The harmful effects of urban life on physical and mental health have long been recognized, such as higher rates of cardiovascular and respiratory diseases. Depression is on the rise, particularly in urban areas, and is characterized by depressed mood and a feeling of helplessness. In this post, we will focus on a specific type of the urban forest: individual street trees, and on how they can strengthen mental health. Street trees are an important component of the urban forest because they provide various ecosystem services for human health and wellbeing, such as improving air quality and reducing the urban heat island effect. They are public amenities laced throughout the urban matrix and they can be retrofitted into urban areas. The potential impact of street trees on mental health was unknown and no previous study has investigated the relationship between ecological quality of street trees, the presence of street trees, and antidepressant prescriptions. An interdisciplinary research team from UFZ, iDiv and the University of Leipzig applied objective indicators (antidepressant medication and individual-level greenspace exposure, using NDVI) to analyse this relationship. To calculate the amount of contact that an individual has with urban greenspace, the researchers applied geographic metrics, using Euclidean buffers of 100, 300, 500 and 1000 m around the residences. The sampling involved 596 people who were prescribed antidepressants. All the participants were living in the city of Leipzig, and represented a representative sample. In the city of Leipzig, street trees are planted throughout the city, while concentrated more densely in some areas than in other, with a total of 66,179 street trees, comprised of 51 genera and 131 species (Figure 1). This figure shows the distributions of street trees and antidepressant prescriptions among the participants. The circles indicate the location of the participants within the city of Leipzig, Germany. The circles with a black outline represent individuals who have been prescribed antidepressants. The yellow-green colored circles reflect the density of street trees within 100m of the house. Tree density values are the number of trees per meter of road within a 100m buffer.
Subsequently, Figure 2 shows that the people who have a higher risk of antidepressant prescriptions are women, overweight or obese, smoking, or have pessimistic thoughts; there is also a higher risk during winter and spring. By contrast, reduced risk of antidepressant prescriptions was associated with being young (18–39) or old (age 65 +), employed, and optimistic. People living in homes with greater density of street trees within 100 m were less likely to be prescribed antidepressants.
Species richness was not significantly associated with antidepressant prescriptions at any distance, this is well explained in the next figure. The results of Figure 3 show that the quantity of street trees around the home may be more important for preventing depression than the ecological quality of street trees. This is in line with previous studies. For example, a Chinese study (Elsadek, M., Liu, B., Lian, Z. & Xie, J. The influence of urban roadside trees and their physical environment on stress relief measures: A field experiment in Shanghai. Urban For. Urban Green. 42, 51–60, 2019) walks along roads, each with a different species of street tree, resulted in better mental health compared to walks in a road without street trees, suggesting the mere presence of trees on streets, but not their species affiliation, is important. Given that most people cannot identify different plant species in general, benefits of street trees may rather be provided through people experiencing tree abundance.
The net result showing the graphs in Figure 4 is that under low street tree density, individuals with low SES tend to have higher probabilities of antidepressant prescriptions. For the medium and high SES groups, the effect of street tree density at 100 m from the home did not significantly change the probability of being prescribed antidepressants.
The study shows that street trees, as an urban green space accessible to the public on a small scale, could contribute to an “equigenic environment”, as nature-based solutions that can help close the gap in health inequalities between individuals with low and high SES. During the COVID-19 pandemic, forests in cities, green spaces, tree-lined streets, but also having a small green space in front of the house, has acquired more importance in the eyes of many citizens. So, as this study suggests, ‘unintentional’ contact with nearby nature in daily life is important for mental health, but also reduces social inequalities and contributes to multiple Sustainable Development Goals. The study thus calls for a different urban green planning, no longer aimed at designing green spaces for intentional or targeted visits for recreation, but above all targeting green planning for daily contact with nature. Planting and maintaining street trees thereby provides a proactive public health measure that also meets conservation goals. Such information can inform health professionals, urban foresters, urban planners and urban planners about the necessary policy, planning and management decisions needed to ensure that urban forest has a positive impact on both public health and nature conservation.
