PLANT FOR LIFE
Briefing Report 6: April 2004
Ross Cameron and Sarah Swan
University of Reading
Biophilia and Tackling Environmental Issues
Biophilia is a term popularised by the Harvard biologist Edward O Wilson in
1984 and he defined it as “the connections that human beings subconsciously seek
with the rest of life”. Wilson stated that biophilia is determined by a biological need
and is an emotional or spiritual relationship between man and nature. It is the
phenomenon that explains why patients recover quicker if they are exposed to
greenery, even pictures of greenery, rather than purely artificial environments. It has
been argued that biophilia relates to our evolution, e.g. the fact that Homo sapiens
developed in a ‘parkland like’ savannah habitat and have a close affinity to certain
aspects of nature. (NB aspects of our evolution also relate to biophobia – e.g. the
sometimes un-rationale fear of spiders and snakes).
Penn (2003) argues that evolutionary forces explain our negative impacts on
nature - why people often overpopulate, over-consume, exhaust common-pool
resources, discount the future, and respond poorly to modern environmental hazards.
These also provide insights into why we cherish plants and animals and often support
environmental and conservation efforts. Penn (2003) feels that only by being aware of
these evolutionary forces can they be effectively triggered to help alleviate
environmental problems. For example, education about environmental and
conservation issues, although necessary, is not enough and that society also requires
incentives before action will be taken. Individual incentives are likely to be the most
effective, but these include much more than narrow economic interests (e.g., they
include ones reputation in society). Moralizing and other forms of social pressure
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used by environmentalists to bring about change appear to be effective, but this idea
needs more research. Finally, Penn suggests that integrating evolutionary perspectives
into the environmental sciences will help to break down the artificial barriers that
continue to divide the biological and social sciences, which he feels obstruct our
ability to understand ourselves and fully address environmental problems.
The case for such incentives has been highlighted in a study carried out in the
Czech Republic (Tesitel et. al., 2001). During the Communist regime of the 1970s
and 1980s the aesthetic and symbolical relations of humans to nature were not
properly considered either in theory or in practice within urban planning. Based on
surveys undertaken in housing estates in the town of Tabor results suggest that 1 /
Absence of nature, at least in its symbolical form, proved to be the factor limiting the
"pleasant existence" of the people living within the estates. 2/ Low willingness of
inhabitants to actively participate in the process of making their urban environment
liveable seems to remain one of the most crucial problems inherited from the former
totalitarian regime.
Phifer (1999) comes to similar conclusions. He claims that urban biodiversity
is important not only in the provision of tangible goods and services, but also in the
achievement of our psychological and psychosocial well-being –“Without repeated
and spontaneous interactions with other biodiversity, our humanity is challenged”. He
argues that environmental assessments need to take account of psychological impact
as well as the physical and biological. Specifically, he argues that in the USA
environmental assessments often fail to acknowledge the importance of ecological
baselines and the value of an area'
s restoration potential. It is this restoration potential
he feels that could have maximum potential from a human psychological viewpoint.
Further aggravation of environmental problems and apathy towards the issues
in general may be linked to people being ‘un-coupling’ from the natural world.
Comparisons of psychological profiling and the development of folkbiological
knowledge between children brought up in urban and rural environments show stark
differences in appreciation of nature. Research conducted by Ross et. al. (2003) with
urban majority culture children, rural majority culture children, and rural Native
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American (Menominee) children showed that each group produced a unique profile of
development. Only urban children showed evidence for early anthropocentrism, (man
as the ‘centre’ of the universe and that the world exists only for human needs). This
suggests that the co-mingling of psychology and biology may be a product of an
impoverished experience with nature. In comparison to urban majority culture
children even the youngest rural children generalized in terms of biological affinity.
In addition, all ages of Native American children and the older rural majority culture
children (unlike urban children) gave clear evidence of ecological reasoning. These
results show that both culture and expertise (exposure to nature) play a role in the
development of folkbiological thought (and hence influence appreciation of nature
and comprehension of environmental issues). Pyle (2003) echoes some of these
thoughts and states that unless young people have more exposure to the natural world,
the results will be an “inexorable cycle of disconnection, apathy, and progressive
depletion of the environment”. He states that small, humble habitats can be as
important as big reserves in awakening biophilia in young people in urban settings,
but exposure to these, needs to be done in conjunction with nature being given a
greater priority in the educational curriculum.
