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Scientific ideas on the human population tend to be rooted in a “slow demography” paradigm, which emphasizes an inertial, predictable, self-contained view of population dynamics, mostly dependent on fertility and mortality. Yet, demography can also move fast. At the country level, it is crucial to empirically assess how fast demography moves by taking migratory movements into account, in addition to fertility and mortality. We discuss these ideas and present new estimates of the speed of population change, that is, country-level population turnover rates, as well as the share of turnover due to migration, for all countries in the world with available data between 1990 and 2020. Population turnover is inversely related to population size and development, and migratory movements tend to become important factors in shaping demography for both small and highly developed countries. Longitudinally, we analyze annual turnover data for Italy and Germany, documenting the changing speed of population change over time and its determinants. Accepting the “fast and slow” demography perspective has several implications for science and policy, which we discuss.

Over the past few decades, anaerobic ammonium oxidation (anammox) has been extensively documented at different scales in natural ecosystems. Previous studies have stated that the community composition of anammox bacteria is shaped mainly by environmental factors, whereas spatial factors have been largely overlooked. This study investigated biogeographical patterns of anammox bacterial communities using 42 sediment samples along a 4300-km stretch of the Yangtze River, the longest river in Asia. A significant distance-decay relationship was observed for anammox bacterial community similarity, which was significantly influenced by mean dendritic distance rather than environmental factors. This implied that dispersal limitation plays an important role in shaping biogeographical pattern of anammox community. Furthermore, our results revealed that neutral processes played vital role in shaping community assembly of anammox bacteria, and their communities were seriously dispersal limited. These findings contrast with previous studies on community similarities between broad taxonomic groups, which are mainly determined by niche-based selection owing to greater niche distances within broad taxonomic groups than in anammox bacteria. Importantly, the slope of the distance-decay curve was much steeper than previously reported for whole bacteria, which indicating the species turnover rate of anammox bacterial community was significantly higher than that of the whole bacterial community. Anammox bacteria harbor strong adhesion ability and low dispersal potential, and ultimately exhibited a high species turnover rate. Together, in the context of biogeography, our results highlight the importance of dispersal limitation in shaping the biogeographical pattern of anammox bacterial community.

Carbon (δ13C) and nitrogen (δ15N) stable isotopes (SI) serve as natural markers for evaluating fish food sources. However, interpreting SI isotope values in newly hatched fish becomes intricate due to the transfer of maternal resources during early development (egg, larvae). This research investigates maternal influences on neotropical freshwater fish larvae growth through SI analysis, focusing on the pacú fish (Piaractus mesopotamicus). The study utilizes a commercial inert feed to assess carbon and nitrogen contributions to larval tissue growth while evaluating the turnover rate, providing valuable insights into early-life nutritional dynamics. Both SI exhibit variations during larval development, following a chronological pattern corresponding to ontogeny, with a significant shift at 13 days after hatching (DAH). Maternal transmission significantly influences isotopic signatures in early larval stages, showing linear correlations between isotopic ratios and standard length (SL) until 15 DAH. C:N ratios decrease from 6.3 ± 0.1 at 0 DAH to 4.2 ± 0.1 at 13 DAH. The isotopic composition of maternal origin aligns with egg stage values, emphasizing the stability of maternal transmission. Under experimental conditions, elemental carbon half-life in tissue (t50) is 6.44 days, and nitrogen t50 is 3.82 days. Maternal isotopic ratios in initial larval development stages offer a potential method for estimating nutritional tracers in field-collected eggs, contributing to understanding the role of freshwater nurseries in comprehending migratory routes, critical hatchery areas, and stock assessment of neotropical migratory fishes. This research provides valuable insights for fisheries management of continental fish species, emphasizing the efficiency of using maternal transmission as an indicator for estimating contributions from nurseries to fish stock recruitment.

The mechanism that causes the difference in carbon (C) turnover rate in root populations is unclear. The carbon utilization strategy is assumed to be the main causal factor responsible for differences in root turnover rate. In this study, we determined the correlations between root turnover rate, production, and proportions of C allocated to roots using 13CO2 as a labeling gas in a 13C pulse labeling experiment. The proportions of δ13C were measured in various organs of the grass Bothriochloa ischaemum sampled 0, 6, 24, 48, 216, and 360 h after labeling in three treatments: control (CK), mild water stress (MS), and serious water stress (SS). We found that drought stress increased short-term C allocation to belowground. Fine roots have stronger C demand than coarse root under drought condition. The amount of 13C gradually decreased in leaves and increased in soil with time after 13C pulse labeling. Stem 13C increased with the level of stress and peaked at 24 h, while both fine- and coarse-root 13C peaked at 216 h. 13C distributed to fine roots in MS was significantly higher than in the other treatments at 216 h. The fine-root turnover rate in SS treatment was positively correlated with root biomass but not the amount of 13C. Larger C allocation to roots increased fine-root mass in MS, stimulated rapid fine-root turnover, and increased C input to both the rhizosphere and soil. The fine-root turnover in CK was significantly positively correlated with both 13C amount and biomass, which indicated that increasing short-term C input accelerated turnover in the fine-root pool. The C allocation difference between the fine roots and coarse roots may be a key cause of the different turnover rate in the root population.

