Biological soil crusts are an important indicator of the long-term productivity of grazed landscapes. Healthy biocrust communities can improve soil fertility by increasing soil stability, enhancing moisture retention, as well as facilitating both carbon and nitrogen cycling and fixation. The Rain Ready Rangelands project, funded through the Australian Government Future Drought Fund analysed biocrust health on three producer demonstration sites in central Australian woodlands and shrublands and the Barkly Tablelands Mitchell grass regions of the Northern Territory. In this paper we focus on a producer demonstration site located approximately 250 km northwest of Alice Springs in tall open Acacia shrublands with deep red earths, sandy red earths, red clayey sands and deep sandy loams over mixed short grasses. Samples were collected under varying grazing intensities (with distance from water and inside vs. outside cattle exclosures) and with different grazing management (current vs. recommended grazing management). To detect the functional contribution of these communities baseline samples were collected and analysed for biocrust species composition, total carbon and nitrogen and DNA analysis. 16S rRNA marker gene sequencing was used to profile bacterial community diversity along grazing gradients from watering points, and inside and outside cattle exclosures. Bacterial community composition shifted significantly with distance from water at the central Australian sites. Diversity was highest at the most disturbed site 50 meters from the water point at one of these locations, while community composition had not diverged inside vs. outside newly established exclosures after the first year. Changes in total carbon and total nitrogen were observed only with distance from water, with enhanced C and N adjacent waterpoints compared to all other distances. The ecological implications o f these changes are being further investigated. We plan to monitor these sites through time to see if alternative management regimes and cattle exclusion results in different trajectories in biocrust community composition and function.
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