The biophilia / biophobia theory may also explain results in a couple of recent
psychological studies. In the first, relating to colour preference, Yhang, (1995) carried
out a study to determined how variation in the visibility of green, blue, yellow, and
brown colour in mixed pine-hardwood forests affected perceptions of scenic beauty,
and how season of the year and silvicultural treatment affected these colours. Greater
green visibility was associated with higher scenic beauty estimations, while greater
brown visibility was associated with lower values. Blue visibility detracted from
scenic beauty, while yellow enhanced it. The biophilia hypothesis predicts that,
because of evolutionary processes, humans will be attracted to natural landscapes
containing mostly green vegetation because these promise food, water, and other
basic survival needs. However, humans will be repelled from scenes containing
mostly brown vegetation because these do not satisfy basic survival needs.
The study also demonstrated that season had a significant impact on colour
visibility. Green was most visible in summer, whereas brown was most visible during
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winter. The highest blue visibility ratings occurred in winter and spring, probably
because there was less foliage to screen blue sky during these seasons. Yellow was
most visible in the fall, most likely due to autumn leaf-colour change in hardwoods.
Silvicultural treatment did not affect green or brown visibility.
The second study investigated the influence of nature-orientated and nonnature orientated images on people’s relaxation responses (Segal, 1999). Relaxation
was assessed via heart rate, subjective rating of relaxation, and cold pressor duration
(pain threshold). Thirty-six students served as subjects. Subjects were selected from a
pool based on questionnaire responses of their experiences. Those subjects whose
responses indicated a lack of bias for engaging in either nature or non-nature oriented
activities were selected. Subjects provided pre and post imagery presentation
measures in both conditions for subjective rating of relaxation and heart rate. Each
subject provided cold pressor duration measurements once at baseline and following
each imagery presentation. Results supported the hypothesis that the nature oriented
guided imagery would lead to significantly greater relaxation as measured by both
heart rate and self rating. Cold pressor duration data did not support the hypothesis,
with results for the non-nature images being marginally better-favoured (differences
not significant). Preference data showed that subjects preferred the nature oriented
content over the non-nature oriented content and that overall the results generally
support the use of nature oriented imagery to produce relaxation in applied settings.
In addition to these two studies, work carried out in the Netherlands recently
(de Groot and van den Born, 2003) has attempted to categorise people’s perception of
nature and the landscape. Specifically the study aimed to define 1/ the types of nature
that people distinguish and the levels of naturalness ascribed to these types of nature;
2/ the images that people hold of the appropriate relationship between people and
nature (e.g. mastery over nature, responsibility for nature and participation in nature)
and the level of adherence to these images, and 3/ people'
s preference of broadly
defined landscape types. The results showed that people defined the images roughly
as (1) landscape made by and for people; (2) park-like, arcadian landscape; (3) wild,
interactive landscape and (4) landscape "in which one may experience the greatness
and forces of nature". Strikingly, more than half of the respondents expressed
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preference for this last ('
deep ecology'
) landscape type, with another third preferring
the wild, interactive landscape. The highest preference of the '
greatness and forces'
landscape was found among the respondents adhering to the participation-in-nature
image of relationship. The authors state that the preferences for landscape types as
defined in this study should be distinguished from visual or behavioural landscape
preferences;- even if people may not select landscapes of the '
greatness and forces of
nature'in daily behaviours, these landscapes of wilderness and greatness do connect
with human visions and desires.
