Global Climate Change

By clearing vegetation and burning fossil fuels human beings are drastically increasing the concentration of carbon dioxide (CO2) in the atmosphere. CO2 is the main greenhouse gas and is associated with the shift in the greenhouse effect that is leading to global warming. While global warming is enough to worry about in its own right, the CO2 itself has a direct impact on plants and therefore on ecosystems, since plants use CO2 as the raw material out of which they construct sugars, proteins, oils, leaves, wood, flowers, fruit and all ultimately all food on the surface of the planet. Plants are very sensitive to changes in the concentration of CO2 in the atmosphere, and therefore all other living things are also affected by changes in the concentration of CO2

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The concentration of CO2 is increasing rapidly (see figure above). So is the global temperature (see figure below). The impacts of these two factors are likely to be immense for both natural and managed ecosystems. The TasFACE experiment is one of only a handful in the world that is examining the impact of both increasing CO2 concentration and global warming on an intact ecosystem

Southeastern Australian grasslands

Grasslands of southeastern Australia are of immense importance both in conservation terms and as an agricultural resource. Since European settlement, 99% of Australia’s natural temperate grasslands have been destroyed or significantly modified, making them perhaps the vegetation type most altered in southeastern Australia. However, modified grassland or “native pasture” still occupies large areas in southeastern Australia. In Tasmania, for instance, “native pasture” accounts for approximately 40% of the 1.3 million hectares of grazed lands. Furthermore, these grasslands contain a large number of threatened genotypes, species and communities, making the successful management of grassy vegetation a crucial aspect of maintaining biodiversity. Grassy vegetation also has great economic importance, since these vegetation types are used extensively for cattle and sheep production. It has been shown that the health of native pasture is declining, which is a matter of concern to both the grazing industry and the conservation community.

The major problems identified for the southeastern Australian grasslands include:

So far, work on the management of native pastures in southeastern Australia has not considered the impact of global climate change. However, the very factors that are seen as the major problems in pasture decline, namely loss of native perennial grasses and the proliferation of weeds, are highly likely to be exacerbated by global climate change. The increase in atmospheric CO2 is a particularly important determinant of the changes to species composition, as evidenced in much research from other parts of the world.

This project aims to investigate the likely impacts of global climate change on southeastern Australian native pasture by determining the effects of elevated CO2 and temperature on the physiology, growth, reproduction and recruitment of pasture species, as well as on species composition, overall pasture productivity and nutritional quality. It also aims to investigate the individual and interactive effects of increases in temperature and increases in CO2, thereby increasing our ability to predict pasture responses to different climatic scenarios.