Link to the article: https://www.nature.com/articles/s41598-020-79924-5
Cities are home to more than half of the global population. As urbanisation increases at an unprecedented rate, by 2050, about two thirds of the worldwide population are anticipated to live in cities (UN, 2018). But let’s look a bit closer at who else is calling cities their home: Urban areas also provide shelter to a considerable range of growing, flying and crawling diversity, living in the soil, on street trees, in urban parks, woodlots, urban forests and their surrounding natural habitat. Read on to learn more about the nexus between urban forests and biodiversity and why a healthy, biodiverse city is critical for the future of human societies.
The impact of humanity on our planet is becoming increasingly visible through climate disasters and the global biodiversity crisis. It is a complex relationship of living things and systems and a growing damage towards our planet’s biodiversity that result in significant risks to humankind. Facing this development, it becomes ever more vital to conserve, protect, restore and sustainably manage those places that offer shelter for different species.
The role of urban biodiversity
Efforts to preserve biodiversity often focus on large natural habitats. However, the urban environment, with a landscape that can harbour relatively high amounts of biodiversity (Alvey, 2016), represents a significant potential for the preservation and promotion of species, genetic and ecosystem diversity. Humanity relies on a range of ecosystem services provided by the natural environment, including regulating, cultural, supporting and provisioning services – and a diverse urban forestry landscape is necessary to ensure the long-term provision of those ecosystem services in cities. Safeguarding biodiversity must therefore become an integral part of sustainable urban development. To effectively halt and reverse the loss of nature, the adoption of a transformative post-2020 global biodiversity framework needs to be high on the political agenda. COP 15 is on its way to tackle this challenge.
COP 15 – ‘Ecological Civilization – Building a Shared Future for All Life on Earth’
The UN Biodiversity Conference and the Fifteenth meeting of the Conference of the Parties to the Convention on Biological Diversity (COP 15) kicked off online on 11 October 2021. While the first phase of the summit is being held virtually from 11 to 15 October 2021, the second phase is inviting for an in-person meeting from 25 April to 8 May 2022 in the Chinese city of Kunming. The two-part conference will further host the Tenth meeting of the Conference of the Parties serving as the meeting of the Parties to the Cartagena Protocol on Biosafety (CP-MOP 10), and Fourth meeting of the Conference of the Parties serving as the meeting of the Parties to the Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilisation (NP-MOP 4).
COP 15 will shed light on the delivery and achievements of the CBD’s Strategic Plan for Biodiversity 2011-2020. The summit aims to finalise the post-2020 global biodiversity framework and establish mid-century long-term goals and short-term targets for 2030 to fight biodiversity loss. Looking back to the previous global targets set, objectives were largely missed. More than ever, it is of utmost importance to agree on clear, measurable targets to boost nature preservation and ensure those targets are anchored within national policies. Read more about the conference and registration here.
The importance of SDG 15 – Life on Land – Urban green matters
Forests provide shelter to more than 80% of all terrestrial animal, plant and insect species. With plant life itself providing 80% of the human diet, the intact functioning of a diverse natural environment is crucial to support food and water security while helping to adapt to and mitigate climate change and fostering peace and security (UNDP). In this context, food security is closely tied to the role of insect pollinators – and those also live in urban areas. Initiatives to promote bee-friendly urban green area management exist beyond Europe. By choosing the right plants, applying appropriate mowing and pruning practices, promoting the creation of planted road margins, flowering green roofs, vertical gardens or by harnessing the potential of urban agriculture initiatives, cities can contribute a significant part to supporting human livelihood based on nature – with potential for upscaling (Van der Slujis & Vaage, 2016).
Urban Forests & Biodiversity
About healthy trees, planting trees in the right places and planting the right trees
Fortunately, urban forests provide critical ecosystem services to sustain human health and well-being and support environmental quality in and around urban areas. As a vital part of the city infrastructure, urban forests also face numerous threats due to climatic changes, conflict over land use, strong anthropogenic influence as well as pests and diseases. To ensure that people can rely on benefits provided by urban forests in the future, it is crucial to understand those threats and foster a healthy and resilient urban forestry landscape.
