The full programme book (PDF) - Royal Geographical Society

T8
Measuring Landscape Resilience using tephra
Dugmore A.J. 1 * and Streeter, R.T. 2
1 Institute of Geography and the Lived Environment, University of Edinburgh, Drummond Street,
Edinburgh, EH8 9XP
2 Department of Geography and Sustainable Development, University of St Andrews, Irvine Building,
North Street, St Andrews, Fife, KY16 9AL
We report a novel use of volcanic ash layer variation as a measure of land surface
resilience to better understand proximity to threshold-crossing change at the time of the
ash fall. This is possible because the morphology of volcanic ash layers a few cm thick
reflects surface stability and the spatial patterning of vegetation for the period the ash is
exposed. We illustrate this with high-resolution thickness data from the Grímsvötn 2011
tephra measured from within stable grassland into an area of active cryoturbation. As in
the case of migrating rofabard erosion fronts and expanding deflation patches (Streeter
and Dugmore 2013), these data show strong early warning signals of threshold change
(rising autocorrelation and increasing standard deviation in the detrended data set). This
shows the potential use of tephra layer morphology to interpret the resilience of past land
surfaces marked by the abundant archive of buried tephra layers, and thus a new way to
use terrestrial stratigraphy to understand processes of landscape evolution.
Keywords: Tephra; resilience; early warning signals; thresholds; erosion.
Streeter, R. and Dugmore, A. J. 2013 ‘Anticipating land surface change’: Proceedings of the National
Academy of Sciences 110, 15, 5779-5784.