Search

Global warming is anticipated to have profound effects on terrestrial carbon fluxes and thus feed backs to future climate change. Ecosystem respiration (Reco) is one of the dominant components of biosphere CO2 fluxes, but the effects of warming on Reco are still unclear. A field warming experiment using open top chambers (OTCs) was conducted in a meadow grassland on the Tibetan Plateau to study the effects of warming on the components of Reco. Warming significantly enhanced above-ground plant respiration (Ragb) and total autotrophic plant respiration (Rplant) by 28.7% and 19.9%, respectively, but reduced heterotrophic respiration (Rh) by 10.4%. These different responses resulted in the insensitive responses of Reco and soil respiration (Rs) to the experimental warming. The warming treatment also increased Rplant/Reco and Ragb/Reco by 8.4% and 17.3%, respectively, while decreasing Rh/Reco by 19.0%, suggesting that warming could eventually cause Reco to be dominated by Rplant. Enhancements in Rplant and Ragb were related to the warming-induced increases in aboveground biomass (AGB) while reduced Rh was closely coupled with warming-induced decrease of microbial biomass carbon. Our results highlight that the differential responses of the components of Reco to different environmental physics under warming scenarios should be taken into consideration to project the future carbon-climate feed backs.

Responses of grassland carbon (C) cycling to climate change and land use remain a major uncertainty in model prediction of future climate. To explore the impacts of global change on ecosystem C fluxes and the consequent changes in C storage, we have conducted a field experiment with warming (+3 °C), altered precipitation (doubled and halved), and annual clipping at the end of growing seasons in a mixed-grass prairie in Oklahoma, USA, from 2009 to 2013. Results showed that although ecosystem respiration (ER) and gross primary production (GPP) negatively responded to warming, net ecosystem exchange of CO2 (NEE) did not significantly change under warming. Doubled precipitation stimulated and halved precipitation suppressed ER and GPP equivalently, with the net outcome being unchanged in NEE. These results indicate that warming and altered precipitation do not necessarily have profound impacts on ecosystem C storage. In addition, we found that clipping enhanced NEE due to a stronger positive response of GPP compared to ER, indicating that clipping could potentially be an effective land practice that could increase C storage. No significant interactions between warming, altered precipitation, and clipping were observed. Meanwhile, we found that belowground net primary production (BNPP) in general was sensitive to climate change and land use though no significant changes were found in NPP across treatments. Moreover, negative correlations of the ER/GPP ratio with soil temperature and moisture did not differ across treatments, highlighting the roles of abiotic factors in mediating ecosystem C fluxes in this grassland. Importantly, our results suggest that belowground C cycling (e.g., BNPP) could respond to climate change with no alterations in ecosystem C storage in the same period.

Unique soil properties in rhizosphere can affect plant growth and biogeochemical cycles of ecosystems. While rhizosphere has been widely investigated, little is known about differences in the rhizosphere effect (RE) between co-existing overstory trees and understory shrubs and herbs in forest ecosystems. In this study, we investigated REs on soil chemical properties of overstory trees and understory shrubs and herbs in forest plantations of southern China. Bulk soil and rhizospheres were sampled in April, July and December 2017. Soil pH, nitrate and ammonium nitrogen, dissolved organic carbon, available phosphorus, total carbon, total nitrogen, and total phosphorus were tested. The REs were defined as the ratios of the chemical properties of the rhizospheres to those of the bulk soil. Our results showed that pH was lower and nutrient contents were higher in the plant rhizospheres than the bulk soil. REs were generally larger in trees than understory plants. The REs were larger in July than April and December. Our findings indicated that the RE varied among plant life forms, species and sampling times, emphasizing the functional role of the RE of understory vegetation in subtropical forests.

Infections with human papillomavirus in the anogenital area result in warty, papillary, and condylomatous lesions. The giant anogenital wart is relatively uncommon. Treatment of giant wart is challenging, especially in the immunosuppressive population. Here, a patient with systemic lupus erythematosis had extensive, fast-growing, recurrent anogenital condylomatosis shaped as giant cauliflowers. We reported this case and the successful treatment of photodynamic therapy combined with surgical management. It provided the feasibility for surgical ablation combined with ALA-PDT performed for these kinds of challenging cases.

Large scale software-defined IoT (SD-IoT) networking need to deploy multiple controllers. How to ensure load balancing among multiple controllers is important to network performance. This paper proposes a switch migration strategy (MMM) which aims to minimize the global migration cost in SD-IoT networks. MMM not only considers the migration cost when making a migration decision, but also takes both the load of the overloaded domain and other domains after migration into consideration when selecting a switch for migration. Simulation experiments prove the effectiveness of the proposed scheme.

Image motion deblurring technology is an essential topic. Traditional methods with a high algorithm complexity when estimating the blur kernel require a lot of calculations. To solve this problem, we proposed Octave convolution residual block, and proposed Octave Residual Network (ORN) based on this block. ORN is a Generative Adversarial Networks, where the generator is a multi-scale recurrent network, and the discriminator is a deep neural network. ORN restore sharp images in an end-to-end manner where blur is caused by various sources. We present multi-scale loss function that mimics conventional coarse-to-fine approaches. To verify the validity of ORN, we trained our model on GOPRO dataset, the peak signal-to-noise ratio (PSNR) of the model reached 30.04, and the operation time of each step is reduced by 0.04 seconds. Experimental results show that our method achieves the state-of-the-art performance of image motion deblurring not only in performance but also in training speed.