PurposeThis paper aims to explore the key risk factors affecting the Personnel Localization Management of international construction projects under the major public emergencies represented by the novel coronavirus pneumonia pandemic (hereinafter COVID-19) and how the public emergency affected the Personnel Localization Management from three levels: staff turnover rate, the number of different personnel, the salary and performance of workers. The paper also helps to enhance the construction enterprises' response capacity of major public emergencies and provides a comprehensive framework of optimization strategies for the Personnel Localization Management of international construction projects (hereinafter projects).Design/methodology/approachThe main research method of this paper is the case study, and ten representative international construction projects are selected for case study in China construction enterprises (hereinafter CCE). And this study used the failure mode and effects analysis (FMEA) and comparative analysis to find out all potential risk factors under the COVID-19 and analyze how the epidemic affects the Personnel Localization Management of projects which based on the primary data from 10 projects obtained through in-depth interviews and the secondary data from China First Metallurgical Group and Central South Construction Group's Overseas Enterprise.FindingsThe findings show that the outbreak of the major public emergencies not only greatly increased eight risk factors but also directly led to an increase in staff turnover rate. Meanwhile, the numbers of Chinese and local managers and workers are all affected, and an increase in the number and the salary performance of local workers can be reduced, to a certain extent, to the cost-to-output ratio of the projects. The findings would help construction enterprises better cope with Personnel Localization Management and enhance the response capacity of major public emergencies.Research limitations/implicationsThis study will broaden researchers' horizons regarding “Personnel Localization Management under major public emergencies” and “risk factors of Personnel Localization Management in an international context.” Furthermore, construction enterprises looking for a better mechanism of Personnel Localization Management can benefit from research findings and lessons learned from the authors' case study during or before an outbreak of major public emergency. Lastly, the framework of optimization strategies for Personnel Localization Management can be used both for research purposes and practice issues in international construction projects.Practical implicationsThe findings from the authors' case study offer the direction for international construction enterprises in China and other countries to formulate effective measures, strengthen overseas business and establish a crisis management mechanism for Personnel Localization Management under major public emergencies, and the findings provide emergency plans for projects to improve the public crisis handling capacity and respond to major public emergencies such as the COVID-19.Social implicationsThis study analyzes the impact of the COVID-19 on the Personnel Localization Management of international construction projects from the perspective of personnel. This study provides a theoretical reference for the international construction industry to actively respond to major public emergencies. Besides, the research is conducive to improving the emergency response mechanism in the construction industry, and further promoting the high-quality and globalized development of international construction.Originality/valueThis study provides other researchers with a comprehensive understanding of the risk factors affecting the Personnel Localization Management of projects under the COVID-19 and insight for further research on localization management, risk management, and project management.

Manufacturing companies often provide supplies of raw materials so that the production process runs smoothly. Initial observations on halal frozen food businesses that use chicken and shrimp as the main ingredients show that material procurement activities are carried out daily and materials are purchased more when prices on the market are down. The company’s historical data shows a shortage of chicken raw material supplies in April due to increased demand, while raw material supplies were insufficient, and raw material prices tended to be high. This research was conducted to measure the performance of raw material inventory at halal frozen food companies using the inventory turnover rate, inventory days of supply, and fill rate methods and to calculate the optimal amount of raw material inventory with EOQ, safety stock, and reorder point (ROP). The inventory turnover rate calculation for chicken raw materials shows the best value in June 2022 of 68.35, the results of the analysis of the best inventory turnover rate for shrimp raw materials in March 2022 are 68.79. The calculation of inventory days of supply for chicken raw materials shows the best value in December 2022 of 0.98 days, calculation of inventory days of supply for shrimp shows the best value in February 2023 of 0.91 days. The fill rate is 100%. The research results show that inventory performance in the halal frozen food business is good. To avoid raw material shortages in the future, companies can use the Economic Order Quantity guide in ordering raw materials.

