Improved field facilities to study climate change impacts and adaptations in pasture
Authors: Mark Lieffering; Paul Newton
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Introduction
Climate (or more properly global) change describes a complex of changes in the environment that are currently happening and expected to continue into the future. The most predictable of these is an increasing concentration of CO2 in the atmosphere (Newton et al 2006). Against this background of higher CO2 we can also expect to see higher temperatures and changes in patterns of rainfall (Mullan et al 2008). Experimentation is essential to understanding the impacts of climate change as our ecosystems are being exposed to combinations of factors that are beyond our experience.
Experimental studies of climate change impacts are difficult: it is essential to avoid artefacts introduced by the experimental method and to continue the experiment for sufficiently long periods so longer term biogeochemical responses are captured. In New Zealand, it is also essential to study pastoral systems under grazing by animals as the presence of animals markedly modifies ecosystem responses to climate change (Newton et al 2005). To meet these criteria we have constructed a Free Air Carbon Dioxide Enrichment (FACE) facility to enable us to study the effects of future levels of atmospheric CO2 on grazed pasture ecosystem processes. Ours is one of a number of such experiments internationally but the only one to include grazing animals, making it a unique facility. Our experiment is described as the NZFACE by the international community ((see http://cdiac.esd.ornl.gov/programs/FACE/face.html). The NZFACE has been running for 10 years looking at the impact of the concentration of CO2 expected in 25–30 years (a selection of publications from this experiment is provided in the Appendix).
In terms of results from the NZFACE, we have found that the initial impact of elevated CO2 on plant photosynthesis cascades through the ecosystem and ultimately influences the cycling of nutrients in the soil, the amount and quality of herbage available for animals and the soil drainage characteristics among others. Many of these changes occur over a number of years; this makes the NZFACE experiment an extremely valuable resource as it has been running long enough to capture these long term impacts and thus avoids the misleading results that can be produced from short term impact studies.
Our intention now is to extend our understanding of climate change impacts on NZ pastoral systems by introducing a warming treatment into the NZFACE. Worldwide, night time air and soil temperatures have been rising twice as fast as daytime (IPCC, 2007). This greater increase in night time temperatures has led to projections for New Zealand of decreases in the number of frost days (Mullan et al 2008).
MAF funding in 2008 has enabled us to design and test a warming treatment. In this report we discuss some of the issues related to warming large areas of vegetation, describe our method of choice and present the results of a design and testing process leading to installation of this treatment in the NZFACE.
Contact for Enquiries
Sustainable Land Management and Climate Change
MAF
Pastoral House
25 The Terrace
PO Box 2526, Wellington
Tel: 0800 CLIMATE (254 628)
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