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20 Weaponizing Nature: The Psychological Power of Trees
Accep ng that diff erences in environment correspond to
diff erences in human health, it is understood that landscape
architects, through the design and improvement of spaces
of nature, act to posi vely shape physical and mental states.
Indeed, it is cri cal to the profession of landscape architec-
ture to make a strong asser on that how nature is de signed,
and consequently perceived, ma ers, for if there was no
measurable diff erence between the health impacts of a self-
genera ng nature and the work of the trained landscape
architect, then design services would be far less necessary.
This being the case, the landscape architect is responsible
for shaping environments which aim to have a controlled,
predictable and measurable impact on the mental health
and well-being of the public. This paper extends the trajec-
tory of this argument, asking, what if any, is the professions
obliga on to contribute design exper se to sites facing the
combined challenges of a signifi cant depression of human
health and the loss of nature.
There is a large body of evidence that supports the idea that
contact with nature promotes human health. Studies have
shown that environmental factors play an important role
in trea ng, maintaining and improving mental health and
wellbeing. Whether physical or visual, exposure to nature
has been demonstrated to alter mental states through
reducing stress, restoring a en on, and improving emo-
onal connec on to place, to name only a few mechanisms
recognized in the scien fi c literature.
1
While there remains
controversy over defi ni ons of both nature and health, only
a skep c would deny that the human mental state is altered
by the sensed environment. Furthermore, it stands to rea-
son that the quality of the environment under observa on
by our senses ma ers: some environments are be er than
others, and what we would reasonably qualify as a be er
mental state is associated with a be er perceptual environ-
ment. Here of course the term be er is open to debate, but
that should not deny us from accep ng the proposi on.
So, advoca ng for the inclusion of nature in one’s immedi-
ate environment is a supposi on that nature represents an
improved environment and will correspondingly improve that
individual’s mental condi on.
This was indeed one of the main tenets of Frederick Law
Olmsted’s work. In the industrializing city of New York,
Olmsted witnessed that the working class had increasingly
limited opportuni es to perceive nature. He deduced that
for this popula on, the degrada on of mental health and
wellbeing was as a direct result of the lack of nature in the
urban environment. In response, Olmsted, working with
Calvert Vaux, completed their most famous work, New York’s
Central Park, which was in many ways a public health ini a-
ve. An explicit goal of Central Park was to reinstate good
mental and physical health among the working class of the
city that were exhausted from their labor. In considering
how to address this urban ill of physical and mental exhaus-
on that reduced produc vity and social stability, we have
Olmsted’s words through his biographer Witold Rybczynski:
“It is one great purpose of [Central Park], to supply to the
hundreds of thousands of red workers, who have no oppor-
tunity to spend their summers in the country, a specimen of
God’s handiwork that shall be to them, inexpensively, what a
month or two in the White Mountains or the Adirondacks is,
at great cost, to those in easier circumstances.”2 This pas sage
refers not just to physical exhaus on, as then the prescrip-
on would likely have been more comfortable beds, or more
me in them. The words pertain also to mental exhaus on,
which would be restored through exposure to nature. From
Central Park, designed in 1858, to the present, landscape
architects have con nued to seek the improvement of men-
tal health and wellbeing through incorpora ng nature into
the urban environment. Not surprisingly, since the 1850s,
ongoing research strives to be er understand the rela on-
ship between exposure to nature, designed and otherwise,
and improvements in mental health. Yet, in every case, this
research is aimed at fi nding a posi ve correla on between
the two. One must wonder if exposure to nature will always
posi vely impact mental condi ons, or if me in nature can
also degrade one’s cogni ve state.
