Search

The heat waves (HW) will be more frequent and intense in the future with increased human activity and uncertain implications for ecosystem carbon fluxes. The semi-arid Eurasian grassland is sensitive to climate change and under frequent HWs attacks. Mowing as one of the most common human practices in this region, combining with HW can have comprehensive effects on plant communities, biomass, and nutrient cycling. Hence, a 3-year (2019-2021) field manipulation experiment was conducted to assess how mowing influenced the carbon cycling under HWs, and the interactions between HWs and mowing on carbon fluxes at the community and ecosystem levels in a Eurasian meadow steppe. Over the three years, HW significantly reduced net ecosystem CO

RNA polymerase II (Pol II) associated proteins (RPAPs) have been ascribed diverse functions at the cellular level; however, their roles in developmental processes in yeasts, animals and plants are very poorly understood. Through screening for interactors of NRPB3, which encodes the third largest subunit of Pol II, we identified RIMA, the orthologue of mammalian RPAP2. A combination of genetic and biochemical assays revealed the role of RIMA and other RPAPs in stomatal development in Arabidopsis thaliana. We show that RIMA is involved in nuclear import of NRPB3 and other Pol II subunits, and is essential for restraining division and for establishing cell identity in the stomatal cell lineage. Moreover, plant RPAPs IYO/RPAP1 and QQT1/RPAP4, which interact with RIMA, are also crucial for stomatal development. Importantly, RIMA and QQT1 bind physically to stomatal transcription factors SPEECHLESS, MUTE, FAMA and SCREAMs. The RIMA-QQT1-IYO complex could work together with key stomatal transcription factors and Pol II to drive cell fate transitions in the stomatal cell lineage. Direct interactions with stomatal transcription factors provide a novel mechanism by which RPAP proteins may control differentiation of cell types and tissues in eukaryotes.

The diversity of phytoplankton is fundamental to the health of aquatic ecosystems. Those commonly used diversity indices (e.g., Shannon-weiner diversity index, etc.) were assumed that a uniform distribution was the optimal status of phytoplankton taxa in aquatic system during the assessment of these indices. We discovered that the relative abundance of phytoplankton within an aquatic ecosystem can be fitted with exponential distribution, suggesting that the exponential distribution was the intrinsic and inherent distribution of phytoplankton communities. Through mathematical derivation, taxa capacity (N), competition coefficient (k), critical relative abundance of extinction (a), degree of monopoly, and the residual sum of squares of the phytoplankton community can be obtained to provide a greater insight into phytoplankton diversity. Our results highlight a new methodology based on the above indices has been developed to provide a better insight into the phytoplankton community diversity. It will also help to evaluate the aquatic system ecological health.

Long-term decreases in the incident total radiation and water clarity might substantially affect the underwater light environment in aquatic ecosystems. However, the underlying mechanism and relative contributions of radiation dimming and decreasing water clarity to the underwater light environment on a national or global scale remains largely unknown. Here, we present a comprehensive dataset of unprecedented scale in China’s lakes to address the combined effects of radiation dimming and decreasing water clarity on underwater darkening. Long-term total radiation and sunshine duration showed 5.8% and 7.9% decreases, respectively, after 2000 compared to 1961–1970, resulting in net radiation dimming. An in situ Secchi disk depth (SDD) dataset in 170 lakes showed that the mean SDD significantly decreased from 1.80 ± 2.19 m before 1995 to 1.28 ± 1.82 m after 2005. SDD remote sensing estimations for 641 lakes with areas ≥ 10 km2 showed that SDD markedly decreased from 1.26 ± 0.62 m during 1985–1990 to 1.14 ± 0.66 m during 2005–2010. Radiation dimming and decreasing water clarity jointly caused an approximately 10% decrease in the average available photosynthetically active radiation (PAR) in the euphotic layer. Our results revealed a more important role of decreasing water clarity in underwater darkening than radiation dimming. A meta-analysis of long-term SDD observation data from 61 various waters further elucidated a global extensive underwater darkening. Underwater darkening implies a decrease in water quality for potable water supplies, recession in macrophytes and benthic algae, and decreases in benthic primary production, fishery production, and biodiversity.

Drought represents a major threat to crop growth and yields. Strigolactones (SLs) contribute to regulating shoot branching by targeting the SUPPRESSOR OF MORE AXILLARY GROWTH2 (MAX2)-LIKE6 (SMXL6), SMXL7 and SMXL8 for degradation in a MAX2-dependent manner in Arabidopsis. Although SLs are implicated in plant drought response, the functions of the SMXL6, 7 and 8 in the SL-regulated plant response to drought stress have remained unclear. Here, we performed transcriptomic, physiological and biochemical analyses of smxl6, 7, 8 and max2 plants to understand the basis for SMXL6/7/8-regulated drought response. We found that three D53 (DWARF53)-Like SMXL members, SMXL6, 7 and 8, are involved in drought response as the smxl6smxl7smxl8 triple mutants showed markedly enhanced drought tolerance compared to wild type (WT). The smxl6smxl7smxl8 plants exhibited decreased leaf stomatal index, cuticular permeability and water loss, and increased anthocyanin biosynthesis during dehydration. Moreover, smxl6smxl7smxl8 were hypersensitive to ABA-induced stomatal closure and ABA responsiveness during and after germination. In addition, RNA-sequencing analysis of the leaves of the D53-like smxl mutants, SL-response max2 mutant and WT plants under normal and dehydration conditions revealed an SMXL6/7/8-mediated network controlling plant adaptation to drought stress via many stress- and/or ABA-responsive and SL-related genes. These data further provide evidence for crosstalk between ABA- and SL-dependent signaling pathways in regulating plant responses to drought. Our results demonstrate that SMXL6, 7 and 8 are vital components of SL signaling and are negatively involved in drought responses, suggesting that genetic manipulation of SMXL6/7/8-dependent SL signaling may provide novel ways to improve drought resistance.

