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World Bio Market Insights: Building forests and wetlands as urban infrastructure

2023-11-16 Source:World Bio Market Insights

Constructing ecosystems as part of large-scale urban landscaping is an emerging segment of the bioeconomy. Unlike gardens, parks, living walls, or nature reserves, the objective here is an engineered habitat that serves similar functions to built infrastructure.

Carefully planned urban ecosystems can deliver public goods using soil, plants, animals, and their interactions instead of structures made from carbon-intensive steel, concrete, and glass.

Lying at the intersection of design, social science, and ecology, the practice can generate new ideas about how cities can look and work.

Made-to-order native forests

Tree planting is a common route to increasing the carbon absorbing capacity of land and providing healthier green public spaces.

Too often, however, patchy and ecologically inappropriate monocultures are offered up instead of vibrant habitats that mimic mature natural forests. The former might add a decorative flourish while the latter maximises biodiversity, carbon absorption, and other vital functions.

Bangladeshi company Afforest uses ecological science to build resilient forests from scratch in barren patches where vegetation has been stripped away. Their client projects are diverse, ranging from the gardens of corporate office complexes and sections of Bangalore airport to apartment complexes.

Reasons for growing these forests differ too. Some clients may want to meet corporate sustainability targets or pleasant micro-environments in urban developments while others want to attract biodiversity on residential property.

Regardless of project specifics, Afforest aims to create self-sustaining, maintenance-free forests that can become fully established in 2-3 years. The forests they plant aim to be as close as possible to a native habitat. This means selecting diverse, ecologically appropriate species that balance each other and grow well in concert.

When Afforest begins on a client brief, they know that conditions on no two sites are exactly the same. To guide their forest-building, the company uses the Miyawaki technique – a step-by-step process for assessing a site and selecting species adapted to the ecological conditions that already exist there.

Achieving a resilient, maintenance-free habitat is very different from planting a garden. The Miyawaki method makes habitat-building simpler by systematising it. The first step is surveying what naturally grows in the surrounding area. This requires a local native species survey.

From this list of potential species that could thrive in the area, the company selects which ones will be planted on the site based on the client preferences. Although they can establish forests that require no maintenance, they can also cultivate forests with higher upkeep: ones that bear fruit, attract birds, are deciduous or evergreen, or flower seasonally.

To make sure their habitats take root permanently, Afforest also conduct a detailed survey of the site’s own ecological conditions, testing the soil for its nutrient mix and structure and carefully selecting the right quantity, mixture, and ratio of species that will thrive there. Whatever species ends up on the actual site, all must have the sorts of root systems that can penetrate the soil strata unique to the location.

Science guides the planting process too. Where the saplings will be positioned is guided by knowledge about the synergies between species: which plants will help adjacent plants obtain nutrients, water, and sunlight rather than competing with them for space and resources.

From there, the soil is mulched and enriched, and monthly progress reports are taken for each site.

Turenscape’s urban wetlands

The grandest biobased urban landscaping projects in the world have come from award-winning Chinese urban design company Turenscape. Founded by Harvard-educated landscape architect Kongjian Yu, the company has planned and designed over 300 ecological cities and 1000 landscape projects in China.

Turenscape’s specialism is creating lush green cityspaces that form a permanent, self-sustaining ‘sponge’ to soak up excess rainwater and limit flooding. It utilises a diverse range of site-appropriate plant species that naturally work together to form a living flood defence system.

Yu’s work is inspired by his childhood memories as the son of a rural peasant family. In his youth, Yuan watched as state-led irrigation projects remoulded the landscape around him in ways that unbalanced the habitat, leading to plentiful water supply in some areas but drought in others. Yu has spoken of the need for a ‘revolution’ in landscape design based on practices that works with natural mechanisms to secure essential resources like water.

Yanweizhou Park in Jinhua City is one of Turenscape’s projects. Jinhua, a city of over one million, contained one final undeveloped natural wetland site where three rivers converge to form a bigger river.

The only development on the Yanweizhou Park had been an opera house, which was relatively difficult for people to access. One goal was to achieve higher footfall there by better connecting the space to city districts. This had to be achieved while preserving the natural habitat and ensuring flood control.

Previously, the city authorities had  proposed high, hard walls to protect the wetland area from flooding. Turenscape offered another solution, creating a terraced river embankment full of native plants.  

Using gravel for pedestrian areas, they also created permeable surfaces that made the site less prone to holding rainwater. The filtering provided by the gravel has also helped form a pond inland where visitors can swim safely.

