TY - GEN A1 - McGrath, Gavan S. A1 - Sadler, R. A1 - Fleming, K. A1 - Tregoning, P. A1 - Hinz, Christoph A1 - Veneklaas, Erik J. T1 - Tropical cyclones and the ecohydrology of Australia's recent continental-scale drought Y1 - 2012 U6 - https://doi.org/10.1029/2011GL050263 U6 - https://doi.org/http://dx.doi.org/10.1029/2011GL050263 SN - 0094-8276 ER - TY - GEN A1 - McGrath, Gavan S. A1 - Paik, Kyungrock A1 - Hinz, Christoph T1 - Microtopography alters self-organized vegetation patterns in water-limited ecosystems T2 - Journal of Geophysical Research N2 - In terrestrial systems limited by water availability the spatial distribution of vegetation can self-organize into a mosaic of vegetated patches and bare soil. Spatially extensive competition for water and short-range facilitation underpin many models that describe the process of vegetation pattern formation. Earlier studies investigating this self-organized patchiness have largely considered smooth landscapes. However, topographic variations can significantly alter the redistribution of surface water flow and therefore the pattern-forming process. Here, we consider how microtopographic variations, at the scale of individual plants, alters self-organized vegetation patterns with the use of a simple ecohydrological model. We show that increasing microtopography can induce a change from banded vegetation, oriented across the slope, to irregular drainage patterns, oriented in the downslope direction. The mechanism responsible is shown to be a change in the spatial redistribution of infiltration around plants and plant patches. Only small increases in microtopography are required to cause banded systems with weak facilitation to change to downslope-oriented patterns. When non-periodic boundary conditions were considered, band orientation tended to become oblique to the topographic contour and in some circumstances their migration upslope ceased. These results suggest that diffusive sediment transport processes may be essential for the maintenance of regular periodic vegetation patterns, which implies that erosion may be critical for understanding the susceptibility of these ecosystems to catastrophic shifts. KW - ecohydrology KW - hillslope KW - microtopography KW - self-organization KW - vegetation pattern Y1 - 2012 UR - http://dx.doi.org/10.1029/2011JG001870 U6 - https://doi.org/10.1029/2011JG001870 SN - 0148-0227 VL - 117 IS - G03021 SP - 1 EP - 19 ER - TY - GEN A1 - McGrath, Gavan S. A1 - Nie, Zhengyao A1 - Dyskin, Arcady A1 - Byrd, Tia A1 - Jenner, Rowan A1 - Holbeche, Georgina A1 - Hinz, Christoph T1 - In situ fragmentation and rock particle sorting on arid hills T2 - Journal of Geophysical Research: Earth Surface N2 - Transport processes are often proposed to explain the sorting of rock particles on arid hillslopes, where mean rock particle size often decreases in the downslope direction. Here we show that in situ fragmentation of rock particles can also produce similar patterns. A total of 93,414 rock particles were digitized from 880 photographs of the surface of three mesa hills in the Great Sandy Desert, Australia. Rock particles were characterized by the projected Feret's diameter and circularity. Distance from the duricrust cap was found to be a more robust explanatory variable for diameter than the local hillslope gradient. Mean diameter decreased exponentially downslope, while the fractional area covered by rock particles decreased linearly. Rock particle diameters were distributed lognormally, with both the location and scale parameters decreasing approximately linearly downslope. Rock particle circularity distributions showed little change; only a slight shift in the mode to more circular particles was noted to occur downslope. A dynamic fragmentation model was used to assess whether in situ weathering alone could reproduce the observed downslope fining of diameters. Modeled and observed size distributions agreed well and both displayed a preferential loss of relatively large rock particles and an apparent approach to a terminal size distribution of the rocks downslope. We show this is consistent with a size effect in material strength, where large rocks are more susceptible to fatigue failure under stress than smaller rocks. In situ fragmentation therefore produces qualitatively similar patterns to those that would be expected to arise from selective transport. KW - mesa KW - size sorting KW - fragmentation KW - sediment transport KW - rock KW - weathering Y1 - 2013 UR - http://onlinelibrary.wiley.com/doi/10.1029/2012JF002402/abstract U6 - https://doi.org/10.1029/2012JF002402 SN - 2169-9011 VL - 118 IS - 1 SP - 17 EP - 28 ER - TY - CHAP A1 - Frechen, Tobias Nanu A1 - Hinz, Christoph A1 - McGrath, Gavan S. T1 - Relating biomass and vegetation structure in water limited ecosystems using a celluar automata based model T2 - European Geosciences Union, General Assembly 2015, Vienna, Austria, 13 April - 17 May 2015 Y1 - 2015 UR - http://meetingorganizer.copernicus.org/EGU2015/EGU2015-14274.pdf N1 - EGU2015-14274 PB - European Geophysical Society CY - Katlenburg-Lindau ER -