|
|
abstracts
Did prehistoric anthropogenic soil erosion cause a shift in Mediterranean biomes over the Holocene? (YSM POSTER PRIZE)
Pamela Collins, Jed Kaplan
The paleoecological record of the Mediterranean basin shows widespread changes in vegetation cover from the mid-Holocene to the present. While these changes vary from place to place, the overall trend is a transition from temperate forests to xerophytic shrublands. The cause of this transition is generally believed to have been a drying trend in regional climate. However, prehistoric and preindustrial anthropogenically-induced soil degradation could have altered soil characteristics enough to cause a shift in Mediterranean biomes without major changes in climate. To test this hypothesis, we analyze pollen records from the European Pollen Database for 56 locations in Mediterranean Europe and North Africa that demonstrate the Holocene trend towards more xeric vegetation cover. For each site, we specify a typical soil profile for “undisturbed” and “degraded” soil conditions and simulate the resulting vegetation cover using the ARVE-DGVM. Physical characteristics of the 17-layer soil column used in the ARVE-DGVM include particle size distribution, organic matter content, coarse fragments, and depth to bedrock. By manipulating these parameters in a series of experiments consistent with the effects of human exploitation of the land for agriculture and pasturing, our preliminary results show that a simple change in soil physical characteristics, such as that caused by anthropogenically-induced soil erosion and degradation, could be sufficient to cause the biome shifts observed in the paleorecord without invoking climate change. These findings allow us to quantify early human impact on the terrestrial biosphere and may alter the way pollen records are interpreted for climate reconstruction.
Pamela Collins, ENAC-ARVE-GRKAP, The Ecole Polytechnique Federale de Lausanne,Station 2, 1015 Lausanne, Switzerland, Pamela.Collins@epfl.ch
Jed Kaplan, The Ecole Polytechnique Federale de Lausanne, ENAC-ARVE-GRKAP, Station 2, 1015 Lausanne, Switzerland
Session: F4: Human-Climate-Ecosystem Interactions
Download Poster:
> CollinsYSM09.pdf
|
|
