Cities are landscapes too: Green infrastructure for healthy forests, water and people

Cities need effective water management; forests help clean and regulate water. How can urban landscapes make the most of this important connection? In the lead up to International Day of Forests 2016 and World Water Day 2016, IUCN's Becca Andrasko explores how green infrastructure and forest landscape restoration principles are linked.

Sitting atop a parking garage and rail yard, Chicago's Millennium Park is considered the largest green roof in the world.

Seventy per cent of the world’s population is projected to live in cities by 2050, and infrastructure will have to dramatically scale up to meet these increased demands. Environmentally minded city planning – including sustainable access to healthy water and food resources – is needed to prevent potential disastrous consequences to ecosystems as cities expand.

Typically, traditional or gray infrastructure is focused on getting people or resources from one place to another as efficiently as possible, which often results in negative consequences for ecosystems. A service road running through a forest to get to a filtration plant, for example, splits a forested ecosystem into pockets. With few connections between these areas, local wildlife are restricted to smaller, possibly more polluted habitats, with nowhere to go if a forest fire or drought leaves the area uninhabitable. A population may become displaced altogether.

Gray infrastructure can also pose a threat to water resources. Leakage from sewage lines might enter groundwater or factories might pollute with industrial runoff. Rainfall and snowmelt often runs off roads and buildings and directly into water bodies, causing soil erosion and introducing toxins into reservoirs and aquatic habitats. Connecting people with clean, reliable drinking water and managing wastewater and storm runoff are tenacious problems for cities.  

Many cities are turning to green infrastructure to address these issues. Although it is often associated with stormwater runoff management, either as a replacement for or in concert with drains and sewers, the accepted definition green infrastructure is more comprehensive: the “combined structure, position, connectivity and types of green spaces which together enable delivery of multiple benefits as goods and services.” Green infrastructure can be a holistic, landscape level approach, as well as an option for small-scale sites.

And cities are starting to put this green infrastructure to good use. Ljubljana, the capital and largest city of Slovenia, won the 2016 European Green Capital prize for its commitment to environmentally friendly waste and wastewater treatment facilities, and it has constructed urban forests and floodwater retention areas. Bulgaria’s capital city, Sofia, relies on two mountainous, forested national parks for a majority of its potable water supply.

Linking the forest and the city

Forests are at the heart of green infrastructure principles, making use of the absorption power of plants, trees and soil to prevent flooding, filter water, and prevent erosion. Urban planners examine the landscape to find the best types of green interventions in the most appropriate places, while ensuring the space remains fully functional for its multiple uses.

We see these same principles in IUCN’s forest landscape restoration (FLR) activities: analysing a landscape as a whole to restore its full ecological potential for all involved. For example, IUCN and partners in China are helping restore the mountain forests that surround the Miyun watershed, in order to clean and increase the water yield that supplies all of Beijing.

A key component of FLR is mosaic restoration, which aims to restore and connect landscape types – from farmland to protected forests – by leveraging restoration methods that can be adapted to best fit each situation. Mosaic restoration specifically targets land that is fragmented into patches with different land use types on each patch. And doesn’t this describe many city environments, with small parks and other green spaces mingling with buildings and roads? Small-scale green infrastructure implementation can range from urban wetlands for wastewater treatment, to permeable pavements, to green roofs, all of which can decrease cities’ burden on the environment while also providing benefits to people. Just as forested landscapes are often fragmented, so are cities, and a combination of a mosaic approach to FLR and green infrastructure could be the first step to addressing some of these problems.

Of course there are limits to what green infrastructure can do. Like traditional infrastructure, green infrastructure is only one way to solve a problem, and only under specific situations, whether that is to connect a city to water resources or to manage stormwater. But adding it to the suite of other FLR interventions makes it an important part of a powerful restoration toolbox that can be used by both urban and rural land use planners.

Ultimately, connecting these two methodologies may be able to create better linkages across landscapes – both urban and rural – and potentially better outcomes for both the ecosystems and the communities that depend on the land’s environmental functions.

Work area: 
Forest Landscape Restoration
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