Nighttime warming and nitrogen addition effects on the microclimate of a freshwater wetland dominated by Phragmites australis

The critical impacts of microclimate on carbon (C) cycling have been widely reported. However, the potential effects of global change on wetland microclimate remain unclear, primarily because of the absence of field manipulative experiment in inundated wetland. This study was designed to examine the effects of nighttime warming and nitrogen (N) addition on air, water, and sediment temperature and also reveal the controlling factors in a Phragmites australis dominated freshwater wetland on the North China Plain. Nighttime warming increased daily air, water, and sediment temperature by 0.24 °C, 0.27 °C, and 0.36 °C, respectively. The diurnal temperature range of water was decreased by 0.44 °C under nighttime warming, whereas warming had no effect on diurnal temperature range of air and sediment. In addition, N addition caused a reduction of 0.20 °C and 0.14 °C in daily water and sediment temperature by increasing vegetation coverage. There was a significant interaction between nighttime warming and N addition on water temperature. Furthermore, the vapor pressure deficit is the main factor affecting the extent of the warming-induced increases in air temperature. The changes of height and leaf area index of Phragmites australis are responsible for the cooling effects in the N addition plots. This study provides empirical evidence for the positive climate warming - microclimate feedback in freshwater wetland. However, N deposition leads to decreased water and sediment temperature. Our findings highlight the importance of incorporating the differential impacts of nighttime warming and N addition on air, water, and sediment temperature into the predictions of wetland C cycling responses to climate change.

Diet changes due to urbanization in South Africa are linked to microbiome and metabolome signatures of Westernization and colorectal cancer

Transition from traditional high-fiber to Western diets in urbanizing communities of Sub-Saharan Africa is associated with increased risk of non-communicable diseases (NCD), exemplified by colorectal cancer (CRC) risk. To investigate how urbanization gives rise to microbial patterns that may be amenable by dietary intervention, we analyzed diet intake, fecal 16 S bacteriome, virome, and metabolome in a cross-sectional study in healthy rural and urban Xhosa people (South Africa). Urban Xhosa individuals had higher intakes of energy (urban: 3,578 ± 455; rural: 2,185 ± 179 kcal/d), fat and animal protein. This was associated with lower fecal bacteriome diversity and a shift from genera favoring degradation of complex carbohydrates (e.g., Prevotella) to taxa previously shown to be associated with bile acid metabolism and CRC. Urban Xhosa individuals had higher fecal levels of deoxycholic acid, shown to be associated with higher CRC risk, but similar short-chain fatty acid concentrations compared with rural individuals. Fecal virome composition was associated with distinct gut bacterial communities across urbanization, characterized by different dominant host bacteria (urban: Bacteriodota; rural: unassigned taxa) and variable correlation with fecal metabolites and dietary nutrients. Food and skin microbiota samples showed compositional differences along the urbanization gradient. Rural-urban dietary transition in South Africa is linked to major changes in the gut microbiome and metabolome. Further studies are needed to prove cause and identify whether restoration of specific components of the traditional diet will arrest the accelerating rise in NCDs in Sub-Saharan Africa.

Nitrogen addition does not alter symmetric responses of soil respiration to changing precipitation in a semi-arid grassland

