Trees encroaching on Tallgrass Prairie National Park in the US. A new study shows that as tree cover increases in North America, livestock productivity can decrease (Photo credit: Miguel Vieira, via flickr)
Livestock like beef cows can suffer when grasslands, shrublands and savannas shift to a more tree-covered landscape and new research has put a number on this effect. Using computer models the authors show that for every 1 per cent increase in tree cover, the number of reproductive cows per square kilometre drops by about 2 per cent of the current average value.
Tree cover in North America is estimated to be increasing at 0.5 to 2 per cent per year as a result of land management practices, introduction of non-native trees, loss of natural browsing animals and climate change. The researchers also compare different land management approaches in the United States and Argentina to show how socio-economic factors affect woody-plant encroachment and its impacts.
Original research paper published in PNAS on August 18, 2014.
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