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Soil N 2 O emissions depend on the status of stoichiometric balance between organic C and inorganic N. As a beneficial management practice to sustain soil fertility and crop productivity, partial substitution of organic fertilizers (OFs) for synthetic fertilizers (SFs) can directly affect this balance status and regulate N 2 O emissions. However, no multi-year field studies of N 2 O emissions under different ratios of OF S to SFs have been performed. We conducted a 4-year experiment to measure N 2 O emissions in a maize-wheat rotation in central China. Six treatments were included: total SF (TS), total OF, no N fertilizer, and ratios of to SF with 1: 2 (LO), 1: 1 (MO), and 2: 1 (HO), based on N content. Two incubation experiments were performed to further interpret the field data. In the first year, cumulative N 2 O emissions (kg N ha−1) in LO, MO, and HO were 4.59, 4.68, and 3.59, respectively, significantly lower than in TS (6.67). However, from the second year onwards, organic substitution did not reduce N 2 O emissions and even significantly enhanced them in the fourth year relative to TS. Soil respiration under OF-amended soils increased over the course of the experiment. From the second year onwards, there was no marked difference in mineral N concentrations between OF- and SF-amended soils. OF caused a drop in soil pH. Cumulative N 2 O was negatively correlated with pH. Long-term organic substitution enhanced N 2 O emissions produced via denitrification rather than nitrification and resulted in higher temperature sensitivity of N 2 O emissions than TS. The enhanced N 2 O emissions from the OF-treated soils were mainly attributable to accelerated OF decomposition, increased denitrification-N 2 O emissions, and lessened N 2 O reduction due to lower pH and greater NO 3 −. These results indicate that OF substitution can reduce N 2 O emissions in the first year, but in the long-term it can increase emissions, especially as soils warm. • Long-term organic substitution increased temperature sensitivity of N 2 O emissions. • Organic substitution could not reduce N 2 O emissions in the long-term. • Soil temperature mediated N 2 O peak sizes in the wheat season. • Organic substitution enhanced N 2 O emissions produced via denitrification. [ABSTRACT FROM AUTHOR]

Monthly mean sea-levels have annual maxima in August in the northeast Asian marginal seas (NEAMS). Based on satellite altimetry data, the rising rate of the August NEAMS sea-level (ANS, 4.2 mm∙yr−1) is greater than those of the NEAMS (3.6 mm∙yr−1) and global (3.4 mm∙yr−1) annual mean sea-levels. Thus, the interannual variations of ANS are classified as relatively high (period H) and low (period L) years and have been analysed because of the high risk of sea-level fluctuation to the coastal regions in August. In period H, there are large atmospheric pressure gradients between the high pressure zone in the Kuroshio Extension (KE) and the low pressure zone in the west of Taiwan (WT). In period L, the atmospheric pressure gradients are small between the above-mentioned zones. Large atmospheric pressure gradients induce strong west-northwestward wind stresses and more Ekman transport from the northwest Pacific Ocean into the NEAMS. The correlation coefficient between August NEAMS sea-level index (ANSI), which is the difference of atmospheric pressure anomalies between the KE and the WT, and the August NEAMS sea-level anomaly (ANSA) is 0.73. Although there is a significant correlation (coefficient: 0.64) between ANSA and the East Asian summer monsoon index (EASMI), ANSI might be more useful in estimating the variability of ANSA. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) in aquaculture-influenced sediments pose a threat to both aquatic ecosystems and human health via aquatic product intake. Based on a long-term (from 2011 to 2018) study, the concentrations of five HMs in oyster-cultured sediments in the Maowei Estuary, China, were ranked as follows: Pb (17.58 ± 10.82 mg/kg) > Cu (17.15 ± 8.61 mg/kg) > As (10.27 ± 5.24 mg/kg) > Cd (0.16 ± 0.14 mg/kg) > Hg (0.067 ± 0.033 mg/kg). These concentrations were all close to the guide values in China and those reported in other studies. However, through the Mann-Kendall test, Cu showed obvious increasing interannual trends, and according to ecological risk assessment, the sediments were highly contaminated with Cu and Hg. The health risks to local residents via oyster intake showed that both noncarcinogenic and carcinogenic risk did not exceed the safety criteria (THQ = 1, TCR = 10−6). The current study suggests that ecological and human health risks be integrated to control HMs in the Maowei Estuary. • Heavy metals (HMs) in oyster-cultured sediments were observed from 2011 to 2018. • Cu showed obviously increasing trends according to the Mann-Kendall test. • Health risk of HMs via oyster intake has not exceeded the criteria (THQ = 1, TCR = 10−6). • Ecological risk and health risk should be combined to control the HMs. [ABSTRACT FROM AUTHOR]

