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Monitoring pre-and post-fire changes in land cover including biocrusts using high resolution satellite imagery in a grazed tropical savanna
Author
Myint Swe, T
Williams, WJ
Zhao, Y
Potgieter, A
Eastaughffe, J
Cowley, R
Schmidt, S
Publisher
XII International Rangeland Congress
Publication Year
2025
Body

Biocrusts play a pivotal role as ecosystem engineers, mitigating soil erosion, enhancing soil stability, and enriching nitrogen availability in rangelands. In northern Australian savannas, prescribed fires are a common land management strategy. However, fi re impacts biocrust function, making it important to monitor biocrust cover to assess ecosystem health and guide sustainable land management practices. In this study, we investigated land cover with a focus on biocrusts, before and after prescribed fire events at Victoria River Research Station in the Northern Territory. A 2.6 km² patch situated more than 2 km from water in the north-west corner of a 14.7 km2 paddock was burnt in October 2022. Cattle were left in the paddock both during and after the fire. High-resolution PlanetScope imagery was used to track changes in land cover between July 2022 and June 2023. Reference sites that included bare soil, biocrusts (95% coverage) and vegetative cover (grass, shrubs and trees), were collected in the field. Crust Index was employed to discriminate between land cover classes. Using supervised classification with a random tree classifier, we achieved 90% accuracy in identifying these land cover classes across multiple time points. Post-fire, early wet season, biocrust cover decreased by 10.8%, from 67 ha pre-burn to 39 ha, partially due to an increase of 10% in vegetation cover (189 ha to 215 ha). Grass canopies had obscured the biocrusts underneath them. Bare soil areas expanded by 20%, from 7.9 ha to 9.7 ha, likely due to cattle preferentially utilising the burnt areas post fire during the following wet season. These findings underscore the importance of monitoring and adaptive strategies such as spelling paddocks from grazing post fire, essential for sustainable and resilient ecosystems.

Language
English
Resource Type
Text
Document Type
Conference Proceedings
Additional Information
This paper is part of the larger XII International Rangelands Congress Proceedings. Page Numbers: 2193-2196. Theme: Hosted session / Extending the boundaries in rangeland management to include the soil microbiome
ISSN
978-0-646-72121-7
Conference Name
International Rangeland Congress
Collection
International Rangelands Congress
Keywords
Monitoring ground cover
biocrusts
rangelands
savanna