Central Park is an important precedent because it assists in
defi ning what we mean by nature. Olmsted dis nguishes
between wilderness beyond the urban, the White Mountains
for example, and the urban park. Yet, at the same me, he
asserts that a designed set of proper es drawn from the wil-
derness can be successfully introduced into the urban park
with similar healing eff ects. This radical scale shi and reduc-
on in structural complexity of what cons tutes nature has
far-reaching impacts. For example, we can no longer argue
for the preserva on of large intact natural areas on the basis
of human health because the same benefi ts can be provided
through urban simula on. Certainly, there is a diff erence in
amount of nature between that which is found in urban envi-
ronments, parks and the like, and tracts of wilderness beyond
the city, but Olmsted has set forward a posi on that there is
Weaponizing Nature: The Psychological Power of Trees
FIONN BYRNE
University of Bri sh Columbia
PLAY with the Rules: (tac cal) OPERATION 21
not a diff erence in kind with increasing scale. This conces-
sion is necessary if one aspires to design scaled wilderness
experiences in urban se ngs.3 For the purpose of this paper,
the only point to be drawn from this is that, for the benefi t
of mental health, nature has been defi ned in a very limited
way. Indeed, the American Society of Landscape Architects
(ASLA), of which the sons of Olmsted and Vaux were founding
members, prominently cite on their website the conclusions
of a paper published in the Journal of Epidemiology and
Community Health. It reads: “living close to parks, or at least
near lots of trees, can have far reaching mental health ben-
efi ts for people.”4 Notwithstanding the obviously problema c
quan ta ve measure of “lots,” nature is here reduced to a
variable number of trees in so far as human mental health
benefi ts are concerned. In summary, we take forward three
conclusions: fi rst, that diff erences in environments corre-
spond to diff erences in mental states and wellbeing; second,
that landscape architects, through the design and improve-
ment of human environments, act to posi vely shape physical
and mental states; and third, that trees, a common design
element of the landscape architect, posi vely aff ect mental
health and wellbeing.
As the ASLA prepares for a “broad communica ons campaign
to educate the public about the health benefi ts of nature,”
5
with aims at transforming our urban environments to include
more trees and securing ongoing work for the profession, it
is important to ques on the limits of this work. For exam-
ple, can any degraded landscape be improved through the
plan ng of trees? Or, are there levels of degrada on and con-
sequent challenges to physical and mental health that are
too great for trees to posi vely impact? We should also ask
if there are any risks to plan ng trees in treeless urban areas
and to carrying out plan ng eff orts in areas that are o en also
the poorest parts of the city. Returning to the ASLA’s website,
on a page about stress, we read “that trees and green space
are a major predictor of longevity, especially among people
living [in] lower-incomes communi es.”
6
When considering
depression, we learn from the website, “living in places with-
out parks or trees, especially if you are young or poor, can
have major nega ve impacts.”7 As presented by the ASLA,
and popularly accepted in the profession, trees act always in
service of the public good.
Yet, it is worth considering even more dras cally de-vege-
tated environments. Afghanistan was listed as having one
of the lowest forest covers in the world, at 1.3 percent by
a 2007 report out of the University of Bri sh Columbia
(UBC), Canada.8 Contrary to the common media portrayal of
Afghanistan as a desert na on, this country once had lush for-
ests. However, these forests have been decimated by human
ac on. The UBC report also tells us that rates of deforesta on
had reached up to 70 percent in some provinces at the me
Figure 1: The Afghan Peace Volunteers plant a tree in Kabul, Afghanistan
on Monday, March 31, 2014., Afghan Peace Volunteers, ourjourneytos-
mile.com.
22 Weaponizing Nature: The Psychological Power of Trees
of publica on. This high rate was measured over a twenty-
year period, since around the end of the Soviet-Afghan
war. Presumably, even more trees were destroyed during
that war, and deforesta on has likely con nued since 2007.
Afghanistan then appears to be an extreme case to study the
impacts of both the loss of nature and consequent reforesta-
on eff orts on popula on health. The UBC report discusses
the work of Doctor Gary Q. Bull, then Associate Professor and
now Head of the Forest Resources Management Department.
Bull worked in collabora on with the Wildlife Conserva on
Society (WCS) on a project funded by the United States
Agency for Interna onal Development (USAID) that helped
to protect and restore Afghanistan’s largest remaining for-
est found in the province of Nuristan. It is interes ng that
USAID is funding a forest restora on project. On the face of
it, this model of an American organiza on paying to protect
and plant trees in a foreign sovereign na on feels distant
from the advocacy of the ALSA concentra ng on domes c
plan ng in the United States, yet, it is also so noted by the
ASLA that peoples very strong preference for a natural set-
ng is cross-cultural.