Climate warming is leading to greater precipitation variability, resulting in increased frequency and intensity of both drought and wet extremes. However, how these extreme events interact with climate warming and hay-harvest in grasslands to impact ecosystem functions has not yet been well explored. In this study, we took advantage of a long-term experiment to examine how climate warming and clipping (i.e., mimicking hay harvest) regulated impacts of naturally occurring drought and wet extremes on ecosystem CO2 fluxes of a tallgrass prairie in the Great Plains, USA. Warming resulted in net ecosystem carbon release (i.e., positive net ecosystem CO2 exchange, NEE) in the extreme drought year of 2011, but significantly enhanced net carbon uptake in the extremely wet year of 2015 in comparison with NEE in normal years. Warming-induced carbon release in the drought year was due to significantly enhanced ecosystem respiration (ER) from mid-summer to early-autumn, whereas warming-enhanced NEE in the wet year was due to an increase in aboveground net primary production (ANPP) compared to those in normal years. Drought diminished warming-induced increases in ANPP to about one sixth of that in the wet year in the unclipped plots. Interestingly, clipping offset the drought-mediated ecosystem carbon loss by increasing GPP and weakened the wet-enhanced ANPP. Overall, our results suggest that a future, warmer climate may exacerbate carbon losses in terrestrial ecosystems during drought extremes but stimulate the ecosystem carbon sink under wet extremes.

Ecosystem carbon (C) transit time is a critical diagnostic parameter to characterize land C sequestration. This parameter has different variants in literatures, including a commonly used turnover time. However, neither of them has been carefully examined under transient C dynamics in response to climate change. In this study, we estimated both C turnover time as defined by the conventional stock-over-flux (i.e., Olson method) and mean C transit time as defined by the mean age of C mass leaving the system (i.e., Rasmussen method). We incorporated them into Community Atmosphere-Biosphere-Land Exchange model (CABLE) to estimate C turnover time and transit time, respectively, in response to climate warming and rising atmospheric [CO2]. Modeling analysis showed that both C turnover time and transit time increased with climate warming but decreased with rising atmospheric [CO2]. The increase of C turnover time with warming was estimated to be 2.4 years with Olson method whereas the transit time increased by 11.8 years with Rasmussen method. The decrease with rising atmospheric [CO2] was estimated to be 3.8 years with Olson method and 5.5 years with Rasmussen method. Our analysis based on Rasmussen method showed that 65 % of the increase in global mean C transit time with climate warming results from the depletion of fast-turnover C pool. The remaining 35 % increase results from accompanied changes in compartment C age structures. Similarly, the decrease in mean C transit time with rising atmospheric [CO2] results approximately equally from replenishment of C into fast-turnover C pool and subsequent decrease in compartment C age structure. Greatly different from the Rasmussen method, the Olsen method, which does not account for changes in either C age structure or composition of respired C, underestimated impacts of either warming or rising atmospheric [CO2] on C diagnostic time and potentially lead to biases in estimating land C sequestration.

Food consumption is under the tight control of the brain, which integrates the physiological status, palatability, and nutritional contents of the food, and issues commands to start or stop feeding. Deciphering the processes underlying the decision-making of timely and moderate feeding carries major implications in our understanding of physiological and psychological disorders related to feeding control. Simple, quantitative, and robust methods are required to measure the food ingestion of animals after experimental manipulation, such as forcibly increasing the activities of certain target neurons. Here, we introduced dye-labeling-based feeding assays to facilitate the neurogenetic study of feeding control in adult fruit flies. We review available feeding assays, and then describe our methods step-by-step from setup to analysis, which combine thermogenetic and optogenetic manipulation of neurons controlling feeding motivation with dye-labeled food intake assay. We also discuss the advantages and limitations of our methods, compared with other feeding assays, to help readers choose an appropriate assay.

The interaction between terrestrial carbon (C) and nitrogen (N) cycles has been incorporated into more and more land surface models. However, the scheme of C-N coupling differs greatly among models, and how these diverse representations of C-N interactions will affect C-cycle modeling remains unclear. In this study, we explored how the simulated ecosystem C storage capacity in the terrestrial ecosystem (TECO) model varies with three different commonly-used schemes of C-N coupling. The three schemes (SM1, SM2, and SM3) have been used in three different coupled C-N models (i.e., TECO-CN 2.0, CLM 4.5, and O-CN, respectively). They differ mainly in the stoichiometry of C and N in vegetation and soils, plant N uptake strategies, pathways of N import, and the competition between plants and microbes for soil mineral N. We incorporated them into the C-only version of TECO model, and evaluated their impacts on the C cycle with a traceability framework. Our results showed that all of the three C-N schemes resulted in significant reductions in steady-state C storage capacity compared with the C-only version, but the magnitude varied with −23 %, −30 % and −54 % for SM1, SM2, SM3, respectively. The reduced C storage capacity is the combination of decreases in net primary productivity (NPP) by −29 %, −15 % and −45 % with changes of mean C residence time (MRT) by 9 %, −17 % and −17 % for SM1, SM2, and SM3, respectively. The divergent NPP are mainly attributed to the different assumptions on plant N uptake, plant tissue C:N ratio, down-regulation photosynthesis, and biological N fixation. In comparison, the alternative representations of the plant and microbe competition strategy and the plant N uptake, combining with the flexible C:N ratio in vegetation and soils, led to a notable spread MRT. These results highlight that the diverse assumptions on N process representation among different C-N coupled models could cause additional uncertainty to land surface models. Understanding their difference can help us to improve the capability of models to predict future biogeochemical cycles on land.