External loading reduction has been implemented to improve water quality in China since the 2000s. To evaluate the effects of nutrient reduction on phytoplankton, long-term monitoring data for Lake Wuli from 1998 to 2017 were analyzed. After the restoration since 2003, nitrogen decreased significantly from 8 to 2 mg/l until 2008 and then remained stable until 2017, while total phosphorus declined progressively from 0.2 mg/l to approximately 0.08 mg/l during 2003 and 2017. Biological data indicated that phytoplankton biovolume decreased after restoration until 2010 and then increased slightly from 2010 to 2017, mainly due to increasing of cyanobacterial biovolume. The dominant taxa shifted from cryptophyta to cyanobacteria since 2009. The results of both nonmetric multidimensional scaling and random forest regression showed that changes in nutrients, especially decreases in nitrogen, were the main drivers for phytoplankton community variation and increasing of cyanobacterial biovolume to the total phytoplankton biovolume ratio in summer and autumn. In addition to nutrients reduction, climatic variables such as wind speed decrease also played vital roles in increasing of cyanobacterial dominance in Lake Wuli. Our study confirmed that phytoplankton community respond strongly to nitrogen reduction in the subtropics and that climate change mediates the response.

The ontogeny of seed plants usually involves a dormant dehydrated state and the breaking of dormancy and germination, which distinguishes it from that of most organisms. Seed germination and seedling establishment are critical ontogenetic stages in the plant life cycle, and both are fueled by respiratory metabolism. However, the scaling of metabolic rate with respect to individual traits remains poorly understood. Here, we tested metabolic scaling theory during seed germination and early establishment growth using a recently developed model and empirical data collected from 41 species. The results show that (i) the mass-specific respiration rate (Rm) was weakly correlated with body mass, mass-specific N content, and mass-specific C content; (ii) Rm conformed to a single Michaelis-Menten curve as a function of tissue water content; and (iii) the central parameters in the model were highly correlated with DNA content and critical enzyme activities. The model offers new insights and a more integrative scaling theory that quantifies the combined effects of tissue water content and body mass on respiratory metabolism during early plant ontogeny.

Eutrophication mitigation is an ongoing priority for aquatic ecosystems. However, the current eutrophication control strategies (phosphorus (P) and/or nitrogen (N)) are guided mainly by nutrient addition experiments in small waters without encompassing all in-lake biogeochemical processes that are associated largely with lake morphological characteristics. Here, we use a global lake data set (573 lakes) to show that the relative roles of N vs P in affecting eutrophication are underpinned by water depth. Mean depth and maximum depth relative to mixing depth were used to distinguish shallow (mixing depth > maximum depth), deep (mixing depth < mean depth), and transitional (mean depth ≤ mixing depth ≤ maximum depth) lakes in this study. TN/TP ratio (by mass) was used as an indicator of potential lake nutrient limitation, i.e., N only limitation if N/P < 9, N + P colimitation if 9 ≤ N/P < 22.6, and P only limitation if N/P ≥ 22.6. The results show that eutrophication is favored in shallow lakes, frequently (66.2%) with N limitation while P limitation predominated (94.4%) in most lakes but especially in deep ones. The importance of N limitation increases but P limitation decreases with lake trophic status while N and P colimitation occurs primarily (59.4%) in eutrophic lakes. These results demonstrate that phosphorus reduction can mitigate eutrophication in most large lakes but a dual N and P reduction may be needed in eutrophic lakes, especially in shallow ones (or bays). Our analysis helps clarify the long debate over whether N, P, or both control primary production. While these results imply that more resources be invested in nitrogen management, given the high costs of nitrogen pollution reduction, more comprehensive results from carefully designed experiments at different scales are needed to further verify this modification of the existing eutrophication mitigation paradigm.

1. The quantification of the allocation of nitrogen (N) and phosphorus (P) among plant organs is essential to improve our understanding of plant growth, life-history strategies, and ecosystem nutrient and energy cycles. However, allocation strategies of N and P between terrestrial plant leaves and fine roots are unclear. 2. Here, we compiled a global dataset comprising 807 terrestrial plant species to analyze the stoichiometric scaling of N and P between leaves and fine roots across species, families, plant groups, biomes, and locations. 3. We found that N and P, and N:P ratios manifest different scaling exponents (α-values) between leaves and fine roots. Specifically, overall αN and αP were >1 and, This work was funded by the European Research Council Synergy project SyG-2013-610028 IMBALANCE-P, the Catalan Government grants AGAUR-2020PANDE00117 and SGR 2017-1005, the Spanish Government grant PID2019-110521GB-I00, the Fundac ió n Ra mó n A reces gr a nt ELEMEN TA L-CLIM ATE, t he N at io na l Sc ie nc e Fund for Excellent Young Scholars (31822010), the B iod iver s it y Sur ve y a nd A ssess me nt Pro ject o f t he M inis tr y o f Ecology and Environment, C hina (2019HJ2096001006), National Scientific and Technological Program on Basic Resources Investigation (2019FY102002) and the Innovation Base Project of Gansu Province (20190323).