9
In this light, Afghanistan appears as a
valid and extreme interna onal case study to speculate on
the limits of mental health benefi ts gained through exposure
to nature. In addi on, working across cultures which at mes
hold deep ideological division places increasing pressure on
species selec on, formal design strategies, and plan ng and
maintenance decisions.
The purpose of this specula on is to challenge the afore
men oned conclusions. If it remains true that diff erences
in environments correspond to diff erences in mental states
and wellbeing, then it is expedient to entertain the possibil-
ity that our other two conclusions are not always posi ve in
their outcome. Returning to them in turn, we ask fi rst, is it
possible that landscape architects, through the design and
improvement of human environments, can act to nega vely
shape physical and mental states? If the answer is no, then
design can proceed without cau on. Yet if the answer is yes,
then one would need to understand the mechanism at play
in order to avoid this outcome. Second, can trees, a common
design element of the landscape architect, nega vely aff ect
mental health and wellbeing? In admi ng that the posi ve
health benefi ts of one tree species can be stronger than
another species, we establish a gradient. Each tree would fi nd
itself rated against others and we would ask if any nega vely
aff ect our health, thinking for example about an off scented
species, a scary looking tree, one struck down by lightning,
one festering with sickness. Studying Afghanistan then allows
us to be er resolve if the mental health benefi ts gained by
exposure to trees are universally posi ve, no ma er the spe-
cies, site and situa on in which the interac on takes place.
As it turns out, American taxpayers have already been funding
a military reforesta on campaign in Afghanistan through the
well-supported Commander’s Emergency Response Program
(CERP). The Department of Defense (DOD) established CERP
in 2004. The program was designed to allow military com-
manders to spend money on reconstruc on projects and
urgent humanitarian relief in ac ve theaters. Projects were
implemented in every Afghan province, and between fi scal
year (FY) 2004 and FY 2014, Congress appropriated a total of
$3.7 billion for CERP alone. The origins of this program stem
from the widely held belief that development assistance con-
tributes to the security and stability of war-torn regions and
increases tolerance for the presence of occupying forces.10
The popularity of this program is also connected to the writ-
ing of Joseph Nye, former Dean of the Harvard’s Kennedy
School of Government, who coined the term “So Power”
to describe a strategy of non-coercive warfi gh ng. Through
this doctrine, aid is an integral component of the American
military’s popula on-centered counterinsurgency (COIN)
approach of winning the ci zenry away from insurgents and
to the Afghan government.
11
For example, CERP’s Standard
Opera ng Procedure (SOP), en tled Money as a Weapon
System - Afghanistan (MAAWS-A), is a strategy for using aid
as a COIN tool. The CERP MAAWS-A SOP is a procedural guide
that explains how U.S. military commanders can successfully
apply for funding usable in their local area of opera ons.
Through CERP, the work of tree plan ng has most o en
been a minor component of larger “bulk funding” projects,
and revegeta on has o en been a reconciliatory expense
to cover ba le damage to exis ng orchards. However, there
are also more tree specifi c projects such as the “Parwan
DAIL (Directorate of Agriculture, Irriga on, and Livestock)
Pinetree saplings,” an expense of $10,900 for 3,000 pine tree
saplings to be distributed and planted for educa on, erosion
preven on, and as a renewable source of income.12 Another
example at a larger scale and cost are the mul ple “Seed Kits
and Almond Tree Distribu on” projects. At least ten such pro-
grams were run at a cost of $98,837 and through which seeds
and fer lizer were distributed to mul ple families with a goal
to support a viable small-scale agricultural economy.13 A fi nal
example, “TX ADT IV Bulk CERP Funds APR 11,” supported
with $50,000 in taxpayer dollars, is indica ve of how explicitly
tree plan ng was a tool of warfi gh ng. The descrip on of
Invoice #003 to the fund states, “This project paid Muhibullah
Ekhpelwak, the Qarabagh District Sub Governor to purchase
3,000 fruit tree saplings (green/red plums and apricot) to
plant in front of shops in the Qarabagh bazaar, Qarabagh
District, Ghazni Province during Nawruz (the Afghan New
Year). This project enhanced the credibility of the Qarabagh
District government and the Gahzni Provincial government.”
