Study finds Australian drylands are vulnerable to negative impact of overgrazing

Western Sydney University

A new international study including researchers from Western Sydney University has found that increased grazing can have positive effects on ecosystem services, particularly in species-rich rangelands, but these effects can turn negative in warmer, species-poor drylands, a landscape common in Australia.

Published in Science , the study suggests that considering local conditions when managing livestock and herbivores in drylands is crucial, as the effects of grazing, particularly over grazing, vary across the globe.

Unlike previous studies on the matter, the research, conducted across 326 drylands located in 25 countries and 6 continents, assessed the impacts of increased grazing pressure on the capacity of drylands to deliver nine essential ecosystem services, including soil fertility and erosion, forage and wood production and climate regulation.

Co-author Distinguished Professor Brajesh Singh, from Western Sydney University’s Hawkesbury Institute for the Environment, said the findings of the study are particularly relevant within Australia.

“About 75 per cent of the Australian continent is comprised of drylands, compared to 41 per cent of global land. Evidence from this research suggests that Australian dryland ecosystems with low plant biodiversity and high temperature are vulnerable to the negative impact of overgrazing,” said Distinguished Professor Singh.

“The study shows us that we must preserve the biodiversity of our drylands, so they can continue to function optimally and deliver essential services for people across Australia and also reduce the impact on climate change.”

When subject to increased grazing pressure, carbon stocks decreased and soil erosion increased, something that was not observed under low grazing pressure. The researchers also observed that higher rates of diversity in plant and herbivore species was positively linked to the provision of essential services such as carbon storage, which plays a fundamental role in climate regulation.

The findings of this study highlight the importance of achieving a more sustainable management of grazing – an essential land use that sustains the livelihood of billions of people linked to many of the United Nation’s Sustainable Development Goals, as well as establishing effective management and restoration actions aimed at mitigating the effects of ongoing climate change and desertification across global drylands.

“Not only does grazing play a vital role in maintaining biodiversity and proper functioning of ecosystems, but it also maintains animal community, promotes plant diversity and nutrient cycling, ultimately effecting the productivity of ecosystems,” said Distinguished Professor Singh.

Western Sydney University’s contribution to this research was funded by the Australian Research Council (Discovery program).

The study titled, ‘Grazing and ecosystem service delivery in global drylands’ is available to download here .

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