Concrete vs greenery. Is it worth fighting for every tree in the city? (Part I)

03 of April '23

Katarzyna Kobierska

...

The article is from A&B issue 03|23

The designer begins his work by looking at a map provided by a surveyor. He notices symbols marking existing trees in the area. So he draws a protective area around these symbols, a meter, well maybe a meter and a half, because after all, it's already a lot. He finalizes the design and is satisfied that he has saved the tree. But has he assessed the condition and value of the ecosystem services of these trees? Has he considered whether he is able to provide them with suitable habitat conditions during and after the project, and whether he is able to balance the ecosystem services they provide if they have to be removed?

FUTUWAWA 2021 - award-winning work showing the relationship between trees, people and other organisms proj. by J. Hernik, K. Kobierska, J. Paniec, M. Skibińska, K. Sluzewska, A. Wiktorko-Rakoczy, J. Woźniak

In many cases, trees that we have saved in an inadequate manner will begin to become diseased, die, breaking branches and weakened statics will threaten safety. So the question is, is it worth protecting every tree in the city? Definitely yes, if we have the knowledge, awareness and conditions to do so.

There is no more multi-purpose piece of infrastructure in the city than a tree. Nor more spectacular. A tree is an unattainable ideal for designers of an ergonomic, economic and ecological infrastructure element. It is a brilliant organism that we are getting to know better and better. We already know that trees produce oxygen, biosequester carbon dioxide, locally reduce temperature, increase humidity, prevent erosion, absorb dust, improve the water resources of an area, retention and delay of surface runoff of rainwater, improve the structure andquality of soil with soil microorganisms, provide shade, protection from wind, snow, rain, provide shelter and food for many organisms, have a positive impact on our well-being, health and aesthetics, the composition of cities.

Preserved trees at the newly built Port Popowice housing estate in Wroclaw - design unit: Leaf Project Studio Piotr Reda, including: landscape architecture branch - lead designer Kamila Rogaczewska designer - KA KOBIERSKA Katarzyna Kobierska architecture branch: TECLA - Architecture and Urban Planning investor - Vantage Development completion date - 2022

Trees, however, are not lonely islands. They need three key ingredients to perform these functions: solar energy, water and soil. They obtain water in their natural environment from rain, snow, open and closed water bodies. They are helped by neighboring trees, which, like water pumps, suck up groundwater, improving the water resources of the land nearby. However, in order to best absorb and use this water, they need the right soil structure. This is provided by the right amount of humus, soil humus. And this, in turn, guarantees the circulation of organic matter and soil microorganisms.

The world of biodiversity also, or perhaps primarily, lies underground, but it is only in recent decades that we have begun to discover the backstory of soil life and this dynamically changing matter. In order for soil to support trees in addition to its anchoring function and to be a well-functioning ecosystem, it needs the right conditions, which as designers we can create for it. How? By not concreting and sealing the area around and under the trees, leaving contact with the native soil, space for decomposition and reintroduction of dead organic matter, fallen leaves, needles, branches and even tree trunks. By providing access to native soil, we also allow the soil, and consequently groundwater, to be supplied with water.

"One gram of forest soil can contain as many as a billion bacteria, nearly a million fungi, hundreds of thousands of protozoa and nearly a thousand hermaphrodites," - reports Sue Grayston, who studies the complex interrelationships between plants and soil microbes and the importance of these connections for ecosystems.

What does this mean in practice? Closed circulation of matter and self-fertilization of trees. Creation of soil regeneration sites. Virtually maintenance-free green areas resembling, on a very small scale, the familiar forest ecosystem. Plants, carrying out photosynthesis, release some of the processed components, such as carbon molecules, through their roots into the soil, where they become food for microbes and fungi, which return the favor by helping to process inaccessible forms of nutrients like nitrogen, phosphorus, potassium. Only such a functioning microhabitat can we in good conscience call a biologically active area and valuable habitat conditions for a tree.

trees planted as a result of a number of agreements with the network operators - design unit: Leaf Project Studio Piotr Reda, including: landscape architecture industry - lead designer Kamila Rogaczewska designer KA KOBIERSKA Katarzyna Kobierska architecture industry: TECLA - Architecture and Urban Planning investor - Vantage Development implementation date - 2022 (fragment from the side of the renovated street under construction)

an old tree is like an old building - it tells a story

An old tree, just like an old building, carries with it a story that is decades or even centuries old. It is the largest and most majestic creation of the plant world. For years it has been an inspiration for artists, scientists. Age-old trees were once considered the dwelling places of deities, they were associated with beliefs, the Celtic calendar, they were given reverence and respect. Local communities gave them meaning and metaphysical symbolism. The tree in the culture is a symbol of spirituality and art, an inspiration for architecture. The tall and soaring arches of Gothic buildings remind us of those familiar from walking among the treetops. By depriving ourselves of trees, we deprive ourselves - in addition to the natural values - of the daily delight of this dynamic unique sculpture in the landscape. To quote Leopold Staff:
"Oh, what is more beautiful than tall trees,In the bronze of the west forged by the evening ray".

let's not be afraid of agreements and new technologies

As planners, managers, investors and even residents, we often want to protect and design and plant trees in cities. We are stopped and discouraged by bureaucracy. The use of so-called root screens and anti-compression systems is often the only way to introduce trees into urban spaces. Since it is common to have a densely packed network of underground infrastructure, planting a tree requires many agreements with network managers, as well as jointly worked out compromises. Thanks to such a painstaking path, we are able to turn a dull lawn, which does not provide high ecosystem services, into a tree-covered area that is valuable in terms of nature and composition.

Basin at the Elementary School in Wroclaw, on Grecka Street outside the area of the SOD - design unit: KA KOBIERSKA investor: Elementary School No. 28 named after General Leopold Okulicki in Wroclaw implementation date: 2021

development in symbiosis with existing greenery

The protection of trees begins at the stage of making a dendrological operation, or even an idea for the area. The key here, however, is the site development project. Shaping pedestrian routes requires compromises, and most importantly, knowledge of how trees and ecosystems function, the ability to zone functions and delineate main traffic routes, analysis of the surroundings, future developments and major nodes for pedestrians, cyclists and other space users. Our assessment of the condition of trees, their natural, compositional, as well as cultural value will allow us to make appropriate design decisions. Sometimes by doing theoretically useful initiatives, like establishing retention gardens, we can do more harm than good. Doing them at the expense of old trees does not bring a positive balance of ecosystem services of the investment.

A bridge near the Osobowice housing estate in Wroclaw built to minimize the negative impact on tree roots

how much unpaved area does a tree need to preserve it?

As much as possible, that is, as much as we are able to provide for it, taking into account, of course, the standards for Tree Preservation Zones (SOD) in the investment process issued, among others, by the Society of Landscape Architecture (SAK) in cooperation with the Eco-development Foundation. This applies not only to digging in SODs, but also to the over-sodding of tree roots and the necessary knowledge of the physiognomy of the root system. We can also protect trees by using appropriate paving technologies that minimize the negative impact on the root system of trees during and after the project.