Work

Assessing cattle grazing impact on biomass and soil carbon pools in an Australian semi-arid woodland

Year: 2025

Type: article

Abstract: This study assessed the impact of grazing, with and without cattle, on carbon pools in an Australian semi-arid woodland using field measurements and simulations within the Full Carbon Accounting Model (FullCAM). Field measures of total carbon aboveground and in soil to 10 cm soil depth was 72-75 t ha-1, with about 41-44 t ha-1 aboveground and 31 t ha-1 belowground. Total carbon in cattle-excluded grazed sites (75 t ha-1) did not differ from cattle-included grazed sites (72.4 t ha-1). However, cattle grazing significantly reduced biocrust carbon (from 0.24 t ha-1 to 0.06 t ha-1; p = 0.003), emphasizing the vulnerability of biocrusts to hard-hooved tramping by large and heavy cattle.The field measures of carbon pools were subsequently used to adjust model parameters within the FullCAM, so that simulations of carbon pools approximated field-measured carbon stocks. Following the calibration step, grazing scenarios with and without cattle, were simulated from 1900 to 2300, including periodic wildfire occurrences. These simulations showed lower live tree carbon stock in cattle-included grazing treatment that led to a gradual decline in total carbon. The total carbon stock under cattle-excluded grazing scenario remained 90–103 t ha-1 between 1900–2100, but it decreased to 86–100 t ha-1 afterwards under cattle-included grazing condition. These results highlight the degrading impacts of cattle-included grazing on biocrusts that in turn undermines soil stability and carbon retention. Cattle-excluded grazing, by contrast, supports biocrust conservation and sustains carbon sequestration potential of the woodlands.Australia's Australian Carbon Credit Units (ACCUs) scheme includes aboveground carbon and does not include belowground carbon that contributes approximately 40% of total woodland carbon. If the ACCUs framework included SOC, root carbon and biocrust it would incentivize smallholders to adopt vegetation projects (under ACCUs scheme) more widely, thereby contributing to (inter)national climate change mitigation and biodiversity conservation goals.

Source: Ecological Modelling

DOI: 10.1016/j.ecolmodel.2025.111404

Authors: Hari Krishna Laudari, Liubov Volkova, Stephen H Roxburgh, Christopher J Weston

Institutions: The University of Melbourne, Commonwealth Scientific and Industrial Research Organisation

Language: English

Topic: Soil Carbon and Nitrogen Dynamics

Subfield: Soil Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDGs: Climate action, Life on land

Open Access status: hybrid

Estimated APC paid: $2,810