Concurrent changing precipitation regimes and atmospheric nitrogen (N) deposition can have profound influences on soil carbon (C) cycling. However, how N enrichment regulates the responses of soil C fluxes to increasing variability of precipitation remains elusive. As part of a field precipitation gradient experiment with nine levels of precipitation amounts (-60 %, -45 %, -30 %, -15 %, ambient precipitation, +15 %, +30 %, +45 %, and +60 %) and two levels of N addition (0 and 10 g N m-2 yr-1) in a semi-arid temperate steppe on the Mongolian Plateau, this work was conducted to investigate the responses of soil respiration to decreased and increased precipitation (DP and IP), N addition, and their possible interactions. Averaged over the three years from 2019 to 2021, DP suppressed soil respiration by 16.1 %, whereas IP stimulated it by 27.4 %. Nitrogen addition decreased soil respiration by 7.1 % primarily via reducing microbial biomass C. Soil respiration showed symmetric responses to DP and IP within all the four precipitation variabilities (i.e., 15 %, 30 %, 45 %, and 60 %) under ambient N. Nevertheless, N addition did not alter the symmetric responses of soil respiration to changing precipitation due to the comparable sensitivities of microbial biomass and root growth to DP and IP under the N addition treatment. These findings indicate that intensified precipitation variability does not change but N addition could alleviate soil C releases. The unchanged symmetric responses of soil respiration to precipitation variability under N addition imply that N deposition may not change the response pattern of soil C releases to predicted increases in precipitation variability in grasslands, facilitating the robust projections of ecosystem C cycling under future global change scenarios.

Soil microbial diversity and network complexity drive the ecosystem multifunctionality of temperate grasslands under changing precipitation

Soil microbiomes play a critical role in regulating ecosystem multifunctionality. However, whether and how soil protists and microbiome interactions affect ecosystem multifunctionality under climate change is unclear. Here, we transplanted 54 soil monoliths from three typical temperate grasslands (i.e., desert, typical, and meadow steppes) along a precipitation gradient in the Mongolian Plateau and examined their response to nighttime warming, decreased, and increased precipitation. Across the three steppes, nighttime warming only stimulated protistan diversity by 15.61 (absolute change, phylogenetic diversity) but had no effect on ecosystem multifunctionality. Decreased precipitation reduced bacterial (8.78) and fungal (22.28) diversity, but significantly enhanced soil microbiome network complexity by 1.40. Ecosystem multifunctionality was reduced by 0.23 under decreased precipitation, which could be largely attributed to the reduced soil moisture that negatively impacted bacterial and fungal communities. In contrast, increased precipitation had little impact on soil microbial communities. Overall, both bacterial and fungal diversity and network complexity play a fundamental role in maintaining ecosystem multifunctionality in response to drought stress. Protists alter ecosystem multifunctionality by indirectly affecting microbial network complexity. Therefore, not only microbial diversity but also their interactions (regulated by soil protists) should be considered in evaluating the responses of ecosystem multifunctionality, which has important implications for predicting changes in ecosystem functioning under future climate change scenarios.

Long-Term Daytime Warming Rather Than Nighttime Warming Alters Soil Microbial Composition in a Semi-Arid Grassland

Climate warming has profoundly influenced community structure and ecosystem functions in the terrestrial biosphere. However, how asymmetric rising temperatures between daytime and nighttime affect soil microbial communities that predominantly regulate soil carbon (C) release remains unclear. As part of a decade-long warming manipulation experiment in a semi-arid grassland, we aimed to examine the effects of short- and long-term asymmetrically diurnal warming on soil microbial composition. Neither daytime nor nighttime warming affected soil microbial composition in the short term, whereas long-term daytime warming instead of nighttime warming decreased fungal abundance by 6.28% (p < 0.05) and the ratio of fungi to bacteria by 6.76% (p < 0.01), which could be caused by the elevated soil temperature, reduced soil moisture, and increased grass cover. In addition, soil respiration enhanced with the decreasing fungi-to-bacteria ratio, but was not correlated with microbial biomass C during the 10 years, indicating that microbial composition may be more important than biomass in modulating soil respiration. These observations highlight the crucial role of soil microbial composition in regulating grassland C release under long-term climate warming, which facilitates an accurate assessment of climate-C feedback in the terrestrial biosphere.

