|
|||
|
|||
 |
 |
 |
 |
Rapid loss of tropical rain forest, isolation of remnant habitats and continued degradation of forest remnants and eventual disappearance, constitute a pressure never before exerted on the adaptive flexibility of bird and mammal species. Documentation of how the members of these two animal communities respond to such environmental changes is fundamental to develop conservation strategies.
| The case of
Los Tuxtlas, Veracruz, Mexico Los Tuxtlas harbors the northernmost representation of the Amazon rain forest in the American continent. The forests present in the region are particularly rich in plant and animal species. For example, biologists have documented the presence of about 550 species of birds, 110 species of mammals, 150 species of reptiles and about 60 species of amphibians at Los Tuxtlas. The components of the avian and mammalian communities are relatively numerous, they have diurnal and nocturnal representatives, they ocuppy a great variety of trophic levels, they are sensitive to habitat degradation caused by man, and they are relatively easy to observe and study. These aspects make these two animal communities adequate biological material to investigate the impact of habitat loss, fragmentation and isolation on the conservation of biodiversity in the tropics. The severe transformation of the tropical rain forest landscape of Los Tuxtlas by man and the high biological richness documented for this region, have served as a model to describe and understand the effects of fragmentation and isolation of the tropical rain forest on the avian and mammalian communities. |
The region of Los Tuxtlas by the Gulf of Mexico has undegone a severe transformation by man in the last 50 years. About 80-85% of the original (2,500 km square) tropical rain forest has disappeared. Black areas represent remaining tropical rain forest, white areas indicate pastures. |
Tropical rain forest transformation by human activity goes through a phase of fragmentation and isolation before terminating in elimination of all plant and animal species originally present in the forest. In many tropical landscapes much of what remains of the original rain forest is represented by constellations of forest fragments. Under these scenarios, an important scientific and conservation research problem is to investigate the biological richness of forest remnants and to develop local conservation scenarios of land-management that will result in the conservation of remaining biodiversity. Model II is an alternative way to manage tropical land. In this scenario, forest fragments are preserved and some of the open space is used to plant arboreal crops. Our research in Los Tuxtlas shows that such scenarios of land management tend to preserve a significant nomber of avian and mammalian species, including assemblages of dung-beetle species. . |
 |
| Because dung-beetles depend on a very patchy resource produced by forest mammals, they mantain a close relationship with the source of dung. Since, hunting, forest loss and forest fragmentation result in important declines in large and medium size mammals, dung beetle populations may be affected. Our research on forest fragmentation in Los Tuxtlas is exploring this relationship. So far results indicate important changes in dung-beetle species assemblages in fragmented landscapes and dceclines in their population. This suggests that dung-beetles could be used as "ecological thermometers" to quickly assess the ecological health of forest fragments, beofore proceeding with more labor and time intensive biotic surveys at new study sites. |  |
|
|
|
|
 |
The orderly and long-term documentation of the diversity and species richness of remaining forest fragments in tropical landscapes is an important scientific task needed to provide qualitative and quantitative information to enhance our data banks on the natural history, biology, ecology and behavior of forest plants and animals. Such information is essential to understand the flexibility of response of species and of plant and animal populations to the process of fragmentation and isolation of native habitat caused by human activity, thusl improving the precision of conservation models.
 |
 |
 |
Results of this research can be found in the publications listed by activating the link "publications of this lab..." in the main page.
For more information about this research program and the activities of our laboratory please write to [email protected]
Support the conservation of tropical rain forests in southern Mexico
Copyright @ 2004 Alejandro Estrada
