The well-publicized instance of the "Coldplay forest", in which a forestry project supported by the British band Coldplay resulted in a grove of dead mango trees, illustrates the difficulties of guaranteeing the permanence of tree-planting offsets. When discussing "tree offsets, forest campaigner Jutta Kill of European environmental group FERN, clarified the physical reality that "Carbon in trees is temporary: Trees can easily release carbon into the atmosphere through fire, disease, climatic changes, natural decay and timber harvesting." Monocultures and invasive species. In an effort to cut costs, some tree-planting projects introduce fast-growing invasive species that end up damaging native forests and reducing biodiversity. For example, in Ecuador, the Dutch FACE Foundation has an offset project in the Andean Páramo involving 220 square kilometres of eucalyptus and pine planted. The NGO Acción Ecológica criticized the project for destroying a valuable Páramo ecosystem by introducing exotic tree species, causing the release of much soil carbon into the atmosphere, and harming local communities who had entered into contracts with the FACE Foundation to plant the trees. However, some certification standards, such as the Climate Community and Biodiversity Standard require multiple species plantings. Methane. A 2006 study claimed that plants are a significant source of methane, a potent greenhouse gas, raising the possibility that trees and other terrestrial plants may be significant contributors to global methane levels in the atmosphere. However, this claim was disputed by findings in 2007 study. The albedo effect. Another study suggested that "high latitude forests probably have a net warming effect on the Earth's climate", because their absorption of sunlight creates a warming effect that balances out their absorption of carbon dioxide. Necessity. Corporate tree-planting is not a new idea; farming operations have been used by companies making paper from trees for a long time. If farmed trees are replanted, and the products made from them are placed into landfills rather than recycled, a very safe, efficient, economical and time-proven method of geological sequestration of greenhouse carbon is the result of the paper product use cycle. This only holds if the paper in the land fill is not decomposted. In most landfills, this is the case and leads to the fact that more than half of the greenhouse gas emissions from the life cycle of paper products occur from landfills methane emissions. A business-as-usual philosophy Some activists disagree with the principle of carbon offsets, arguing that they prolongs a