Succession theory predicts altered sensitivity of ecosystem functions to disturbance (i.e., climate change) due to the temporal shift in plant community composition. However, empirical evidence in global change experiments is lacking to support this prediction. Here, we present findings from an 8-year long-term global change experiment with warming and altered precipitation manipulation (double and halved amount). First, we observed a temporal shift in species composition over 8 years, resulting in a transition from an annual C3 -dominant plant community to a perennial C4 -dominant plant community. This successional transition was independent of any experimental treatments. During the successional transition, the response of aboveground net primary productivity (ANPP) to precipitation addition magnified from neutral to +45.3%, while the response to halved precipitation attenuated substantially from -17.6% to neutral. However, warming did not affect ANPP in either state. The findings further reveal that the time-dependent climate sensitivity may be regulated by successional change in species composition, highlighting the importance of vegetation dynamics in regulating the response of ecosystem productivity to precipitation change.

The objective of this work was to analyze the effects of thermosonication (TS) on induction of a viable but non-culturable (VBNC) state in Salmonella Typhimurium and to examine incubation factors affecting subsequent resuscitation of cells. A TS treatment of 380 W at 53°C for 30 min induced the VBNC state in S. Typhimurium cells in beef peptone yeast (BPY) broth, apple/carrot juice, physiological saline and phosphate buffer solution. The logarithmic and decline phases of growth were more sensitive to the TS treatment compared to stationary phase cells. Meanwhile, VBNC S. Typhimurium could be resuscitated back to culturable cells by using suitable incubation temperatures and media. Addition of Tween 20 hindered resuscitation compared to the use of BPY medium alone. The optimal growth temperature (i.e. 37°C) was the most suitable temperature to resuscitate cells from the VBNC state. The VBNC incidence index decreased with the addition of sodium pyruvate during TS treatment, as it accelerated resuscitation. The results demonstrated that free radicals produced during TS processing and the growth phase of cells affected induction of the VBNC state in S. Typhimurium. Hence, the kinds and amounts of free radicals generated during TS treatment should be analyzed in the future.

Quantifying the ecological patterns of loss of ecosystem function in extreme drought is important to understand the carbon exchange between the land and atmosphere. Rain-use efficiency [RUE; gross primary production (GPP)/precipitation] acts as a typical indicator of ecosystem function. In this study, a novel method based on maximum rain-use efficiency (RUEmax) was developed to detect losses of ecosystem function globally. Three global GPP datasets from the MODIS remote sensing data (MOD17), ground upscaling FLUXNET observations (MPI-BGC), and process-based model simulations (BESS), and a global gridded precipitation product (CRU) were used to develop annual global RUE datasets for 2001–2011. Large, well-known extreme drought events were detected, e.g. 2003 drought in Europe, 2002 and 2011 drought in the U.S., and 2010 drought in Russia. Our results show that extreme drought-induced loss of ecosystem function could impact 0.9% ± 0.1% of earth's vegetated land per year and was mainly distributed in semi-arid regions. The reduced carbon uptake caused by functional loss (0.14 ± 0.03 PgC/yr) could explain >70% of the interannual variation in GPP in drought-affected areas (p ≤ 0.001). Our results highlight the impact of ecosystem function loss in semi-arid regions with increasing precipitation variability and dry land expansion expected in the future.

Climatic changes are altering Earth's hydrological cycle, resulting in altered precipitation amounts, increased interannual variability of precipitation, and more frequent extreme precipitation events. These trends will likely continue into the future, having substantial impacts on net primary productivity (NPP) and associated ecosystem services such as food production and carbon sequestration. Frequently, experimental manipulations of precipitation have linked altered precipitation regimes to changes in NPP. Yet, findings have been diverse and substantial uncertainty still surrounds generalities describing patterns of ecosystem sensitivity to altered precipitation. Additionally, we do not know whether previously observed correlations between NPP and precipitation remain accurate when precipitation changes become extreme. We synthesized results from 83 case studies of experimental precipitation manipulations in grasslands worldwide. We used meta-analytical techniques to search for generalities and asymmetries of aboveground NPP (ANPP) and belowground NPP (BNPP) responses to both the direction and magnitude of precipitation change. Sensitivity (i.e., productivity response standardized by the amount of precipitation change) of BNPP was similar under precipitation additions and reductions, but ANPP was more sensitive to precipitation additions than reductions; this was especially evident in drier ecosystems. Additionally, overall relationships between the magnitude of productivity responses and the magnitude of precipitation change were saturating in form. The saturating form of this relationship was likely driven by ANPP responses to very extreme precipitation increases, although there were limited studies imposing extreme precipitation change, and there was considerable variation among experiments. This highlights the importance of incorporating gradients of manipulations, ranging from extreme drought to extreme precipitation increases into future climate change experiments. Additionally, policy and land management decisions related to global change scenarios should consider how ANPP and BNPP responses may differ, and that ecosystem responses to extreme events might not be predicted from relationships found under moderate environmental changes. Fil: Wilcox, Kevin R.. University of Oklahoma; Estados Unidos Fil: Shi, Zheng. University of Oklahoma; Estados Unidos Fil: Gherardi, Laureano. Arizona State University; Estados Unidos Fil: Lemoine, Nathan P.. State University of Colorado - Fort Collins; Estados Unidos Fil: Koerner, Sally E.. University of South Florida; Estados Unidos Fil: Hoover, David L.. United States Department of Agriculture. Agricultural Research Service; Argentina Fil: Bork, Edward. University of Alberta; Canadá Fil: Byrne, Kerry M.. Humboldt State University; Estados Unidos Fil: Cahill Jr., James. University of Alberta; Canadá Fil: Collins, Scott L.. University of New Mexico; Estados Unidos Fil: Evans, Sarah. Michigan State University; Estados Unidos Fil: Gilgen, Anna K.. Swiss Federal Institute of Technology Zurich; Suiza Fil: Holub, Petr. Czech Academy of Sciences; República Checa Fil: Jiang, Lifen. University of Oklahoma; Estados Unidos Fil: Knapp, Alan K.. State University of Colorado - Fort Collins; Estados Unidos Fil: LeCain, Daniel. United States Department of Agriculture. Agricultural Research Service; Argentina Fil: Liang, Junyi. University of Oklahoma; Estados Unidos Fil: García Palacios, Pablo. Universidad Rey Juan Carlos; España Fil: Peñuelas, Josep. Consejo Superior de Investigaciones Científicas. Centre de Recerca Ecológica I Aplicacions Forestals; España. Universitat Autònoma de Barcelona; España Fil: Pockman, William T.. University of New Mexico; Estados Unidos Fil: Smith, Melinda D.. State University of Colorado - Fort Collins; Estados Unidos Fil: Sun, Shanghua. Northwest A & F University; China Fil: White, Shannon R.. Government of Alberta; Canadá Fil: Yahdjian, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. ; Argentina Fil: Zhu, Kai. Rice University; Estados Unidos. University of Texas; Estados Unidos Fil: Luo, Yiqi. University of Oklahoma; Estados Unidos

