[27] Pandit, R. & Laband, D. (2010). Energy Savings from Tree Shade. Ecological Economics 69 1324-1329
PART 2
STRATEGIES FOR INCREASING THE URBAN FOREST
Parks are not the only way to increase the number of trees in the
city, and the access to green areas. And indeed, the concept of the park
– where it is, how large, what shape, and whether wild or cultivated -
needs a little rethinking. Urban waterways, green streets, green
buildings, community gardens also provide strategies for increasing the
urban forest and access to nature.
Parks:
More important than just more, bigger parks is how accessible a park
is. It is not sufficient to draw a quarter mile radius around the
periphery of a park to determine how many people that park serves. Some
large parks may be fenced, with only one or two entrances, so a quarter
mile walk from that entrance may only reach a handful of homes. On the
other hand, a small strip park alongside a stream in a densely populated
area in the center of the city may offer easy access to thousands of
families living within a quarter mile walk.
More trees and parks in poor neighborhoods:
The great scandal in the US is that while white and more affluent
communities often have many old-growth trees and are well supplied with
parks, low-income and ethnic neighborhoods have fewer parks
[1]
. This inequality clearly contributes to the lower health levels in
poor neighborhoods. Poor neighborhoods are in greater need of street
trees, and easy access to parks and community gardens than are wealthier
neighborhoods. Following Kardan’s suggestions
[2], one powerful way to make a city healthier would be to plant 10 trees per block in poor neighborhoods.
Create Green Fingers:

We need to follow the examples of new neighborhoods such as Vauban,
in Freiburg, Germany that connect the green places, for the sake of
humans and biodiversity. A small stream running along the southern edge
of the Vauban neighborhood is protected as a natural area, and from
this, three green fingers reach deep into the neighborhood, providing
undisturbed natural habitat, natural play areas for different ages, and
simple community areas for barbecues and social events.

The city of Portland is justly proud of its Park Blocks that run
almost continuously for 17 blocks north to south through the city
center. This extensive linear park contains 335 mature elm, oak, and
maple trees and a rich assortment of wildlife, as well as human life.
Portland is attempting to create additional natural corridors by linking
neighborhood parks with green streets. The ultimate aim is to enable
these green streets to function as biodiversity corridors.
Restore Urban Waterways:
Many of our cities used the river as their industrial heart. Rivers
and river banks became polluted, unsuitable both for nature and for
humans. Many cities have made major efforts to reclaim the industrial
banks and clean the rivers, but there is much still to do. Trees such as
willows need to be planted to help foster biodiversity, and to
reconnect the regenerative power of the land-water interface. Ljubljana
just won title of 2016 Green Capital of Europe in large part for their
admirable restoration of their river banks.
Streams are biodiversity corridors but most streams in our cities
have been channeled underground so as not to interfere with our use of
the surface for construction and car access. Wherever possible we should
try to bring them back to the surface as urban streams.

This
has been accomplished in numerous European cities and towns. Freiburg,
Germany uncovered the tiny streams called Bächle that run off the Black
Forest through the streets of the old city, and these are now used to
paddle in, and cool hot feet in the summer. The university town of
Tübingen, Germany uncovered a stream that ran through the historic heart
of the city. It now helps to cool the air in summer.
In slightly less dense urban areas it is possible to restore the
stream’s natural banks. The reconstructed town of Plessis-Robinson, just
south of Paris has restored streams and lakes as a central feature of
their development, creating walkways, parks, and gardens along the
banks.
Green Streets:
Streets are potential green fingers and biodiversity corridors. A few
trees can encourage social life on the street. More trees, diverse
trees, and a mix of bushes, earth, and rainwater ditches can foster
greater species diversity. Street trees also help clean the air.
In Vauban, Freiburg, the narrow residential streets are an extension
of the green fingers. These are Wohnstrasse (Living Streets), intended
for children’s play, bikes and pedestrians. The only reason a vehicle is
allowed in is for delivery or emergency access. Only handicapped
residents are allowed to park there. Permeable stone lined rainwater
channels are provided by the city, and residents may choose what tree
they want in the strip owned by the city.

Vauban also has a network of traffic-free bike/pedestrian lanes through the most heavily wooded sections of the development.
Green pedestrian networks are also needed into and around the city
center, to provide healthy pedestrian commuter routes. Almost every
small town in England has a fine web of almost secret green rights of
way that weave into the town center, nipping between houses and along
the banks of streams in the suburban areas, through city blocks and
along the borders of parks in the city center. Poundbury has created
such a wealth of these pedestrian short cuts that the streets themselves
sometimes seem deserted.
In Krakow, Poland a major pedestrian commuter route leads into the city center through a park.

