Transport and ecosystems

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Article Published 29 Jun 2016 Last modified 11 May 2021
6 min read
Transport networks have become a commonplace feature of the European landscape. They connect people, boost economic activity and provide access to key services, but they also introduce barriers between natural areas, while their use emits pollutants and introduces non-local species to ecosystems. Strong policy measures and a network of green spaces can help preserve and protect Europe’s natural wealth.

The European continent is connected by an extensive transport network, comprising motorways, roads, rail tracks, navigable rivers, cycle paths, flight routes and sea routes. In addition to bringing goods and services to people, transport networks shape and impact the environment around them.

Less space for nature?

Transport is often associated with economic development. Connecting a city or region to major transport networks can give an initial boost to the local economy and create new jobs. However, once a region has reached a certain level of connectivity, additional transport infrastructure does not give comparable benefits. It can, however, generate substantial environmental impacts. Transport networks can also facilitate the spread of urban areas and other built-up areas into relatively rural and sparsely populated parts of Europe, exerting pressure on natural habitats. For example, connecting remote mountain regions or islands to the European transport system could attract more tourists to the area, resulting, for example, in a boost to accommodation and food-catering services. However, increased economic activity also often comes with the negative impacts of human settlements — more wastewater, more solid waste etc.

Similarly, an increasing demand for biofuels can also result in additional demand for land and freshwater resources in Europe. When combined with land required for food production, it can lead to more natural areas being converted to agricultural land.

Air and noise pollution in nature

Transport also leads to releases of pollutants, which can spread beyond the reach of transport networks. They can contribute to background concentrations of particulate matter, ozone and nitrogen dioxide, affecting people, plants and animals. Some areas, including mountainous regions, coastal zones and seas, can be particularly vulnerable to pollution from transport. Transport corridors through Alpine valleys or along large rivers like the Danube are essential for the European economy, but also exert pressure on unique ecosystems. Certain pollutants, such as ground-level ozone, are known to lower crop yields, affect tree growth and cause acidification in lakes.

Similarly, oil spills or the release of hazardous substances at sea can cause considerable damage to marine life. Recognising these risks, many measures have been put in place at European and international levels.

Noise pollution from transport is another concern and its impacts are not limited to land ecosystems alone. Large ships generate significant amounts of noise. Their hulls tend to amplify the mechanical noise from the engine and propellers. Due to its low frequency, this type of noise propagates very far in water and disturbs marine life. Research indicates that whales and other species that communicate and orient themselves through sound are particularly affected. Potential impacts suffered by small fish and marine invertebrate populations are also becoming clearer thanks to ongoing research.

Some solutions are already available and are quite effective in reducing noise pollution at sea and on land. For example, ships can be designed with their engines placed further from the hull (e.g. electric propulsion motors in pods outside the hull) to minimise noise amplification. Similarly, car engines and parts (e.g. tyres) could be redesigned to reduce noise levels at source, or noise barriers along motorways could be extended.

Unwanted free riders on board

In addition to pollution, transport can also bring non-local species into new habitats, risking significant harm to local species. Construction of large transport projects, such as the Suez Canal, can alter the key characteristics of an entire ecosystem. Since the building of the canal, more than 500 non-indigenous marine species were introduced to the Mediterranean Sea, contributing to ‘a catastrophic anthropogenic ecosystem shift in the Mediterranean Sea’. In the case of maritime transport, large ships, especially those used in freight transport, take in water to stabilise the vessel. Depending on their cargo load, they release this ballast water, which often carries in it many bacteria, microbes, small invertebrates, eggs and larvae of various species. If introduced in sufficient quantities and in the absence of predators, the impact of alien species can be devastating.

The case of the comb jellyfish ,Mnemiopsis leidyi— a species native to the American Atlantic coast — is well known and well-documented. Mnemiopsiswas introduced into the Black Sea through ballast water in the early 1980s and had devastating effects on local marine life, affecting fish populations and fishing communities. Recognising the ecological risk posed by ballast waters, a number of international measures and guidelines have been set by the International Maritime Organisation, including the Convention on Ballast Water Management.

