Global Change Biology最新文献

Conservationists are increasingly leveraging systematic conservation planning (SCP) to inform restoration actions that enhance biodiversity. However, restoration frequently drives ecological transformations at local scales, potentially resulting in trade-offs among wildlife species and communities. The Conservation Interactions Principle (CIP), coined more than 15 years ago, cautions SCP practitioners regarding the importance of jointly and fully evaluating conservation outcomes across the landscape over long timeframes. However, SCP efforts that guide landscape restoration have inadequately addressed the CIP by failing to tabulate the full value of the current ecological state. The increased application of SCP to inform restoration, reliance on increasingly small areas to sustain at-risk species and ecological communities, ineffective considerations for the changing climate, and increasing numbers of at-risk species, are collectively intensifying the need to consider unintended consequences when prioritizing sites for restoration. Improper incorporation of the CIP in SCP may result in inefficient use of conservation resources through opportunity costs and/or conservation actions that counteract one another. We suggest SCP practitioners can avoid these consequences through a more detailed accounting of the current ecological benefits to better address the CIP when conducting restoration planning. Specifically, forming interdisciplinary teams with expertise in the current and desired ecosystem states at candidate conservation sites; improving data availability; modeling and computational advancements; and applying structured decision-making approaches can all improve the integration of the CIP in SCP efforts. Improved trade-off assessment, spanning multiple ecosystems or states, can facilitate efficient, proactive, and coordinated SCP applications across space and time. In doing so, SCP can effectively guide the siting of restoration actions capable of promoting the full suite of biodiversity in a region.

The concepts of planetary boundaries are influential in the sustainability literature and assist in delineating the ‘safe operating spaces’ beyond which critical Earth system processes could collapse. Moving away from our current trajectory towards ‘hothouse Earth’ will require knowledge of how Earth systems have varied throughout the Holocene, and whether and how far we have deviated from past ranges of variability. Such information can inform decisions about where change could be resisted, accepted or where adaptation is inevitable. The need for information on long-term (Holocene) change provides an interface for palaeoecology and sustainability that remains underexploited. In this position paper, we explore this interface, first discussing the need for long-term perspectives and introducing examples where palaeoecology has been used in defining safe operating spaces and constraining limits of acceptable change. We describe advances in quantitative methods for analysis of time-series data that strengthen the contribution of palaeoecology to the concepts of planetary boundaries and safe operating spaces. We consider the importance of issues of scaling from landscape to regional and global scales in operationalising planetary boundaries concepts. We distil principles for this field of research going forward and introduce three case studies which will form the basis of research on these topics.

The Qinghai-Tibet Plateau (QTP) has an extensive frozen soil distribution and intense geological tectonic activity. Our surveys reveal that Qinghai-Tibet Plateau earthquakes can not only damage infrastructure but also significantly impact carbon dioxide emissions. Fissures created by earthquakes expose deep, frozen soils to the air and, in turn, accelerate soil carbon emissions. We measured average soil carbon emission rates of 968.53 g CO₂ m⁻²·a⁻¹ on the fissure sidewall and 514.79 g CO₂ m⁻²·a⁻¹ at the fissure bottom. We estimated that the total soil carbon emission flux from fissures caused by M ≥ 6.9 earthquakes on the Qinghai-Tibet Plateau from 326 B.C. to 2022 is 1.83 × 10¹² g CO₂ a⁻¹; this value is equivalent to 0.51% ~ 1.48% and 2.34% ~ 5.14% of the increased annual average carbon sink resulting from the national ecological restoration projects targeting forest protection and grassland conservation in China, respectively. These earthquake fissures thus increased the soil carbon emission rate by 0.71 g CO₂ m⁻²·a⁻¹ and significantly increased the total carbon emissions. This finding shows that repairing earthquake fissures could play a very important role in coping with global climate change.

Climate change can impact marine ecosystems through many biological and ecological processes. Ecosystem models are one tool that can be used to simulate how the complex impacts of climate change may manifest in a warming world. In this study, we used an end-to-end Atlantis ecosystem model to compare and contrast the effects of climate-driven species redistribution and projected temperature from three separate climate models on species of key commercial importance in the California Current Ecosystem. Adopting a scenario analysis approach, we used Atlantis to measure differences in the biomass, abundance, and weight at age of pelagic and demersal species among six simulations for the years 2013–2100 and tracked the implications of those changes for spatially defined California Current fishing fleets. The simulations varied in their use of forced climate-driven species distribution shifts, time-varying projections of ocean warming, or both. In general, the abundance and biomass of coastal pelagic species like Pacific sardine (Sardinops sagax) and northern anchovy (Engraulis mordax) were more sensitive to projected climate change, while demersal groups like Dover sole (Microstomus pacificus) experienced smaller changes due to counteracting effects of spatial distribution change and metabolic effects of warming. Climate-driven species distribution shifts and the resulting changes in food web interactions were more influential than warming on end-of-century biomass and abundance patterns. Spatial projections of changes in fisheries catch did not always align with changes in abundance of their targeted species. This mismatch is likely due to species distribution shifts into or out of fishing areas and emphasizes the importance of a spatially explicit understanding of both climate change effects and fishing dynamics. We illuminate important biological and ecological pathways through which climate change acts in an ecosystem context and end with a discussion of potential management implications and future directions for climate change research using ecosystem models.

The concept of “blue carbon” is, in this study, critically evaluated with respect to its definitions, measuring approaches, and time scales. Blue carbon deposited in ocean sediments can only counteract anthropogenic greenhouse gas (GHG) emissions if stored on a long-term basis. The focus here is on the coastal blue carbon ecosystems (BCEs), mangrove forests, saltmarshes, and seagrass meadows due to their high primary production and large carbon stocks. Blue carbon sequestration in BCEs is typically estimated using either: 1. sediment carbon inventories combined with accretion rates or 2. carbon mass balance between input to and output from the sediment. The inventory approach is compromised by a lack of accurate accretion estimates over extended time periods. Hence, short-term sedimentation assays cannot be reliably extrapolated to long timescales. The use of long-term tracers like ²¹⁰Pb, on the other hand, is invalid in most BCEs due to sediment mobility by bioturbation and other physical disturbances. While the mass balance approach provides reasonable short-term (months) estimates, it often fails when extrapolated over longer time periods (> 100 years) due to climatic variations. Furthermore, many published budgets based on mass balance do not include all relevant carbon sources and sinks. Simulations of long-term decomposition of mangrove, saltmarsh (Spartina sp.), and eelgrass (Zostera sp.) litter using a 3-G exponential model indicate that current estimates of carbon sequestration based on the inventory and mass balance approaches are 3–18 times too high. Most published estimates of carbon sequestration in BCEs must therefore be considered overestimates. The climate mitigation potential of blue carbon in BCEs is also challenged by excess emissions of the GHG methane (CH₄) and nitrous oxide (N₂O) from biogenic structures in mangrove forests and saltmarsh sediments. Thus, in many cases, carbon sequestration into BCE sediments cannot keep pace with the simultaneous GHG emissions in CO₂ equivalents.