This study presents the climatological characteristics and physical mechanisms of Guinea Coast precipitation in June. Traditionally, the low-tropospheric air temperature and equivalent potential temperature ( θ e ) play crucial roles in the generation of monsoon precipitation through the following mechanisms: 1. Near-surface atmospheric front, depicted by steep ∂ θ e ∂ y , corresponds to the vertical motion in the lower troposphere. 2. Strong easterly wind in the middle troposphere (600–500 hPa), generated by a steep ∂ T ∂ y near the surface at 12° N, induces a positive vorticity to the south and vertical motion over the Guinea Coast (~5° N). Meanwhile, the strong Guinea Coastal precipitation, in association with the interannual variability, is mainly determined by the sea-surface temperature (SST) anomaly in the eastern equatorial Atlantic Ocean. In years of warm SST in the eastern equatorial Atlantic, ∂ θ e ∂ y in the lower troposphere is less pronounced than in normal years. However, the atmospheric buoyancy (moist static instability) increases, owing to a strong vertical θ e gradient ( ∂ θ e ∂ p ) arising from the increase in moisture and warm temperature in the lower troposphere over the warm SST area. Consequently, the eastern equatorial Atlantic warm SST modulates the Guinea Coastal thermodynamic structure, causing deep convection that increases precipitation south of the Guinea Coast. Forced by the eastern equatorial Atlantic warm SST anomaly, the strong precipitation and corresponding atmospheric structures are successfully simulated from the Geophysical Fluid Dynamics Laboratory global atmosphere model 2.1. [ABSTRACT FROM AUTHOR]

As the carbon monoxide (CO) total column over Asia is among the highest in the world, it is important to characterize its variations in space and time. Using Measurements of Pollution in the Troposphere (MOPITT) and Atmospheric InfraRed Sounder (AIRS) satellite data, the variations and trends in CO total column over Asia and its seven subregions during 2003–2017 are investigated in this study. The CO total column in Asia is higher in spring and winter than in summer and autumn. The seasonal maximum and minimum are in spring and summer respectively in the regional mean over Asia, varying between land and oceans, as well as among the subregions. The CO total column in Asia shows strong interannual variation, with a regional mean coefficient of variation of 5.8% in MOPITT data. From 2003 to 2017, the annual mean of CO total column over Asia decreased significantly at a rate of (0.58 ± 0.15)% per year (or −(0.11 ± 0.03) × 1017 molecules cm−2 per year) in MOPITT data, resulting from significant CO decreases in winter, summer, and spring. In most of the subregions, significant decreasing trends in CO total column are also observed, more obviously over areas with high CO total column, including eastern regions of China and the Sichuan Basin. The regional decreasing trends in these areas are over 1% per year. Over the entire Asia, and in fire-prone subregions including South Siberia, Indo-China Peninsula, and Indonesia, we found significant correlations between the MOPITT CO total column and the fire counts from the Moderate Resolution Imaging Spectroradiometer (MODIS). The variations in MODIS fire counts may explain 58%, 60%, 36%, and 71% of the interannual variation in CO total column in Asia and these three subregions, respectively. Over different land cover types, the variations in biomass burning may explain 62%, 52%, and 31% of the interannual variation in CO total column, respectively, over the forest, grassland, and shrubland in Asia. Extremes in CO total column in Asia can be largely explained by the extreme fire events, such as the fires over Siberia in 2003 and 2012 and over Indonesia in 2006 and 2015. The significant decreasing trends in MODIS fire counts inside and outside Asia suggest that global biomass burning may be a driver for the decreasing trend in CO total column in Asia, especially in spring. In general, the variations and trends in CO total column over Asia detected by AIRS are similar to but smaller than those by MOPITT. The two datasets show similar spatial and temporal variations in CO total column over Asia, with correlation coefficients of 0.86–0.98 in the annual means. This study shows that the interannual variation in atmospheric CO in Asia is sensitive to biomass burning, while the decreasing trend in atmospheric CO over Asia coincides with the decreasing trend in MODIS fire counts from 2003 to 2017. [ABSTRACT FROM AUTHOR]

