Greening Australia

Fire management under changing climatic conditions presents several challenges, including the need to manage fire regimes for multiple objectives, such as reducing risk to people while also protecting or maintaining the environment. One approach that could be added to existing management toolkits is green firebreaks. Green firebreaks are strategically placed low flammability plantings aimed at improving habitat and carbon storage while reducing fire risk. However, green firebreaks have not yet been explored in the context of shifting climates. Here, we use spatially explicit fire simulations in a fire regime simulation tool (FROST) to test green firebreak effectiveness under climate change across five landscapes in south-eastern Australia. We simulated fire regimes with and without green firebreaks and in conjunction with prescribed burning in the surrounding landscape. We evaluated effectiveness by examining changes in area burnt, fire frequency, and risk to people, property and the environment. In three out of the five regions, annual area burnt was predicted to increase under future climate trajectories and in most regions the introduction of green firebreaks decreased area burnt in one or both climate epochs but often resulted in increased fire frequency. When both green firebreaks and prescribed burns were used, area burnt, and fire frequency declined in most regions. Results were variable between climate models, reflecting how changes in precipitation and fuel load influenced management effectiveness i.e. prescribed burns and green firebreaks, under future climate predictions. Risks to people and property generally increased slightly with green firebreaks because additional fuel was introduced into the landscape. However, these risks were also negated when prescribed burning was also applied. As a stand-alone fire management method, green firebreaks may not be suitable for every location. However, when used in conjunction with other methods, such as prescribed burning, they could be a viable solution for managing fire and providing co-benefits to the environment.

New incentives and instruments for financing ecosystem restoration require frameworks that support planning, monitoring and reporting, including the identification and use of leading indicators. Leading indicators have the potential to predict the outcomes of restoration interventions before full recovery has occurred. State-and-transition models are a form of ecosystem dynamics modelling that has been widely and systematically applied to classify and describe ecosystem dynamics in North America and Australia, including ecosystem recovery efforts. State-and-transition models provide a framework for the organisation and selection of leading, lagging and coincident indicators for monitoring restoration outcomes. We outline a process for strengthening the application of state-and-transition models to restoration. This includes key considerations that are unique to restoration, such as the importance of starting states and how restoration management interventions can be incorporated into models as drivers of transitions. We demonstrate the approach through a case study and apply our restoration state-and-transition model to help guide the timing of restoration management actions informed by indicators. We then use insights on ecological recovery dynamics provided by the restoration state-and-transition model to generate hypotheses for identifying and selecting leading indicators. For example, the soil nutrient status of retired farmland is predicted to be a leading indicator of potential native forb establishment. Restoration-targeted state-and-transition models play a key role in systematically translating detailed practitioner insights, ecological data and indicators into structured formats that are accessible to a broad audience. To credibly implement the framework and leading indicators in nature markets, complementary scientific tools and governance processes are needed. This includes establishing agreed benchmarks for indicators, designing robust audit mechanisms and conducting further research to develop the evidence base for leading indicators.

Native vegetation restoration is a key strategy for restoring degraded lands globally. While this process can reshape belowground microbial communities, the extent to which such changes restore soil ecosystem functions, and whether different microbial traits recover synchronously or on distinct timescales remains less clear. Understanding the sequence of functional recovery is essential for evaluating restoration success, as distinct microbial traits drive different ecosystem services, from carbon storage to plant growth promotion, and serve as meaningful indicators of long-term ecological recovery. To address this, we applied deep metagenomic sequencing to characterise soil microbial responses following native vegetation restoration (spanning 1-31 years prior to sampling) on grazing agricultural lands. We found that microbial functional changes occurred in distinct phases: an early, rapid restructuring of core soil health processes, detectable as early as three years, including enrichment of nutrient retention and carbon fixation pathways, followed by a more gradual development of plant growth-promoting traits as the plant community matures. Genome-resolved analyses of nearly 500 metagenome-assembled genomes revealed a fundamental shift in dominant microbial life history strategies. Specifically, communities transitioned from a resource-scavenging and stress tolerance profile in grazing soils to strategies that prioritise biosynthesis and growth yields in restored soils. These lifestyle shifts have important implications for enhancing the microbial biomass and carbon sink potential of soils. Together, these findings show that microbial functional shifts following restoration are temporally structured – informing expectations for when key restoration targets may be achieved, and providing a practical framework for monitoring ecosystem recovery.

Direct seeding of restorative plants is a difficult task in arid environments due, in part, to the low moisture levels inherent to these areas. This barrier to restoration has stimulated a number of methods to help combat this issue, including the burial of seeds just below the soil surface, the addition of fertiliser and the use of other suitable low-cost soil amendments aimed at improving germination and survival. This study examines the effects of burial depth and application of soil amendments on seedling emergence under different watering regimes on four semi-arid zone species. The soil amendments used were hydrogel (EarthCare Water Crystals), fertiliser (Osmocote), and a commercial soil microbial inoculant (Bactivate5). It was found that, while heavier seeded species were able to emerge from deeper below the soil surface, all seeds in the study preferred to emerge from shallow burial depths of around 6-10 mm. Soil amendments were shown to have minimal effect on emergence rates, regardless of the watering regime, while the watering regime was found to have the largest impact. Seedlings under a low watering regime (30% water holding capacity) were found to have the lowest emergence rate, while a moderate watering regime (55% water holding capacity) produced the highest emergence across most species. Results obtained from this study suggest that shallow burial of seeds 6-10 mm below the soil surface, as opposed to surface placement or deeper burial, may enhance emergence for the species tested. Although the soil amendments did not improve plant species emergence, amendment application may still be beneficial for developing seedlings by enhancing seedling resilience to adverse growing conditions such as moisture stress or extreme temperatures.

Restoration of arid vegetation is an essential and difficult task, making the selection of the right methods for restoration an important choice. One way to determine which methods would be most effective is by accessing the accumulated knowledge of restoration practitioners, which is often unreported in the scientific literature. This study created an online survey asking questions of practitioners on the effectiveness of different methods for arid restoration, including how effective they are at promoting restoration and their financial and labour inputs. The survey was distributed to arid restoration practitioners within Australia, with a focus on the southern areas, and found that the methods most commonly used are ones that appear most effective at promoting restoration and are generally the most highly recommended. The cost and labour input did not correlate with the most used or most recommended method, suggesting that these are secondary factors and are not necessarily the most important concerns for the survey respondents. While mechanical direct seeding was indicated to have lower financial and labour inputs, both it and hand-planting were indicated to be similar in restoration ability and were both highly recommended. Grazing control methods and chemical weed control were also indicated to be effective at restoration, likely due to damage that grazing and weed competition can inflict upon plantings. Pre-seeding treatments were found to be both effective at restoration and have low labour and cost requirements, making them one of the most highly recommended methods. Soil amendments, such as water-holding gels and biochar, despite being low-to-moderate in terms of cost and labour input, were not indicated to be effective at restoration and were subsequently not highly recommended. Though some general trends could be found, respondents also commonly pointed out that the choice of methods will often depend on the site-specific conditions.