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Mountain Water and Life

Climate Change in Mountain Environments (part 2)

From rain to snow, erosion and more, there are many potential effects of climate change on water in the mountains. In this issue we take a look a few likely scenarios in relation to some important watery places.

Extreme events are an obvious area of interest. More extreme or more frequent events such as floods and droughts affect waterways not just in the mountains, but all the way down to the sea. In places where drier conditions prevail, the beds of waterways may become hardened, especially if vegetation is lost along the margins. When rain does come it contributes to ‘flashy’ run-off patterns (because little water soaks into the ground), and has effects on the risk of flooding further downstream. In wetter places large floods may become more frequent and new erosion patterns are a potential concern.

The flow of water is itself a major aspect of healthy waterways. In mountain areas snow-melt can help maintain stream flows for substantial parts of the year. A reduced snowpack can translate to an earlier peak in the spring flows and more likelihood of very low flow levels as the summer months come on. Lower flows also affect water temperature not only in the hills but right throughout the catchment areas. As a result, impacts on cold-water species, including fish, are expected in New Zealand due to climate change. Unfortunately, that is just the tip of the iceberg. Climate change has the potential to cause many effects on our native species, especially in places where there isn’t much room to move.

Water is essential for all life and the amount, timing, and quality of what’s available can all have large effects. Wetlands and floodplains are areas that may be especially vulnerable. Those places have already been heavily impacted by historical change and are important to protect for their many unique plants and animals. There are also whole systems that may disappear if conditions become unfavourable.

So what can we do? On the one hand climate change is actually nothing new. Many negative effects are expected as a result of the compounding of existing stresses rather than the changing climate itself. Erosion, pollution, and the spread of invasive species and diseases are all in that category. The most problematic aspect could simply be that the rate of change is much faster than in recent history and will be difficult to deal with. It may not be possible to cover every scenario but reducing existing impacts where we can and keeping alert to what’s changing are obvious places to start.

Living snow banks

That’s right, snow banks are an official ecosystem! In dry places that wind-drift behind your favourite bank feature can be the key to a thriving ecosystem over the summer months. In these systems, the slowly melting snow provides essential moisture for specialist colonist plants, which in turn promote soil formation upon which other plants depend. The result is a unique and diverse oasis of life in an otherwise hostile environment. Snow bank systems have thin soils that are often soft and easy to damage. If you see one, give it a wide berth to help it stay intact until the snows come again!

by Shane Orchard

Colourful snow bank ecosystems in the Sinclair valley, Rangitata headwaters. Photo: Shane Orchard

Colourful snow bank ecosystems in the Sinclair valley, Rangitata headwaters.
Photo: Shane Orchard

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Colourful snow bank ecosystems in the Sinclair valley, Rangitata headwaters. Photo: Shane Orchard


This article first appeared in The Climber issue 94. You can view the full issue at climber.co.nz.

Posted: 30/08/16

Posted By: Kester Brown