Leaf traits of global plants reveal the fundamental trade-offs in plant resource acquisition to conservation strategies. However, which leaf traits are consistent, converged, or diverged among herbs, shrubs, and subshrubs in an arid environment remains unclear. In the present study, we evaluated the trade-offs in six leaf functional traits (LFTs): leaf fresh mass (LFM), leaf dry mass (LDM), leaf dry matter content (LDMC), leaf area (LA), specific leaf area (SLA), and leaf thickness (LTh) of 37 desert plant species. LFTs differed between different plant life forms; LFM, LDM, and LA were slightly higher in herbs, LDMC and LTh in shrubs, and SLA in subshrubs. Conversely, the correlations among LFTs were inconsistent in different life forms, which may indicate their different adaptation strategies in an arid environment. Legumes and C

It is commonly believed that climate plays an important role in shaping the patterns of plant species richness. However, it remains unclear how climate may affect plant richness across large spatial scales and also over long-terms, for example across massive arid regions during the Quaternary and into the future. To fill this knowledge gap, we examined the long-term trends in plant species richness across vast drylands in China based on our newly developed climate-species richness models. We first generated optimal random forest models based on the relationships between the current (CUR, 1970–2000) annual, perennial, woody and total species richness and climatic variables. We subsequently hindcasted and forecasted plant species richness in five other periods: last interglacial (LIG, 120,000–140,000 years BP), last glacial maximum (LGM, about 22,000 years BP), mid-Holocene (MH, about 6000 years BP), 2041–2060 (2050), and 2061–2080 (2070). Our results showed that total and herbaceous species richness exhibited similar patterns that were driven by temperature and precipitation. Both groups of species formed a transition zone between arid and semi-arid regions in all periods except LIG. In contrast, woody species richness did not form any transition zone because it was regulated mainly by temperature. Furthermore, the mean richness of herbaceous, woody and all species exhibited gradually increasing trends from LIG to 2070 across drylands in China. On the one hand, herbaceous species were much more sensitive to climate change than woody species. On the other hand, plant species richness in mountain-basin systems and Taklamakan Desert regions were more sensitive to climate change than in meadows and steppes. These results shed new insights into the past and future changes in plant species richness over vast drylands and provide valuable information for future conservation efforts under global warming.

China has made a concerted effort to successfully improve water quality of rivers, but lake water quality has not improved. Lakes require controls on both catchment external nutrient loads and in-lake internal loads, where nature-based solutions are coupled with engineered systems to achieve the United Nations Sustainable Development Goals (SDGs).

Anthocyanins can help plants adapt and resist adverse environments and have important nutritional and medicinal effects on human beings. However, how environmental factors affect the anthocyanins accumulation of plants and how to improve the anthocyanins content of plants in different soils needs further exploration. Hence, this study aimed to investigate the effects of environmental factors on the accumulation of cyanidin, petunidin, malvidin, and delphinidin in the fruits of Lycium ruthenicum in sandy desert grassland (SS), gravel desert grassland (GD), and saline-alkali desert grassland (SD) in the lower reaches of the Shiyang River Basin. The variable importance screened the key environmental factors affecting anthocyanin accumulation in projection (VIP) and multiple stepwise regressions. The structural equation model (SEM) was established to understand how the climate and soil factors affect the total anthocyanin accumulation. For establishing soil nutrient optimization schemes by partial least squares regression (PLS) and the simplex algorithm used to improve the anthocyanin content in different types of desert grassland. In SS, electrical conductivity (EC) and microbial biomass carbon (SMBC) showed highly significant and positive effects on the content of total anthocyanin, cyanidin, and petunidin. In GD, soil moisture and microbial biomass nitrogen (SNBN) significantly negatively affected total anthocyanin content. In SD, catalase (CAT), phosphatase (PHO), and total potassium (TK) had the greatest impact on total anthocyanin content. It is indicated that the targeted improvement measures are necessary to increase anthocyanin content in the fruit of Lycium ruthenicum.

Laser-assisted ferroelectric polarization switching recently has been proved to be an effective mean to manipulate the ferroelectric domain structure, but with the possibility to damage the specimen surface due to high energy input and large thermal expansion. Compared to laser, sunlight with moderate energy is expected to be more accessible. Here, we employed a simulated sunlight illumination instead of high-energy lasers to realize the sunlight-assisted ferroelectric domain switching in Sn2P2S6 single crystals. The origin is the enhancement of localized carrier concentration due to the disproportionation reaction of Sn ions, which induces an additional internal field and assists the domain switching. The migration and accumulation of the Sn ions are also verified with scanning probe technique, which can be utilized as a resistive memory prototype. It is noteworthy that this memory effect can be significantly enhanced by sunlight illumination and, thus, make it suitable for the sunlight control of ferroelectric domain switching and ionic memory devices.

