Page Contents:
Introduction: Urban Tree Planting Strategies
Components of Pembrokeshire’s Urban Tree Planting Strategy
The key benefits of urban trees
Introduction
Urban Tree Planting Strategies
1.1 Trees and woodlands are an essential element of our urban environment and crucial to sustainable growth and development. A healthy, well managed ‘urban forest’ has the potential to perform a range of environmental functions and provide multiple benefits for people and nature.
1.2 Pembrokeshire’s urban tree planting strategy promotes a strategic approach to tree planting and management across 11 Pembrokeshire settlements. This will ensure that additional planting will deliver the greatest benefits and help to protect and enhance the distinctive character of the county’s settlements into the future.
1.3 Whilst there is a resource implication to increasing the amount of urban trees across Pembrokeshire, the benefits that may be derived from this positive investment are many and varied. Increasing tree ‘canopy cover’ is a priority of the UK and Welsh government and comprises a central pillar in efforts to reach net zero emissions. Increasing woodland cover is an underpinning principle of the Welsh government’s 2022 woodlands for Wales action plan (PDF) (Opens in new window):
1.4 ‘Optimise the sustainable benefits that forestry, woodlands and trees can provide across rural, peri-urban, and urban areas to meet the needs of people and local communities.’ (Woodland for Wales action plan, Cymru 2022).
1.5 Both mitigating and adapting to the effects of a changing climate are themes that are associated with many of the potential benefits of trees.
Components of Pembrokeshire’s Urban Tree Planting Strategy
1.6 Pembrokeshire’s urban tree planting strategy promotes a strategic approach to tree planting and management across 11 Pembrokeshire settlements.
1.7 Individual strategies for urban tree planting have been developed for each of the 11 settlements included within the strategy.
Overarching Principles
1.8 All of the individual settlement strategies are underpinned by a set of overarching principles. The overarching principles will guide the design and delivery of all tree planting projects across the settlement.
Tree Planting Zones and Sub-Principles for 11 Settlements
1.9 A spatial strategy for tree planting in each settlement has been developed. This comprises strategic tree planting zones that have been established for each settlement. Each tree planting zone has a set of accompanying sub-principles, which build on the overarching principles and provide more detail on where and how tree planting projects will likely need to come forward in each zone.
1.10 A set of set of tree planting typologies has been developed. Information on where the planting typologies and species recommendations may be used to develop project plans is indicated as part of the tree planting zones for each settlement.
Delivery
1.11 A framework and further guidance on delivery is also provided. This includes:
- The key steps required for bringing tree planting projects forward;
- Overview of standards for planting and maintenance; and
- Species recommendations and a framework for species selection.
The key benefits of urban trees
1.12 Trees provide a wide range of environmental, social, health and wellbeing benefits.
1.13 Benefits of the project, as depicted in Figure 1.1 below, include:
- Providing natural shade and urban cooling.
- Improving air quality and noise regulation.
- Reducing the risk of flooding and improving water quality.
- Aesthetic value and reinforcing sense of place.
- Carbon sequestration and mitigation climate change.
- Helping create social spaces & may increase sense of safety.
- Space for biodiversity and improved resilience.
- Economic benefits & improved visitor experience.
Figure 1.1: The key benefits of urban trees
Trees enhance our environment
1.14 Trees provide natural shade and cool air.
- Trees provide shelter and reduce wind speed. Trees have been shown to have a cooling effect and reduce the surface temperature in some European cities by up to 12 degrees in some regions. In contrast, green spaces without trees have a negligible effect on surface temperature. [See reference [1]] Trees have been found to reduce the risk of heat related morbidity and mortality and improve thermal comfort in outdoor spaces [See reference [2]].
1.15 Trees release the oxygen we breath and absorb carbon dioxide.
- A mature tree can store 22 kilograms of carbon every year. An average tree will uptake around 1 tonne of CO2 in its lifetime. [See reference [3]]
1.16 Trees provide shelter and food for wildlife.
- Shelter belts, avenues and tree lined streets can provide important linear wildlife corridors that are integrated into the urban setting. Trees can provide a range of habitat from nesting sites to food such as nectar, seeds and berries. One mature oak can support over 280 different species of invertebrates.