When things get MESI: The Manipulation Experiments Synthesis Initiative-A coordinated effort to synthesize terrestrial global change experiments

Responses of the terrestrial biosphere to rapidly changing environmental conditions are a major source of uncertainty in climate projections. In an effort to reduce this uncertainty, a wide range of global change experiments have been conducted that mimic future conditions in terrestrial ecosystems, manipulating CO₂ , temperature, and nutrient and water availability. Syntheses of results across experiments provide a more general sense of ecosystem responses to global change, and help to discern the influence of background conditions such as climate and vegetation type in determining global change responses. Several independent syntheses of published data have yielded distinct databases for specific objectives. Such parallel, uncoordinated initiatives carry the risk of producing redundant data collection efforts and have led to contrasting outcomes without clarifying the underlying reason for divergence. These problems could be avoided by creating a publicly available, updatable, curated database. Here, we report on a global effort to collect and curate 57,089 treatment responses across 3644 manipulation experiments at 1145 sites, simulating elevated CO₂ , warming, nutrient addition, and precipitation changes. In the resulting Manipulation Experiments Synthesis Initiative (MESI) database, effects of experimental global change drivers on carbon and nutrient cycles are included, as well as ancillary data such as background climate, vegetation type, treatment magnitude, duration, and, unique to our database, measured soil properties. Our analysis of the database indicates that most experiments are short term (one or few growing seasons), conducted in the USA, Europe, or China, and that the most abundantly reported variable is aboveground biomass. We provide the most comprehensive multifactor global change database to date, enabling the research community to tackle open research questions, vital to global policymaking. The MESI database, freely accessible at doi.org/10.5281/zenodo.7153253, opens new avenues for model evaluation and synthesis-based understanding of how global change affects terrestrial biomes. We welcome contributions to the database on GitHub.

Overcompensation of ecosystem productivity following sustained extreme drought in a semiarid grassland

Drought events are projected to be more extreme and frequent in the future and have profound influences on the structure and functions of terrestrial ecosystems. Thus, better understanding the mechanisms of recovery is critical for predicting the future dynamics of terrestrial ecosystems. We performed a 7-year field precipitation experiment to examine recovery of a grassland ecosystem from different magnitudes of sustained drought, from slight to extreme. The ecosystem was exposed to precipitation treatments in the first 3 years (2010-2012) and recovered during the last 4 years (2013-2016) without precipitation treatments. Overall, large reductions of aboveground net primary productivity (ANPP, -43.3%) and perennial forb biomass (-83.1%) were observed in the third year (2012) of extreme drought only. Nevertheless, ANPP fully recovered within 1 year after the drought treatments were terminated, and the rapid recovery was mainly due to increased soil total nitrogen and root biomass allocation after drought. Surprisingly, large increases of ANPP under the extreme drought treatment occurred during the recovery periods from 2013 to 2015 (+74.1, +88.5, and +119.8 g m^-2  year^-1 ) compared to the control. The overcompensation offset the extreme drought-induced reduction of ANPP in the treatment years and was primarily ascribed to the enhanced biomass of perennial grasses (PG). Higher resistance to drought and fast resource acquisition strategy might drive the rapid recovery and expansion of PG. Our findings revealed the rapid recovery of grasslands and the critical role of community overcompensation in maintaining grassland ecosystem function and stability under future climate change scenarios.

Increased precipitation and nitrogen addition accelerate the temporal increase in soil respiration during 8-year old-field grassland succession

Ecological succession after disturbance plays a vital role in influencing ecosystem structure and functioning. However, how global change factors regulate ecosystem carbon (C) cycling in successional plant communities remains largely elusive. As part of an 8-year (2012-2019) manipulative experiment, this study was designed to examine the responses of soil respiration and its heterotrophic component to simulated increases in precipitation and atmospheric nitrogen (N) deposition in an old-field grassland undergoing secondary succession. Over the 8-year experimental period, increased precipitation stimulated soil respiration by 11.6%, but did not affect soil heterotrophic respiration. Nitrogen addition increased both soil respiration (5.1%) and heterotrophic respiration (6.2%). Soil respiration and heterotrophic respiration linearly increased with time in the control plots, resulting from changes in soil moisture and shifts of plant community composition from grass-forb codominance to grass dominance in this old-field grassland. Compared to the control, increased precipitation significantly strengthened the temporal increase in soil respiration through stimulating belowground net primary productivity. By contrast, N addition accelerated temporal increases in both soil respiration and its heterotrophic component by driving plant community shifts and thus stimulating soil organic C. Our findings indicate that increases in water and N availabilities may accelerate soil C release during old-field grassland succession and reduce their potential positive impacts on soil C accumulation under future climate change scenarios.