Atmospheric nitrogen (N) deposition is becoming an increasingly important factor affecting the nutrient level of lakes, especially considering the long-term control measures for external N inputs in developed regions. However, few studies have investigated the effects of atmospheric N deposition and the respective ecological significance in eutrophic waters. In this study, bulk and wet deposition rates of all N species and water N concentrations in Lake Taihu were determined based on the long-term (2010-2018) high-resolution (weekly or monthly) systematic observations. The results indicated that the decline in wind speed and change in land-use type likely decreased the N deposition rate. The bulk N deposition rates decreased from 45.77 kg N ha

Relationships between biodiversity and multiple ecosystem functions (that is, ecosystem multifunctionality) are context-dependent. Both plant and soil microbial diversity have been reported to regulate ecosystem multifunctionality, but how their relative importance varies along environmental gradients remains poorly understood. Here, we relate plant and microbial diversity to soil multifunctionality across 130 dryland sites along a 4,000 km aridity gradient in northern China. Our results show a strong positive association between plant species richness and soil multifunctionality in less arid regions, whereas microbial diversity, in particular of fungi, is positively associated with multifunctionality in more arid regions. This shift in the relationships between plant or microbial diversity and soil multifunctionality occur at an aridity level of ∼0.8, the boundary between semiarid and arid climates, which is predicted to advance geographically ∼28% by the end of the current century. Our study highlights that biodiversity loss of plants and soil microorganisms may have especially strong consequences under low and high aridity conditions, respectively, which calls for climate-specific biodiversity conservation strategies to mitigate the effects of aridification.

Arid and semiarid regions account for ∼ 40% of the world's land area. Rivers and lakes in these regions provide sparse, but valuable, water resources for the fragile environments, and play a vital role in the development and sustainability of local societies. During the late 1980s, the climate of arid and semiarid northwest China dramatically changed from "warm-dry" to "warm-wet". Understanding how these environmental changes and anthropogenic activities affect water quantity and quality is critically important for protecting aquatic ecosystems and determining the best use of freshwater resources. Lake Bosten is the largest inland freshwater lake in NW China and has experienced inter-conversion between freshwater and brackish status. Herein, we explored the long-term water level and salinity trends in Lake Bosten from 1958 to 2019. During the past 62 years, the water level and salinity of Lake Bosten exhibited inverse "W-shaped" and "M-shaped" patterns, respectively. Partial least squares path modeling (PLS-PM) suggested that the decreasing water level and salinization during 1958-1986 were mainly caused by anthropogenic activities, while the variations in water level and salinity during 1987-2019 were mainly affected by climate change. The transformation of anthropogenic activities and climate change is beneficial for sustainable freshwater management in the Lake Bosten Catchment. Our findings highlight the benefit of monitoring aquatic environmental changes in arid and semi-arid regions over the long-term for the purpose of fostering a balance between socioeconomic development and ecological protection of the lake environment.

Tong et al. (1) demonstrate an increased mass ratio of total nitrogen to total phosphorus (TN:TP) and decreased TP concentration in many Chinese lakes in association with widespread construction of sewage collection and treatment plants during 2008 to 2017. We argue this conclusion is not true and likely leads to reduced pressure for nutrient loading reduction. We examined the difference of TP and TN:TP between 2008 and 2018 in 30 lakes (15 lakes were included in ref. 1) and found that TP increased in 47% of lakes and decreased in 23% of lakes, and TN:TP increased in 13% of lakes and decreased in 20% of lakes ( P < 0.05). We collected monthly monitored TP and TN:TP of 12 representative large lakes (nine lakes were included in ref. 1) during 2007 to 2018. TP increased in seven lakes and decreased in five lakes (Fig. 1 A ), and TN:TP mass ratios increased in two lakes and decreased in … [↵][1]1To whom correspondence may be addressed. Email: qinbq{at}niglas.ac.cn. [1]: #xref-corresp-1-1

Metacommunity theory emphasizes that local communities are jointly affected by environmental filtering and spatial processes. However, the roles of spatial processes are often given insufficient attention in bioassessment practices, which may bias the assessments of ecological status based on biotic metrics. Here, we quantified the relative importance and the seasonal stability of spatial processes, natural conditions and human-induced factors in structuring variation in different bioassessment metrics based on macroinvertebrate communities. Our study systems were two extensively sampled large and shallow lakes with strong nutrient gradients related to human disturbance. The roles of different drivers were examined for three kinds of indicators: general diversity, trait-based and taxonomic distinctness metrics, and their performance in characterizing human disturbance was evaluated. Overall, human-induced and spatial factors were all important in explaining variation in the three types of bioassessment metrics. Contrary to our expectations, however, we found that the importance of spatial processes on bioassessment metrics can be comparable to the effects of local environmental conditions at the within-lake scale. Furthermore, the results showed substantial seasonal variability in the relative roles of different drivers, which might be linked to life-cycle seasonality of macroinvertebrates. As expected, trait-based metrics generally were best associated with human-induced variables in both lakes, whereas general diversity and taxonomic distinctness metrics performed poorly. The low effectiveness of taxonomic distinctness metrics might due to low species richness associated with high nutrient levels. To conclude, our results suggest that bioassessment cannot exclusively rely on the idea of environmental filtering even if we focus on fine spatial scales. We hence strongly urge that spatial processes, natural drivers and temporal variability should be better considered in combination in the development and application of bioassessment approaches. In addition, taxonomic distinctness measures should be used with caution, especially for the ecosystems and organism groups typically characterized by low species richness.

