The development of Oslo has gone through several phases in response to varying environmental qualities and challenges. The regional challenges of Oslo's urban development and sprawl were, up until the last war, largely focused on the need for coordinated planning and development between the City of Oslo and the surrounding Aker Local Authority. The European Union (EU) commitment to organize an annual Green Capital Award is a following up of its Thematic Strategy on the Urban Environment. Urban development seriously reduced the green structure in the city, and the application of new industrialized forestry methods in the Oslo forest reduced both the biodiversity and the natural and recreational quality. The city's practical strategy has been to allow densification at the expense of green areas on private land designated for urban development, and to concentrate the efforts on the protection and/or acquisition of green areas specifically designated as part of the city's green space.