Long‐term, slow ecological processes such as changes in plant community structure and composition strongly regulate ecosystem responses to climate change. Shifts in plant community are expected in chronically altered environments under warming. However, experimental evidence for long‐term shifts and the associated mechanisms is still scarce in temperate grasslands. Here, we explore the long‐term responses of a prairie plant community to 14‐year (2000–2013) manipulations of climate warming and clipping in Oklahoma, USA. Infrared heaters were used to elevate soil temperature by about 2 °C all year round, and annual clipping was applied to mimic hay harvest. Community composition was resistant to experimental warming in the first seven years, but started to show responses starting from the eighth year; clipping consistently affected community composition over the years. Compositional change under long‐term warming was mainly due to one invasive species and three dominant species. The negative correlations in relative abundance between the invasive species and the dominant species suggest interspecific competition. Community structure (i.e. richness, evenness and diversity) had no overall response to experimental warming. However, in 2007, the extreme wet year, warming reduced species richness by 30%. Clipping promoted species richness by 10% on average over the 14 years but decreased community evenness. Warming did not interact with clipping in influencing the plant community variables. Synthesis. Our study provides experimental evidence for long‐term shifts in plant community composition due to warming and revealed novel mechanisms (i.e. species invasion and associated biotic interactions) underlying the long‐term shift. The results also suggest that climate extremes may elicit or advance community responses to climate warming. The findings highlight that long‐term climate change experiments are essential to reveal potential shifts in community composition.

Model intercomparisons and evaluations against observations are essential for better understanding of models’ performance and for identifying the sources of uncertainty in their output. The terrestrial vegetation carbon simulated by 11 Earth system models (ESMs) involved in phase 5 of the Coupled Model Intercomparison Project (CMIP5) was evaluated in this study. The simulated vegetation carbon was compared at three distinct spatial scales (grid, biome, and global) among models and against the observations (an updated database from Olson et al.’s “Major World Ecosystem Complexes Ranked by Carbon in Live Vegetation: A Database”). Moreover, the underlying causes of the differences in the models’ predictions were explored. Model–data fit at the grid scale was poor but greatly improved at the biome scale. Large intermodel variability was pronounced in the tropical and boreal regions, where total vegetation carbon stocks were high. While 8 out of 11 ESMs reproduced the global vegetation carbon to within 20% uncertainty of the observational estimate (560 ± 112 Pg C), the simulated global totals varied nearly threefold between the models. The goodness of fit of ESMs in simulating vegetation carbon depended strongly on the spatial scales. Sixty-three percent of the variability in contemporary global vegetation carbon stocks across ESMs could be explained by differences in vegetation carbon residence time across ESMs (P < 0.01). The analysis indicated that ESMs’ performance of vegetation carbon predictions can be substantially improved through better representation of plant longevity (i.e., carbon residence time) and its respective spatial distributions.

The effects of thermosonication (TS) and 100 ppm nisin-assisted TS (TS + nisin) on the inactivation of naturally occurring microorganisms, retention of nutritional quality and extension of shelf life of fresh apple juice were evaluated, with nisin and mild heat (nisin + MH) treatments as control. Fresh apple juice was addressed by nisin + MH, TS and TS + nisin at 37, 42, 47, and 52 °C for 5–40 min. After processing, microbial growth was evaluated during storage at 8 °C at every 5 days. Temperature played a vital role in the inactivation of aerobic bacteria and yeasts and molds by TS and TS + nisin, higher temperature up to 52 °C could cause a considerable inactivation of microbial cells in apple juice. As apple juice was subjected to TS and TS + nisin at 52 °C for 30 min, retention of original quality including 89% ascorbic acid, non-visible color change, no significant alteration in BD, pH, TA and TSS values of fresh apple juice, and extension shelf life to 15 d at 8 °C were obtained. Nisin exhibit additional inactivation effect of aerobic bacteria in apple juice while not obviously effect on yeast and molds. These results indicated a potential application of TS and TS + nisin (100 ppm) to produce fresh-like quality apple juice and/or to extend its shelf life.

