Sunday, June 8, 2008

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The Oyamel Fir forest of Angangueo, central Mexico, is an important habitat for wintering Monarch butterflies. Because this forest occurs within the tropics at high elevation, it provides a relatively stable microclimatic envelope that protects the butterflies from freezing on cold nights during the five month overwintering season. Adiabatic rainfall together with fog condensation on the fir and pine boughs provides the moisture that prevents the butterflies from desiccating as the dry season advances. A comparison of the 1986 image to the 2001 image reveals that parts of the forests have been degraded severely. The two close-up images (below) serve to illustrate the most affected areas. In these images, the unaffected forest is green in colour while the degraded area is tan. In spite of two presidential decrees intended to protect this area, it is estimated that between 1984 and 1999, 38 per cent of the forest area has been degraded. View detailed information

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