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However, in any country there are a number of environmental resources which are not flow resources. They include habitats for a variety of plant and animal species whose survival depends on the maintenance of key functional relationships within intact ecological systems. Disrupting these functional relationships through fragmentation of ecosystems (e.g. logging and roading in the case of a forest) leads to the degradation of the functional integrity of those ecosystems, which in turn leads to the loss of habitat for those species which depend on unmodified environments. While no ecosystem is free from natural disturbance, the character of human induced disturbance (e.g. roading) is often fundamentally different from natural disturbance (e.g. wind damage, landslides, floods) which have occurred for millennia. Indeed the regime of natural disturbance is an integral part of any ecological system. Add human induced disturbances to this natural regime and you change the entire disturbance pattern, and in turn change the functional interdependencies which make up a habitat. A good example is roading which riddles an area with access routes for predators, pests, and weeds, increases edge effects, disrupts water tables, and opens areas up to wind damage. Roads are to forests as borer is to wood. Logging removes biomass and nutrients (wood) from the forest, it increases the rate of canopy openings, it removes trees that would otherwise die standing, it creates bigger canopy openings (i.e. from the falling of a healthy tree), and it can change the age structure of the forest.