Cambridge Tree Trust

www.treetrust.org.nz

A very wet summer

It has been a very wet summer in the Waikato. According to my records in the last 6 months we have had about 700 mm rain, compared to the same period last year when we had 300mm. Last year the Tree Trust was obliged to water some of the trees we had planted, this year we cannot keep up with the weeds! This photo was taken in the maple arboretum two weeks ago showing some of our team dwarfed by head-high weed growth. We often cart away three truckloads of weeds and nd ourselves still unable to keep up. However, the good news is that the trees too are growing at the rate of knots. But even that brings its challenges when Cyclone Gabrielle broke some of the biggest and most beautiful maples in the arboretum, not to mention many other trees around Cambridge. There has been much talk since the cyclone of the importance of ‘sponge cities’ in which urban landscapes work with nature to absorb rainwater, rather than using ever-larger concrete structures to channel it away.

David Hall, a New Zealand contributor on climate adaptation to the Intergovernmental Panel on Climate Change, is quoted in the recent ‘Listener’ saying ‘Urban trees manage to capture or delay water ows from extreme rainfall … you might get 30% captured in the canopy and then returned to the atmosphere through evapotranspiration. This means you are not getting the [same] ashooding.’

There is no single solution but ‘green infrastructure is often the most cost-e ective intervention’, [besides being good for physical and mental health, biodiversity and carbon sequestration.] So despite the challenges we need to plant more trees in urban areas, in streets, gullies, wetlands and gardens.

Cambridge Tree Trust would like to thank Mitre 10 for their support for these monthly articles which are intended to raise interest and awareness of trees in Cambridge.