World over there are tree plantations being made.In the changing urban scenario the transformations of built environment has denuded the cities . Adding trees in the streets which were earlier part of the house has become the norm.Much as we know the advantages of street trees in promoting the environmental quality climatologically and socially there are difficulties encoutered in growwing streets for the nusaince they create. in this context what are the parameters to be considered in the selection of street trees?
Street trees should be native species if possible, or at least avoid selecting invasive species. I would select a species that does not make a big mess or attract wildlife as a food source as people don't want to deal with the excessive mess of bird dropping on them or their car, etc. If it is an urban park, your selection might be somewhat different. The tree needs to be able to handle conditions of stress as their root systems are apt to be limited, and some trees send out roots that will eventually break up streets or adjacent side walks. Trees that flower, have unique leaves, change color seasonally are nice as long as they are not overly attractive to bees or produce fruit or seed to be a nuisance. Trees that produce shade are desirable in most places and have a pleasant form and shape. The trees need to be hearty enough to withstand dogs and other sources of stress of the city. If you live in a wet or dry area, that could cause added stress as some plants do not have adequate rooting space or soil drainage along streets. You dont want trees that are not windfirm or would cause a public hazard in storms for breaking up, so hardwoods may be preferable. You don't want a tree that is too tall, has a crown that is too wide. If you have urban foresters or landscape designers, this subject is within their training. I could come up with more, but I am pretty sure you can google on the subject and find many ideas, possibly books, training courses, etc.
Trees that don't cause allergy are preferable. If the trees will grow along avenues and highways, they must be good filters and be highly resistant to car emissions.
Power lines along streets can be damaged by growing trees, that demands cutting branches. Maybe some trees in your area are more easy manageable in such situations.
I would like add to the above suggestions that it should be trees with good root systems so that they will not easily fall during strong winds. Tree type and planting distance has to be good enough to provide good shade cover and prevent interference with drainage canals.
I would like add to the above suggestions that it should be trees with good root systems so that they will not easily fall during strong winds. Tree type and planting distance has to be good enough to provide good shade cover and prevent interference with drainage canals.
Plant small-stature trees in groups if shade is desired near buildings.
Canopies catch the wind, and trees can blow over when they grow substantially above the roof line.
But large trees (>50 ft at mature height) are the obvious choice for providing shade to large open spaces and for planting along streets if there is proper space above and below ground.
Medium or large trees will cast the most shade onto a building, which can reduce air conditioning bills when the trees are placed properly.
Keep in mind,however, that larger trees are more likely to be damaged and cause damage than small trees.
If the trees are to be planted near to residential buildings, it would be appropriate to choose non-flowering and non-fruit bearing trees. This would help avoiding the pollen allergy issues among people and the accumulation of fruits and bird droppings on the ground (which attracts insects too).
If the trees are meant for public parks, flowering and fruit bearing trees can be included (afterall our intention is NOT to keep the birds at bay, they too are entitled for their share! and they are part of mother nature!
regards
Rathish
If leaves fall on the ground, it also creates jobs to remove them, and perhaps to transform the leaves into compost to be recycled!
Cheers
I appreciate the concerns that have been raised about roots needs, and wind resistance. There are surely technical concerns to take into account, but I deeply believe we have to move forward from this way of thinking and move towards a completely different urbanism (less manicured, more 'agroecological'). I claim that we should grow edible, and fruit-bearing trees within our cities (from nuts to citrus - not only soft fruits), on a number of grounds:
1) they will expose people to food - most urbanites have lost knowledge of what is seasonal, therefore don't know anymore how to make sustainable consumer choices;
2) a wider variety of trees is important for biodiversity. many birds and bees are at risks because of the amount of pesticides used in conventional agriculture in rural and peri-urban areas. perhaps they could have some chances in cities?!
3) there is growing urban malnutrition everywhere. It is absurd to grow exclusively ornamental species when we could have edible species.
4) aesthetic criteria are socially constructed. In Portugal is pretty much common to see orange trees in public space. The taste and social expectations for flowering trees can be shaped.