Surface wind speed has declined significantly globally. However, the response of aquatic systems to decreasing wind speeds has received little attention. We examined the effects of a long-term decrease in wind speed on shallow, eutrophic Lake Taihu, China's third largest lake, by combining high-frequency monitoring, long-term meteorological and water quality data with short-term laboratory sediment nutrient release experiments. The annual mean wind speed showed a significant decreasing trend and the maximum continuous days with wind speed

An increased nutrient loading drives eutrophication of lake ecosystems. Nutrient loading has two different origins: (1) internal loading due to nutrients release from sediments and (2) external loading due to nutrients entering the lake ecosystem from catchment and atmospheric deposition. A 10-day mesocosm experiment was conducted to assess the effects of two nutrient origins on algal photosynthetic capacity, biomass, and phytoplankton community composition of Lake Taihu in the Yangtze River zone. The experiment was specifically designed to mimic (1) internal loading including sediment release in both static and turbulent situations, and (2) external loading including addition of P only, N only, and co-addition of both N and P. Sediment resuspension significantly increased nutrient loading and decreased algal photosynthetic capacity. Resuspension brought benthic algae into water column, resulting in an increase of algal biomass. Nutrient addition significantly changed N:P ratios and phytoplankton community composition. Nutrient addition optimized the dominant species. N Addition favored cyanobacteria reproduction, while P addition did not benefit algal growth and chlorophytes was the dominant in summer. With N and P co-addition, both cyanobacteria and chlorophytes were dominant. Hence, a long-term nutrient management strategy for Taihu watershed should reduce the inputs of both N and P.

Plants need water and energy for their growth and reproduction. However, how water and energy availability influence dryland plant diversity along the aridity gradient in water-limited regions is still lacking. Hence, quantitative analyses were conducted to evaluate the relative importance of water and energy to dryland plant diversity based on 1039 quadrats across 184 sites in China’s dryland. The results indicated that water availability and the water–energy interaction were pivotal to plant diversity in the entire dryland and consistent with the predictions of the water–energy dynamic hypothesis. The predominance of water limitation on dryland plant diversity showed a weak trend with decreasing aridity, while the effects of energy on plants were found to be significant in mesic regions. Moreover, the responses of different plant lifeforms to water and energy were found to vary along the aridity gradient. In conclusion, the study will enrich the limited knowledge about the effects of water and energy on plant diversity (overall plants and different lifeforms) in the dryland of China along the aridity gradient.

Compared to AgNbO3 based ceramics, the experimental investigations on the single crystalline AgNbO3, especially the ground state and ferroic domain structures, are not on the same level. Here, based on successfully synthesized AgNbO3 single crystal using a flux method, we observed the coexistence of ferroelastic and ferroelectric domain structures by a combination study of polarized light microscopy and piezoresponse force microscopy. This finding may provide a new aspect for studying AgNbO3. The result also suggests a weak electromechanical response from the ferroelectric phase of AgNbO3, which is also supported by the transmission electron microscope characterization. Our results reveal that the AgNbO3 single crystal is in a polar ferroelectric phase at room temperature, clarifying its ground state which is controversial from the AgNbO3 ceramic materials.

Udveksling af drivhusgasser mellem søer og luften har kun i sjældnetilfælde været undersøgt systematisk og sjældent omfattet både kuldioxid,metan og lattergas. Det er overraskende, da søer kan værevigtige kilder til især kuldioxid og metan. Vi har som de første undersøgtudledningen af de tre drivhusgasser fra nye danske søer for atvurdere gassernes relative betydning. Målingerne har kun været foretagetsom en ugelang kampagne i august, så generalisering er vanskelig,men der tegner sig alligevel et billede.

The extent to which key factors at the global scale influence plant biomass allocation patterns remains unclear. Here, we provide a theory about how biotic and abiotic factors influence plant biomass allocation and evaluate its predictions using a large global database for forested communities. Our analyses confirm theoretical predictions that temperature, precipitation, and plant height and density jointly regulate the quotient of leaf biomass and total biomass, and that they have a much weaker effect on shoot (leaf plus stem) biomass fractions at a global scale. Moreover, biotic factors have larger effects than abiotic factors. Climatic variables act equally on shoot and root growth, and differences in plant body size and age, as well as community species composition, which vary with climate in ways that drown out the variations in biomass fractions. The theory and data presented here provide mechanistic explanations of why climate has little effect on biomass fractions.