Biodiversity of Urban Forests
The long-term provision of ecosystem services provided by healthy urban forests counts on species diversity, diversity within species, age and structural diversity. The many different regulating, cultural, supporting or provisioning services we obtain from urban forests are related to the tree’s characteristics – with some species providing a single ecosystem service better than others due to their individual characteristics.
“To optimise one ecosystem service, diversity is unnecessary. But in order to optimise multiple ecosystem services, high urban tree diversity is essential.”
In many European cities, urban areas harbour high species richness but are often dominated by few species, especially on stressed sites. To work towards a resilient future city, efforts to decrease the dominance of a small number of species are needed. But which species are best suited for a changing urban environment? And what is the role of non-native species? The wide range of site-adapted species growing (and dying) in urban environments comprises both native and introduced species. While the potentials and risks of non-native species are passionately discussed among scientists, the suitability of long-term resilient tree species appears to be a topic far from black and white. In this context, the role of non-native species remains an understudied topic (Schwarz et al., 2017).
Biodiversity of Fauna supported by Urban Forests
Urban forests also provide shelter for adapted species, including insects and birds. Trees and forests in cities can be regarded as extreme habitats due to their high anthropogenic influences. Looking at urban forests as faunal biodiversity habitats, studies show the important role of native trees for bird species richness and abundance. However, also exotic trees can harbour interesting habitats invertebrates, being an important food resource for insect-eating animals. Newer suburbs are anticipated to provide high-quality habitats with native tree species able to promote faunal biodiversity, albeit non-native trees also form part of cities now and in the future (Livesley et al., 2016).
Since the city lives of being a shared place, the coexistence of nature and people does not come without challenges. Overcrowded urban green areas and recreational overuse can disturb urban biodiversity. The considerable potential of urban forests to increase and hold biodiversity needs to be taken into account when balancing different interests and promoting nature in cities for all beings. In this context, planting trees in the right places provides an important opportunity to create connections between urban biodiversity and surrounding forests and ecosystems.
Improving environmental quality = Improving quality of life?
Preserving biodiversity in urban areas brings more than the inherent value of biodiversity conservation itself. It also presents significant societal benefits, such as environmental awareness and improvements for mental health and well-being through interacting with a biodiverse natural environment (Morgenroth & Nielsen, 2016). Recent studies suggest that daily contact to nature through street trees close to residents’ homes may reduce the risk of depression (Marselle et al., 2020), while older studies also hint at the fact that improved health may derive from an area perceived as highly biodiverse by residents, without necessarily being highly biodiverse (Qiu et al. 2013). Read more about the nexus between functional biodiversity and a healthy society here.
It remains – diversity is key. Strategic planning, decision-making and management will be crucial in an increasingly urbanising world, with urban forests as a promising stage for the fight against biodiversity loss.
Learn more about Urban Forests and their potential for rehabilitating, reconnecting and restoring urban ecosystems in the Sino-European H2020 CLEARING HOUSE project.
Thriving communities need healthy ecosystems. The conservation of biodiversity is closely tied to the health and well-being of people. In recent years, increasing worldwide recognition of this interrelatedness emphasises the need for preserving and enhancing functional biodiversity. We depend on nature as our substantial infrastructure. Especially in expanding urban and peri-urban areas, living with the pandemic has revealed how healthy, biodiverse green spaces are increasingly frequented by urban dwellers and help foster societal resilience. Biodiversity conservation is therefore high on the international agenda.
The IUCN World Conservation Congress 2021 – Managing landscapes for nature and people
The International Union for Conservation of Nature (IUCN) and the French government are holding the IUCN World Conservation Congress from September 3 to 11 2021 in Marseille.
Bringing together the global nature conservation community, the Congress opens the stage to leading conservation scientists, policy experts and practitioners and invites 1,400 Member organisations. Among those organisations, states, civil society and Indigenous Peoples exchange views about pressing issues in nature conservation and ways to tackle them. As one of the main Congress themes, attendees discuss how to manage landscapes for nature and people.
