No abstract

Native forests in Chubut Province cover an area of 1,000,000 hectares, of which 133,000 hectares are considered suitable for timber production. Approximately 10,000 hectares of this productive forest area has been, or is currently, the object of some form of timber exploitation. Pure Nothofagus pumilio forests (known colloquially as "lenga" forests) make up the largest native forest area (90%) in the designated land. In 1992, specific norms were introduced requiring those who intend to extract native forest timber to present management plans. The management plans presented to the provincial forest authority were analyzed with the aim of assessing their actual effectiveness as administrative tools for promoting the sustainable conservation of forest resources. One of the main conclusions which needs to be highlighted is the remarkable lack of coordination between planning and execution. This arises from: 1) Deficiencies in the structural characterization and volumetric estimation of the forest; 2) Conflicts over resource use, and 3) Conflicts of interests between businessmen and the state.

A formalism of continuous media in general relativity is given and the concept of shock waves is defined using manifolds with boundary and the transversality theory of submanifolds. A definition of relativistic incompressibility is proposed and one gets that the shock waves are longitudinal with the speed of light.