Late Holocene vegetation, fire, climate and upper forest line dynamics in the Podocarpus National Park, southeastern Ecuador |
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Authors: | Fernando Rodr��guez Hermann Behling |
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Institution: | (1) Department of Palynology and Climate Dynamics, Albrecht-von-Haller Institute for Plant Sciences, University of G?ttingen, Untere Karsp?le 2, 37073 G?ttingen, Germany |
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Abstract: | Late Holocene vegetation, fire, climate and upper forest line dynamics were studied based on detailed pollen and charcoal
analyses. Two sediment cores, from the Rabadilla de Vaca mire (RVM) and the Valle Peque?o bog (VP), with an age of about 2100
and 1630 cal yrs b.p., respectively, were taken at the modern upper forest line in the Parque Nacional Podocarpus (Podocarpus National Park) in
southeastern Ecuador. The two pollen records reflect relatively stable vegetation with slight changes in floral composition
during the recorded period. Changes of the proportion between subpáramo and páramo vegetation are related to lower and higher
frequency of fires. The RVM records show that the upper forest line moved to a higher elevation between 1630 and 880 cal yrs
b.p., stabilising after 310 cal yrs b.p. Human impact is suggested by a high fire frequency, mainly between 1800–1600 and 880–310 cal yrs b.p. The VP records indicate no marked changes in the upper forest line. The charcoal records suggest an increased human impact
from 230 cal yrs b.p. to the present. The results indicate that high fire frequency is an important factor in reducing the expansion of subpáramo
vegetation and upper montane rainforest and in favouring the distribution of grass páramo. Since there is a clear correlation
between fire and vegetation dynamics, it is difficult to detect how far climate change also played a significant role in upper
forest line changes during the late Holocene. |
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