In quiet neighborhoods, such as Carmel, or Berkeley, California trees
also perform a grand job of calming traffic. This is a model easily
adopted by residential neighborhoods.
Arterial roads carrying a great deal of traffic are in major need of
greening to reduce pollution and slow traffic. This is especially
important when the roads have stores and residential buildings on either
side that require the ability to easily and safely cross the street. In
these situations, even roads carrying heavy traffic need to widen
sidewalks, add buffered bike lanes, reduce the number and width of
traffic lanes, add crosswalks and roundabouts, and plant trees.
Green Buildings:
Trees can also help to provide green walls and roofs. In addition to
climbers and vines trained on a scaffold across a façade, fruit trees
have traditionally been grown in this way. Just imagine, leaning out of
your bedroom window and picking a fresh pear for breakfast!
Trees can also be grown on roofs and terraces. Green roofs improve
biodiversity, slow rainwater and keep buildings cool. Even green arbors,
vines, small trees and gardens in pots on roof terraces – as can be
seen on every other rooftop in Rome - help to cool the atmosphere,
without requiring immensely high-tech structural solutions.

The most successful and well-tested projects I have seen are those by
the artist Friedensreich Hundertwasser. The Hundertwasser House in
Vienna is public housing commissioned by the City. It is human scale – 5
and 6 stories – with gardens and trees on terraces and on the roofs.
The building is beloved by residents and tourists.
Hundertwasser has designed dozens of buildings all over Europe, but
perhaps his most ambitious project is Bad Blumenau, an extensive spa
village in Eastern Austria. Each building is a little hill, covered with
grass and trees, creating a rolling green landscape. Here, the spa park
is atop the buildings.
-Trees in Urban Public Places
We have a huge need in North America to rebuild community, regenerate
a social network and increase democratic dialogue and civic engagement.
This is important for many reasons, including the social and physical
health of the population. Preventative action on the level of creating a
healthy environment would also save billions of dollars in health care
expenses.
Researchers in public health and social science have discovered that
when people are tied into a rich daily pattern of face-to-face
interaction with friends, familiars and neighbors, they do not fall ill
so often, if they get sick it is not so serious, and they live to a
riper old age. They have what is called a strong
“Social Immune System”.
It is a central tenet of IMCL that we desperately NEED more Community
Places – squares and piazzas that generate social interaction. It is
absolutely essential to bring people together, to build community in
neighborhoods, to facilitate civic engagement and strengthen social
immune systems.
Trees are an essential tool for achieving that goal. They shape social life.
In a community place, a tree creates the ideal location for an
outdoor cafe or restaurant, or for public benches where elders can sit
and watch the children playing, or lovers can embrace. A broad canopied
tree filtering the sunlight will enhance a café or restaurant. A smaller
tree giving dark shade will provide a cool corner for a couple of
benches.
Trees keep the paving cooler. So a square with many trees supports
many conversations on the move, peripatetic, as people’s paths cross,
while they make errands, commute to and from work.
Whenever
we want to bring people together in the city, trees must play a major
part. Outdoor farmers markets, like those in Aix-en-Provence, or on
Portland’s South Park blocks, benefit from the trees. The plane trees in
Aix, and the oak, elm and maple trees in Portland keep the produce
fresh, and make the market even more inviting for humans.
Munich’s Viktualienmarkt, a combination of a vast farmers market and
beer garden, at the heart of Munich, is magnificently shaded by chestnut
trees.
We need more public squares that are free of traffic, where people
shop, meet, walk, eat out, meet friends, and enjoy their city, and these
squares need trees!
This is the second part of a talk presented at the Livable
Communities through Urban Forestry Conference in Washington DC, August
6, 2015 by Suzanne H. Crowhurst Lennard, Ph.D. (Arch.), Director,
International Making Cities Livable Conferences.
[1]
Estabrooks PA1, Lee RE, Gyurcsik NC. (2003) Resources for physical
activity participation: does availability and accessibility differ by
neighborhood socioeconomic status? Ann Behav Med. 2003
Spring;25(2):100-4.
Powell LM, Slater S, Chaloupka FJ, Harper D. Availability of
physical activity-related facilities and neighborhood demographic and
socioeconomic characteristics: a national study. Am J Public Health.
2006;96:1676–80.
[2]
Kardan, O. et al. Neighborhood greenspace and health in a large urban
center. Sci. Rep. 5, 11610; doi: 10.1038/srep11610 (2015).