Ballast water is only one of the ways alien species are transported. Fruit seeds thrown from passenger cars, bacteria or insect eggs in the discarded soil found in imported flowerpots, and exotic fish or bird species released into nature can all impact local ecosystems.

Investing in green infrastructure

All man-made infrastructure networks — road, rail and inland water canals — connect urban areas, rural areas and people. But they also build barriers and divide the natural landscape into smaller areas. A multi-lane motorway cutting through a forest represents a physical barrier for animal and plant species. In addition to reducing the total area available for wild life, a lack of connectivity between different habitats makes their populations more vulnerable. Animals need to move around to find food and mate, and risk being injured or killed while trying to cross roads or rail tracks. Even fences around transport networks could isolate the population of a particular species such that their genetic pool is limited, making them more vulnerable to diseases, and ultimately dying out.

Better connectivity through tunnels or bridges would certainly reduce the pressure on Europe’s biodiversity and ecosystems. In fact, these initiatives could be better planned on a much wider scale than a single infrastructure project, involving a multitude of different stakeholders (planners, investors, citizens, public authorities at various governance levels etc.).

A ‘green infrastructure’ consists of a strategically planned network of high-quality green spaces. It requires a wider look at all green spaces — in remote, rural and urban areas, and beyond national borders — connects between them so as to facilitate movement of species. To this end, the European Union adopted a Green Infrastructure Strategy aimed at providing a vision for a trans-European green network, as well as facilitating coordination among stakeholders, and exchange of ideas and information.

Better connectivity is not the only positive outcome of green infrastructure. In addition to improving public health, it is increasingly seen as a cost-efficient way of reducing current (or future) weather- and climate-related natural hazards. For example, instead of building sewerage systems to transport extreme rainwater, cities can create green areas to absorb excess water.

Planning with nature in mind

Transport infrastructure projects, including those related to the Trans-European Network, have contributed to enhancing quality of life across Europe, bringing services and public goods to remote parts. Several studies[1] partly link the Trans-European Transport Network (TEN-T) to the EU’s failure to meet its target to halt biodiversity loss. Other studies[2] highlight the potential impacts of TEN-T projects on protected areas.

The EU’s recent transport policy has significantly strengthened nature and biodiversity considerations. Now, these concerns need to be taken into account from the planning phase. Moreover, Member States need to carry out environmental impact assessments for such projects. EU legislation also covers the potential impacts of infrastructure projects taking place outside protected areas, but which can still affect them.

This approach could translate into various measures on the ground. For example, in the case of rail and road networks, the route proposal could be changed to leave larger areas untouched and to avoid landscape fragmentation. Similarly, tunnels or nature bridges could be planned and built to increase connectivity between protected areas, and facilitate the movement of animal populations. If the project does not comply with these rules, EU funding can be withdrawn.

Stricter environmental protection rules have already led to changes in several projects. An inland navigation project, aimed at deepening the Weser River in Germany, would allow ships to easier access to the Bremerhaven harbour. An environmental NGO challenged the project plans, arguing that the deepening the river would change the salinity level and create stronger tides, posing a threat to animal species dependant on the river as well as to people living on its banks. The European Court of Justice ruled that the project would deteriorate the water quality in the Weser and constitute a breach of the EU’s Water Framework Directive. Consequently, the project was cancelled.

Similar to transport and energy networks bringing economic wealth across Europe, a trans-European network of green infrastructure could actually help foster healthy and rich nature.


[1] Green Infrastructure - Sustainable Investments for the Benefit of Both People and Nature (Study commissioned by Interreg funds); Towards an integrated waterway transport system in the Danube Region

[2] TERM 2015, p.42-43, and Box 4.5


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