Terrestrial ecosystems absorb roughly 30 % of anthropogenic CO2 emissions since preindustrial era, but it is unclear whether this carbon (C) sink will endure into the future. Despite extensive modeling, experimental, and observational studies, what fundamentally determines transient dynamics of terrestrial C storage under climate change is still not very clear. Here we develop a new framework for understanding transient dynamics of terrestrial C storage through mathematical analysis and numerical experiments. Our analysis indicates that the ultimate force driving ecosystem C storage change is the C storage capacity, which is jointly determined by ecosystem C input (e.g., net primary production, NPP) and residence time. Since both C input and residence time vary with time, the C storage capacity is time-dependent and acts as a moving attractor that actual C storage chases. The rate of change in C storage is proportional to the C storage potential, the difference between the current storage and the storage capacity. The C storage capacity represents instantaneous responses of the land C cycle to external forcing, whereas the C storage potential represents the internal capability of the land C cycle to influence the C change trajectory in the next time step. The influence happens through redistribution of net C pool changes in a network of pools with different residence times. Moreover, this and our other studies have demonstrated that one matrix equation can exactly replicate simulations of most land C cycle models (i.e., physical emulators). As a result, simulation outputs of those models can be placed into a three-dimensional (3D) parameter space to measure their differences. The latter can be decomposed into traceable components to track the origins of model uncertainty. Moreover, the emulators make data assimilation computationally feasible so that both C flux- and pool-related datasets can be used to better constrain model predictions of land C sequestration. We also propose that the C storage potential be the targeted variable for research, market trading, and government negotiation for C credits.

© 2016, National Academy of Sciences. All rights reserved. The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

©2015. American Geophysical Union. All Rights Reserved. Soil carbon (C) is a critical component of Earth system models (ESMs), and its diverse representations are a major source of the large spread across models in the terrestrial C sink from the third to fifth assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Improving soil C projections is of a high priority for Earth system modeling in the future IPCC and other assessments. To achieve this goal, we suggest that (1) model structures should reflect real-world processes, (2) parameters should be calibrated to match model outputs with observations, and (3) external forcing variables should accurately prescribe the environmental conditions that soils experience. First, most soil C cycle models simulate C input from litter production and C release through decomposition. The latter process has traditionally been represented by first-order decay functions, regulated primarily by temperature, moisture, litter quality, and soil texture. While this formulation well captures macroscopic soil organic C (SOC) dynamics, better understanding is needed of their underlying mechanisms as related to microbial processes, depth-dependent environmental controls, and other processes that strongly affect soil C dynamics. Second, incomplete use of observations in model parameterization is a major cause of bias in soil C projections from ESMs. Optimal parameter calibration with both pool- and flux-based data sets through data assimilation is among the highest priorities for near-term research to reduce biases among ESMs. Third, external variables are represented inconsistently among ESMs, leading to differences in modeled soil C dynamics. We recommend the implementation of traceability analyses to identify how external variables and model parameterizations influence SOC dynamics in different ESMs. Overall, projections of the terrestrial C sink can be substantially improved when reliable data sets are available to select the most representative model structure, constrain parameters, and prescribe forcing fields.

In this study, we investigated Phragmites australis' use of different forms of nitrogen (N) and associated soil N transformations in response to petroleum contamination. 15N tracer studies indicated that the total amount of inorganic and organic N assimilated by P. australis was low in petroleum-contaminated soil, while the rates of inorganic and organic N uptake on a per-unit-biomass basis were higher in petroleum-contaminated soil than those in un-contaminated soil. The percentage of organic N in total plant-assimilated N increased with petroleum concentration. In addition, high gross N immobilization and nitrification rates relative to gross N mineralization rate might reduce inorganic-N availability to the plants. Therefore, the enhanced rate of N uptake and increased importance of organic N in plant N assimilation might be of great significance to plants growing in petroleum-contaminated soils. Our results suggest that plants might regulate N capture under petroleum contamination.

A reliable determination of the response of soil organic carbon decomposition to temperature is critical in the context of global warming. However, uncertainties remain in estimated temperature sensitivity of soil respiration, which may be partly due to different experimental conditions. To investigate the possible effects of laboratory incubation procedures on estimated Q10 value, soil samples taken from various ecosystems were incubated under changing temperature with different experimental conditions or procedures: 1) different rate of temperature change; 2) different intervals of temperature change; 3) equilibration time after temperature change; 4) the duration of chamber closure and 5) the size of incubated soil sample. The results indicated that respiration rate was affected by experimental procedures. The respiration rate of soil samples containing high concentration of organic carbon decreased quickly if the soil container sealed longer than 2 h. Estimated Q10 values across all soils ranged from 1.56 to 2.70, with respect to the effects of incubation procedures. Temperature rate change, equilibration time, the duration of chamber closure and soil sample size had no effect on estimated Q10 values of soil respiration. However, Q10 values derived from temperature changing intervals of 2 and 7 °C were significantly different, despite the fact that the exponential function fitted well for the relationship between respiration rate and temperature for both intervals. The results of these experiments suggested that incubation procedures have different effects on measured soil respiration and estimated Q10 values. For soil incubations of short-duration, the effects of incubation procedures on soil respiration and estimated Q10 values based on respiration rate should be appropriately tested with experimental setting-up, and estimating Q10 values with few temperatures should be avoided.

The monosaccharide compositions, molecular weights, structure were investigated for the black fungus polysaccharides. Analysis of sugar components by gas chromatograph-mass spectrometer (GC-MS) showed that component ratios of neutral sugars in the polysaccharides were Glc:Man=82.97:12.93. Fourier transform infrared (FT-IR) analysis showed that the band at about 1649cm(-1) can indicate the presence of CO groups or CC groups vibration in structures. Pharmacological experiment showed that black fungus polysaccharides administration could significantly reduce malondialchehyche (MDA), lipofuscin (LF) contents and enhance superoxide dismutase (SOD) activities in skin. This indicated that black fungus polysaccharides may slow down skin aging.

