Catherine E. Lovelock’s research while affiliated with The University of Queensland and other places

Climate change and anthropogenic activities threaten biodiversity and ecosystem services. Climate-smart conservation plans address these challenges by focusing protection in climate-resilient areas. However, integrating climate change in the design of conservation plans is often deemed too expensive, as it may require larger networks or protecting more costly sites. Using mangroves as a case study, we evaluated the efficiency of protecting mangroves in climate-smart versus climate-naïve reserve networks. We found that climate-smart conservation plans could provide sizable benefits for relatively small increases in protected area. Moreover, transboundary plans, involving cooperation among countries, require less area and protect more climate-resilient mangroves than nation-by-nation plans. Implementing these strategies would improve the current network of protected areas for mangroves, which currently has poor climate resilience. These findings could also be applied in other ecosystems.

Prevalence of mangrove progradation in the Gulf of Carpentaria revealed by satellite time series. The distribution of mangroves has been declining, predominantly driven by anthropogenic impacts, and increasingly climate change is proposed to be impacting their extent and condition. Projections of sea-level rise imply that the seaward extent of mangroves may retract with extension on the landward margin. The archive of Landsat imagery enables broad-scale regional assessment of changes through Digital Earth Australia, from 1988 to the present. Changes to the extent and condition of open coast mangroves can be interpreted using indices of vegetation and surface water conditions calculated from Landsat data. These dense timeseries data can be extracted and visualised along transects. In the Gulf of Carpentaria in northern Australia, where there are limited anthropogenic influences, we investigated shore-normal transects that were systematically spaced along a coastline of approximately 1500 km. This coastline includes a range of geomorphologically complex features such as chenier ridges, tidal creeks, spits and tide-dominated beaches. We found widespread occurrence of progradation of the seaward margin. Changes to the landward mangrove extent were highly variable. Despite the extensive dieback of mangroves in recent years, including events in the early 1990s and 2015-2016, recovery of vegetation cover was evident in subsequent years. This analytical approach offers potential to explore changes to both seaward and landward mangrove margins in open-coast settings. In contrast to highly populated coastlines where infrastructure and assets cause coastal squeeze, landward expansion of mangroves in northern Australia is anticipated across the widespread low-lying coastal plains, which offer accommodation space under a higher sea level. Observations of progradation of the mangrove seaward margin over the past three decades are contrary to expectations under sea-level rise.

Mangroves offer many important ecosystem services including carbon sequestration, serving as nursery grounds to many organisms, and acting as barriers where land and sea converge. Mangroves exhibit environmental flexibility and resilience and frequently occur in nutrient-limited systems. Despite existing research on mangrove microbiomes, the effects of nutrient additions on microbial community structure, composition, and function in intertidal and landward zones of mangrove ecosystems remain unclear. We utilized a long-term nutrient amendment study in Exmouth Gulf, Western Australia conducted in two zones, the intertidal fringe and supralittoral scrub forests, dominated by Avicennia marina . Root samples were fractionated into rhizosphere, rhizoplane and endosphere compartments and analyzed by 16S rRNA gene amplicon sequencing to determine the effects of nutrient stress on community structure and function. Our data showed species richness and evenness were significantly higher in the scrub forest zone. PERMANOVA analysis revealed a significant effect of nutrient enrichment on beta diversity ( p = 0.022, R ² = 0.012) in the fringe forest zone only. Cylindrospermopsis , which has been associated with harmful algal blooms, was found to be significantly enriched in fringe phosphate-fertilized plots and nitrogen-fixing Hyphomicrobiales were significantly depleted in the scrub nitrogen-fertilized plots. Meanwhile, root compartments and forest zone had a greater effect on beta diversity ( p = 0.001, R ² = 0.186; p = 0.001, R ² = 0.055, respectively) than nutrient enrichment, with a significant interaction between forest zone and root compartment ( p = 0.001, R ² = 0.025). This interaction was further observed in the distinct divergence identified in degradative processes of the rhizosphere compartment between the two forest zones. Degradation of aromatic compounds were significantly enriched in the fringe rhizosphere, in contrast to the scrub rhizosphere, where degradation of carbohydrates was most significant. Despite the highly significant effect of forest zone and root compartments, the long-term effect of nutrient enrichment impacted community structure and function, and potentially compromised overall mangrove health and ecosystem stability.