Urban Forests as Nature-based Solutions
As defined by IUCN, Nature-based solutions are “actions to protect, sustainably manage, and restore natural or modified ecosystems, that address societal challenges effectively and adaptively, simultaneously providing human well-being and biodiversity benefits”.
The Sino-European CLEARING HOUSE Horizon2020 project is developing a novel typology for urban forests, urban green and urban trees. In this context, Urban Forests as Nature-based Solutions (UF-NBS) are built on tree-based ecosystems in urban areas and play a fundamental role in providing ecosystem services for biodiversity benefits, human health and well-being. Focussing on Europe and China, the project’s diverse typology assumes a broad perspective and intends to provide grounding knowledge on UF-NBS beyond the project scope. On the way towards sustainable urbanisation, UF-NBS connect urban and peri-urban ecosystem services with societal demands. Do you want to learn more about the typology and its role to gather and exchange knowledge and integrate models and data on UF-NBS? Join the Humboldt University Berlin, the European Forest Institute (EFI) and the CLEARING HOUSE project in an Online Workshop on October 7th (8:15 – 11:15 CEST) – click here to register.
Urban trees and green spaces provide multiple benefits for people. Through CO2 sequestration and pollutant absorption, urban forests improve air quality. The rapid worldwide urbanisation entails increasing extensive ranges of impermeable hard surfaces in the built-environment, exacerbating the urban heat-island effect. Through shade provisioning and the process of evapotranspiration, urban trees and forests mitigate heat stress whilst saving energy through less use of air-conditioning and increasing urban liveability. Urban green spaces further reduce stormwater runoff, improve water filtration and water storage and reduce soil erosion. No less crucial, urban forests shelter numerous species, serving as a biodiversity hub for declining flora and fauna.
UF-NBS: A focus on health, well-being and inclusivity
Trees and forests in cities invite urban dwellers to connect with nature and provide an open space for physical activities and interactions with others. Why is this increasingly relevant? While projections assume a global urban population of 68% by 2050, nearly 85% of the worldwide population will live in cities by 2100 (UN, 2018). This trend is associated with rising levels of illnesses, stress and anxiety. Peoples’ nowadays communication patterns, characterised mainly by less direct contact and more screen-to-screen interaction, tend to bring communities further away from nature.
Reconnection with nature plays a vital role in preventing the development of illnesses, treating developed illnesses and ultimately in helping to reduce costs of health care. The positive effects of nature on health and well-being are rapidly becoming recognised on a broader scale. To better align stakeholders in the healthcare sector, the last IUCN World Conservation Congress, which took place in Hawaii in 2016, brought the IUCN Resolution 064 ‘Strengthening cross-sector partnerships to recognise the contributions of nature to health, well-being and quality of life’ to life. This resolution includes the urban context as: “Recognising that places, including urban areas, with a rich natural heritage, improve physical and mental health and spiritual well-being, and can increase the appreciation of nature including by the elderly”.
Biodiversity and UF-NBS enhance the health and well-being of urban dwellers in different environments, be it urban forests, parks or trees, public gardens, urban gardening projects or green spaces around health institutions allowing for nature encounters and boosting the well-being of patients and staff. However, it deserves mentioning that to build a flourishing connection to nature for all, inclusivity is essential. In many urban scenarios, opportunities to engage with nature leave out those who may benefit most, resulting in green gentrification and social exclusion. The IUCN World Conservation Congress 2021 invites attendees to discuss initiatives designed to deliver social justice together with benefits for people and the environment. See the latest news from the Congress.