A global database of plant production and carbon exchange from global change manipulative experiments

Numerous ecosystem manipulative experiments have been conducted since 1970/80 s to elucidate responses of terrestrial carbon cycling to the changing atmospheric composition (CO₂ enrichment and nitrogen deposition) and climate (warming and changing precipitation regimes), which is crucial for model projection and mitigation of future global change effects. Here, we extract data from 2,242 publications that report global change manipulative experiments and build a comprehensive global database with 5,213 pairs of samples for plant production (productivity, biomass, and litter mass) and ecosystem carbon exchange (gross and net ecosystem productivity as well as ecosystem and soil respiration). Information on climate characteristics and vegetation types of experimental sites as well as experimental facilities and manipulation magnitudes subjected to manipulative experiments are also included in this database. This global database can facilitate the estimation of response and sensitivity of key terrestrial carbon-cycling variables under future global change scenarios, and improve the robust projection of global change‒terrestrial carbon feedbacks imposed by Earth System Models.

Measurement(s)	organic material • plant production • carbon exchange
Technology Type(s)	digital curation
Factor Type(s)	climate characteristics • vegetation traits
Sample Characteristic - Environment	climate system
Sample Characteristic - Location	global

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.12932843

Asymmetric responses of plant community structure and composition to precipitation variabilities in a semi-arid steppe

Changing precipitation regimes can profoundly affect plant growth in terrestrial ecosystems, especially in arid and semi-arid regions. However, how changing precipitation, especially extreme precipitation events, alters plant diversity and community composition is still poorly understood. A 3-year field manipulative experiment with seven precipitation treatments, including - 60%, - 40%, - 20%, 0% (as a control), + 20%, + 40%, and + 60% of ambient growing-season precipitation, was conducted in a semi-arid steppe in the Mongolian Plateau. Results showed total plant community cover and forb cover were enhanced with increased precipitation and reduced under decreased precipitation, whereas grass cover was suppressed under the - 60% treatment only. Plant community and grass species richness were reduced by the - 60% treatment only. Moreover, our results demonstrated that total plant community cover was more sensitive to decreased than increased precipitation under normal and extreme precipitation change, and species richness was more sensitive to decreased than increased precipitation under extreme precipitation change. The community composition and low field water holding capacity may drive this asymmetric response. Accumulated changes in community cover may eventually lead to changes in species richness. However, compared to control, Shannon-Weiner index (H) did not respond to any precipitation treatment, and Pielou's evenness index (E) was reduced under the + 60% treatment across the 3 year, but not in each year. Thus, the findings suggest that plant biodiversity in the semi-arid steppe may have a strong resistance to precipitation pattern changes through adjusting its composition in a short term.

Shifts of growing-season precipitation peaks decrease soil respiration in a semiarid grassland

Changing precipitation regimes could have profound influences on carbon (C) cycle in the biosphere. However, how soil C release from terrestrial ecosystems responds to changing seasonal distribution of precipitation remains unclear. A field experiment was conducted for 4 years (2013-2016) to examine the effects of altered precipitation distributions in the growing season on soil respiration in a temperate steppe in the Mongolian Plateau. Over the 4 years, both advanced and delayed precipitation peaks suppressed soil respiration, and the reductions mainly occurred in August. The decreased soil respiration could be primarily attributable to water stress and subsequently limited plant growth (community cover and belowground net primary productivity) and soil microbial activities in the middle growing season, suggesting that precipitation amount in the middle growing season is more important than that in the early, late, or whole growing seasons in regulating soil C release in grasslands. The observations of the additive effects of advanced and delayed precipitation peaks indicate semiarid grasslands will release less C through soil respiratory processes under the projected seasonal redistribution of precipitation in the future. Our findings highlight the potential role of intra-annual redistribution of precipitation in regulating ecosystem C cycling in arid and semiarid regions.