Air pollution, Allergens and UV light
Forests in Britain produce social and environmental benefits, in addition to
marketable timber outputs. One such non-market benefit is the reduction in air
pollution, linked to health impacts (mortality and morbidity). A study by Powe and
Willis (2004) assesses the benefits of SO2 and PM10 (air particles with a diameter of
less than or equal to 10 micrometers) absorption by trees in terms of extending life
expectancy of the population and reducing hospital admissions. Working at a
resolution of 1 km2 with woodland over 2 ha, it is estimated that, for Britain as a
whole, woodland saves between 5 and 7 deaths, that would otherwise have been
brought forward, and between 4 and 6 hospital admissions each year. The economic
value of the health effect of woodland is estimated to be at least £900,000 per year.
Smaller areas of woodland, often located closer to population, sometimes strategically
planted close to pollution sources, will generate additional air pollution absorption
benefits to those estimated as a whole. However, the authors claim that health benefits
of woodland are relatively small in comparison to other non-market forestry benefits.
In contrast, there have been conflicting reports related to the role plants play in
indoor environments with respect to allergenic reactions such as asthma and
rhinoconjunctivitis.
Carrer et. al. (2001) state that indoor allergen exposure is
recognised as the most important risk factor for asthma in children and that house dust
mites, pets, insects, plants, moulds and chemical agents in the indoor environment are
important causes of allergic diseases. The authors concentrate of the extent to which
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mites and pets contribute, with limited information on plants. It is not clear if the dust
attracting /absorbing properties associated with plants outweigh the negative factors.
In a study looking at the effects of building characteristics of schools in Sweden, it
was noted that plants had a positive effect in alleviating respiratory problems,
especially in classrooms and in older buildings (Walinder, et. al. 2001).
Data from Canada links outdoor allergens and hospitalisations for asthma.
These results support the hypothesis that air-borne allergens are an important cause of
severe asthma morbidity across Canada (Dales et. al., 2004). Allergens associated
with trees were associated with a 2.9% increase in asthma hospitalisation, with weeds
a 3.0% increase and grass a 2.0% increase. Other allergens such as fungal spores
showed similar increases. After accounting for the independent effects of trees and
ozone, the combination of the 2 was associated with an additional 0.22% increase in
admissions averaged across cities. This was a significant level and suggests that in
some situations there might be a modest synergistic adverse effect of ozone and other
allergens combined.
Carbon Sequestration
A further study has highlighted the issue of carbon sequestration (locking up
of atmospheric carbon dioxide). In this case the report concentrates on soil carbon and
implies enhancing the concentrations/pools of soil organic matter and secondary
carbonates (Lal et. al., 2003). It is achieved through adoption of recommended
management practices (RMPs) on soils of agricultural, grazing, and forestry
ecosystems, and conversion of degraded soils and drastically disturbed lands to
restorative land use. Of the 916 million hectares (Mha) comprising the total land area
in the continental United States and Alaska, 157 Mha (17.1%) are under cropland, 336
Mha (36.7%) under grazing land, 236 Mha (25.8%) under forest, 14 Mha (1.5%)
under Conservation Reserve Programs (CRP), and 20 Mha (2.2%) are under urban
land use. Land areas affected by different soil degradative processes include 52 Mha
affected by water erosion, 48 Mha by wind erosion, 0.2 Mha by secondary
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salinisation, and more than 4 Mha affected by mining. Adoption of RMPs can lead to
sequestration of soil organic carbon (SOC) at an annual rate of 45 to 98 Tg (teragram
= 1 X 10(12) g = 1 million metric tons or MMT) in cropland, 13 to 70 Tg in grazing
land, and 25 to 102 Tg in forestlands. In addition, there is an annual soil C
sequestration potential of 21 to 77 Tg by land conversion, 25 to 60 Tg by land
restoration, and 15 to 25 Tg by management of other land uses. Thus, the total
potential of C sequestration in soils of the United States is 144 to 432 Tg/y or an
average of 288 Tg C/y. With the implementation of suitable policy initiatives, this
potential can be realised within 30 years or when the soil C sink capacity is filled. In
comparison, emission by agricultural activities is estimated at: 43 Tg C/y, and the
current rate of SOC sequestration is reported as 17 Tg C/y. According to Lal et. al.
(2003) the challenge the policy makers face is to be able to develop and implement
policies that are conducive to realization of this potential.
