life, but I’ve never really understood what it means. Answer: Most gardeners and farmers know compost to be a rich, organic soil amendment,… More
The following info on conserving urban soil was provided by Ellyn Shea (arborist and consultant in San Francisco). 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… More
Soil. Stormwater. Sustainable Infrastructure.
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