The objectives of this research were to assess in different forest fragments the effects of disturbance produced by human activities on tree regeneration (by seedling and from the seed bank); to evaluate seedling survival and growth of native tree species in response to light availability in natural (by seedling transplant in the field) and controlled conditions (using shade houses); and to predict population viability in forest fragments of two of the selected species using a transition matrix model. The study was carried out in six forest fragments located in Veracruz, Mexico using <i>Carpinus caroliniana, Fagus grandifolia </i>var. <i>mexicana, Quercus acutifolia </i>and <i>Symplocos coccinea. </i>The least disturbed fragments (which were less accessible to local people) showed the highest density of seedling regeneration of shade-tolerant species, and the most disturbed fragments (near to human settlements) showed a high density of shade-intolerant tree species that were regenerating from the seed bank. The results of shade house and seedling transplant experiments suggest that <i>Fagus </i>and <i>Symplocos </i>(both native species with a restricted distribution) can be used in areas with no severe disturbance, whereas <i>Quercus </i>and <i>Carpinus </i>(considered on the basis of these results as a intermediate species) can be used in areas that need to be rehabilitated such as disturbed fragments or near the forest edge. In the fragments the effect of frequent tree removal harvesting on population viability will be greater in <i>Fagus </i>(the shade-tolerant species) than in <i>Carpinus </i>(the intermediate species). According to the results, even the smallest human disturbance in the forest fragments (such as the use of forest paths) can influence tree regeneration favouring the increase in density (seed or seedling) of shade-intolerant species. The understanding of the species response to irradiance provides for improved management of regeneration for forest rehabilitation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:640443 |
| Date | January 2002 |
| Creators | Alvarez-Aquino, Claudia |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11971 |
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