A clear understanding of the dynamics of photosynthetic capacity is crucial for accurate modeling of ecosystem carbon uptake. However, such dynamical information is hardly available and has dramatically impeded our understanding of carbon cycles. Although tremendous efforts have been made in coupling the dynamic information of photosynthetic capacity into models, using "proxies" rooted from the close relationships between photosynthetic capacity and other available leaf parameters remains the popular selection. Unfortunately, no consensus has yet been reached on such "proxies", leading them only applicable to limited cases. In this study, we aim to identify if there are close relationships between the photosynthetic capacity (represented by the maximum carboxylation rate, Vcmax) and leaf traits for mature broadleaves within a cold temperature deciduous forest. This is based on a long-term in situ dataset including leaf chlorophyll content (Chl), leaf nitrogen concentration (Narea, Nmass), leaf carbon concentration (Carea, Cmass), equivalent water thickness (EWT), leaf mass per area (LMA), and leaf gas exchange measurements from which Vcmax was derived, for both sunlit and shaded leaves during leaf mature periods from 2014 to 2019. The results show that the Vcmax values of sunlit and shaded leaves were relatively stable during these periods, and no statistically significant interannual variations occurred (p > 0.05). However, this is not applicable to specific species. Path analysis revealed that Narea was the major contributor to Vcmax for sunlit leaves (0.502), while LMA had the greatest direct relationship with Vcmax for shaded leaves (0.625). The LMA has further been confirmed as a primary proxy if no leaf type information is available. These findings provide a promising way to better understand photosynthesis and to predict carbon and water cycles in temperate deciduous forests. [ABSTRACT FROM AUTHOR]

Principal component analysis (PCA) has been applied to a temporal series 1999-2002 of a yearly maximum value composite of the SPOT/VEGETATION normalized difference vegetation index for the Sardinia Island for extracting interannual variations affecting vegetation covers. Both naturally vegetated areas (forest, shrub-land, and herbaceous cover) and agricultural lands have been investigated in order to obtain information on the most prominent natural and/or man-induced alterations affecting vegetation behavior. Although a correct interpretation of PCA results generally requires additional information, such as geographical knowledge, climatological data, and field surveys, the main finding of the current investigation suggests that PCA can be a feasible tool to separately map areas showing different degrees of interannual variability, providing valuable information for discriminating unidirectional changes [ABSTRACT FROM PUBLISHER]

Food habits are important factors in the adaptation of wild nonhuman primates. White-headed langurs ( Trachypithecus leucocephalus ) are endemic to heavily fragmented limestone forests and adapt to unique living environments via flexible food selection strategies. In this study, we compared the dietary data for white-headed langurs living in Chongzuo White-headed Langur National Nature Reserve in 2013 and 2016 to evaluate interannual variations in diet. Our results indicated that young leaves were the main food source for langurs, accounting for 52.4% ( SD 25.4%) and 65.2% ( SD 22.4%) of their diet in 2013 and 2016, respectively. The pattern of plant part consumption was similar between the two years. The consumption of young leaves varied with the availability of young leaves, whereas the consumption of mature leaves was negatively correlated with young leaf availability. The consumption of plant species and diet diversity were higher in 2013 than in 2016. In both 2013 and 2016, although diet diversity varied with the consumption of mature leaves, it was negatively correlated with the consumption and availability of young leaves. Dietary interannual variation is likely to either be linked to phenological variations or indicate that white-headed langurs have a flexible ecological adaptation coping with habitat fragmentation., Competing Interests: None declared., (© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Sex ratios are commonly skewed and variable in wild populations, but few studies track temporal trends in this demographic parameter. We examined variation in the operational sex ratio at two protected and declining breeding colonies of Magellanic Penguins (Spheniscus magellanicus) in Chubut, Argentina. Penguins from the two colonies, separated by 105 km, migrate north in the non-breeding season and have overlapping distributions at sea. Conditions during the non-breeding season can impact long-term trends in operational sex ratio (i.e., through sex-specific survival) and interannual variation in operational sex ratio (i.e., through sex-specific breeding decisions). We found an increasingly male-biased operational sex ratio at the two disparate colonies of Magellanic Penguins, which may contribute to continued population decline. We also found that the two colonies showed synchronous interannual variation in operational sex ratio, driven by variation in the number of females present each year. This pattern may be linked to sex-specific overwintering effects that cause females to skip breeding, i.e., to remain at sea rather than returning to the colony to breed, more often than males. Contrary to our predictions, colony-wide reproductive success was not lower in years with a more male-biased operational sex ratio. We did find that males showed more evidence of fighting and were less likely to pair when the operational sex ratio was more male biased. Our results highlight an indirect mechanism through which variation in the operational sex ratio can influence populations, through a higher incidence of fighting among the less abundant sex. Because biased sex ratios can reduce the size of the breeding population and influence rates of conflict, tracking operational sex ratio is critical for conservation., (© 2019 by the Ecological Society of America.)