Think global, act local
Looking at how pressing environmental threats such as the global biodiversity crisis evolve and how devastating those effects turn on a global scale, one can easily get frustrated and some of the challenges can appear as very remote. What can be done to drive change? How can individuals contribute to a sustainable transition that acknowledges the importance of biodiversity protection and human well-being? The concept “Think global, act local” has been introduced in 1915 by Patrick Geddes, a Scottish pioneering town planner and conservationist. Following a strong belief to work with the environment, rather than against it, Geddes’ concept shaped the idea in architecture and planning. Putting a spotlight on the impact urban development has on its surrounding environment, Geddes makes an important point that becomes increasingly meaningful in the face of a globalised world. Whilst a local action may not directly lead to saving the Amazon rainforest from deforestation or saving species on the brink of extinction, showing solidarity through local activities must not be underestimated. Enhancing consciousness about pressing environmental topics starts on a local scale.
All around the globe, local communities take initiatives to improve the liveability of their urban neighbourhoods. This development enhances cooperation among urban dwellers such as bottom-up and citizen engagement approaches, grassroots movements and urban agriculture initiatives. The positive effect of shaping common spaces in a community is shown through manifold benefits: shaping and meeting in urban green areas has a catalysing impact on social cohesion and social capital, fosters personal and societal resilience and enables early development of landscape stewardship through educational networks.
Life on earth relies on intact ecosystems. However, to collectively shape the healthy planet we want to live on, change does not emerge out of political agendas but also needs to be driven actively from the bottom. Turning ambition into science-informed action, engaging in volunteer programs, harnessing opportunities of citizen science and getting to know the ecosystems in front of your own door are important and impactful steps on the way towards creating environmental consciousness and tackling the biodiversity crisis.
Written by Prof Dr Alan Simson, Chair of the WRF Governance Committee and the WRF Steering Committee
The White Rose Forest (WRF) was initially launched in the City of Leeds on Yorkshire Day – 1st August – in 2000. Set up as a West Yorkshire Regeneration Initiative, it aims to encourage economic investment and human health and well-being through environmental improvement, in particular through the planting of trees. The WRF has now expanded to include North Yorkshire, and thus now covers an area of some 9424 km².
A Community Forest is a place with a Forestry Plan, and a partnership to deliver that plan. We therefore work in partnership with local authorities, landowners, businesses and communities to plant millions of trees in our urban centres and countryside that will help manage flood risk, combat climate change, create jobs and provide happier and healthier places for us all to live, love, work in and enjoy. The WRF engages with five specific planting zones, comprising the urban forest, the sub-urban forest, the peri-urban forest, the ex-urban forest (commute areas) and rural woodland.
Each zone requires a specific design approach, and the ex-urban areas are coming under increased pressure to expand as a result of the COVID-19 pandemic, and the shift of employment and habitation away from town and city centres to ‘greener’ localities.
WRF activity is transdisciplinary and adopts a multi-cultural community approach. Get to know the three prime themes running at the moment:
Green Streets: Improving the design of urban streets by reducing traffic, increasing urban green especially street trees and providing better facilities for pedestrians and cyclists;
Landscapes for Water: Planting trees in the right places to help slow the flow of surface water into streams and rivers, thus helping to prevent urban flooding downstream;
Trees for Learning: Working with schools and community groups to promote the concept of urban forestry, enhancing the process of widening and deepening community involvement and connection to the planning, planting and management of their trees and woodland.
WRF planted approaching 2 million trees to date. Once these trees are established, they will also store significant quantities of carbon and help to deliver the Government’s commitment to achieving net zero carbon emissions in the UK by 2050.
The WRF is one of four Community Forests in the north of England working together to create the Northern Forest. The Northern Forest was set up by the UK Government in January 2018 as an environmental counterpart to their Northern Powerhouse Strategy, aiming to plant in excess of 50 million trees by 2032 to significantly increase the canopy cover of the region, and to improve the quality of life there for both people and wildlife. The Government has set up a Nature for Climate fund, which has earmarked £12.1 million (over €14 million) for tree planting this season, led by the Community Forests, and the White Rose Forest has benefitted from received £3.7 million (over €4.29 million) from this fund to plant 218 ha of new woodland this season, which has also enabled WRF to increase staff by three.