Tidal marshes are threatened coastal ecosystems known for their capacity to store large amounts of carbon in their water-logged soils. Accurate quantification and mapping of global tidal marshes soil organic carbon (SOC) stocks is of considerable value to conservation efforts. Here, we used training data from 3,710 unique locations, landscape-level environmental drivers and a newly developed global tidal marsh extent map to produce the first global, spatially-explicit map of SOC storage in tidal marshes at 30 m resolution. We estimate the total global SOC stock to 1 m to be 1.44 Pg C, with a third of this value stored in the United States of America. On average, SOC in tidal marshes' 0-30 and 30-100 cm soil layers are estimated at 83.1 Mg C ha ⁻¹ (average predicted error 44.8 Mg C ha ⁻¹ ) and 185.3 Mg C ha ⁻¹ (average predicted error 105.7 Mg C ha ⁻¹ ), respectively. Our spatially-explicit model is able to capture 59% of the variability in SOC density, with elevation being the strongest driver aside from soil depth. Our study reveals regions with high prediction uncertainty and therefore highlights the need for more targeted sampling to fully capture SOC spatial variability.

With the passage of the one-year anniversary of the Kunming-Montreal Global Biodiversity Framework (GBF), substantial effort is still needed to progress Target 2 — the ‘restoration target’. The restoration target guides parties to “ensure that by 2030 at least 30 per cent of areas of degraded terrestrial, inland water, and marine and coastal ecosystems are under effective restoration, in order to enhance biodiversity and ecosystem functions and services, ecological integrity and connectivity”. This target is a critical step towards upscaling global restoration, but almost every word of it provides scope for legal and ecological interpretation. This could result in markedly different on-the-ground outcomes for conservation once applied at a national level. Although nebulous targets are a common by-product of the international negotiation process, definitional uncertainty in the meaning of key terms can lead to markedly different models of implementation across different countries and make success difficult to assess and measure2,3. More fundamentally, it is crucial that the key elements of Target 2 are interpreted in the spirit of the GBF — that is, to achieve rapid, ambitious and large-scale restoration of global ecosystems, which is a critical goal given the ongoing deterioration of ecosystems globally. Here, we unpack the elements of Target 2 — none of which are defined in the GBF itself — to highlight areas of definitional ambiguity, better guide consistency in implementation and encourage genuine progress towards its achievement.

Managing coastal wetlands is one of the most promising activities to reduce atmospheric greenhouse gases, and it also contributes to meeting the United Nations Sustainable Development Goals. One of the options is through blue carbon projects, in which mangroves, saltmarshes, and seagrass are managed to increase carbon sequestration and reduce greenhouse gas emissions. However, other tidal wetlands align with the characteristics of blue carbon. These wetlands are called tidal freshwater wetlands in the United States, supratidal wetlands in Australia, transitional forests in Southeast Asia, and estuarine forests in South Africa. They have similar or larger potential for atmospheric carbon sequestration and emission reductions than the currently considered blue carbon ecosystems and have been highly exploited. In the present article, we suggest that all wetlands directly or indirectly influenced by tides should be considered blue carbon. Their protection and restoration through carbon offsets could reduce emissions while providing multiple cobenefits, including biodiversity.

Global forecasts of ecosystem responses to increasing climatic and anthropogenic pressures are needed to inform adaptation planning. However, data of appropriate spatio-temporal resolution are not typically available to parameterise complex processes at the global scale. Forecast uncertainty associated with ‘data-process’ scale incongruities must be quantified and effectively communicated to avoid over-confident decision-making. Here, we used network models to make probabilistic forecasts of the direction of change in mangrove extent globally under the SSP5-8.5 climate emissions scenario by 2040-2060. We forecast that seaward net loss is the most likely outcome in 77% [±37-78%; 95% confidence] of mangrove forest units, while 30% [±15-59%] will experience landward net gain or stability. Parameter uncertainty limited our capacity to make reliable forecasts everywhere, highlighting where current understanding and global datasets are deficient. However, with action to manage or restore, the number of mangrove forest units likely to experience net gain or stability could nearly double.