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Dept of Physics

Vegetation Patterns

[pattern formation on a golf course, courtesy Art Brunneau (NCSU Turf Science)]

Spatial patterns of 'dead' lawn grass have often been ascribed to Turing-type reaction-diffusion processes related to water scarcity. We have suggested an alternative hypothesis: that the air within the grass canopy is unstable to a convective instability, such that chill damage caused by falling cold air is responsible for the creation of brown and green bands of grass. This hypothesis is consistent with several features of small-scale vegetation patterns, including their length scale, rapid onset and transient nature. We find that the predictions of a porous medium convection model based are consistent with measurements made for a particular instance of lawn-patterning in North Carolina. In the image at left (courtesy Art Brunneau of the NCSU Turf Science program), it is clear that only the longer grass (taller fluid layer) is subject to this pattern-forming instability, as would be predicted by the convection model we propose.


Publications

  • Sally E. Thompson and Karen E. Daniels. A Porous Convection Model for Small-Scale Grass Patterns. The American Naturalist. 175: E10-E15 (2010) [Link]

  • Gopal G. Penny, Karen E. Daniels, and Sally E. Thompson. Local properties of patterned vegetation: quantifying endogenous and exogenous effects. Philosophical Transactions of the Royal Society A. 371: 20120359 (2013) [Link] [PDF]



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