GRASSLANDS

Grasslands are areas with few natural trees or shrubs and are dominated be grasses as the name suggests.  These are some of the world’s most iconic landscapes – think of the plains of the Serengeti in Africa, the savannas of North America and the steppes of Europe and Asia. 

Here on the Plains grasslands are a vital part of our livestock business supporting significant cattle production.  An important part of our business management is matching the needs of our livestock with pasture availability.  This ensures that the land is not overgrazed and the welfare of the livestock is maintained. 

A particular issue we have with the grasslands on Anna Plains is the encroachment of Mealeuca (paperbark) species on the grasslands of Anna Plains.  Photo monitoring from station management together with aerial photos and satellite images shows the encroachment of paperbark. 

These trees obviously reduce pasture availability to livestock and they reduce the abundance of foraging ground for migratory shorebirds.  In addition they also provide refuge for predators such as birds of prey and feral cats. 

The encroachment of trees onto grasslands is not a situation unique to this part of the world.  Reports of trees encroaching onto grasslands have been made in Africa and North America. 

The reasons for the tree encroachment are on grasslands are not fully understood.  One reason could be increasing levels of carbon dioxide in the atmosphere which favour the growth of trees as opposed to grasses.

 

Most of the grasses in this part of the world use the C3 pathway for photosynthesis as opposed to the C4 pathway which many trees have evolved to use.  C4 plants are more efficient than C3 plants and are well adapted to high temperatures and moist environments, both features of our grasslands here on the Plains, particularly in the wet season.

The concentration of carbon dioxide in the atmosphere will continue to increase.  If the higher levels of carbon dioxide are a factor in the spread of trees on the grassland then we will have to learn to deal with it.  Potential management solutions include the use of fire to control tree growth and the use of grazing animals to knock back the trees.  The use of herbicides could also be considered in some areas although the scale of the rangelands means this solution would be impractical. 

FURTHER READING

Grasslands in a changing world.  Drovers Cattle Network.  http://www.cattlenetwork.com/expert-columns/?author=Joseph+Craine&aid=213203031

Wildlife and Cattle Production

It is often assumed and sometimes promulgated by anti-farming groups that all agricultural production comes at an environmental cost.  In our case, we have a great example of conservation and food production in a nice balance with mutual advantages. 

Our station is adjacent to Eighty Mile Beach – a vast coastline which is home to a number of migratory wader birds.   Despite its name the Eighty mile beach is approximately 230 kilometres long.  Many of these species migrate to the northern hemisphere to breed, often flying thousands of kilometres in a single journey all without complaining about the airline food.  The farthest journey from the Kimberley is to Siberia which is sometimes completed in a single journey. 

A few of these species feed on the grass plains of the station while seeking refuge on the beach during the hot part of the day.  The birds benefit from the presence of cattle as they keep grass shorter reducing potential hiding places for predators including birds of prey and feral cats.   Water points provided for cattle, can also serve as thermal refuges for the birds at hot times during the day. 

Three key bird species that forage on the grasslands but roost on Eighty-mile beach during the hottest period of the day are the Oriental Plover, Charadrius veredus, Little Curlew, Numenius minuta and Oriental Pratincole, Glareola maldivorum. 

The birds do a great job of reducing the burden of grasshoppers and thus benefiting pasture production.  In addition to being able to fly across the world, the birds appear to know where rain has fallen in Australia and thus the best places to feed. 

Being an extensive grazing property in the rangelands, inputs are minimal – no fertilisers or herbicides are used in cattle production.  Raising cattle in the rangelands of Australia is one of the most environmentally benign forms of food production in the world.  In addition to a light environmental footprint, pastoralists also perform a number of other important environmental services including the control of weeds and feral animals such as cats, wild dogs and camels.  The control of wildfires either by controlled burns or by extinguishing fires when they start is also an important environmental service. 

 

FURTHER READING

Hollands, D and C Minton  2012  Waders.  The Shorebirds of Australia.  Bloomings Books Pty Ltd. 

Rogers DI, CJ Hassell, A Boyle, K Gosbell, C Minton, KG Rogers and Clarke, RH  2011  Shorebirds of the Kimberley Coast – Populations, key sites, trends and threats.  Journal of the Royal Society of Western Australia, 94: 377-391.