Hydrometeor, which involves precipitation and cloud water net income, is the direct source of precipitation and the main component of cloud. It plays an important role in the climate system. In this study, we analyzed the climatology and interannual variation of the summer hydrometeor over Eastern China during 1979–2016 using ERA-Interim reanalysis datasets. The study region was divided into southern and northern sub-regions. Moreover, the hydrometeor budget analysis was diagnosed to further shed light on the formation and variation of the summer hydrometeor. The results showed that the summer hydrometeor pattern is more over the south and less over the north. In climatology, the hydrometeor is mainly contributed by evaporation and vertical moisture advection over the southern sub-region, while the most significant two contributions are evaporation and horizontal moisture advection over the northern sub-region. The interannual variation of hydrometeor over Eastern China exhibits the "north-south seesaw" pattern, which is mainly caused by atmospheric vertical motion. The hydrometeor interannual variation depends strongly on the vertical and horizontal moisture advections over the northern sub-region, but it is primarily contributed by vertical moisture advection over the southern sub-region. The anomalous anticyclone located over the southeast coast of China - the northwest Pacific is in favor of the northward shift of the Western Pacific Subtropical High (WPSH), leading to the hydrometeor increase over the northern sub-region and the opposite over the southern sub-region. It indicates that the hydrometeor distribution pattern over Eastern China is mainly regulated by the WPSH. Further analysis indicated that the interannual variation of horizontal moisture advection over the northern area and vertical moisture advection are mainly caused by the change of the dynamic component, while the horizontal moisture advection over the southern area has both dynamic and thermodynamic drives, which offset each other. • The hydrometeor over Eastern China exhibits the "north-south seesaw" pattern. • The interannual variation of hydrometeor is mainly caused by atmospheric vertical motion. • the interannual variation of hydrometeor over Eastern China is closely related to the WPSH. [ABSTRACT FROM AUTHOR]

• The temporal patterns of VIs match well with that of leaf-litterfall. • Broadband NDVI and MODIS EVI best track the interannual trend of EOS. • The EOS by VIs is 0 – 11 d earlier than that by leaf-litterfall. • Leaf-litterfall collection is a useful method for monitoring autumn phenology. Autumn (i.e., leaf-fall) phenology plays an important role in regulating the canopy duration and is often monitored using near-surface and satellite remote sensing techniques, but the measurements have rarely been validated by the ground observation. The objectives of this study were to: (1) evaluate the performance of radiometer-based broadband vegetation index (VI B) and Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation index (VI M) in monitoring the autumn phenology of a Chinese temperate deciduous forest with decadal (2008 – 2018) leaf-litterfall measurements, and (2) explore the feasibility of using VI B to validate the VI M products for monitoring the autumn phenology. We found that the seasonal and interannual trends of both VI B and VI M agreed well with those of the leaf-litterfall (correlation coefficients r > 0.93). The broadband normalized difference vegetation index (NDVI B) best tracked the interannual variation in the end-of-season (EOS) among the six metrics of the VI B investigated, while the MODIS enhanced vegetation index (EVI M) did so among the six metrics of the VI M , with the corresponding determination coefficient (R 2) of 0.66 and 0.44 with the EOS estimated by the leaf-litterfall. The EOS estimated by VI B and VI M was 0 – 11 d earlier than that by the leaf-litterfall. Comparing the six metrics of VI M with the corresponding ones of VI B , the EOS derived from the NDVI had the closest correlation with each other (R 2 = 0.67). Conclusively, our study validated the remote-sensed leaf-fall phenology with decadal ground measurements, and suggested that radiometer and MODIS could effectively track the autumn phenology in temperate deciduous forests and the leaf-litterfall collection could be used as a complementary approach. [ABSTRACT FROM AUTHOR]

