{"id":1782,"date":"2012-12-19T13:01:25","date_gmt":"2012-12-19T18:01:25","guid":{"rendered":"http:\/\/www.thenatureofcities.com\/?p=1782"},"modified":"2015-06-01T14:20:30","modified_gmt":"2015-06-01T18:20:30","slug":"natural-disasters-and-the-nature-of-cities","status":"publish","type":"post","link":"https:\/\/www.thenatureofcities.com\/TNOC\/2012\/12\/19\/natural-disasters-and-the-nature-of-cities\/","title":{"rendered":"Natural Disasters and the Nature of Cities"},"content":{"rendered":"

Environmental traumas are here. \u00a0Global climate is a reality that is bringing extremes in weather as we have seen recently with the devastating impacts of Hurricane Sandy in the northeast of the USA. \u00a0And in the last several years there have been massive earthquakes that have devastated cities in Japan, Haiti and New Zealand. \u00a0To manage the effects of these traumas on the urban environment, we first must identify the socio-ecological drivers governing the urban ecosystems and then ascertain the degree of departure of the \u201cnew-normal\u201d state from the pre-trauma conditions. \u00a0Individual and institutional responses set the trajectory of recovery and subsequently create a \u201cnew-normal\u201d not only for ecological but also social systems.<\/p>\n

The Christchurch earthquakes that began in September 2010 provided a unique opportunity to address the impacts of traumas on the urban environment and in particular, identifying \u201cresilient\u201d components of coupled ecological-social systems. \u00a0In this blog I will outline a study focussing on urban vegetation succession post-earthquakes. \u00a0 In later contributions I will update the findings of this study based on further data analysis and discuss other aspects, such as the effects on urban fauna, and implications and options for future urban greening thru ecological design.<\/p>\n

The Christchurch earthquakes<\/strong><\/p>\n

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Images of the devastation following the magnitude 6.3 earthquake in February, 2011.\u00a0 http:\/\/www.healthybeing.co.nz\/christchurch_earthquakes.html<\/a><\/figcaption><\/figure>\n

A shallow earthquake<\/a> of 7.1 magnitude<\/a> struck the South Island<\/a> of New Zealand at 4:35 am on 4 September 2010. \u00a0The quake caused widespread damage and several power outages, particularly in the city of Christchurch<\/a>, New Zealand’s second largest city. \u00a0Mass fatalities were avoided as the quake during the night when most people were off the street.<\/p>\n

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http:\/\/www.stuff.co.nz\/national\/christchurch-earthquake\/photos\/4688271\/Christchurch-quake-the-first-images<\/a><\/figcaption><\/figure>\n

Aftershocks have continued into\u00a02012 with some causing significant damage themselves. \u00a0The strongest to date<\/a>, of magnitude 6.3, occurred on 22 February 2011. \u00a0Because this was centred very close to Christchurch and it occurred during the day, it was much more destructive, with 185 fatalities. \u00a0Significant liquefaction<\/a> affected the eastern suburbs, producing around 400,000 tonnes of silt. \u00a0The total cost to insurers of rebuilding has been estimated at NZ$15 billion, making it by far New Zealand’s costliest natural disaster, and the third-costliest earthquake (nominally) worldwide.<\/p>\n

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Soil liqu\u00e9faction resulting from the earthquake.\u00a0 http:\/\/liquefactionmitigation.weebly.com\/problem-statement.html<\/a><\/figcaption><\/figure>\n

In the aftermath of the earthquakes (and there have been >12,000 aftershocks as I write this) significant decisions meant that several parts of Christchurch city would not be re-built as the ground was deemed too unstable. \u00a0This residential \u201cred zone\u201d (see the map below) includes over 7,000 residential properties which have been abandoned and are being progressively demolished.<\/p>\n

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Liquefaction in the eastern suburbs of Christchurch. http:\/\/www.ngdc.noaa.gov\/hazardimages\/picture\/show\/1432<\/a>. Credit: New Zealand Defence Force.<\/figcaption><\/figure>\n
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The Christchurch residential \u201cred zone\u201d along the Avon River in Christchurch. The CBD is at the bottom left of this map. Credit: http:\/\/www.headliner.co.nz\/news\/6433.html<\/a>.<\/figcaption><\/figure>\n

The current proposal for the residential \u201cred zone\u201d is to convert it into a public park called Avon-Otakaro (see the map below). \u00a0Here is an excerpt from the Avon-\u014ctakaro Network<\/a> [AvON] charter:<\/p>\n

\u201cAvon-Otakaro is a network of individuals and organisations promoting the future use of the residential red zone lands as an ecological and recreational reserve. We wish to establish a community-driven science-informed living memorial to rejuvenate and nurture the long-term environmental, economic, community and spiritual wellbeing of the eastern suburbs and of those living throughout greater Christchurch. Our aim is to turn a tragedy into an opportunity, a polluted drain into a vibrant river system, and exhaustion and despair into hope and inspiration.\u201d <\/em><\/p>\n

Various volunteer groups have been collecting ecological information on the area, particularly on the occurrence of notable mature native and exotic trees that should be preserved.<\/p>\n

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Map of Avon-Otakaro Network urban woodland proposal Credit: http:\/\/www.avonotakaronetwork.co.nz\/<\/a><\/figcaption><\/figure>\n

Vegetation dynamics in the residential \u201cred zone\u201d<\/strong><\/p>\n

The majority of the properties in this zone were abandoned after the earthquakes in September 2010 or February 2011 with little or no subsequent maintenance to gardens and road verges. \u00a0We sampled 100 properties over 9 suburbs with a view to determining the regeneration responses of native and exotic woody tree and shrub species after abandonment. \u00a0The regeneration of native species has been rapid and, in some situations, prolific.<\/p>\n

