Setting the Baseline for Regeneration of Temperate Native Grassy Ecosystems in Montane Agricultural Landscapes: An Agroecological Approach to Soil Health

As the Earth and humanity face an uncertain climate future, finding solutions to alleviate the impacts of anthropogenic climate change is more important than ever. Land use changes for agricultural production significantly contribute to the accelerating rates of land degradation and biodiversity loss in Australia and globally. In response, there has been a shift in agroecological thinking, giving rise to the regenerative agriculture movement. This movement aims to go beyond sustainable land management by employing agroecological approaches to regenerate, restore, and enhance biodiversity, soil health, and ecosystem function on farm. Regenerative agriculture is a non prescriptive approach to land management that is focused on outcomes. However, there is limited research explicitly exploring how to monitor and measure the impacts of a regenerative transition. Establishing a quantitative ecological health baseline through the measurement of a suite of vegetation and soil health indicators will enable long-term ecological monitoring of a regenerative transition on farm. This project employs a descriptive ecological case study to demonstrate how this can be achieved in an impacted montane agricultural landscape dominated by native grassy vegetation in NSW, Australia. The study establishes a comprehensive understanding of the case study site's native vegetation and soil health by measuring a range of vegetation and soil health indicators. The selected indicators were chosen for their simplicity, repeatability of methods, and sensitivity to changes in land management. Five soil profiles were assessed through full characterisation and classification surveys to a depth of one metre. Vegetation health was evaluated using a modified biometric tool that assesses percentage cover, canopy cover, species richness, and habitat availability. Topsoil chemical and microbiome health were measured through comprehensive nutrient analysis and microbiome DNA metabarcoding. Results from soil and vegetation surveys were compared across a toposequence of landform elements aligned with the contours of the site. This study provides a detailed holistic understanding of the case study site's current soil and native vegetation health. Soils were classified as red dermosols on the crest, upper slope, and mid slope; yellow dermosols on the lower slope and in drainage depressions; and a redoxic hydrosol on the flat. The vegetation across the site has high conservation value but low species richness compared to NSW benchmark conditions. The percentage ground cover varied dynamically, reflecting changes in vegetation formation, with the highest percentages of exotic species found in the upper and mid slopes. The topsoil exhibited moderately acidic pH across the entire site, and high organic matter and carbon levels on the crest and on the flat. The estimated cation exchange capacity of the topsoil correlated with available organic matter, while available nutrients were predominantly low overall. Soil microbiological biodiversity appeared more closely associated with vegetation formation and high native species richness. Carbon-associated microbial indicators did not correlate with available nutrients or carbon measures. Beneficial microbiology varied across the site, with ectomycorrhizal fungi highest in wooded areas and endomycorrhizal fungi prevalent in grassy areas. Soilborne pathogen abundance was highest on the flat and in the modified pastures of the mid and lower slopes. The study explores the implications of these findings and how they can inform future agroecological management of the site. Tailored agroecological strategies, such as strategic adaptive grazing, the utilization of woody debris on cleared slopes for regeneration, and the integration of biodiversity conservation, are discussed. This research addresses the knowledge and research gaps surrounding native vegetation and soil health in the montane agricultural landscapes of NSW and provides a quantitative framework for measuring and verifying regenerative agricultural outcomes on farm.

Author dc:creator

• Martin-Stuart, Bonnie Clare

Language dc:language.iso

en_AU

Handle dc:identifier.uri

https://hdl.handle.net/1885/733794068

OAI identifier oai:identifier

oai:openresearch-repository.anu.edu.au:1885/733794068