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Over the past 70 years, the world has witnessed extraordinary growth in crop productivity, enabled by a suite of technological advances, including higher yielding crop varieties, improved farm management, synthetic agrochemicals, and agricultural mechanization. While this “Green Revolution” intensified crop production, and is credited with reducing famine and malnutrition, its benefits were accompanied by several undesirable collateral effects (Pingali, 2012). These include a narrowing of agricultural biodiversity, stemming from increased monoculture and greater reliance on a smaller number of crops and crop varieties for the majority of our calories. This reduction in diversity has created vulnerabilities to pest and disease epidemics, climate variation, and ultimately to human health (Harlan, 1972). The value of crop diversity has long been recognized (Vavilov, 1992). A global system of genebanks (e.g., www.genebanks.org/genebanks/) was established in the 1970s to conserve the abundant genetic variation found in traditional “landrace” varieties of crops and in crop wild relatives (Harlan, 1972). While preserving crop variation is a critical first step, the time has come to make use of this variation to breed more resilient crops. The DivSeek International Network (https://divseekintl.org/) is a scientific, not-for-profit organization that aims to accelerate such efforts.

AbstractSeagrass conservation is critical for mitigating climate change due to the large stocks of carbon they sequester in the seafloor. However, effective conservation and its potential to provide nature-based solutions to climate change is hindered by major uncertainties regarding seagrass extent and distribution. Here, we describe the characterization of the world’s largest seagrass ecosystem, located in The Bahamas. We integrate existing spatial estimates with an updated empirical remote sensing product and perform extensive ground-truthing of seafloor with 2,542 diver surveys across remote sensing tiles. We also leverage seafloor assessments and movement data obtained from instrument-equipped tiger sharks, which have strong fidelity to seagrass ecosystems, to augment and further validate predictions. We report a consensus area of at least 66,000 km2 and up to 92,000 km2 of seagrass habitat across The Bahamas Banks. Sediment core analysis of stored organic carbon further confirmed the global relevance of the blue carbon stock in this ecosystem. Data from tiger sharks proved important in supporting mapping and ground-truthing remote sensing estimates. This work provides evidence of major knowledge gaps in the ocean ecosystem, the benefits in partnering with marine animals to address these gaps, and underscores support for rapid protection of oceanic carbon sinks.

AbstractChanges in the distribution of rainfall and the occurrence of extreme rain events will alter the size and persistence of aquatic ecosystems. Such alterations may affect the structure of local aquatic communities in terms of species composition, and by altering species interactions. In many aquatic ecosystems, leaf litter sustains detrital food webs and could regulate the responses of communities to changes in rainfall. Few empirical studies have focused on how rainfall changes will affect aquatic communities and none have evaluated if basal resource diversity can increase resistance to such rainfall effects. In this study, we used water‐holding terrestrial bromeliads, a tropical aquatic ecosystem, to test how predicted rainfall changes and litter diversity may affect community composition and trophic interactions. We used structural equation modeling to investigate the combined effects of rainfall changes and litter diversity on trophic interactions. We demonstrated that changes in rainfall disrupted trophic relationships, even though there were only minor direct effects on species abundance, richness, and community composition. Litter diversity was not able to reduce the impact of changes in rainfall on trophic interactions. We suggest that changes in rainfall can alter the way in which species interact with each other, decreasing the linkages among trophic groups. Such reductions in biotic interactions under climate change will have critical consequences for the functioning of tropical aquatic ecosystems.

