Global Change Biology最新文献

Nitrous oxide (N₂O) reductase, the sole natural microbial sink for N₂O, exists in two microbial clades: nosZI and nosZII. Although previous studies have explored inter-clade ecological differentiation, the intra-clade variations and their implications for N₂O dynamics remain understudied. This study investigated both inter- and intra-clade ecological differentiation among N₂O reducers, the drivers influencing these patterns, and their effects on N₂O emissions across continental-scale river systems. The results showed that both nosZI and nosZII community turnovers were associated with similar key environmental factors, particularly total phosphorus (TP), but these variables explained a larger proportion of variation in the nosZI community. The influence of mean annual temperature (MAT) on community composition increased for more widespread N₂O-reducing taxa. We identified distinct ecological clusters within each clade of N₂O reducers and observed identical ecological clustering patterns across both clades. These clusters were primarily characterized by distinct MAT regimes, coarse sediment texture as well as low TP levels, and high abundance of N₂O producers, with MAT-related clusters constituting predominant proportions. Intra-clade ecological differentiation was a crucial predictor of N₂O flux and reduction efficiency. Although different ecological clusters showed varying or even contrasting associations with N₂O dynamics, the shared ecological clusters across clades exhibited similar trends. Low-MAT clusters in both the nosZI and nosZII communities were negatively correlated with denitrification-normalized N₂O flux and the N₂O:(N₂O + N₂) ratio, whereas high-MAT clusters showed positive correlations. This contrasting pattern likely stems from low-MAT clusters being better adapted to eutrophic conditions and their more frequent co-occurrence with N₂O-producing genes. These findings advance our understanding of the distribution and ecological functions of N₂O reducers in natural ecosystems, suggesting that warming rivers may have decreased N₂O reduction efficiency and thereby amplify temperature-driven emissions.

Global change is rapidly reshaping species' habitat suitability ranges, hence leading to significant shifts in the distribution of marine life. Contrasting distributional responses among species can alter the spatial overlap between predators and prey, potentially disrupting trophic interactions and affecting food web dynamics. Here, we evaluate long-term changes in the spatial overlap of habitat suitability ranges for trophically related species, including crustaceans, fish, penguins, and pinnipeds across 12 Large Marine Ecosystems from the Southern Hemisphere, merged into three primary regions: South America, Southern Africa, Australia and New Zealand. To this aim, we first use Boosted Regression Trees (BRTs) to hindcast and project species-specific changes in suitable habitat from 1850 to 2100 under two future climate scenarios: SSP1-2.6 (low climate forcing) and SSP5-8.5 (high climate forcing). We then analyze changes in species habitat suitability and potential predator–prey spatial overlaps. Findings reveal that marine species generally exhibit changes in their suitable habitats, with pronounced shifts towards higher latitudes under the SSP5-8.5 scenario. However, contrasting trends emerge among predators across functional groups and regions of South America, Southern Africa, Australia and New Zealand. These variations highlight the need for species and regional-specific management responses. We also project contrasting spatial mismatches between predators and prey: predators experiencing declines in suitable habitat tend to exhibit greater overlap with their prey in future scenarios, whereas those with expanding suitable habitat show reduced spatial overlap with their prey. This study provides valuable insights that can inform spatial management strategies in response to climate change and illustrate how climate change may weaken species' ability to adapt to climate-driven environmental changes due to trophic disruptions.

Understanding how bleaching severity varies across space and among and within taxa helps predict changes in community composition due to climate change and informs conservation efforts. Photogrammetry offers a non-invasive and time effective method for quantifying attributes of thousands of coral colonies across large, environmentally diverse reef areas. This approach circumvents the limitations of traditional survey methods, where detailed tracking of individual colonies comes at the expense of large sampling areas and sample sizes. Using photogrammetry, we measured colony size and scored bleaching severity of > 5000 colonies of 13 taxa across 26 sites (> 7400 m² of reef) during a mild bleaching event in the central Great Barrier Reef (GBR) in 2022. We quantified the relationship between bleaching severity and key biological and environmental factors: colony size, taxonomic identity, degree-heating weeks (DHWs), water velocity, various measures of reef structural complexity, depth, and distance to coast. Our results show that bleaching probability decreased with increasing colony size for most taxa, contradicting the current understanding of size-dependent bleaching. Counter to conventional thinking, tabular Acropora spp. presented very low levels of bleaching in 2022 despite being among the most severely bleached taxa during the bleaching event in 1998, suggesting possible adaptation in the last two decades. Our results show a high level of idiosyncrasy in environmental gradients of bleaching severity. For instance, the effect of depth on was taxon-dependent and the effect of wave velocity differed between inshore and offshore reefs. Our results challenge prevailing paradigms around the role of colony size and environment in regulating bleaching susceptibility, suggesting that refugia are not universal but instead depend on specific environment-taxonomic combinations and taxon-specific colony sizes.