Ecological functions of bioturbation in ecosystems have received increasing attention over the recent decades, and crab burrowing has been considered as one of the major bioturbations affecting the physical and chemical processes in salt marshes. This study assessed the integrated effects of crab excavating and burrow mimic trapping on sediment turnover and vertical C and N distributions in a Chinese salt marsh in the Yangtze River estuary. Crab burrowing increased soil water content and the turnover of carbon and nitrogen and decreased bulk soil density. Vertical movement of materials, nutrient cycling and reuse driven by crab burrowing might be obstructed by vegetation (Phragmites australis and Spartina alterniflora communities). The amount of soil excavated by crab burrowing was higher than that deposited into burrow mimics. In Phragmites marshes, Spartina marshes and unvegetated mudflats, net transport of soil to the marsh surface was 171.73, 109.54, and 374.95 g m−2 d−1, respectively; and the corresponding estimated soil turnover time was 2.89, 4.07 and 1.83 years, respectively. Crab burrowing in salt marshes can mix surface and deeper soil over a period of years, accelerating litter decomposition and promoting the efficient reuse of nutrients by plants. Therefore, bioturbation affects soil physical processes and functioning of ecosystems, and needs to be addressed in ecosystem management.

Biomass allocation is an important plant trait that responds plastically to environmental heterogeneities. However, the effects on this trait of pollutants owing to human activities remain largely unknown. In this study, we investigated the response of biomass allocation of Phragmites australis to petroleum pollution by a 13 CO 2 pulse-labelling technique. Our data show that plant biomass significantly decreased under petroleum pollution, but the root–shoot ratio for both plant biomass and 13 C increased with increasing petroleum concentration, suggesting that plants could increase biomass allocation to roots in petroleum-polluted soil. Furthermore, assimilated 13 C was found to be significantly higher in soil, microbial biomass and soil respiration after soils were polluted by petroleum. These results suggested that the carbon released from roots is rapidly turned over by soil microbes under petroleum pollution. This study found that plants can modulate biomass allocation in response to petroleum pollution.

Tidal creeks are an important structure of salt marshes in estuarine ecosystems, providing valuable ecosystem services to wildlife in the estuary. To determine the effects of environmental heterogeneities within tidal creeks on the features of crab burrows, we divided a typical creek section into four parts (i.e., microhabitats): bottom, slope, edge and flat, investigated the distribution of crab burrows and sediment properties on creek sections in the Yangtze River estuary, and compared the burrow distribution in tidal creeks with that in non-creek areas. Our results showed that from the creek bottom to flat soil water content declined (F3, 60 = 93.8, p 10 mm) was lower in tidal creeks than in non-creek habitats. Therefore, sediment properties showed a gradual transition from hydrophytic to terrestrial environments on the creek section, which caused significant differences of burrow distribution among the microhabitats. The creeks of tidal salt marshes could affect ecological processes and functioning through affecting crab burrows.

In this study, we compared the differences of bacterial abundance and diversity between rhizosphere and surrounding bulk soils under soil salinization and petroleum contamination in the Yellow River Delta on a 110-km-distance scale. In comparison with bulk soils, rhizosphere soils were mainly characterized by lower salinity and higher water content in saline soils. For bacterial abundance, the numbers of total bacteria and hydrocarbon degraders were significantly higher in rhizosphere soils than those in bulk soils. Although there was no significant difference in total petroleum hydrocarbon (TPH) concentration between the two types of soils, TPH had distinctly different effects on bacterial abundance in rhizosphere and bulk soils. TPH concentration was the major determinant of total bacterial abundance and had positive effects on abundances of hydrocarbon degraders. However, the abundances of total bacteria and hydrocarbon degraders in bulk soils were primarily determined by soil salinity and water content. Great abundance of rhizosphere bacteria suggested that plant roots could alleviate the stresses from soil salinization and provide more favorable microhabitats for bacterial growth. TPH had positive effects on bacterial diversity of both rhizosphere and bulk soils. Our results support the view that petroleum in the environments functions as both toxic chemicals and carbon sources to soil bacteria. Great abundance and diversity of total bacteria in plant rhizospheres would potentially improve the roles of bacteria in maintaining ecosystem functioning in the degraded ecosystems. Our results would improve our understanding of the relationships between rhizosphere effects and multiple environmental stresses that control the development of bacterial community in fragile anthropologically-affected ecosystems.

Age-dependent ectopic fat accumulation (EFA) in animals contributes to the progression of tissue aging and diseases such as obesity, diabetes, and cancer. However, the primary causes of age-dependent EFA remain largely elusive. Here, we characterize the occurrence of age-dependent EFA in Drosophila and identify HDAC6, a cytosolic histone deacetylase, as a suppressor of EFA. Loss of HDAC6 leads to significant age-dependent EFA, lipid composition imbalance, and reduced animal longevity on a high-fat diet. The EFA and longevity phenotypes are ameliorated by a reduction of the lipid-droplet-resident protein PLIN2. We show that HDAC6 is associated physically with the chaperone protein dHsc4/Hsc70 to maintain the proteostasis of PLIN2. These findings indicate that proteostasis collapse serves as an intrinsic cue to cause age-dependent EFA. Our study suggests that manipulation of proteostasis could be an alternative approach to the treatment of age-related metabolic diseases such as obesity and diabetes.

The Yangtze River estuary is an important ecoregion. However, Spartina alterniflora, native to North America, was introduced to the estuary in the 1990s through both natural dispersal and humans and now it is a dominant species in the estuarine ecosystems, with its invasions leading to multiple consequences to the estuary. S. alterniflora had great competitive effects on native species, including Scirpus mariqueter and Phragmites australis, and could potentially exclude the natives locally. The presence of S. alterniflora had little influence on the total density of soil nematodes and macrobenthonic invertebrates, but significantly altered the structure of trophic functional groups of nematode and macrobenthonic invertebrate communities. The conversion of mudflats to Spartina meadows had significant effects on birds of Charadriidae and Scolopacidae, which might be attributable to the reduction of food resources and the physical alterations of habitats for shorebirds. S. alterniflora invasions increased the primary productivity of the invaded ecosystems, and altered carbon and nitrogen cycling processes. Our studies focused mainly on the effects of S. alterniflora invasions on the structure of native ecosystems; thus further studies are clearly needed to investigate how ecosystem functioning is affected by the modification of the structure of estuarine ecosystems by S. alterniflora invasions.