Convergence is commonly caused by environmental filtering, severe climatic conditions and local disturbance. The basic aim of the present study was to understand the pattern of leaf traits across diverse desert plant species in a common garden, in addition to determining the effect of plant life forms (PLF), such as herb, shrub and subshrub, phylogeny and soil properties on leaf traits. Six leaf traits, namely carbon (C), nitrogen (N), phosphorus (P), potassium (K), &delta, 13C and leaf water potential (LWP) of 37 dominant desert plant species were investigated and analyzed. The C, N, K and &delta, 13C concentrations in leaves of shrubs were found higher than herbs and subshrubs, however, P and LWP levels were higher in the leaves of subshrubs following herbs and shrubs. Moreover, leaf C showed a significant positive correlation with N and a negative correlation with &delta, 13C. Leaf N exhibited a positive correlation with P. The relationship between soil and plant macro-elements was found generally insignificant but soil C and N exhibited a significant positive correlation with leaf P. Taxonomy showed a stronger effect on leaf C, N, P and &delta, 13C than soil properties, explaining &gt, 50% of the total variability. C3 plants showed higher leaf C, N, P, K and LWP concentration than C4 plants, whereas C4 plants had higher &delta, 13C than C3 plants. Legumes exhibited higher leaf C, N, K and LWP than nonlegumes, while nonlegumes had higher P and &delta, 13C concentration than legumes. In all the species, significant phylogenetic signals (PS) were detected for C and N and nonsignificant PS for the rest of the leaf traits. In addition, these phylogenetic signals were found lower (K-value &lt, 1), and the maximum K-value was noted for C (K = 0.35). The plants of common garden evolved and adapted themselves for their survival in the arid environment and showed convergent variations in their leaf traits. However, these variations were not phylogenetics-specific. Furthermore, marks of convergence found in leaf traits of the study area were most likely due to the environmental factors.

Rainstorm events can flush large amounts of terrestrial organic-rich material into lakes that are used for drinking water. To date, few studies have been carried out to investigate how rainstorm events change the molecular composition, bio-lability, and flux of upstream-imported dissolved organic matter (DOM), which can impact the odor and taste of drinking water as well as the efficiency of wastewater treatment. We undertook high-frequency buoy monitoring and point sample collection (n = 495), during high, moderate, and low inflow discharge, in Lake Qiandao, a key drinking water source for about 10 million people. Data from two online fluorescent DOM sensors deployed and field samples collected at the river site, Jiekou, and the lake site, Xiaojinshan, showed that rainstorm events increased the specific UV absorbance (SUVA254), humification index (HIX), humic-like components (C1-C2), and FT-ICR MS derived condensed aromatic and polyphenolic compounds (p < 0.001) and decreased the spectral slope of DOM (S275–295), spectral slope ratio (SR), biological index (BIX), and highly bio-degradable peptide-like and aliphatic substances (p < 0.001). Our results suggest that rainstorm events enhanced the export to the lake of colored, hydrophobic, and aromatic DOM. Upstream-derived dissolved organic carbon (DOC) concentrations decreased (p < 0.001), while DOC bio-availability (BDOC) increased only slightly (p < 0.05) during rainstorm events. The loss rate of DOC in Lake Qiandao is 0.82 × 104 t C yr−1, of which 0.30 × 104 t C yr−1 is highly bio-labile, and higher occurrences of both ≥ 25 mm d − 1 and ≥ 50 mm d − 1 rainfall events are anticipated by linear fittings for this region in the future. The application of in situ fluorescence sensors provides an early warning of DOC surge incidents caused by rainstorm events and may be useful in advising drinking water treatment plant managers of changes in raw water DOM quality and treatability.

Speciation modeling of bioavailability has increasingly been used for environmental risk assessment (ERA). Heavy metal pollution is the most prevalent environmental pollution issue globally, and metal bioavailability is strongly affected by its chemical speciation. Dissolved organic matter (DOM) in freshwater will bind heavy metals thereby reducing bioavailability. While speciation modeling has been shown to be quite effective and is validated for use in ERA, there is an increasing body of literature reporting problems with the accuracy of metal-DOM binding in speciation models. In this study, we address this issue for a regional-scale field area (Lake Tai, with 2,400 km2 surface area and a watershed of 36,000 km2) where speciation models in common use are not highly accurate, and we tested alternative approaches to predict metal-DOM speciation/bioavailability for lead (Pb) in this first trial work. We tested five site-specific approaches to quantify Pb-DOM binding that involve varying assumptions about conditional stability constants, binding capacities, and different components in DOM, and we compare these to what we call a one-size-fits-all approach that is commonly in use. We compare model results to results for bioavailable Pb measured using a whole-cell bioreporter, which has been validated against speciation models and is extremely rapid compared to many biological methods. The results show that all of the site-specific approaches we use provide more accurate estimates of bioavailability than the default model tested, however, the variation of the conditional stability constant on a site-specific basis is the most important consideration. By quantitative metrics, up to an order of magnitude improvement in model accuracy results from modeling active DOM as a single organic ligand type with site-specific variations in Pb-DOM conditional stability constants. Because the biological method is rapid and parameters for site-specific tailoring of the model may be obtained via high-throughput analysis, the approach that we report here in this first regional-scale freshwater demonstration shows excellent potential for practical use in streamlined ERA.

