Copy the page URI to the clipboard
Cárdenas, Macarena Lucia
(2011).
DOI: https://doi.org/10.21954/ou.ro.0000ffa1
Abstract
Amazonia is one of the most biodiverse regions of the world, a reputation largely earned by the floristic richness of western Amazonia, namely the Ecuadorian Andes. In particular, montane cloud forest in western Amazonia on the Andean flank has been identified as of high ecological value because of its large floristic diversity. Unfortunately, montane forests' biodiversity have suffered a strong detrimental impact due the ongoing human activity and climate change. Consequently, understanding the dynamics of montane forest and identifying the main factors that control them is fundamental to manage and protect these ecosystems.
This thesis focuses upon paleoecological data obtained from organic sediments from Erazo (Ecuador), located today within the lower montane forest. Examination of modern vegetation and pollen rain close to Erazo revealed floristic variation at the kilometer scale related to human disturbance. Modem data provided the basis for interpreting the fossil record. Radiometric dating of interbedded volcanic ash indicates the sediments were deposited c. 525,000-193,000 years ago, well before the arrival of humans in America. Fossil pollen and wood preserved within organic sediments suggest that the composition of the forest was different to modern and changed significantly during the middle Pleistocene. Taxonomic changes in the fossil pollen assemblage, coupled with the presence of Podocarpus spp. macro fossils within the sediments, indicate that temperatures reached c. 5°C cooler than modem. Given the timing and magnitude of vegetation change observed in the Erazo sediments it therefore seems likely that the variations were instigated by global temperature changes associated with Marine Isotope Stage (MIS) 9 and the MIS 7-6 transition from interglacial-glacial conditions.
The palaeoecological data from Erazo indicate that far from being a relatively stable 'museums' tropical forests are in fact dynamic systems undergoing long term floristic re-assortment as well as being susceptible to abrupt short term floristic reorganization.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)