We tested the relation between the below- and aboveground tree phenology, determining if beech and oak have a greater fine-root lifespan and a smaller turnover rate than birch and if thinner fine-roots or fine-roots born in spring have a shorter lifespan and greater turnover rate than thicker fine-roots or fine-roots born in another season. The fine-root phenology, bud burst, and leaf senescence in Belgian stands were monitored using minirhizotrons, visual observations, and chlorophyll measurements, respectively. The fine-root phenology and the lifespan and turnover rate were estimated using generalized additive models and Kaplan–Meier analyses, respectively. Unlike the aboveground phenology, the belowground phenology did not show a clear and repeating yearly pattern. The cumulative root surface remained stable for birch but peaked for beech and oak around summer to autumn in 2019 and spring in 2020. The new root count was larger in 2019 than in 2020. The mean lifespan of fine-roots with a diameter below 0.5 mm (308 to 399 days) was shorter than those with a diameter between 0.5 to 1 mm (438 to 502 days), 1 to 2 mm (409 to 446 days), or above 2 mm (418 to 471 days). Fine-roots born in different seasons showed a species-specific lifespan and turnover rate.

Fine roots (φ ≤ 2 mm) play an important role in the process of material and nutrient cycling in forest ecosystems, but the effect of tree species diversity on the functional characteristics of fine roots is unclear. In this study, 1−7 subtropical communities with different species richness were selected to study the morphological characteristics, productivity (PRO), and turnover rate (TUR) of fine roots by continuous soil core extraction, ingrowth soil core method, and root analysis system. The effects of tree species diversity on fine root morphological characteristics, PRO, and TUR are also analyzed. The results showed that with the increase in tree species diversity in the community, the effect of fine root morphological characteristics including specific root length (SRL) and specific surface area (SSA) of each community was not significant, but the fine root PRO in the community increased from 71.63 g·m−2·a−1 (Ligustrum lucidum pure forest) to 232.95 g·m−2·a−1 (Cinnamomum camphora mixed forest with seven species richness communities), and the fine root TUR increased from 0.539 times·a−1 to 0.747 times·a−1. Correlation analysis and redundancy analysis showed that species richness, root functional traits, and soil physicochemical properties were important driving factors affecting root characteristics. The increase in tree species diversity did not change the morphological characteristics of fine roots but increased the PRO and TUR of fine roots.

Organic carbon in grassland mainly exists in the soil, and root production and turnover play important roles in carbon input into the soil. However, the effects of climate change on plant root dynamics in desert steppe are unknown. We conducted an experiment in a desert steppe, which included ambient temperature (T0); temperature increased by 2 °C (T1); temperature increased by 4 °C (T2); natural precipitation (P0); precipitation increased by 25% (P1); precipitation increased by 50% (P2); and the interaction between warming and increased precipitation. Plant community aboveground characteristics; root production; and root turnover were measured. We found that the root length production of the T0P2; T1P1; T2P0; and T2P1 treatments were significantly higher than that of the T0P0 treatment, with an increment of 98.70%, 11.72%, 163.03%, and 85.14%, respectively. Three treatments with temperature increased by 2 °C (T1P0; T1P1; and T1P2) and significantly increased root turnover rate compared to the T0P0 treatment, with increases of 62.53%, 42.57%, and 35.55%, respectively. The interaction between warming and increased precipitation significantly affected the root production of the community (p < 0.01), but this interaction was non-additive. Future climate warming will benefit the accumulation of root-derived carbon in desert steppe communities.

The allocation of net primary production (NPP) between above- and belowground components is a key step of ecosystem material cycling and energy flows, which determines many critical parameters, e.g., the fraction of below ground NPP (BNPP) to NPP (fBNPP) and root turnover rates (RTR), in vegetation models. However, direct NPP estimation and partition are scarcely based on field measurements of biomass dynamics in the alpine grasslands on the Northern Tibetan Plateau (NTP). Consequently, these parameters are unverifiable and controversial. Here, we measured above- and belowground biomass dynamics (monthly from May to September each year from 2013 to 2015) to estimate NPP dynamics and allocations in four typical alpine grassland ecosystems, i.e., an alpine meadow, alpine meadow steppe, alpine steppe and alpine desert steppe. We found that NPP and its components, above and below ground NPP (ANPP and BNPP), increased significantly from west to east on the NTP, and ANPP was mainly affected by temperature while BNPP and NPP were mainly affected by precipitation. The bulk of BNPP was generally concentrated in the top 10 cm soil layers in all four alpine grasslands (76.1% ± 9.1%, mean ± SD). Our results showed that fBNPP was significantly different among these four alpine grasslands, with its means in alpine meadow (0.93), alpine desert steppe (0.92) being larger than that in the alpine meadow steppe (0.76) and alpine steppe (0.77). Both temperature and precipitation had significant and positive effects on the fBNPP, while their interaction effects were significantly opposite. RTR decreased with increasing precipitation, but increased with increasing temperature across this ecoregion. Our study illustrated that alpine grasslands on the NTP, especially in the alpine meadow and alpine desert steppe, partitioned an unexpected and greater NPP to below ground than most historical reports across global grasslands, indicating a more critical role of the root carbon pool in carbon cycling in alpine grasslands on the NTP.