Urban greening in the fight against the biodiversity crisis

The plan to create a wildflower meadow at Trinity’s front arch is a welcome step in saving our declining biodiversity

Trinity recently held a public vote on a plan to plant wildflowers on the grass area at College Green next to the front arch. The vote came as part of a plan to boost campus biodiversity. 

Many ecologists believe that Ireland, and the world as a whole, is going through a ‘biodiversity crisis’. This view was bolstered by an assessment published by the Intergovernmental Panel on Biodiversity and Ecosystem Service (IPBES) in May 2019. The assessment outlined that of the 31,000 species known to occur in Ireland, only 10% have had their conservation status fully assessed. There is a huge gap in our knowledge about the welfare of many of our native species. We simply do not know enough about how Ireland’s biodiversity is changing. With one in every three species of bee in Ireland facing the threat of extinction, it remains unclear why conservation efforts continue to be chronically underfunded by the government. 

The plan to create a wildflower meadow at Trinity’s front arch comes as a welcome change to many. Urban greening is starting to become more popular in some cities around Europe such as Malmö, Sweden and Zurich, Switzerland. Globally, we are facing biodiversity, climate and ecological crises that are becoming increasingly threatening to our planet. Urban greening is just one of many methods which can help in the solution to these crises. Planting a variety of plants in an urban landscape has been shown to improve the area’s microclimate as evaporation processes help cool cities. They can also help clean the air of harmful pollutants and increase the overall air quality of a city. 

“With one in every three species of bee in Ireland facing the threat of extinction, it remains unclear why conservation efforts continue to be chronically underfunded by the government”

Professor Jane Stout of the Botany Department, who is the director of the Irish Forum on Natural Capital and the deputy chair of the All Ireland Pollinator Plan, has carried out research focusing on human impacts on biodiversity and ecosystem services. She sees this urban greening as a necessary action that will improve many aspects of our natural world: “Urban Green space can provide a wide range of benefits including amelioration of urban heat-island effect, sequestration of carbon, production of oxygen, filtration of pollutants, control of dust, attenuation of water, reducing noise, recycling of nutrients, provision of habitat for wildlife, physical and mental well-being in urban populations, landscape and aesthetics etc.” 

According to Stout, the planting of this meadow seeks to boost our biodiversity on campus: “By increasing the number of species of plant in the lawns, and increasing the structural diversity of the plants, both food and shelter can be provided to a range of insects and other species (e.g birds) – increasing species diversity. Also, creating new habitat types (such as the wildflower gardens), there will be an increase in habitat diversity.”

Ecosystem services are also likely to be affected. Ecosystem services are “the outputs from ecosystems that have a benefit to humans”. As biodiversity gets a boost from these green areas, so too should the services that are gifted to us by that biodiversity: “For flower-visiting insects, who provide the ecosystem service of pollination, allowing seed and fruit production in plants, green space provides both places to forage (as long as the green spaces have suitable flowers) and places to nest, breed, and over-winter. Other insects, such as beetles and flies, are important for recycling nutrients (e.g. from dead leaves), turning them back into inorganic forms that can be taken up by plants.”

Choosing the correct species of plants to be planted is a task that should be carefully considered. Which plant species is best for the purpose of urban greening? It seems to depend on how we define ‘best’ in this situation. According to Prof. Stout, the best species to plant for the benefit of humans would be “species that don’t look too messy, don’t attract pests, and are easy to manage”. She continues: “Best for pollinating insects would be the species they lack in the urban landscape – a complementary group of species that together provide floral resources through the year and provide a variety of resources for a variety of species.” Different insects have different needs and so certain specialist plant species would provide enormous benefits to some of the more niche needs of our insect fauna. “However, there are unlikely to be specialist species in the city – cities tend to favour generalists (those that can use a variety of resources).” Finally, if we are looking for those species of plants that will be of huge benefit to themselves and other surrounding plants, then we might look for “native plant species that are rare in rural areas and so need refuges in the city. But more practically, it would be those that can cope with the environmental conditions within the city (in terms of temperature, pollution, disturbance).”

“More than a quarter of Ireland’s breeding birds are declining”

Professor Stout believes that the biodiversity crisis in Ireland is a problem that requires our focused attention: “In the most recent report to the European Commission, Ireland reported >90% of protected habitats were in unfavourable status. In terms of species, more than a quarter of Ireland’s breeding birds are declining, with 37 species (20%) on the Birds of Conservation Concern in Ireland Red List. Not many invertebrate species have been assessed, but of those that have, one third of Ireland’s wild bee species and 18% of butterfly species are at threat of extinction.”

The solution to this biodiversity crisis appears to require attention from politicians more so than ever before, as programmes to save our native biodiversity are in desperate need of funding and more niche programmes targeting more specific aspects of biodiversity are needed. According to Professor Stout: “To combat this crisis, we need to protect and restore biodiversity, not just in the countryside but in rapidly expanding urban areas as well. We need to retain habitat heterogeneity in landscapes (maintain hedgerows and manage them appropriately, re-wet bogs, restore and replant native woodlands etc.) and instigate agricultural policies that don’t penalise farmers for ‘unproductive’ land – this land is often the best for wildlife.”

Raising awareness is also very important in the fight against losing our biodiversity: “We need to address the climate crisis – this can impact biodiversity even further. We need to raise awareness of the importance of biodiversity in everyone’s everyday lives, educate people on the implications of their choices when shopping, gardening, travelling, disposing of waste. Everyone can do something.”

The biodiversity crisis is real and is threatening the welfare of species throughout the world. Although the crisis is currently only getting worse there is still hope on the horizon for those who wish to save our natural world. For those looking for specific guidance on how to help, visiting www.pollinators.ie can provide sectoral guidelines on what to do to promote pollinators.

Cian Lynch

Cian Lynch is the current SciTech Editor of Trinity News.