1.17 Trees alleviate impacts from flooding and reduce stormwater pollution.
- With appropriate siting and species choice, trees can reduce ground water run off and intercept pollution. This can in turn reduce the severity of flooding and help to protect river and marine water quality and aquatic life. It has been estimated that a 5% increase in tree canopy cover can reduce run-off by 2% [See reference [4]]. Broadleaved trees have been shown to intercept around 38% of gross precipitation; slowing the flow of water during rainfall events. [See reference [5]]
1.18 Trees enhance landscape character and can soften the built environment.
- The full range of planting types including street trees, parkland trees, hedgerows, community orchards or woodland all have the potential to reinforce sense of place and provide aesthetic value if planted in the right locations.
Trees provide social, health and wellbeing benefits
1.19 Trees intercept particulates and improve air quality.
- Trees can help to intercept and remove a number of pollutants from the atmosphere – including nitrogen oxide, ozone and particulates. Particulate levels can be up to 60% lower on tree lined streets than those without trees.
1.20 The presence of trees in urban areas has been associated with lower levels of crime.
- Some studies have shown that areas with high canopy trees have lower rates of crime when compared to areas with lower vegetation such as mown grass [See reference [6]]. Public spaces with trees also tend be used more, and a flow of people will increase informal surveillance and sense of safety.
- The presence of trees could reduce crime levels by as much as 7%. One study, conducted in the USA, found that apartment blocks surrounded by mature trees experienced 52% fewer reported crimes than those without greenery [See reference [7]]. A review of literature by Wolf et al. [See reference [8]] found that trees may reduce the incidence of various types of crime, although there may be influencing factors such as tree size, location and overall health status of trees in an area.
1.21 Trees help create social spaces and foster social inclusion.
- One study has shown a positive relationship between higher tree canopy cover and higher self-reported neighbourhood ‘social capital’, connection and association amongst individuals. [See reference [9]]
1.22 Trees help reduce noise pollution.
- It has been shown that a 30-metre shelter belt of trees can reduce noise levels by around five to ten decibels. [See reference [10]]
1.23 Trees can have economic benefits.
- It has been found that people visiting business districts are generally willing to pay more for goods and services in landscaped areas when compared to non-landscaped areas. The quality of landscaping on approach routes to business districts can positively influence visitor perceptions. [See reference [11]] [See reference [12]]
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Overarching Principles
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References
[1] Schwaab et al. (2021) The role of urban trees in reducing land surface temperatures in European cities. Nature Communications, 12, 6763
[2] Wolf et al. (2020) Urban Trees and Human Health: A scoping Review. International Journal of Environmental Research and Public Health 2020, 17, 4371
[3] Green Blue Urban. (2015) A guide to the benefits of urban trees (PDF) (Opens in new window)
[4] Coder, KD. (1996) Identified Benefits of Community Trees and Forests, University of Georgia Cooperative Extension Service – Forest Resources Publication FOR96-39
[5] Smets, V. et al. (2019) The importance of city trees for reducing net rainfall: comparing measurements and simulations. Hydrology and Earth System Sciences, 23, 3865-3884
[6] Kuo, FE and Sullivan, WC, (2001(a)), Environment and Crime in the Inner City. Does Vegetation Reduce Crime Environment and Behaviour 33(3), pp 343 – 367
[7] Green Blue Urban. (2015) A guide to the benefits of urban trees (PDF) (Opens in new window)
[8] Wolf et al. (2020) Urban Trees and Human Health: A scoping Review. International Journal of Environmental Research and Public Health 2020, 17, 4371
[9] Holtan, M.T., Dieterlen, S.L., Sullivan, W.C. (2015) Social life under cover: Tree canopy and social capital in Baltimore, Maryland. Environmental Behaviour 47, 502-525
[10] Parliamentary Office of Science & Technology (2016) Green Space and Health
[11] Wolf, K, (2000) Community Image – Roadside Settings and Public Perceptions, University of Washington College of Forest Resources, Factsheet #32
[12] Wolf, K, (2003) Public Response to the Urban Forest in Inner-City Business Districts, Journal of Arboriculture 29(3) pp 117 – 126