European Commission, Environment DG

Balancing urban expansion with biodiversity conservation

In developing countries economic growth is linked with expansion of urban areas and changes in land use, including conversion of forests to agricultural land. An investigation of the impacts of two neighbouring cities in central Panama has revealed that continued expansion is likely to cause future habitat loss, which in turn could lead to a decline in species diversity.

A key factor underpinning biodiversity conservation is the protection of natural habitats. This often conflicts with the activities of humans, who cause habitat destruction when expanding urban areas or changing land-use. This causes 'habitat fragmentation', the loss of the preferred habitat of a species and leads to a loss of biodiversity.

In the Panama Canal corridor, in Central America, two neighbouring cities, the capital, Panama City and Colon, neighbour forests rich in biodiversity. These natural habitats are at risk as increased urbanisation is predicted to follow a planned expansion of the shipping canal, with new roads, railways and bridges being built on land released by the exit of the US military in 1999. In addition, 61 per cent of the rural population live below the poverty threshold and have few economic opportunities other than to clear forested land for agricultural purposes.

To discover the impact of these changes on biodiversity, researchers have looked at the relationships between socio-economic factors including; population density and growth, road density and poverty levels, and biophysical factors; including annual rainfall, forest age, land topography and use (agricultural or urban).

Rainfall and topography were negatively associated with urbanisation; the cities are not expanding into the mountainous ranges, covered in mature forests, where rainfall is high and there is a risk of landslides. Population wealth is positively associated with the conversion of land to urban areas, whereas people living below the poverty threshold are mainly found in rural areas. Agriculture is expanding into areas, such as mature forests, which are less suitable for urban development.

Half of the forests in the Panama corridor are protected, but as urban development continues there is growing pressure to clear forests as the value of land increases. This could have a devastating impact on forests habitats, which are necessary to maintain high biodiversity levels. The forests also protect the Canal watershed1 by preventing landslides.

If the needs of the human population and biodiversity protection are to be balanced, a better understanding of the socio-economic and biophysical factors driving habitat change are needed. This knowledge could enable land-planners and policymakers to make informed decisions about which areas should be conserved. Ecotourism and agroforestry could be alternative economic opportunities, which would help rural populations to move above the poverty threshold, whilst protecting the biodiversity upon which it would depend.

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