Importance of Domestic Garden in Supporting Urban Green Infrastructure

Introduction

Domestic gardens have been a significant component in urban green infrastructure and recent research also has highlighted its positive role in terms of eco system services [1, 2] in addition to health issues [3]. Yet, the term urban green infrastructure itself is often ill defined [21] as it covers a wide range of landscape types such as green corridors, urban forests, parks, public green space, allotments, private gardens, etc. Due to its different morphology and associated complexity, green infrastructure has posed certain problems to assess its contribution to urban planners as well. Even urbanization tends to decrease the portion of area which is dedicated to gardens [4, 5].Within this context, domestic gardens play a major role in green infrastructure [6] though less attention is given to their relative value and importance.

Carbon Balance and Energy Conservation

In the past, gardening was viewed as an environmental friendly approach. But this notion has been questioned with the evolvement of garden activities in the present scenario as today’s gardeners heavily depend on fertilizers, pesticides along with mechanized tools. As a result, carbon dynamics of the domestic garden is variable due to its available vegetation types, design and management.
In domestic gardens, an average of 2.5 × 10³ g m⁻² of carbon is stored with 16% in trees and shrubs, 83% in soil (to 600 mm depth) and only 0.6% on average in grass and herbaceous plants [7]. Even a less impact in terms of CO₂ release has been reported in gardens that mimic low maintenance meadow landscapes, forests or follow practices aligned with permaculture principles such as low chemical use, heterogeneous vegetation, minimum soil cultivation, use of recycled water and organic matter etc [8, 9]. Although urban trees provide such environmental benefits with a significant volume of carbon, it has a minor impact compared to the storage of carbon (359 × 10¹⁵ g carbon) in the world’s forests [10].
Urban trees are one of the factors providing cooling via shade and evapo-transpiration. They are estimated to offer over 950 MJ (almost 270 kWh) cooling per day, per tree, solely due to evapo-transpiration effects [11]. Though 25% of non-woodland trees in the urban matrix account for domestic gardens [12], the extent to which domestic garden contribution to cooling is unclear. It has been predicted that up to ¼ of cooling effect by urban trees in USA cities may relate to street/garden trees which directly contribute in cooling of adjacent buildings [13]. This can vary due to species, tree size, maturity and architecture [14].

Biodiversity

Obviously, domestic gardens will never replace natural habitats which are rich with species. Nevertheless, it can be viewed as an alternative which provides close encounters with nature to urban residents. It has been quite evident that the value of urban gardens for biodiversity may be substantial [20]. By several studies, the potential importance and enhancing ways of domestic gardens to biodiversity have been highlighted. The BUGS project for example which surveyed 61 domestic gardens in Sheffield, UK [22] confirmed that collectively such private gardens reasonably can be described as the UK’s important nature reserve. It also demonstrated that, small city centre gardens tend to support much the same invertebrate wild life compared to large suburban gardens where the isolation from countryside and the size do not seem to be a problem at all. In Toronto, Canada small field microcosms which were introduced into gardens recruited seeds, plants and invertebrates in a similar way as those placed in forest or grassland [23]. It has been reported by a recent research that gardens in Manhattan, New York, USA with flower rich patches were able to support pollinator communities as well [24].

Usage of Water

Heavy water usage is associated with domestic gardens where the potable water proportion rises with increased aridity especially during periods of dry weather. For example, in Barcelona, Spain an average of 30% of household water is consumed within the garden where it goes to 50% during summer [15]. It signals a clear indication that water usage of domestic gardens must be assessed systematically restricting potable usage of water by giving much more attention to water storage units (eg. water butts), grey water usage, efficiency of garden water usage (eg. seep hose irrigation).
Apart from that, vegetation found in domestic gardens especially trees, provide interception in precipitation while holding water temporarily within their canopy and thus reducing the peak flow [16]. Additionally, vegetation mitigates risk of floods by reducing surface flow and increasing infiltration into the soil [17]. Despite such benefits, paving in domestic gardens has been increased. It has been reported that 13% increase in impervious surfaces over 30 years in Leeds, UK where 75% was due to residential paving of front gardens [18]. This was linked with sever and frequent flooding in the particular area. From 2008, permission is required for impermeable paving as the benefits of vegetative front gardens have been recognized by the UK planning system [19].

As Therapeutic Landscapes

The domestic garden can influence on an individual’s well being and it can relate to the attitude towards gardening. Some individuals may view as a land resource for providing food and not appreciate the aesthetic nature of domestic garden. Actually, gardening encourages and provides opportunities for high physical activity. Particular studies that primarily focused on gardening and related activities highlight certain benefits such as lower blood pressure, reduced mortality, lower cholesterol level and higher bone density [25, 26]. To maximize the health benefits consistent gardening throughout the year should be encouraged. Even gardens facilitate some or all of the components identified with Attention Restoration Therapy (ART) and greatest restoration was provided by the landscapes which contained increased natural features [27].
Yet, in reality most of the individuals who garden may not be consciously aware of health issues. Hence the health scope of domestic gardener should be investigated in detail as gardening can be viewed as an antidote to associated changes of life style.

Finally…..

The attitude towards domestic garden is different though it is an essential component in our life style which provides an opportunity to be a part of nature. It plays a vital role in minimizing surface runoff of stormwater while providing a natural wildlife habitat in the urban environment. It also provides a platform for promotion of exercises and stress relief with linked benefits of human well being. Even new housing development schemes tend to have communal green areas by removing or providing a less private garden space for each individual. So, the potential of domestic gardens should be realized via community educational programmes especially as the current society tends to displace from nature more and more at a regular pace.

References

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