Trees and UV light
The role of trees in urban environments is often documented in relation to
absorbing air pollutants and dust, and modifying microclimate via effects on
temperature, wind and humidity. Less well documented is their interaction with UV
radiation. A report by Heisler et. al., (2002) highlights that many of the effects of
ultraviolet radiation on people and their environment (damage to various materials,
survival of insects and microbial pathogens, growth of vegetation, and adverse or
beneficial effects on human health) are modified by the presence of trees. Human
epidemiological investigations generally consider exposure as given by indices of
UVR irradiance on horizontal surfaces in the open. Though many people are exposed
to UVR while reclining at a beach or swimming pool, thus experiencing irradiance on
essentially horizontal surfaces in the open, exposure to UVR during daily routines in
urban areas may also be important in affecting human health. Exposure to UVB is not
directly related to the degree of shadow that a person or object is subjected to. Tree
influences on UVR irradiance, particularly in the UVB, can differ substantially from
those influences on the visible portion of the solar spectrum. Trees greatly reduce
UVB irradiance in their shade when they obscure both the sun and sky. Where trees
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obscure the sun but leave much of the sky in view, UVB irradiance will be greater
than suggested by the visible shadow. In small sunny areas near trees that block much
of the sky from view, UVB irradiance is reduced substantially, whereas visible
irradiance may be nearly as great or slightly greater than in the open.
References
Carrer P., Maroni M., Alcini D., Cavallo D. (2001). Allergens in indoor air:
environmental assessment and health effects. Science Of The Total Environment 270
(1-3): 33-42 Sp. Iss.
Dales R.E., Cakmak S., Judek S., Dann T., Coates F., Brook J.R., Burnett R.T.
(2004). Influence of outdoor aeroallergens on hospitalization for asthma in Canada.
Journal Of Allergy And Clinical Immunology 113 (2): 303-306
de Groot W.T., van den Born R.J.G. (2003). Visions of nature and landscape type
preferences: an exploration in The Netherlands. Landscape And Urban Planning 63
(3): 127-138
Heisler G.M., Grant R.H., Gao W. (2002). Urban tree influences on ultraviolet
irradiance. Proceedings Of The Society Of Photo-Optical Instrumentation Engineers
(spie) 4482 277-290
Lal R., Follett R.F., Kimble J.M. (2003). Achieving soil carbon sequestration in the
United States: A challenge to the policy makers. Soil Science 168 (12): 827-845
Penn D.J. (2003). The evolutionary roots of our environmental problems: Toward a
Darwinian ecology. Quarterly Review Of Biology 78 (3): 275-301
Phifer P.R. (1999). Conservation biology and urban sustainability: Policy and
practice.Dissertation-Abstracts-International:-Section-B:-The-Sciences-andEngineering 59(8-B): 3991
Powe N.A., Willis K.G. (2004). Mortality and morbidity benefits of air pollution
(SO2 and PM10) absorption attributable to woodland in Britain. Journal Of
Environmental Management 70 (2): 119-128
Pyle R.M. (2003).
Oryx 37 (2): 206-214
Nature
matrix:
reconnecting
people
and
nature
Ross N., Medin D., Coley J.D., Atran S. (2003). Cultural and experiential differences
in the development of folkbiological induction. Cognitive Development 18 (1): 25-47.
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Segal, P.S. (1999). The effects of nature-oriented and non-nature-oriented guided
imagery content on relaxation. Dissertation-Abstracts-International:-Section-B:-TheSciences-and-Engineering 59(8-B): 4484
Tesitel J., Kusova D., Bartos M. (2001). Tabor. Landscape And Urban Planning 53
(1-4): 29-36
Walinder R., Norback D., Wieslander G., Smedje G., Erwall C., Venge P. (2001).
Acoustic rhinometry and lavage biomarkers in relation to some building
characteristics in Swedish schools. Indoor Air 11 (1): 2-9
Yhang, W. (1995). The effect of color on the perceived scenic beauty of pine-oak
plots in the Ouachita National Forest, Arkansas. Dissertation-Abstracts-InternationalSection-A:-Humanities-and-Social-Sciences. 56(2-A): 0703.
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