Plant metabolism determines the structure and dynamics of ecological systems across many different scales. The metabolic theory of ecology quantitatively predicts the scaling of metabolic rate as a function of body size and temperature. However, the role of tissue water content has been neglected even though hydration significantly affects metabolism, and thus ecosystem structure and functioning. Here, we use a general model based on biochemical kinetics to quantify the combined effects of water content, body size and temperature on plant metabolic rates. The model was tested using a comprehensive dataset from 205 species across 10 orders of magnitude in body size from seeds to mature large trees. We show that water content significantly influences mass-specific metabolic rates as predicted by the model. The scaling exponents of whole-plant metabolic rate vs body size numerically converge onto 1.0 after water content is corrected regardless of body size or ontogenetic stage. The model provides novel insights into how water content together with body size and temperature quantitatively influence plant growth and metabolism, community dynamics and ecosystem energetics.

Cyanobacterial blooms are increasing in magnitude, frequency, and duration worldwide. However, our knowledge of cyanobacterial blooms dynamics and driving mechanisms is still limited due to their high spatiotemporal variability. To determine the potential driving mechanisms of cyanobacterial blooms in oligotrophic lakes, we collected a high-frequency depth profile of chlorophyll fluorescence (ChlF) and synchronous water quality, hydrometeorological data in early spring 2016 in oligotrophic Lake Qiandaohu. The vertical distribution of ChlF exhibited two patterns, "aggregated" and "discrete", using Morisita's index, and the aggregated ChlF presented subsurface chlorophyll maxima during the thermal stratification period. The ChlF concentration was positively correlated with water temperature and negatively correlated with turbidity. Significantly linear relationships were observed between ChlF vertical structure parameters (e.g., Morisita's index, subsurface chlorophyll maxima depth and thickness) and thermal stratification parameters (e.g., mixing layer depth and relative water column stability). After rainstorm floods, the ChlF pattern suddenly change from "aggregated" to "discrete" and a ChlF concentration1 μg/L was observed for 7-11 days with a significant increase in the mixing depth layer and turbidity. The results suggest that cyanobacterial blooms are robustly associated with thermal stratification and rainstorm floods in the deep and oligotrophic lake. Thermal stratification boosts surface phytoplankton accumulation by increasing water temperature, enhancing light availability and restricting phytoplankton vertical distribution. Rainstorm floods interrupt the accumulation by disrupting thermal stratification and decreasing the available light. Furthermore, wind speed and air temperature both regulate the phytoplankton dynamics by affecting thermal stratification. Our research quantifies the cyanobacterial bloom dynamics and their relationship between environmental factors, improving our knowledge of the driving mechanisms of cyanobacterial bloom for the protection of drinking water safety and aquatic organism health in lakes.

In-situ fabricated perovskite nanocrystals in polymeric matrix provide new generation composite materials for plenty of cutting edge technology. In this work, we report the in-situ fabrication of copper halide perovskite (MA2CuCl4, MA:CH3NH3+) embedded poly(vinylidene fluoride) (PVDF) composite films. The optimized MA2CuCl4/PVDF composite films exhibit greatly enhanced piezo-response in comparasion with pure PVDF films. The enhancements were invesitgated and explained by applying piezo-response force microscopy (PFM) measurements and density functional theory (DFT) caculations. We proposed that the high piezoelectric properties of MA2CuCl4/PVDF composite films could be related to the large Cu off-centering displacement, the strong interactions between MA2CuCl4 and PVDF as well as large stress concentration around the MA2CuCl4 particles in the films. These piezoelectric composite films are expected to be suitable functional materials for flexible and/or wearable piezoelectrics.

The structure, morphology and dielectric properties of the oxygen annealed (O2-annealed) and untreated (as-prepared) 0.85(K0.5Na0.5) NbO3-0·15SrZrO3 (KNN-15SZ) ceramics were investigated. The temperature dependence of dielectric permittivity shows two diffuse dielectric peaks associated with duplex core-shell structure, leading to relatively stable dielectric permittivity in a wide temperature range. Interestingly, the O2-annealed sample with the operating temperature range of −104 °C–157 °C could meet the EIA X8R specification, which is superior to the as-prepared one (−98 °C–130 °C) for the EIA X7R specification. Furthermore, the dielectric contribution from cores and shells of both samples was divided by the Lorentz fitting. The relation between relaxation frequency and temperature of both samples obeyed the Vogel-Fulcher law. This finding could pave a possible way to modify dielectric temperature stability for multilayer ceramic chip capacitors applications.

The solid solution (Dy 1−x Mn x )MnO 3−δ (0.037 ≤ x ≤ 0.142) has been synthesized by the conventional solid-state method. Powder X-ray diffraction and selected area electron diffraction reveal that all the samples crystallize in the space group Pnma . The magnetic and dielectric studies on Mn-doped DyMnO 3 reveal existence of three anomaly behaviors in low temperature region. A transition from an incommensurate antiferromagnetic ordering of Mn 3+ spins at T 1 ∼ 37 K, a lock-in transition at T C1 ∼ 18 K. The second antiferromagnetic transition at T 2 ∼ 7 K, originating from the ordering of Dy moments with a slight Mn doping range of 0.037 ≤ x 3 suppresses the ferroelectric ordering, resulting in reduction in ferroelectric ordering temperatures, whereas an increase in antiferromagnetic transition temperatures has been observed.