Obviously, I wouldn't put a bench below a plum tree....but most of the concerns I have heard from policy makers on why not to grow edibles are misplaced (like: if you put an apple tree, kids will start breaking windows by through apples. The same kind of rationale for removing benches from public space.
Why not exploring ways to create resourceful urban environments that prioritize social learning, environmental education, food sovereignty against the limits of modernist urban design?
Good evening
Landscape architects and aboriculturalist are probably best placed to suggest native spicies suitable for planting in the local area. From architectural and urban design point of view you may also want to consider the following:
- Distance from the tree to the nearest building to ensure that there is no adverse effect from the tree onto the adjacent builings.
- Selection of a suitable roots container or barrier system to control the spread of roots and minimise damage to adjacent road, pavement or buildings.
- Suitable system for deep irrigation of the planted trees leading into the roots.
- Select of a tree that will make positive contribution to the environment from sustainability point of view. For example planting decidious trees on the south side of the building can provide shade for the facade during the hot and sunny summer periods whilst reducing the solar gain and overheating inside the building. On other hand in winter after the leaves have been shed it can promote additional solar gains during the colder winter period and support the promotion of the principles of passive solar building design.
- Introduction of trees in the urban environment can assist with cleansing the air and reducing air polution.
- Introduction of trees in the urban environment can also contribute towards the attenuation of the rainfall and prevention of flush flooding.
Regards
Vladimir
Of the above answers, I emphasise that native species would be the best choice. But, I would rather do concern more about the climate effect on the trees considered, since in our tough climate in North Africa, which is getting drier every year, the most important issue in some particular regions is that which tree species could survive the dry climate.
some quick points -
The health benefits of urban trees have been researched and published, as also the benefits for creative thought and well-being.
the measurable benefits of urban trees near dwellings was the focus of the PHD study of Dr David Holmes (I supervised) submitted 2015 - available at https://repository.cardiffmet.ac.uk/dspace/handle/10369/7525
Research at Manchester Uni for example found that a single well-watered mature deciduous tree can alter the environment around it be up to 8 deg C, and so this has to be a significant approach as part of a scaleable response to the threats of climate change. Others have found that appropriately sited urban trees are immensely effective at creating wind shelter.
In my view therefore we have to find effective means of enabling mature trees to be planted safely near urban buildings, particularly on the prevailing solar / prevailing windward sides. To this end the Australians face significant problems with natural disasters and climate change in preserving urban trees, and have developed very effective storm drains that contain the root systems of the trees, and ensure that they are regularly watered.
And what trees city citizens would select when you would give them the opportunity to make a choice between different options?
Why do planted tree species differ between Streets in a given city?
Some trees are known for eating air pollution. Finding out the right tree that can handle that pollution is a good thing. Making sure that tree does not overgrow its barriers and its roots do not infiltrate the sidewalk, street, or pipes running below it are also something to consider. I recommend looking at Ginkgo but be careful the female tree of this species smells horrible. Also, steer clear of fruit bearing trees or flowering since allergies are an issue for many and fruit will cause walking hazards in slippage and plain littering all over the place.
Many UK cities have uprooted mature deciduous trees like London Plane, and replanted with small flowering shrub like trees that are easier to manage but contribute little to overcoming climate change challenges.
Hi to All
In addition to all the benefits mentioned above for the tree, accumulation of contaminants into urban canyons resulting from the traffic, should be consider as a disadvantage.
Alipour
You need to consider the frequency of maintenance as it affects the availability of resources in terms of water. you also need to consider the foliage as it affects visibility for road users
Hi
I would suggest that road traffic users should not usually predominate. Look at all the research into "homezones" and their effect on traffic calming.
About maintenance with water: local trees can grow without human help, so they usually need maintenance only first year, before their roots are big enough to find deeper water levels.
About mature trees and fruit trees: they can be planted in parks or other zones where they are less hazardous.
About allergies I would add that poplars, for example, don't have beautiful big flowers, but cause allergies. And on the contrary, many plants with flowers are less known for that.
I think you shoud consider climate site and the need of solar radiation to choose between deciduous or perennial trees.
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