14
A reading of mul ple funded and executed plan ng programs
makes clear that trees have two primary uses for CERP opera-
ons. The fi rst is increasing local government credibility, and
the second is economic empowerment – in other words,
security and stability. However, the ASLA is poin ng to an
even greater benefi t that trees are poised to contribute to
warfi gh ng opera ons. The preceding conclusion that trees
PLAY with the Rules: (tac cal) OPERATION 23
posi vely aff ect mental health and wellbeing, as advocated
for by landscape architects, is easily weaponized if re-stated:
trees posi vely aff ect minds and hearts.
Winning “hearts and minds” is a strategy whereby the execu-
on of a military opera on is carried out not through force
of strength but by appealing to collec ve individual emo-
onal and intellectual facul es. While the specifi c use of
the term has decreased in popularity, the general defi ni on
expresses the same ra onal as Nye’s So Power. Both are a
component of the Military Informa on Support Opera ons
(MISO) Command, which has the stated objec ve of convinc-
ing “enemy, neutral, and friendly na ons and forces to take
ac on favorable to the United States and its allies,” through
a non-forceful, non-violent use of “logic, fear, desire or other
mental factors to promote specifi c emo ons, a tudes or
behaviors.”15 Wellbeing and mental health are not exactly
synonymous with hearts and minds but are complementary
and interconnected terms. It stands to reason that a popula-
on whose mental health and wellbeing has been improved
will correspondingly experience greater stability and security.
This is similar to the assump on made by the military and
other aid organiza ons that poverty and insecurity are linked
and can be improved with economic development. As we
have seen, this popular belief enabled CERP to become such
an infl uen al program. And while the link between poverty
and stability has recently received cri cism, support seems
only to be growing for the rela onship between trees and
overall human health.16
Upon accep ng the posi on that trees possess the ability to
improve local environments and consequently mental and
emo onal states, we begin to understand the ethical confl icts
inherent in design. The 3,000 plum and apricot trees that were
planted in front of shops in the Qarabagh bazaar were either
done so haphazardly or were planted with design intent. For
landscape architects, the asser on that design ma ers is core
to the profession, for if there was no measurable diff erence
between self-plan ng and the work of the trained landscape
architect, design services would not be needed. Design deci-
sions will o en consider tree species, spacing, organiza on,
circula on, and many other variables, where precision in
plan ng is cri cal for performance, program, and experience.
A plan ng strategy that defi nes a series of outdoor rooms,
for example, can increase social interac on and consequent
wellbeing. A plan ng strategy that organizes alterna ng
groupings of species type can heighten aesthe c pleasure,
enrich the sensory experience through a pa erned diversity,
and consequently improve mental health. Framed in the
context of Afghanistan as a strategy of winning hearts and
minds, the posi ve improvements of wellbeing and mental
health linked to trees could be characterized as a subversive,
or even as an insidious ac on. Diff erent from consuming a
Figure 2: General David Petraeus, ISAF Commander, and U.S. Ambassador
Karl W. Eikenberr y, plant a tree in Kabul, Afghanistan on Sunday, March 6,
2011., Flickr, US Embassy Kabul Afghanistan.
24 Weaponizing Nature: The Psychological Power of Trees
drug or par cipa ng in therapy, the posi ve mental health
benefi ts derived from nature are less tangible. This envi-
ronmental condi oning of mental states celebrated by the
ASLA seems to work gradually and subtly on en re popula-
ons and short of cu ng down the trees, there seem to be
no strategies for resis ng the eff ects of exposure to nature.
Furthermore, trees present themselves as a cost-eff ec ve
tool for large-scale environmental transforma on and con-
sequen al community-wide psychological modifi ca on. This
essay asks both the ASLA and the American military: do trees
always func on to improve environments and is improve-
ment always be erment? In addi on, is consent of a local
popula on necessary before deploying a vegeta ve design
interven on?