Augmentative compression plating versus exchanging reamed nailing for nonunion of femoral shaft fracture after intramedullary nailing : A retrospective cohort study

Aim of the present study was to compare the outcomes between exchanging reamed nailing (ERN) and augmentative compression plating (ACP) in treatment of femoral shaft nonunion after intra-medullary nailing (IMN) retrospectively. A retrospective, multicentre study was performed with 188 patients (190 cases)with femoral shaft nonunion after IMN, who received therapy with either ERN (n = 92) for 44/92 (47.8%) cases of nonisthmal nonunions and 48/92 (52.2%) cases of isthmal nonunions or ACP (n = 98) for 48/98 (49%) cases of nonisthmal nonunions and 50/98 (51%) cases of isthmal nonunions. Operation time, intraoperative blood loss, time to union, union rate, postoperative draining volume and complication rate were compared between ERN and ACP group. After a mean follow-up of 4.6 years (range 1-8.1 years), the bone union occurred in 98/98 (100%) cases in -total ACP group versus 80/92 (87%) cases in total ERN group [odds ratio (OR) = 3.34, 95% confidence interval (CI) 0.8-1.6]. Twelve cases with re-nonunion in the total ERN group included 10/12 (83.3%) cases of nonisthmal nonunions and 2/12 (16.7%) cases of isthmal nonunion with cortical bone defect > 3 cm. The average time to union, the intraoperative blood loss and the complication rate in total ERN group were also both significantly more than that in total ACP group (p = 0.031, p = 0.042, p = 0.028). No -significant difference was found in the average operation time between the two total groups (p = 0.213). However, for nonisthmal nonunions, the mean operation time for ERN group was 126.8 ± 19.6 min in -comparison to ACP group (88.6 ± 15.2 min), significant difference was found between ERN group and ACP group (p = 0.021). ACP could obtain the higher bone union rate and shorter time to union than ERN in the treatment of femoral shaft nonunion after failed IMN. Especially for nonisthmal femoral shaft nonunions or isthmal.

Selective removal of organochlorine pesticides (OCPs) from aqueous solution by triolein-embedded composite adsorbent

A novel composite adsorbent (CA-T) was used for the selective removal of organochlorine pesticides (OCPs) from aqueous solution. The adsorbent was composed of the supporting activated carbon and the surrounding triolein-embedded cellulose acetate membrane. Scanning electron microscopy (SEM), N2 adsorption isotherms and fluorescence methods were used to characterize the physicochemical properties of CA-T. Triolein was perfectly embedded in the cellulose acetate membrane and deposited on the surface of activated carbon. The adsorbent was stable in water and no triolein leakage was detected during the test periods. Some organochlorine pesticides (OCPs), such as dieldrin, endrin, aldrin, and heptachlor epoxide, were used as model contaminants and removed by CA-T in laboratory batch experiments. The adsorption isotherm followed the Freundlich equation and the kinetic data fitted well to the pseudo-second-order reaction model. Results also indicated that CA-T appeared to be a promising adsorbent with good selectivity and satisfactory removal rate for lipophilic OCPs from aqueous solutions when present in trace amounts. The adsorption rate and removal efficiency for lipophilic OCPs were positively related to their octanol-water partition coefficients (log K(ow)). Lower residual concentrations of OCPs were achieved when compared to granular activated carbon (GAC).