A Current White Rose Forest Project: Broughton Sanctuary, Broughton Hall Estate
Broughton Sanctuary at Broughton Hall, an estate some 30 km north-west of the City of Leeds, has become home to the largest tree planting scheme to take place in England this season. WRF has planted 160 ha of resilient woodland between December 2020 and April 2021 – the equivalent of 224 football pitches. Tree species have been selected to meet the objectives of biodiversity and to offer maximum resilience to climate change. The genetic provenance of the native species used were carefully considered prior to planting. The woodland area comprises 57% of high to medium forest; 28% of medium forest to scrub (no more than 20% of which are scrub species) and 15% of open ground. The tree planting marks the beginning of an ambitious nature recovery programme that will transform one third of this 1200 ha estate into a much wilder state, thus increasing biodiversity and wildlife. As well as tree planting, early interventions to kickstart the recovery process will include the natural regeneration of trees, scrub and grasslands, the creation and restoration of wetland habitats and sensitive woodland management.
The project has generated considerable media interest, having been featured in five national newspapers, and has appeared on Channel 4 News in the UK. WRF tried to get the title of the video changed – it isn’t the biggest tree planting operation ever undertaken in England – only the biggest undertaken this season. Guess that’s the media for you!
“We surely have to wake up to the fact that respecting and supporting nature has to be a high priority on the ground now. Our lack of a harmonious existence with the Earth is causing the extinction of species across the globe, as well as a deep lack of belonging for humanity […]. We believe that the change we need to see will come through the union of rewilding our ‘outer nature’, such as the nature recovery and rewilding project at Broughton, along with the rewilding of our ‘inner nature’, which perhaps has been the root cause of deforestation and degradation of nature in England. Our health and future as a species depend on the holistic health of our land […]. We are enormously grateful to everyone who has been involved in our nature recovery project so far. A huge thank you to the White Rose Forest, Defra, Kirklees Council and the Environment Agency.”
Roger Tempest, the custodian of the Broughton Hall Estate, and his partner Paris Ackrill, co-founder of Avalon Wellbeing
“We are committed to tree planting and natural regeneration on an unprecedented scale, and part of that will be a major focus on regenerating land alongside our watercourses. The benefits of doing so are vast, from helping biodiversity recover and absorbing carbon, to slowing the flow of surface water and reducing the risks of floods downstream. The rewilding of Broughton Sanctuary is a fantastic example of this, helping to plant trees where they are needed most and offering vital protection from flooding for communities all along the River Aire”.
Lord Goldsmith, UK Government Forestry Minister
Finally…The successful delivery of this project during a particularly challenging planting season has been achieved through close collaboration between Broughton Sanctuary, the White Rose Forest Delivery Team and the Forestry Commission. The new woodland forms part of WRF’s Landscape for Water Programme, that aims to reduce flood risk for urban areas close to major rivers and waterways in North and West Yorkshire, whilst also improving local water quality, biodiversity and recreational opportunities for local communities. The White Rose Forest is proud to support the Broughton Sanctuary in delivering this hugely important project that will help to protect our environment and the local communities along the River Aire, including Leeds. Broughton Sanctuary joins local authorities across Yorkshire in the leadership they have shown in responding to the climate emergency. Thanks to the support we have received from the Government and businesses, the White Rose Forest has never been in a better position to support this response by working with landowners, communities and fellow professionals across the region to plant trees and to deliver the essential long-term environmental and community benefits they can bring.
England’s Community Forests have been early adoptors and frontrunners regarding community and #urbanforestry in Europe. Great to see they are continuing their wonderful work with a new 12 million GBP grant.
The COVID 19 pandemic is transforming our society. All the basic elements of living together have radically changed in the past weeks: Where and how we work, whom we spend time with, whom we care about, what tasks and activities keep us busy. During the lockdown those that can, have been flocking into green spaces and urban forests for physical exercise and mental calming. At least this applies to those who are not locked down totally. Recent charts by Google, for instance, show an impressive increase of mobility toward places like national parks, public beaches, marinas, dog parks, plazas, and public gardens, amidst a general fall in mobility trends (e.g. the case of Germany).
Read more on the blog of the CLEARING HOUSE-project.