ABSTRACT Over millennia, social and ecological systems have been shaped by fire and have in turn shaped fire regimes. However, recent decades have seen an escalating “fire crisis” characterized by an increasing incidence of large, intense wildfires, most notably in forests. Voices in the academic literature and media often attribute the fire crisis to a narrow range of mechanisms, for example, fuel management or climate change. This failure to acknowledge the complexity of causes leads to simplistic framings of risk, and ultimately, proposed solutions that are either not feasible or may lead to undesired outcomes. In this review we outline the human and bioclimatic factors that are driving this fire crisis. Factors reviewed include the impacts of colonial legacies, which disrupted Indigenous land stewardship and traditional burning practices over centuries; policies of fire suppression; population growth, urbanization and land management practices; biotic disturbances such as insect outbreaks and invasive plant species; and climate change, which is affecting both fire regimes and social‐ecological resilience to fire. Many of these factors co‐occur leading to complex interactions and, often, unexpected outcomes. Our review highlights that climate change is now having a compounding effect, building on a multitude of other factors to drive the fire crisis. Addressing this crisis requires first acknowledging its complexity and moving beyond simple framings of risk. We suggest solutions will vary across different places and through time, but may include supporting Indigenous land stewardship, adopting flexible fire responses, shifting societal expectations from aggressive fire suppression to “living with fire”, and fostering resilient social and ecological communities.
ABSTRACT Increasing soil organic carbon (SOC), central to food security and climate mitigation, is increasingly recognized as being mediated by microbial necromass C (MNC) accrual. However, how microbial production and mineral preservation jointly govern MNC accrual under contrasting resource conditions remains unclear. Here, we analyzed soils from 14 long‐term fertilization experiments (up to 47 years) to assess how edaphic and climatic conditions regulate the response of MNC accrual to manure (M) and non‐manure (NM) fertilization treatments. We found that the primary constraints on MNC accrual varied with resource availability, with microbial production under resource‐limited conditions and mineral preservation under resource‐abundant conditions. Under resource‐limited conditions, M treatments increased MNC by up to 122%, with changes tightly coupled to SOC gains. This accrual was associated with increases in dissolved organic C and microbial C use efficiency, indicating a production‐constrained pathway in which manure inputs alleviate substrate limitation and promote microbial C allocation toward biomass production and necromass formation. Conversely, under resource‐abundant conditions, MNC responses to fertilization were weaker (+56%) and uncoupled from SOC gains. Instead, MNC accrual was primarily associated with mineral protection capacity (e.g., Fe and Al oxides), consistent with a preservation‐constrained pathway. Overall, microbial processing and mineral preservation represent context‐dependent constraints on MNC accrual under contrasting resource conditions. These findings underscore the importance of resource context for site‐specific C management and for understanding soil C dynamics under global change.
ABSTRACT Although climate‐driven changes in ocean circulation are increasingly recognized as key drivers of marine ecosystem structure and dynamics, their consequences for the early life stages of deep‐sea fishes remain difficult to quantify. In the Southern Ocean, variability in frontal systems such as the Polar Front (PF) may influence larval dispersal and retention, with direct implications for recruitment. We investigated how interannual variability in ocean circulation and egg production shapes larval dispersal and retention in suitable recruitment areas of a large body size deep‐sea fish species, Patagonian toothfish ( Dissostichus eleginoides ), around the Kerguelen Plateau. We developed an integrated modeling framework which combined spatially explicit models of egg production with 24 years (2000–2023) of Lagrangian dispersal simulations driven by satellite‐derived geostrophic currents to quantify successful larval retention. Ontogenetic changes in distribution and fecundity were accounted for to model egg production, allowing retention metrics to reflect spatial heterogeneity in reproductive output. Larval retention rate in suitable recruitment areas varied from 9% to 28% over the study period. PF‐associated jet intensity was significantly associated with larval retention variability: years characterized by stronger PF‐associated circulation showed lower larval retention, with more larvae advected away from the shelf toward the eastern part of the plateau. The latter part of the time series, particularly after 2010, was characterized by stronger year‐to‐year fluctuations, a higher contribution of the North‐West recruitment area, and more frequent low‐retention years. Building on new findings on toothfish spawning dynamics and long‐term altimetry data, we showed for the first time that there is the potential for self‐recruitment in the northern part of the Kerguelen Plateau (French EEZ). We also discussed the implications for fishery management since PF‐associated indices may help interpret past recruitment trends and offer useful early‐warning for future recruitment anomalies.
ABSTRACT Anthropogenic warming and shifts in global precipitation regimes are increasing rainfall variability and the frequency of intense precipitation events, raising uncertainty about how conventional meteorological drought indices capture ecosystem water limitation. This uncertainty arises from two key issues: temporal aggregation, as most meteorological drought indices are based on monthly integrated summaries, and drought definition, because atmospheric water deficits do not necessarily translate into vegetation water stress. Here, we quantified ecosystem gross primary productivity (GPP) responses to drought using three approaches: (1) monthly meteorological drought identified from monthly standardized precipitation evaporation index (SPEI), (2) daily meteorological drought defined by daily SPEI, and (3) ecological drought defined using an indicator of actual vegetation water limitation. Comparing monthly and daily SPEI‐based drought isolated the effects of temporal aggregation, while comparing daily meteorological and ecological droughts quantified the influence of drought definition. Across 130 eddy‐covariance sites spanning multiple biomes and climate zones, we analyzed 6691 drought months identified using monthly SPEI. Daily SPEI data revealed that within months classified as meteorological drought, nearly 50% of days did not coincide with atmospheric water deficits owing to daily rainfall variability. As a result, monthly SPEI overestimated GPP responses (20.60% ± 5.28% increase) relative to daily SPEI (4.61% ± 1.21% increase). In contrast, daily meteorological drought metrics underestimated drought‐induced suppression of GPP by ~46% compared with ecological drought, demonstrating that atmospheric drought metrics do not fully reflect water stress experienced by vegetation. Our results show that both temporal resolution and drought definition can bias estimates of ecosystem drought responses, underscoring the need for finer‐scale temporal and ecologically relevant measures of vegetation water limitation to improve understanding of biosphere–climate interactions in an increasingly drought‐prone world.