In another project, the company  redesigned the area of Shanghai Houtan Park, a former industrial site in Shanghai. As the site lay next to the highly polluted, flood-prone Huangpu River, the firm designed a wetland in the park capable of biologically treating the river water solely through plant and microbial activity. The wetland is able to process over 2, 400 tonnes of water pumped in from the river every day while also acting as a floodwater buffer between the river and the city.

Landscaping at different scales

Turenscape’s commissions are possibly the largest-scale examples of biobased urban landscaping in the world today.

Their sheer size and the way they closely mimic natural ecosystems more familiar in rural landscapes are really spectacular. Importantly, these artificial ecosystems are the backbone of city-wide services, offering flood defences and pollution clear-up across a wide area and for large segments of the population.

Other countries are likely to explore biobased urban landscaping on a smaller, more experimental scale. Most design and architectural firms in the space hold a portfolio of smaller projects covering delimited areas like shopping centres, university campuses and industrial complexes.

Felixx, based in the Netherlands, is one of these firms, describing itself as a proactive landscape architecture company.

One of its projects was to design a new development on the Brainport Industries Campus, a 17 hectare tech, education, development and manufacturing complex opened in 2020. To minimise the impacts of this campus extension on the nature reserves that surround the site. One way it plans to do so is by embedding connecting zones for plants and animals into the development. It also plans to site buildings in a way that “responds to the protected nature around it”.

Felixx may also have its sights set on turning whole neighbourhoods and cities into green infrastructure. The company helped to develop a ‘Catalogue of Nature Based Solutions for Urban Resilience’ with the World World Bank Group and Global Facility for Disaster Reduction and Recovery (GFDRR), a how-to guide for policymakers in thinking through their options for improving urban resilience with vegetation.

According to the text, cities could benefit from different functional habitats depending where in the water basin it is located. One close to the sea will be exposed to coastal flooding while flash flooding from stream networks could affect a mountain city.

Each geography will also come with distinctive soil conditions – the sandy shores of a coastal city will be able to support different kinds of vegetative cover than a natural inland wetland or upland area.

This regional-scale thinking does not do away with the need for smaller solutions. Felixx’s document explores how urban landscaping can work at different scales simultaneously, with certain practices that are suited to neighbourhoods and others to whole cities.

Greener urban ecologies can meet the challenges of climate change

Biobased urban landscaping is a type of nature-based solution, a broad-based design practice that uses natural systems to solve social, environmental, and health problems.

The approach may seem utopian but in reality, crafted ecological spaces offer cost-effective solutions to timely urban problems such as the impact of extreme weather events, something that city planners are increasingly prioritising as climate change worsens.

Integrating dynamic ecosystems into cities can rebuild some of the vital environmental services that disappear when areas become built up as biomass cover can offer natural flood defences, local temperature cooling, pollution filtering, water purification and carbon absorption.

As well as being a tool of climate adaptation, establishing dense, functional natural ecosystems in cities can help urban authorities achieve climate mitigation targets too. Cities cover only 3% of the Earth’s land but consume 60-80% of manufactured energy and are responsible for 70% of carbon emissions. Using ecosystems over extracted materials can help reduce overall emissions.

Finally, more vegetation means more biodiversity. One practice in biobased urban landscaping is to build wildlife habitats and corridors onto otherwise developed sites, reducing the impacts of human economic activity on animal populations.

Restoring the city to nature

Focus on decarbonising the city has fallen on changing building materials to renewable or circular options or improving municipal recycling services. Policies around this are essential but can sometimes prevent city planners from seeing the wood for the trees. Scaling biobased solutions means also thinking more expansively, including on a wider geographical scale.

Building nature into the physical make-up of the city itself is a sweeping way to replace large scale services not just with biological materials but with ecological interactions of living things, offering a much deeper, more integrated way of reducing the carbon emissions associated with urban life.

Turenscape’s city-wide landscapes in particular gives inspiration for how these services might reduce emissions and buffer the city from the effects of climate change.

Many architectural companies around the world plant individual buildings with isolated plots of exotic vegetation but Turenscape establishes wide areas with a blend of native species and terraformed landscapes that form permanent semi-natural structures.

This is the kind of vision needed to build low-emission, biobased solutions into the everyday backdrop of life, making them less likely to become isolated interventions but rather essential pieces of civic engineering which large populations can depend on.

Source: https://worldbiomarketinsights.com/building-forests-and-wetlands-as-urban-infrastructure/

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