Often the land set aside is too small to support viable population of threatened species. That many National Parks cannot tolerate the pressure of recreational activities emphasises the incompatibility of what might seem benign use and environmental conservation. General development controls are, claim environmentalists, insufficient and can encourage developers to keep coming back with their proposals, making minor modifications until they finally get their way. For all the real good measures like the creation of national parks have done in specific situations, such piecemeal preservationism cannot cope with saturation levels of human pressure on the environment. As such, it is like the little Dutch boy sticking his finger in the dike, when holes are proliferating all over the sea wall.
Governments frequently commit themselves to quite incompatible conservation and development goals.
Not surprisingly in areas such as the Yorkshire Dales and Peak District National Parks, limestone quarrying continues to damage the environment. Some 'life-support' services, particularly genetic diversity, can only be provided by areas of land and water kept free from all forms of human exploitation. Plans for the sustainable use of tropical rainforests, for example, probably will destroy their essential ecological character as surely as the current operations of loggers, ranchers and miners. Environmentalists argue that globally we should work to create a network of wilderness areas kept free from exploitation in perpetuity. They would centre on key zones such as virgin forests, especially in the tropics, swamps, watersheds, estuaries and barrier reefs, and the habitats of rare plants and animals.