Climate change and invasive species have the potential to alter species diversity, creating novel species interactions. Interspecific competition and facilitation between predators may either enhance or dampen trophic cascades, ultimately influencing total predator effects on communities and biogeochemical cycling of ecosystems. However, previous studies have only investigated the effects of a single predator species on CO2 flux of aquatic ecosystems. In this study, we measured and compared the individual and joint effects of predatory damselfly larvae and diving beetles on total prey biomass, leaf litter processing, and dissolved CO2 concentrations of experimental bromeliad ecosystems. Damselfly larvae created strong trophic cascades that reduced CO2 concentrations by ~46% relative to no-predator treatments. Conversely, the effects of diving beetles on prey biomass, leaf litter processing, and dissolved CO2 were not statistically different to no-predator treatments. Relative to multiplicative null models, the presence of damselfly larvae and diving beetles together resulted in antagonistic relations that eliminated trophic cascades and top-down influences on CO2 concentrations. Furthermore, we showed that the antagonistic interactions between predators occurred due to a tactile response that culminated in competitive displacement of damselfly larvae. Our results demonstrate that predator identity and predator-predator interactions can influence CO2 concentrations of an aquatic ecosystem. We suggest that predator effects on CO2 fluxes may depend on the particular predator species removed or added to the ecosystem and their interactions with other predators.

Land use is central to addressing sustainability issues, including biodiversity conservation, climate change, food security, poverty alleviation, and sustainable energy. In this paper, we synthesize knowledge accumulated in land system science, the integrated study of terrestrial social-ecological systems, into 10 hard truths that have strong, general, empirical support. These facts help to explain the challenges of achieving sustainability in land use and thus also point toward solutions. The 10 facts are as follows: 1) Meanings and values of land are socially constructed and contested; 2) land systems exhibit complex behaviors with abrupt, hard-to-predict changes; 3) irreversible changes and path dependence are common features of land systems; 4) some land uses have a small footprint but very large impacts; 5) drivers and impacts of land-use change are globally interconnected and spill over to distant locations; 6) humanity lives on a used planet where all land provides benefits to societies; 7) land-use change usually entails trade-offs between different benefits—"win–wins" are thus rare; 8) land tenure and land-use claims are often unclear, overlapping, and contested; 9) the benefits and burdens from land are unequally distributed; and 10) land users have multiple, sometimes conflicting, ideas of what social and environmental justice entails. The facts have implications for governance, but do not provide fixed answers. Instead they constitute a set of core principles which can guide scientists, policy makers, and practitioners toward meeting sustainability challenges in land use.

Abstract Current methods of estimating boil-off gas (BOG) rates for large-scale liquefied natural gas (LNG) storage tanks are largely empirical and based on limited available experimental data. More accurate models would be extremely valuable for estimating the potential for excessive BOG generation during LNG storage and transportation scenarios as well as providing critical inputs into the design of BOG re-liquefaction systems. This study reports a series of experiments that have been conducted for LNG-like binary mixtures of methane and ethane to measure the BOG production and resultant pressure change under various industrially relevant conditions. Experimental data and observations made in this work are compared with both the available literature and with the predictions of a new non-equilibrium model that uses the GERG-2008 equation of state to calculate relevant LNG and BOG properties. The data reveal three distinct stages of BOG evolution, here labelled as self-pressurisation, transient, and homogenous. It is observed that, in the self-pressurisation stage, the thickness of a thermally stratified layer adjacent to the liquid–vapor interface increases with time. The transient stage is defined to commence when the system reaches the specified relief pressure and the homogeneous stage is reached upon the effective elimination of thermal stratification in the LNG. Good agreement exists between this new model and the experimental and literature data acquired during the self-pressurisation and homogeneous stages. In the transient stage, the model does not accurately quantify the BOG rate indicating a need to incorporate the effects liquid thermal stratification in future model development.

Abstract This research first examines the link connectivity of major Northeast Asian carriers at country levels, and then uses a dynamic network DEA model to assess these carriers' efficiency performance. The connectivity measure suggests that although China, Japan and Korea differ in the size of domestic markets, the major carriers of the three countries do not differ much in terms of their connectivity performance in their key international markets. Chinese and Japanese carriers are quite similar in technical efficiency while Korea's two carriers take the lead in this measure. We thus present an argument that most of the carriers in this region are operating at a near-level playing field and it is time to push forward the aviation market integration agenda in Northeast Asia.