As a highly coastal city, rising sea levels are likely to have the greatest impact on Auckland in the shortest time period, especially when high tides coincide with severe storms. But droughts are also on the rise in Auckland and other dry parts of Aotearoa New Zealand. Both the frequency and severity of droughts is increasing according to regional climate change projections.
Potential impacts of drought include water scarcity in our water supply catchments, reductions in productivity of food crops and health declines for native vegetation. The 2013 drought cost an estimated $1.3 B in lost agricultural production but the impacts on natural landscapes, including forests, wetlands and other rarer ecosystems, are less clear. Potential impacts include reductions in carbon uptake, slowing of nutrient cycles and in the worst cases, death of vulnerable plants.
My research team is exploring native plant responses to dry periods using several approaches. First, we have established baseline responses of plant water use and growth patterns to current daily and seasonal variations in climatic conditions. We use manipulative experiments (in the shade house and the field) to dry plants while we measure their responses to define stress limits. Finally, we are using remote sensing to look at the distribution of different impacts across different types of forest. We’re finding some good evidence that native forests are reasonably reslient when it comes to drought but we don’t know if they can survive more severe or frequent drought.
Forests can be a fantastic solution to a changing climate because they capture and store CO2 from the atmosphere. But if forests are destroyed by fire or die during drought, the carbon is lost back to the atmosphere. Our best solution is to reduce greenhouse gas emissions. We need to get smart about energy and agricultural emissions. We also need to find ways to protect our coastal areas or at least stop building houses on coastal sand dunes.
I commend Auckland Climathoners for their determination and drive to help ensure Auckland has a bright future – and I hope our native trees and vegetation stay top of mind as the creativity, collaboration and soultion-focused thinking, doing and making begins.
Dr Cate Macinnis-Ng is a Senior Lecturer at the University of Auckland’s School of Biological Sciences in the Faculty of Science. Her research includes plant responses to climatic conditions, carbon fluxes in native forests, and the impact of drought on NZ forests. Read more about Cate Macinnis-Ng
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