Macrophyte-based lake restoration has successfully transitioned lakes from turbid conditions dominated by phytoplankton to a more natural, clear state; however, its impact on microbial carbon pump-mediated dissolved organic carbon (DOM) storage and greenhouse gas (GHG) emissions in the aquatic ecosystem remains largely unexplored. Through a year-long field study, we conducted a comparative analysis of two alternative habitats within the same lake—restored and unrestored areas. Results demonstrated that restoration not only substantially decreases nutrient levels and algal blooms—evidenced by over 50% reductions in nitrogen, phosphorus, and chlorophyll a—but also significantly increases the accumulation of recalcitrant DOM. This is characterized by rises of 9.52% in highly unsaturated compounds, 8.68% in carboxyl-rich alicyclic molecules, 37.54% polycyclic condensed aromatics and polyphenols, and 20.21% in SUVA₂₅₄. Additionallly, key microbial taxa with potent carbon pump functions—primarily Gammaproteobacteria, Alphaproteobacteria, and Actinobacteria—are enriched in restored areas. Structural equation modeling (SEM) further elucidated the complex interrelationships within more pristine lake ecosystems: macrophytes and elevated dissolved oxygen (DO) concentrations enhance carbon sequestration via microbial carbon pump pathways, while the restoration significantly mitigates methane emissions caused by eutrophication. These findings highlight an extra function of aquatic macrophyte restoration, offering valuable insights into microbial processes for future restoration efforts aimed at promoting sustainable aquatic ecosystems and mitigating global warming.

Long-term climatic differences shape the ecological memory of soil bacterial communities, which refers to the ability of past events to influence current environmental responses. However, their ecological mechanisms and consequences for bacterial responses to current environmental changes remain largely unknown, particularly in terms of temporal dynamics. Therefore, soil bacterial communities in the arid (Lhasa River Basin) and humid (Nyang River Basin) grasslands of the Qinghai-Tibet Plateau were compared to explore their temporal dynamics in response to current soil moisture and the resulting ecological consequences. Our results indicate that the differences between current and historical soil moisture determine the degree of divergence in bacterial community composition and potential function. The temporal dynamics of bacterial community composition, life strategies, and potential functions differed with environmental history, even under comparable moisture conditions. In contrast, bacterial communities with the same environmental history exhibited similar temporal dynamics, suggesting that environmental history has an important influence on bacterial community dynamics. This phenomenon may be caused by the continuous accumulation of bacterial community life strategies as an informational legacy, regulating future response patterns to soil moisture changes and thereby affecting biogeochemical cycles in the soil. For example, soil bacterial communities in relatively arid regions may increase their potential for dormancy, even when the current soil environment is moist, thereby enhancing ecosystem resilience by improving their capacity to respond to future drought events. This study provides new insights into the ecological memory of soil bacteria, emphasizing its critical role in influencing the compositional and functional changes of bacterial communities in response to current environmental changes. It highlights the significance of understanding the effect of environmental history in predicting the future responses of bacterial communities to disturbances and environmental changes.

Whether species extinctions have accelerated during the Anthropocene and the extent to which certain species are more susceptible to extinction due to their ecological preferences and intrinsic biological traits are among the most pressing questions in conservation biology. Assessing extinction rates is, however, challenging, as best exemplified by the phenomenon of ‘dark extinctions’: the loss of species that disappear before they are even formally described. These issues are particularly problematic in oceanic islands, where species exhibit high rates of endemism and unique biological traits but are also among the most vulnerable to extinction. Here, we document plant species extinctions since Linnaeus' Species Plantarum in Macaronesia, a biogeographic region comprised of five hyperdiverse oceanic archipelagos, and identify the key drivers behind these extinctions. We compiled 168 records covering 126 taxa, identifying 13 global and 155 local extinction events. Significantly higher extinction rates were observed compared to the expected global background rate. We uncovered differentiated extinction patterns along altitudinal gradients, highlighting a recent coastal hotspot linked to socioeconomic changes in Macaronesian archipelagos from the 1960s onwards. Key factors influencing extinction patterns include island age, elevation, introduced herbivorous mammals, and human population size. Trait-based analyses across the floras of the Azores and Canary Islands revealed that endemicity, pollination by vertebrates, nitrogen-fixing capacity, woodiness, and zoochory consistently tended to increase extinction risk. Our findings emphasize the critical role of geography and biological traits, alongside anthropogenic impacts, in shaping extinction dynamics on oceanic islands. Enhancing our knowledge of life-history traits within island floras is crucial for accurately predicting and mitigating future extinction risks, underscoring the urgent need for comprehensive biodiversity assessments in island ecosystems.