Effect Of Spatially Correlated Disorder On Vegetation Pattern Formation In Arid Drylands.

The dynamics of pattern formation in arid drylands can be explained by scale dependent feedback models.
However the underlying environment is rarely homogeneous. Heterogeneity may arise because of varying hydrogeological conditions which
manifest in the form of varying diffusion, evaporation rates etc. As these hydrogeological fields are often spatially correlated, we study the effect of correlated disorder on vegetation pattern formation in drylands. A random uncorrelated disorder has earlier been shown to reduce the critical threshold below which the collapse to desertified state occurs. We show that the interplay between correlation length of the disorder and the pattern leads to interesting phenomena like coexistent patterns, enhanced resilience to desertification and disorder induced hysteresis. We introduce different types of disorders, including Gaussian and
exponential type, to understand the changes in the nonlinear vegetation dynamics using a well studied model by Reitkerk et. al. Remotely sensed optical data is used to observe some dryland vegetations of the type explored in this work over the Leh regions in the Ladakh Union Territory
of Northern India which show remarkable heterogeniety of hydrological conditions and coexistence of patterns.