A quality or state of being expressing susceptibility to ill health or harm; the relative ability of resources to tolerate sustained use without degradation of the resource base (i e , lowering productivity or desirable resource quality) "Fragility" applies to those resource types or locations that are more or less susceptible to degradation under the presence of whatever use categories have been considered in the evaluation process For example, areas of vegetation-covered sand dunes may be characterized as being "environmentally fragile" for off-road vehicle uses, whereas beaches or un-vegetated dunes may be said to be "environmentally durable" for the same uses