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Native ecosystems – the best risk managers

Native ecosystems – the best risk managers

Image: Steve Attwood, Nina Valley

Native ecosystems – the best risk managers 

“Restoring a third of the areas most degraded by humans and preserving remaining natural ecosystems would prevent 70% of projected extinctions of mammals, birds and amphibians. It would also sequester around 465 gigatonnes of CO2—almost half of the total atmospheric CO2 increase since the Industrial Revolution.” Strassburg et al, 2020.

“Healthy and functional ecosystems help reduce climate change vulnerability and disaster risk by:

  • Reducing physical exposure to hazards by serving as protective barriers or buffers and so mitigating hazard impacts, including in wetlands, forests and coastal ecosystems; and
  • Reducing socioeconomic vulnerability to hazard impacts: sustain human livelihoods and provide essential goods such as food, fibre, medicines and construction materials, which strengthen people’s resilience to disasters.” Convention on Biological Diversity
Fig 1: Click on this map to be taken to the interactive ‘Christchurch natural ecosystems map’: a key to help you unlock the nature of your place. This map may appear differently when you click on it, as it is being updated and expanded to include the Banks Peninsula and other areas. It includes a native plant list guide for nurseries, designers, and the public to know what naturally belongs within different parts of the greater city, and what growing conditions each species prefers. Note that that areas around rivers are braidplains that were naturally free of all but a few low-lying hardy braided rivers plant species. Restoring these areas means removing introduced trees, pest weeds, and in some areas pasturelands.


“Ecosystem-based adaptation (EbA) should be integrated into broader adaptation and development strategies to maintain and increase resilience and reduce vulnerability of ecosystems and people to adverse effects of climate change.

“EbA is the use of biodiversity and ecosystem services as part of an overall adaptation strategy to help people adapt to the adverse effects of climate change. EbA aims to maintain and increase the resilience and reduce the vulnerability of people and the ecosystems they rely upon in the face of the adverse effects of climate change. There are various interpretations of EbA, but all share the rationale of working with nature, and most converge on the principle of sustainable management, conservation and restoration of ecosystems, as part of an overall adaptation strategy.

“Examples of ecosystem-based disaster risk reduction include restoring coastal vegetated areas such as mangroves to protect shorelines from storm surges; managing invasive alien species linked to land degradation and that threaten food security and water supplies; and managing ecosystems to complement, protect and extend longevity of investments in hard infrastructure.

“In many cases, of ecosystem-based disaster risk reduction activities are the same as EbA activities implemented to reduce disaster risk. For example, maintaining and improving the functionality of protection forests is also a key activity within the some countries’ climate protection programmes. Because of the important role of forests in mitigating the risks posed by natural hazards, these programme aim to improve the stability and functionality of forest stand structures, foster adapted species mixtures, promote natural regeneration, prevent forest fires and/or control pests and diseases. “Convention on Biological Diversity

Protect, restore, rebuild

Having recognised the role of ecosystems in helping us mitigate and adapt to climate change, we now need to consider the options available to us.

Option 1 protect what we have: is the most cost-effective in terms of dollars, labour (voluntary as well as paid), biodiversity and cultural outcomes, immediately helps reduce the risks outline above, and prevents more carbon dioxide from entering the atmosphere. In many cases, they also sequesters carbon underground through soils and the formation of peat (although this aspect often fails to be recognised in the carbon trading system).

Option 2 restore those that are damaged, is, depending on the scale and area to be restored, more expensive and less immediately effective than Option 1. In the short-to-mid term, however, this option helps reduce the risks outlined at the top of this page and draws excess carbon dioxide from the atmosphere.

Option 3 re-instate those that have been lost; is costlier and takes longer. However, because we have destroyed so many of these ecosystems, once they begin to grow they will draw far greater volumes of excess carbon dioxide from the atmosphere, help mitigate risks, and provide long term ecosystem services.


It can take decades to centuries to reinstate natural forests, but there are cost effective and proven strategies to achieve this by encouraging regeneration bordering existing pockets of native forests.

Reinstating  ‘wet’ ecosystems including salt water marshes, sea grasses, kelp forests and freshwater wetlands is faster, and crucially, rapidly absorb far higher quantities of carbon dioxide than many established ecosystems.

Resinstating braidplains lost to agriculture and weeds will reduce the risk and scale of flooding and deliver a greater volume of gravels to the coast to replenish coastal margins increasingly at risk of erosion from rising sea levels.

“The conventional wisdom is that you harvest flood water in the winter and store it until it’s needed (for agriculture) in the summer. However, floods are required to carry gravels to the coastal zone and if there’s not enough gravel, the waves get hungry and start eroding the land.” Dr Scott Lanard, NIWA