The changing climate is shifting the seasonality of photosynthesis in vegetation, including the start (SOS), end (EOS), and length (LOS) of the growing season, and the peak photosynthesis timing (PPT). While the SOS, EOS, and LOS have been widely investigated, the PPT of grasslands – as a proxy for the response of seasonal plant photosynthesis to climate change – has been overlooked. In this study, we propose a hybrid generalized additive model (HGAM) method to extract PPT using the Vegetation Photosynthesis Model (VPM)-based gross primary production (GPP) product, and we examine the dynamics, drivers, and consequences of PPT changes in temperate and alpine grasslands in China over 2000–2016. We found that the PPTs in temperate and alpine grasslands have exhibited advancing (with −0.68 days yr−1, p < 0.05) and delaying (with 0.29 days yr−1, p = 0.158) trends, respectively. In addition, preseason precipitation and soil moisture were positively correlated with the PPT in temperate and alpine grasslands, respectively, while the preseason temperature consistently controlled the PPT changes in both grasslands. Furthermore, we found that an earlier PPT was associated with higher annual production in the temperate grasslands but not in the alpine grasslands in China. The divergent PPT patterns indicated the varied adaptation characteristics to climatic constraints in the temperate and alpine grasslands and also caused different consequences on carbon uptake. This study highlights the importance of PPT in understanding the spatiotemporal dynamics of vegetation photosynthesis and the carbon cycle under a changing climate. • Identification of peak photosynthesis timing (PPT) by a hybrid generalized additive model (HGAM). • Divergent PPT trends exist between temperate and alpine grasslands in China. • Different climatic factors affect the PPTs in temperate and alpine grasslands. • The correlation between an earlier peak and higher production exists only in temperate grasslands. [ABSTRACT FROM AUTHOR]

Bioassessment assumes that ecological conditions remain stable in the absence of environmental changes. Evidence suggests this assumption may hold for reference streams, but knowledge gaps remain for impacted streams. Our study quantified interannual variation of benthic macroinvertebrate communities, monitored for at least 14 years in eight impacted streams in the Upper Thames River watershed in Ontario, Canada. Benthic communities exhibited moderate interannual variation in relative abundance of EPT (Ephemeroptera, Plecoptera and Trichoptera) and Chironomidae taxa. Year-to-year changes were reflected in lower community persistence than that observed in studies of reference streams. In contrast, tolerance-based metrics showed minimal interannual variation, suggesting compositional changes were because of taxonomic substitutions, in which one tolerant taxon replaced another. Analyses indicated limited directionality in temporal variation for most bioassessment metrics. An exception was taxa richness, which increased at most sites, possibly because of changes in subsampling. However, no associations between calculated bioassessment metrics and measured environmental factors (stream flow and water chemistry) or sampling procedures were observed. We conclude interannual variation in ecological conditions can be substantial and may not be associated with deterministic factors routinely measured in stream assessments. We recommend increased sampling frequency and traits-based assessment as options for limiting effects of interannual variation on assessment results. [ABSTRACT FROM AUTHOR]

In this study, we use the long-term satellite data to investigate seasonal and interannual variation of low-cloud fraction (LCF) and the associated controlling factors over the eastern and western North Pacific. On the seasonal time scale, the enhanced LCF over the eastern North Pacific in summer is actively coupled with strong estimated inversion strength (EIS) and 700-hPa relative humidity, and the LCF over the western North Pacific in winter is large and mainly caused by increased sensible heat flux and tropospheric low-level cold advection. On the interannual time scale, the increased LCF over the eastern North Pacific in summer is associated with increased EIS and decreased sea surface temperatures, in which the El Niño plays an important role; the enhanced LCF over the western North Pacific in spring and winter has a positive correlation with enhanced sensible heat flux (SHF) and tropospheric low-level cold advection, which can be partly explained by the subpolar frontal zone (SPFZ) intensity. [ABSTRACT FROM AUTHOR]