We’ll take a break from our usual discussion to show you some remarkable shots from one of our colleagues from Greenleaf in the UK.

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What You Need For a Successful Urban Treepit Design:

The benefits that healthy urban trees provide to the environment are significant, but the environmental conditions in urban spaces can often be challenging for their establishment and long-term survival.

In order to provide urban trees with the best chance of survival, it is important to consider the conditions of soil, climate, and water availability that trees face when they are planted in towns and cities. The correct design and installation of tree pits will mitigate the negative effects of the urban environment.

There are several key factors to consider, including root volume availability. The following soil volumes at a minimum are recommended for healthy tree growth:

Small tree 5-15 m³

Medium tree 20-40 m³

Large tree 50+ m³

If in case this amount of space is not available, tree establishment can still happen provided that great care is taken with regard to species selection and root management. In all cases, the deployment of structural root cells can help to prevent soil compaction and ensure that the available rooting volume is fully utilized.

This is very important if the tree is to be located next to a road or another engineered structure, as the soil structure requirements for hard surfaces capable of sustaining large weights are diametrically opposed to those of a healthy tree root network.

Aside from providing sufficient volume for growth for tree roots, it needs to be appropriately directed to ensure that they do not damage surrounding surfaces or underground structures. Paved surfaces and utilities are particularly vulnerable to tree root damage and various types of root management products can be specified depending upon the item that requires protection.

For example, if a tree pit is to be located amidst a continually paved surface then the tree roots will need to be managed downwards by at least 300mm or the depth of the pavement structure to remove the possibility of paving heave.

Next, we’ll discuss more about proper irrigation, drainage and aeration to raise a strong tree network.

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The Global Effort to Improve Urban Environments:

It is undeniable how trees in urban environments bring so many benefits to the community. Aside from creating a sense of place, a local identity and a system of landmarks, they also provide space for leisure and community activities, helping residents take pride in the beauty of their location.

A Dutch study said that every 10% increase in green space can postpone health complaints in communities by five years. Because trees filter polluted air, reduce smog, and provide shade from solar radiation, they have been known to help reduce several illnesses.

Mature trees can even have a positive impact on the levels of petty crime and anti-social behavior in inner-city areas. Research conducted in Chicago by scientists from the University of Illinois concluded that even after socio-economic factors were accounted for, the presence of trees in a location could reduce crime levels by as much as 7%.

The impact of mature trees was even more highlighted in individual buildings and developments. An incredible 52% of residents in apartment blocks surrounded by mature trees experienced fewer reported crimes than those without any greenery. And then there are the road safety effects of having trees strategically placed in roadsides. A UK research showed that drivers slowed down in areas with roadside planting and therefore improve pedestrian safety. It also has a calming effect that results in fewer road rage incidents.

Economically, independent studies in the UK and the US show that properties lined with trees are consistently valued between five to 15% higher than identical properties on roads without trees.

These wide range of benefits are causing people to become increasingly aware of the important role of having trees in urban environments as well as their role in creating a sustainable future. Internationally, this is reflected in the number of tree planting commitments being made by leading politicians.

In New York for instance, there are plans to plant one million trees over the next decade, increasing the size of its urban forest by 20%. London aimed to plant 10,000 extra trees across the capital prior to the start of the 2012 Olympics. Another 1 million trees will be planted throughout the UK by the government over the next five years as part of the Big Tree program.

Policy makers are now prioritizing investments in urban forests despite the uncertain economic climate. This is excellent news for environmentalists and regional and urban dwellers.

However, the benefits of these initiatives can only be fully realized if trees planted have the best chance of survival. This means that care must be taken to ensure that they are planted in conditions that allow them to establish and thrive, rather than being starved of nutrients and growing space, particularly rooting volume, because of hostile urban environments.

Studies have shown that inadequate attention to the needs of trees at the early planting stage costs cities around the world millions of dollars per year in repairing damage to pavements, sewers, building foundations, parking lots, and utilities.

Aside from that, trees frequently do not reach their full potential and therefore are unable to do the benefits mentioned above. Next entry, we will tackle the factors that must be accounted for and controlled to provide urban trees with the best possible chances for successful growth and development.

FREE Urban Forestry Ebook

The last two decades have seen a continued increase in efforts to create urban forests in various cities around the world. The international debates on how to best reduce carbon emissions have also proven to be a driving force in the increasing popularity of urban trees.

Based on the article by Richard J. Magill, Magill & Associates, Inc.

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