Preprint Article Version 1 This version not peer reviewed

Assessing Landsat Fractional Ground-Cover Time Series across Australia's Arid Rangelands: Separating Grazing Impacts from Climate Variability

Current address: Arid Zone Research Institute, Alice Springs, Northern Territory, Australia, 0870
These authors contributed equally to this work.
Version 1 : Received: 31 March 2017 / Approved: 31 March 2017 / Online: 31 March 2017 (12:14:25 CEST)

How to cite: Barnetson, J.; Phinn, S.; Scarth, P.; Denham, R. Assessing Landsat Fractional Ground-Cover Time Series across Australia's Arid Rangelands: Separating Grazing Impacts from Climate Variability. Preprints 2017, 2017030236 (doi: 10.20944/preprints201703.0236.v1). Barnetson, J.; Phinn, S.; Scarth, P.; Denham, R. Assessing Landsat Fractional Ground-Cover Time Series across Australia's Arid Rangelands: Separating Grazing Impacts from Climate Variability. Preprints 2017, 2017030236 (doi: 10.20944/preprints201703.0236.v1).

Abstract

Suitable measures of grazing impacts on ground cover, that enable separation of the effects of climatic variations, are needed to inform land managers and policy makers across the arid rangelands of the Northern Territory of Australia. This work developed and tested a time-series, change-point detection method for application to time series of vegetation fractional cover derived from Landsat data to identify irregular and episodic ground-cover growth cycles. These cycles were classified to distinguish grazing impacts from that of climate variability. A measure of grazing impact was developed using a multivariate technique to quantify the rate and degree of ground cover change. The method was successful in detecting both long term (> 3 years) and short term (< 3 years) growth cycles. Growth cycle detection was assessed against rainfall surplus measures indicating a relationship with high rainfall periods. Ground cover change associated with grazing impacts was also assessed against field measurements of ground cover indicating a relationship between both field and remotely sensed ground cover. Cause and effects between grazing practices and ground cover resilience can now be explored in isolation to climatic drivers. This is important to the long term balance between ground cover utilisation and overall landscape function and resilience.

Subject Areas

fractional ground cover; non-photosynthetic vegetation; landsat; standardised precipitation index; episodic rainfall; landsat; time series; growth-cycles

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