Relatively little work has been done on the role of micronutrients in influencing development and progression of harmful algal blooms, yet micronutrients are ineluctably required for growth. Relatively small changes in micronutrient status have wide-ranging consequences. Here, we report results from mesocosm experiments with Microcystis and Desmodesmus spp., in mono- and mixed-cultures, to probe questions of how copper, iron, and copper-iron amendments affect growth, short-term assemblage progression, and production of siderophore, chalkophore, and microcystin in lake water from a large, hypereutrophic lake (Taihu, China). Our approach offers an entirely new perspective to understanding micronutrient dynamics in aqueous environments, as this is the first work to systematically screen for chalkophores and siderophores separately, as a function of copper/iron amendment, and using community trajectory analysis. Singular findings are summarized as follows: 1) unlike lab-based studies, in our work we observe neither dramatic copper-modulation of iron demand, nor evidence of an iron-protective effect from copper toxicity. 2) The interplay between chalkophore/siderophore production supports a concept model wherein Microcystis spp. varies behavior to individually and uniquely manage copper/iron requirements in a phased manner. In being able to specifically screen for chalkophores, we observe a previously unreported link between chalkophore and microcystin production that may relate to iron-limitation. 3) Regarding harmful algal bloom (HAB) persistance, the lake water itself influences mesocosm changes; differentiated effects for iron regarding growth indicators and/or reduction of Fe-limitation stress were found at an HAB-free field station (Xukou Bay), likely a consequence of low bioavailability of iron in this station as compared to HAB-impacted stations (half the initial dissolved iron concentration, persisting throughout experiments). The low dissolved iron accompanies more intense chalkophore/siderophore community trajectories.

Dielectric and conduction behaviors of [001]-oriented K 0.5 Na 0.5 Nb 0.5 O 3 single crystal (KNN) and 0.5 at% Mn-doped KNN single crystal (KNN-Mn) have been investigated in a broad temperature range. At low temperatures (330–400 K), an observed slight decrease of conductivity could be connected with the decreases of hole carrier concentration and mobility for the KNN-Mn. At high temperatures (723–773 K) above Cure temperature, the dielectric relaxation and conduction behavior of the samples were analyzed by measurements of impedance spectroscopy and universal dielectric response law. The activation energy values for relaxation frequency and conduction were ~ 0.97 eV and 0.60 eV for the KNN-Mn, respectively. They could be attributed to the thermal motion of double ionized oxygen vacancies and the formation of defect dipoles. The defect compensation mechanism was proposed based on Mn 4+ ion substitution. The KNN-Mn promoted a higher concentration of oxygen vacancies compared with KNN crystal, which gave rise to smaller domain size and higher piezoelectric properties.

Ca1−3x/2Y x Cu3Ti4O12 (0 ≤ x ≤ 0.67) ceramics were fabricated by a conventional solid-state reaction method. Lattice parameter of the system increases linearly with increasing x. The high-frequency dielectric loss of Ca1−3x/2Y x Cu3Ti4O12 is suppressed significantly while the dielectric constant decreases slightly. The dielectric, impedance and modulus spectra reveals that the giant dielectric response associates with the Maxwell–Wagner effect. The decrease of dielectric constant is just related to the capacitance of grain boundaries. The dielectric relaxation behavior of the system is independent of Y substitution while the correlation between conductivity and frequency becomes stronger in Y substituted CaCu3Ti4O12. It suggests that space charge and long-range hopping of carriers play important roles on the low-frequency dielectric properties. The decrease of grain-boundary activation energy with Y substitution indicates that the concentration of oxygen vacancies increases in grain boundaries. The mechanisms of depressing low-frequency dielectric constant and high-frequency dielectric loss was discussed.

Microstructure, phase transition and dielectric properties of Yb-doped Bi 0.5 Na 0.5 TiO 3 (BNT) ceramics were investigated. It is found that ytterbium promotes the grain growth and densification of the ceramics while Ti-rich impurity appears due to the compensation of Ti-vacancy. The dielectric operational temperature range of the ceramics with a±15% tolerance was greatly broaden until 500 °C by ytterbium doping. Meanwhile, the diffuseness of the diffuse phase transition increases with the increase of doping Yb. BNT ceramics with 3 mol% Yb doping shows a near-plateau dielectric behavior in a broad temperature range from 147 to 528 °C and a low dielectric loss (

Y 2/3 Cu 3 Ti 4 O 12 (YCTO) ceramics were sintered in air (YCTO-air) and pure O 2 atmosphere (YCTO-O 2 ), respectively. It was found that the permittivity and dielectric loss of YCTO-O 2 were decreased drastically in low frequency. The frequency dependent impedance ( Z ″) and modulus ( M ″) spectra of YCTO-air and YCTO-O 2 show a thermal activated process. The scaling behavior of both Z ″ and M ″ spectra further suggest that the distribution of relaxation times is temperature independent. The Cole–Cole plot in impedance formalism shows that electrical response of the samples originates from both grains and grain-boundaries. Conductivity ( σ ′) spectra follow Universal Dielectric Repose law. The short-range translation hopping assisted by small polaron hopping mechanisms for YCTO-O 2 . Moreover, the scaling behavior of σ ′ spectra further confirms that the distribution of local electrical response time is temperature independent.