Invasive plants strongly affect physical and biotic environments of native ecosystems. Insects and other arthropods as one of the major components of many ecosystems are very sensitive to subtle changes in abiotic and biotic environments. We examined the effects of exotic Spartina alterniflora invasion on community structure and diets of arthropods in a saltmarsh previously dominated by native Phragmites australis in Yangtze River estuary through net sweeping and plant harvesting methods and stable isotope analysis. Our results showed that diversity indices were not significantly different between exotic and native plant communities, but the total abundance of insects estimated through plant harvesting method was found to be lower in Spartina monoculture than that in Phragmites monoculture. Community structure of insects in Spartina monoculture was dissimilar to that in Phragmites monoculture and Phragmites–Spartina mixture. Moreover, stable carbon isotope patterns of arthropods were significantly different between Phragmites and Spartina monocultures. Although some native arthropods (perhaps generalists) shifted their diets, many native taxa did prefer Phragmites to Spartina even in Spartina monoculture. Spartina invasions resulted in reduced abundances of some arthropds, and increased dominance of others feeding preferably on Spartina. This study provides evidence that invasive plants can change the community structure and diets of native arthropods, which will eventually alter the arthropod food web, and affect the integrity and functioning of native ecosystems within a nature reserve that has been set aside for conserving the native biodiversity and maintaining the ecosystem integrity. In this sense, Spartina invasions in the Yangtze River estuary need to be managed appropriately.

Whether plant invasion increases ecosystem carbon (C) stocks is controversial largely due to the lack of knowledge about differences in ecophysiological properties between invasive and native species. We conducted a field experiment in which we measured ecophysiological properties to explore the response of the ecosystem C stocks to the invasion of Spartina alterniflora (Spartina) in wetlands dominated by native Scirpus mariqueter (Scirpus) and Phragmites australis (Phragmites) in the Yangtze Estuary, China. We measured growing season length, leaf area index (LAI), net photosynthetic rate (Pn), root biomass, net primary production (NPP), litter quality and litter decomposition, plant and soil C and nitrogen (N) stocks in ecosystems dominated by the three species. Our results showed that Spartina had a longer growing season, higher LAI, higher Pn, and greater root biomass than Scirpus and Phragmites. Net primary production (NPP) was 2.16 kg C m−2 y−1 in Spartina ecosystems, which was, on average, 1.44 and 0.47 kg C m−2 y−1 greater than that in Scirpus and Phragmites ecosystems, respectively. The litter decomposition rate, particularly the belowground decomposition rate, was lower for Spartina than Scirpus and Phragmites due to the lower litter quality of Spartina. The ecosystem C stock (20.94 kg m−2) for Spartina was greater than that for Scirpus (17.07 kg m−2), Phragmites (19.51 kg m−2) and the mudflats (15.12 kg m−2). Additionally, Spartina ecosystems had a significantly greater N stock (698.8 g m−2) than Scirpus (597.1 g m−2), Phragmites ecosystems (578.2 g m−2) and the mudflats (375.1 g m−2). Our results suggest that Spartina invasion altered ecophysiological processes, resulted in changes in NPP and litter decomposition, and ultimately led to enhanced ecosystem C and N stocks in the invaded ecosystems in comparison to the ecosystems with native species.

Ericoid mycorrhiza (ERM) are expected to facilitate establishment of ericaceous plants in harsh habitats. However, diversity and driving factors of the root-associated fungi of ericaceous plants are poorly understood. In this study, hair-root samples of Vaccinium carlesii were taken from four forest types: old growth forests (OGF), secondary forests with once or twice cutting (SEC I and SEC II) and Cunninghamia lanceolata plantation (PLF). Fungal communities were determined using high-throughput sequencing and impacts of human disturbances and the intra- and inter-annual variability of root-associated fungal community were evaluated. Diverse fungal taxa were observed and our results showed that (1) Intra- and inter-annual changes in root-associated fungal community were found and the Basidiomycota to Ascomycota ratio was related to mean temperature of the sampling month; (2) Human disturbances significantly affected structure of root-associated fungal community of V. carlesii and two secondary forest types were similar in root-associated fungal community and were closer to that of the old growth forest; (3) Plant community composition, edaphic parameters and geographic factors significantly affected root-associated fungal communities of V. carlesii. These results may be helpful in better understanding the maintenance mechanisms of fungal diversity associated with hair roots of ERM plants under human disturbances.

Soil microbes play critical roles in regulating terrestrial carbon (C) cycle and its feedback to climate change. However, it is still unclear how the soil microbial community and abundance respond to future climate change scenarios. In this meta-analysis, we synthesized the responses of microbial community and abundance to experimental warming from 64 published field studies. Our results showed that warming significantly increased soil microbial abundance by 7.6% on average. When grouped by vegetation or soil types, tundras and histosols had the strongest microbial responses to warming with increased microbial, fungal and bacterial abundances by 15.0%, 9.5% and 37.0% in tundra and 16.5%, 13.2% and 13.3% in histosols, respectively. We found significant negative relationships of the response ratios of microbial, fungal and bacterial abundances with the mean annual temperature, indicating that warming had stronger effects in colder than warmer regions. Moreover, the response ratios of microbial abundance to warming were positively correlated with those of soil respiration. Our findings therefore indicate that the large quantities of C stored in colder regions are likely to be more vulnerable to climate warming than the soil C stored in other warmer regions.

