Managing rangeland change in New South Wales for landscape repair

Abstract

The rangelands of southeastern Australia are a landscape with extensive evidence of historical land degradation. Monitoring and managing this historic land degradation is made challenging by the disparities of scale throughout the rangelands, which make implementing solutions to ongoing erosion difficult. Monitoring wind erosion is one metric that has been used as a proxy for landscape condition, with the focus on direct measurement of dust emissions. However, in the past decade there has been a pivot towards using remote sensing products to monitor groundcover as a proxy for dust, allowing more flexible and adaptive monitoring regimes. This in turn creates an opportunity to extend these remote sensing products to monitoring at paddock-scales, thereby informing timely land management decision-making. The approach in this thesis is to explore the evolution of techniques used to inform land management decision-making with a specific lens of wind erosion. This is achieved through a case-study approach, using a series of locations throughout rangeland New South Wales to explore land degradation with a historical perspective. Through these case-studies, the transition from measuring and monitoring dust, to the adoption of using remote sensed groundcover products that provide paddock-scale information relevant to land managers is examined. To do this, this thesis first considers the historical context of erosion in the rangelands of southeastern Australia, and puts this into the context of changing management options. This is supported by comparing DustWatch data against local social metrics, and using a more targeted dust metric for comparison against regional Landsat groundcover and ABARES land use data. While these regional dust analyses produce interesting results about regional dust, they don't successfully localise and geolocate dust emission sources. Therefore, MODIS and Landsat groundcover is used to build a novel cumulative metric of landscape condition, with this cumulative cover product offering a novel way to view and examine fractional cover data. Two common landscape repair treatments (waterponds and wagon wheels) are examined with this cumulative metric to assess the impact of land management interventions. This is then extended through three case-studies focussed on the use of water as a mechanism through which land managers can monitor landscape repair, two focussed on LFA and one on piospheres. This is then supported by an examination of whether landscape repair can be rebuilt by alternative applications of remote sensing. To this end, an index of landscape functionality gain is developed from Landsat fractional cover to extend cumulative cover, using a self-referential control at Bokhara Plains, and connected to land management inflexion points. The results of this thesis are significant, as they indicate that it is potentially possible for land managers to conduct their own remotely sensed paddock-scale monitoring using publicly available datasets. This thesis critically develops alternative ways to view and analyse groundcover data in order to build understanding of trends and patterns within properties. This is valuable, as it empowers the land manager to understand the link between their management decisions and groundcover dynamics- a key element that underpins grazing production and protection from land degradation. Empowering land managers with this knowledge accelerates the capacity to build landscape function and effect landscape repair. This offers land managers opportunities to access emerging natural capital markets, and may have major implications with future policy changes. Through this, further development of the remote sensing capabilities examined in this thesis has major potential to support New South Wales rangeland managers in repairing degraded landscapes and address the legacy of accelerated erosion in rangeland southeastern Australia. Show more