In Afghanistan alone, the American Congress appropriated
$113.1 billion from 2001 to 2015 for relief and reconstruc-
on work. So, while the Offi ce of Research & Analysis at
the Na onal Endowment for the Arts valued the landscape
architecture market as adding $2.3 billion dollars per year to
the U.S. economy, the American tax payers have been spend-
ing $8.1 billion dollars yearly on relief and reconstruc on in
Afghanistan.17 As the American military con nues to plant
trees in ac ve and post-confl ict war zones, it is important to
ask what, if any, is our obliga on to contribute our exper se
in environmental design to vulnerable na ons suff ering a
loss of nature. A diff erence of na onality or a cultural divide
should not outright excuse inac on, yet can we remain mor-
ally jus fi ed in making be er what to some will be considered
a deeply fl awed project? And domes cally, the same holds
true. While designing to restore mental health and wellbe-
ing, do we not also have the obliga on to comment on the
poli cal structures in place which perpetuate this suff ering
and inequality? It is right to strive for a fi rm commitment to
environmental jus ce, yet we must be advocates for social
jus ce as well. Our privilege is also our obliga on to act.
ENDNOTES
1. Lau ra Mena and Ant onio Casad o da Rocha , “Lan dscape and Healt h:
Con nec ng Psyc holog y, Aesthe cs, and Phil osophy thro ugh the Co ncept of
Aff ordance,” Fron ers in Psychology 7, no. 571 (2016): 1-17.
2. Witold Rybczynski, A Clearing in th e Distan ce: Frederick Law Ol msted and
America in the Nineteenth Century (New York: Sc ribner, 20 03): 177.
3. Galen Cranz, The Pol i cs of Par k Design: a histor y of urban parks in Ameri ca
(Cam bridge: MIT Pres s, 1982): 7.
4. “Professional Prac ce: Adult: Depression ,” American Societ y of Landsca pe
Arc hitects (A SLA), acce ssed Novemb er 8, 2017, h p://www.as la.org /
ContentDetail.aspx?id=39551.
5. “We Mu st Be er Comm unicat e the Heal th Benefi t s of Natur e,” The
Dirt, accessed November 8, 2017, h ps://dirt.asla.org/2016/02/02/
we-must-be er-communicate-the-health-benefi ts-of-nature/.
6. “Professional Prac ce: Adult: St ress,” ASL A, acce ssed Novemb er 8, 2017,
h ps://www.asla.org/ContentDetail.aspx?id=39550.
7. ASL A, “Pr ofessi onal Pra c c e: Adult: Depr ession.”
8. “The Lo st Fores ts of Afghanist an,” The Unive rsity of Bri sh Colu mbia
(UBC), accessed November 8, 2017, h ps://news.ubc.ca/2007/11/01/
archive-ubcreports-2007-07nov01-afghanistan/.
9. “Pr ofessi onal Pra c c e: Adult: Wel l-bei ng,” ASLA , accessed November 8, 2017,
h ps://www.asla.org/ContentDetail.aspx?id=39515.
10. Paul Fishstein and Andrew Wilder, Winning Hearts and Minds? Examining
the Rela onship between Aid and Security in Afghanistan (Tu s Univers ity,
Feinstein Interna onal Center, 2012): 2.
11. Fishstein and Wilder, Winning Hearts and Minds?, 4.
12. “Parwan DAIL Pinetree saplings,” ProPublica, accessed
November 8, 2017, h ps://projects.propublica.org/cerp/
projects/851AD04A-1517-911C-C5A1A0C26181AFD7/.
13. “Naw bahar Hy brid Se ed Kits an d Almond Tree Di stribu on,” Pro Public a,
accessed November 8, 2017, h ps://projects.propublica.org/cerp/projects/
E3361264-0A24-E A5E-8F709 B4FC A377669/.
14. “T X ADT IV Bulk CER P Funds APR 11,” Pr oPubli ca, access ed
November 8, 2017, h ps://projects.propublica.org/cerp/
projects/0051F736-A72D-CC36-5CFF66FDC0460A6A/.
15. U.S. Army Special Opera ons Command Public Aff airs Offi ce, “Military
Informa on Support Opera ons Command (Airborne)(Provisional) Fact
Sheet ” (Support Opera ons Command, 2012).
16. Fishstein and Wilder, Winning Hearts and Minds? Examining the Rela onship
between Aid and Security in Afghanistan.
17. O ffi ce of Researc h & Analysis, Na on al Endow ment for the Ar ts, “ACP SA Issue
Brief #8: Value Added by Architec tural and Design Servi ces,” h ps://www.
arts.gov/sites/default/fi les/ADP6- 8_ValueAddedArchitecturalDesign.pdf
(accessed May 17, 2017).