Plantago virginica L. has invaded many lawn ecosystems in the Eastern part of China. The invasion has incurred an economic cost to remove them. In order to prevent the invasion, it is critical to understand the invasive mechanisms of this species. However, few studies have been conducted on the allelopathic mechanisms of its invasion. In this study, we examined allelopathic effects of P. virginica on germination of seeds and growth of seedlings of four widely used lawn species. We found extensive allelopathic potential of P. virginica on other lawn species, which varied with species and developmental stage. While most effects of the extracts of P. virginica were inhibitory, some variables in some species were promoted by the addition of the extracts. The extracts of P. virginica significantly inhibited seed germination of Agrostis matsumurae. While the overall differences in seed germination rate of Poa annua were significant among treatments, difference between control and any of the treatments was not significant. The height of seedlings of A. matsumurae and Cynodon dactylon was significantly lower under the treatments of adding extracts of P. virginica. In contrast, growth of seedlings of Festuca elata and P. annua did not show significant differences among treatments. The root length of A. matsumurae, C. dactylon and P. annua was suppressed by the extracts of P. virginica whereas root length of F. elata was not affected. Aboveground biomass of A. matsumurae and F. elata was significantly higher than control, except for F. elata at the concentration of 50mg/mL, whereas aboveground biomass of C. dactylon and P. annua was reduced at higher concentrations of the extracts. Except for A. matsumurae, root biomass of the other three lawn species declined under the treatments with the extracts of P. virginica. Our results revealed that P. virginica had allelopathic potential on four lawn species and supported the theory of “novel weapons hypothesis”. Invasion by P. virginica in lawn can be moderated by selecting those species that are not affected or promotionally affected by it.

The potential capacity of soil to sequester carbon in response to global warming is strongly regulated by the ratio of rhizosphere respiration to respiration by soil microbial decomposers, because of their different temperature sensitivities. To quantify relative contributions of rhizosphere respiration to total soil respiration as influenced by forest stand development, we conducted a trenching study in two larch (Larix gmelini (Rupr.) Rupr.) plantations, aged 17 and 31 years, in northeastern China. Four plots in each plantation were randomly selected and trenched in early May 2001. Soil surface CO2 effluxes both inside and outside the plots were measured from May 2001 to August 2002. Soil respiration (i.e., the CO2 effluxes outside the trenched plots) varied similarly in the two plantations from 0.8 micromol m(-2) s(-1) in winter to 6.0 micromol m(-2) s(-1) in summer. Rhizosphere respiration (i.e., CO2 efflux outside the trenched plots minus that inside the plots) varied from 0.2 to 2.0 micromol m(-2) s(-1) in the old forest and from 0.3 to 4.0 micromol m(-2) s(-1) in the young forest over the seasons. Rhizosphere respiration, on average, accounted for 25% of soil respiration in the old forest and 65% in the young forest. Rhizosphere and soil respiration were significantly correlated with soil temperature but not with soil water content. We conclude that the role forests play in regulating climate change may depend on their age.

© 2016 Macmillan Publishers Limited. All rights reserved. The majority of the Earth's terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12-17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon-climate feedback that could accelerate climate change.

Identifying binding sites recognized by transcription factors (TFs) is one of major challenges to decipher complex genetic regulatory networks encoded in a genome. A set of binding sites recognized by the same TF, called a motif, can be accurately represented by a position frequency matrix (PFM) or a position-specific scoring matrix (PSSM). Very often, we need to compare motifs when searching for similar motifs in a motif database for a query motif, or clustering motifs possibly recognized by the same TF. In this paper, we have designed a novel metric, called SPIC (Similarity between Positions with Information Contents), for quantifying the similarity between two motifs using their PFMs, PSSMs, and column information contents, and demonstrated that this metric outperforms the other state-of-the-art methods for clustering motifs of the same TF and differentiating motifs of different TFs.

Climate warming affects ecosystem functioning by altering the rates of carbon (C) fixation and release. Modeling warming effect on terrestrial C cycling is critical given the feedbacks between climate and C cycling. However, the effect of warming on key model parameters and the resulting long-term C dynamics has not been carefully examined. In this study, measurements from a nine-year warming experimental site in a tallgrass prairie were assimilated into a terrestrial ecosystem C cycle model to assess warming effect on key model parameters and to quantify uncertainties of long-term C projection. Warming decreased allocation of gross primary production (GPP) to shoot, and turnover rate of the live C pools (i.e., shoot and root C), but increased the turnover rates of litter and fast soil C pools. Consequently, warming increased live C pools, but decreased litter and soil C pools, and overall decreased total ecosystem C in a 90-year model projection. Information content gained from assimilated datasets was m...

—Security is one of key problems in RFID application. This research is to find a security algorithm for RFID with very low computing requirement. Minimalist Cryptography only needs exclusive Or (XOR) and simple logical control, and it can protect privacy and provide mutual authentication. However, the algorithm has hidden security problems while assuming that the attacker couldn’t monitor the data between RFID readers and tags for continuous sessions. The paper proved this weakness and put forward three ways to improve the weakness, i.e. channel encryption etc. The attacker could only crack the improved algorithm by brute-force attack. The experimental result showed that even by brute-force attack the attack needs more continues sessions after improvement, the cracking time and the record number needed for cracking increased with improved algorithm, and the cracking difficulty increases exponentially when the length of channel key increases, and the encryption complication increases in liner. The improved Minimalist Cryptography provided a safer lightweight security algorithm for RFID.