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Native Plagianthus regius (lowland ribbonwood) seedlings 1.5m tall established on silt (liquefaction) in the front garden of a residential property. Photo: Glenn Stewart.<\/figcaption><\/figure>\n

In the absence of garden management we are seeing a \u201cnew\u201d vegetation dynamic driven by new substrate availability, dispersal of seeds by birds, and the presence of surviving seed sources. \u00a0The most common native seedlings are cabbage tree (Cordyline australis<\/em>), Coprosma<\/em> spp. Pittosporum tenuifolium, P. eugenioides<\/em> and Solanum aviculare<\/em>, all of which have fleshy fruits and are dispersed by birds. \u00a0There has also been a dramatic increase in seedlings of exotic species as well. \u00a0Examples include Scotch Broom (Cytisus scoparius<\/em>), Elderberry (Sambucus nigra<\/em>), Prunus<\/em> spp., Sycamore (Acer pseudoplatanus<\/em>), and Buddleja <\/em>spp. \u00a0This is not surprising as disturbed substrates and a high light environment provide an ideal environment for exotic invasion, especially if persistent seed banks are already present.<\/p>\n

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Native Coprosma repens seedlings established in an untended \u201cherbaceous border\u201d in a residential property. Photo: Glenn Stewart<\/figcaption><\/figure>\n

Substantial planting of native trees and shrubs in city residential gardens over the last several decades has provided a seed source for this regeneration. Seedlings are more abundant in suburbs with more mature native trees and also with greater numbers of \u201cperch\u201d trees (for bird-dispersed species). \u00a0There was also a distinctive pattern of compositional change in native species (seedlings) with increasing distance from the coast. \u00a0For example, the dioecious shrub Coprosma repens<\/em> (naturally a coastal species) was more prevalent close to the coast. Prior to the earthquakes this species would not have been as common as it is not regularly planted in residential gardens. \u00a0But after property abandonment it is increasing rapidly as a result of natural successional processes.<\/p>\n

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A typical \u201cabandoned\u201d property in the residential \u201cred zone\u201d, Christchurch. NB the front lawn now resembles an unkempt pasture and contains abundant exotic herbaceous and woody weeds. Photo: Glenn Stewart.<\/figcaption><\/figure>\n

Conclusions and further research<\/strong><\/p>\n

Early indications are that the native flora is remarkably resilient. \u00a0So much so that it seems certain that in the absence of human interference a substantial native-dominated urban forest will establish in the residential \u201cred zone\u201d.<\/p>\n

On the other hand, vigorous and intensive on-going management will be required to control exotic species that are both adaptable and aggressive. \u00a0The introduction of other native species that currently lack a seed source would also increase biodiversity and offer other important food sources for native birds, lizards and invertebrates. \u00a0This area (Avon-Otakaro) has the potential to add to the rich tapestry of natural habitats in the city and become an area of considerable native biodiversity.<\/p>\n

The preliminary results from our pilot study highlights the need for further studies of vegetation dynamics in urban landscapes and the nature of chronic and catastrophic disruption on the mechanisms of and management of vegetation within the context of dynamic physical, social and ecological systems.<\/p>\n

The preliminary results from our pilot study highlights the need for further studies of vegetation dynamics in urban landscapes and the nature of chronic and catastrophic disruption on the mechanisms of and management of vegetation within the context of dynamic physical, social and ecological systems.<\/p>\n

\u00a0\u201cIt is estimated that 220 natural catastrophes, 70 technological disasters and 3 new armed conflicts occur each year\u201d.\u00a0Alexander (2005)<\/a><\/em><\/p>\n

The urban environment and community are key indicators and drivers of a nation\u2019s adaptability and resilience to catastrophic events such as earthquakes, fires, floods, tsunamis, dust storms and hurricanes.\u00a0Yet the urban environment is often ignored or is an afterthought in planning even though accessible and diverse green space is regarded as a predictor of human health, happiness, equity, and biodiversity.\u00a0 In fact, the value of urban green space and more specifically biodiversity is critical to providing ecosystem services, services used by humans to survive and live and achieve resilience in the face of impending global disruption and despite the coming associated environmental and economic trauma(s).<\/p>\n

Glenn Stewart
\nChristchurch, New Zealand<\/p>\n

__________________<\/p>\n

Alexander, D (2005). Towards the development of a standard in emergency and planning.\u00a0Disaster Prevention & Management<\/em>\u00a014: 158-175\u00a0<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Environmental traumas are here. \u00a0Global climate is a reality that is bringing extremes in weather as we have seen recently with the devastating impacts of Hurricane Sandy in the northeast of the USA. \u00a0And in the last several years there have been massive earthquakes that have devastated cities in Japan, Haiti and New Zealand. \u00a0To […]<\/p>\n","protected":false},"author":30,"featured_media":6943,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[273,299,297],"tags":[401,448,66,33],"coauthors":[164],"class_list":["post-1782","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-essay","category-essay-place-and-design","category-essay-science-and-tools","tag-biodiversity","tag-disastersred-zone","tag-parks","tag-resilience"],"_links":{"self":[{"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/posts\/1782","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/users\/30"}],"replies":[{"embeddable":true,"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/comments?post=1782"}],"version-history":[{"count":0,"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/posts\/1782\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/media\/6943"}],"wp:attachment":[{"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/media?parent=1782"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/categories?post=1782"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/tags?post=1782"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.thenatureofcities.com\/TNOC\/wp-json\/wp\/v2\/coauthors?post=1782"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}