<P> Alpine and Subalpine regions have undergone a lot of deforestation and then forestation in the last 300 years . Out of this has emerged much practical experience . One example is the Rotten group, which is a method to bring in stable age mixed tree communities . </P> <P> In Adelaide, South Australia (a city of 1.3 million as of June 2016), Premier Mike Rann (2002 to 2011) launched an urban forest initiative in 2003 to plant 3 million native trees and shrubs by 2014 on 300 project sites across the metro area . The projects range from large habitat restoration projects to local biodiversity projects . Thousands of Adelaide citizens have participated in community planting days . Sites include parks, reserves, transport corridors, schools, water courses and coastline . Only trees native to the local area are planted to ensure genetic integrity . Premier Rann said the project aimed to beautify and cool the city and make it more liveable; improve air and water quality and reduce Adelaide's greenhouse gas emissions by 600,000 tonnes of C02 a year . He said it was also about creating and conserving habitat for wildlife and preventing species loss . </P> <P> The United States is roughly one - third covered in forest and woodland . Nevertheless, areas in the US were subject to significant tree planting . In the 1800s people moving westward encountered the Great Plains--land with fertile soil, a growing population and a demand for timber but with few trees to supply it . So tree planting was encouraged along homesteads . Arbor Day was founded in 1872 by Julius Sterling Morton in Nebraska City, Nebraska . By the 1930s the Dust Bowl environmental disaster signified a reason for significant new tree cover . Public works programs under the New Deal saw the planting of 18,000 miles of windbreaks stretching from North Dakota to Texas to fight soil erosion (see Great Plains Shelterbelt). </P> <P> At their summit in Copenhagen in 2009, organised by the UK based The Climate Group, leaders of subnational governments--states, regions and provinces--unanimously supported a recommendation by Premier Rann to plant one billion trees across their varied jurisdictions . The initiative was strongly supported by leaders present including Quebec Premier Jean Charest, California Governor Arnold Schwarzenegger and Scottish First Minister Alex Salmond . At a subsequent meeting in Rio de Janeiro in June 2012, The Climate Group announced that it had already received commitments by member governments to plant more than 500 million trees . </P>

Aforestration is a form of carbon sequestration in agriculture