Investigating the condition of culturally and ecologically significant desert springs: the rise of buffel grass (Cenchrus ciliaris) and the decline of Melaleuca glomerata

Abstract

Buffel grass (Cenchrus ciliaris) is an invasive species which is critically threatening permanent springs in Central Australia. Ilpili Springs, situated on Pintupi, Luritja and Walpiri Country, are permanent water places in the central deserts. These springs are sacred and have been used and cared for by Aboriginal peoples for all time. Ilpili Springs are crucial to supporting a diverse range of life in the arid region and were historically sheltered by a canopy of Melaleuca glomerata. I adopted a mixed-methods approach incorporating geography, ecology, history and Indigenous methodology. To understand the extent of buffel grass invasion at the springs and to support its management, the probability of buffel grass was modelled and mapped in the landscape using remote-sensed imagery and field data collected for training and validation. Sketch-mapping with Traditional Owners was a supplementary method intended to be a core part of the research process, however due to unforeseen circumstances it did not happen within this research period. This method would have centred the perspectives and knowledge of the Traditional Owners and provided an insight into the history of invasion at the springs. To account for the consequent knowledge gap, an alternative mixed-method approach was taken; combining the spatial mapping of buffel grass with ecological field surveys, community feedback and a review of historical sources compiled since the Mackay and Lasseter colonial expeditions in 1930. Analysis of historical sources reveals the change in condition of Ilpili Springs, where melaleuca canopy has been lost over the last 100 years, facilitated by the invasion of camels and buffel grass. Synthesis of historical and contemporary evidence shows that the condition of the springs is severely threatened by the ongoing presence of buffel grass and camels. Field surveys indicated that buffel grass is a direct threat to melaleuca trees, having already fuelled destructive fires, it is presently competing at the base of all melaleuca trees surveyed in 2024 and dominates the recorded vegetation cover. The probability map supports these findings around the springs and suggests significant occurrence across the landscape particularly in riparian areas, depressions, and disturbed soils. The present output from this research supports documentation and spatially-targeted management by the Central Western Desert Indigenous Protected Area and the current CSIRO project. This research contributes to the literature discussing the impact of buffel grass on ecological and cultural values in a vital water place in the central Australian deserts, and the growing concerns about its imperative management. Future research will include sketch-mapping, refining buffel probability models, considering buffel suitability models and potentially mapping melaleuca in the springs. Show more