Desert (Dec 2018)
Banded vegetation in some Australian semi-arid landscapes: 20 years of field observations to support the development and evaluation of numerical models of vegetation pattern evolution
Abstract
Periodic vegetation patterns (PVPs) are striking features of many global drylands. Although they have attracted wide research study, resulting in many hypotheses, their origin and controlling factors remain unresolved. Theoretical works dominate a large literature seeking to account for the occurrence and properties of PVPs, especially banded vegetation patterns (‘tiger bush’). In light of the plethora of theoretical studies, there is a need for more empirical observation and monitoring of PVPs, especially their responses to climatic variability and to foreshadowed climatic change. This paper highlights key results derived from more than 20 years of field study and monitoring of banded vegetation in arid New South Wales, Australia, where severe drought is a recurring feature. It advances the view that in this study area, and hence perhaps in other regions, local factors including plant physiology, soil properties, and climatic characteristics result in PVPs whose development and functioning might be quite unlike those of other regions. Importantly, these local characteristics appear to confer on the regional PVPs a considerable resilience to drought, and hence perhps to climate change. The field evidence from the study area suggests that, despite predictions of a number of theoretical analyses, the PVPs are not facing imminent collapse. Generalised and non-specific models of PVPs require more realistic parameterisation and more thorough validation than has been customary, and this will require additional field evidence of the kind reviewed here. Highlights: • highlights results of field study of banded vegetation in the Broken Hill region of Australia over more than 20 years • patterned vegetation in this area appears to be resilient in the face of drought and grazing pressure • contrary to most model predictions, the vegetation bands do not migrate upslope, and do not undergo pattern change during severe drought • direct observation of banded vegetation should increasingly accompany attempts at modelling responses of global drylands to climate change
