Conservation management improves agroecosystem function and resilience of soil nitrogen cycling in response to seasonal changes in climate

Understanding how conservation agricultural management improves soil nitrogen (N) stability in the face of climate change can help increase agroecosystem productivity and mitigate runoff, leaching and downstream water quality issues. We conducted a 2-year field study in a 36-year-old rain-fed cotton production system to evaluate the impacts of changing climatic factors (temperature and precipitation) on soil N under conservation management, including moderate inorganic N fertilizer application (0 and 67 kg N ha−1 ), winter cover crops (fallow; winter wheat, Triticum aestivum L.; hairy vetch, Vicia villosa Roth), and reduced tillage (no-till; disk tillage). Structural equation modeling (SEM) was used to quantify and compare the effects of conservation management and climatic factors on soil N concentrations. Fertilizer and vetch cover crops increased soil total N concentration by 16% and 18%, respectively, and also increased microbial N transformation rate by 41% and 168%. In addition, vetch cover crops also increased soil labile N concentrations by 57%, 21%, and 79%, i.e., extractable organic N, ammonium, and nitrate, respectively. The highest soil δ15N value (6.4 ± 0.3‰) was observed under the 67 kg N ha−1 fertilizer-wheat-disk tillage treatment, and the lowest value (4.8 ± 0.3‰) under the zero-fertilizer-wheat-no-till treatment, indicating fertilizer and tillage might accelerate microbial N transformation. The SEM showed positive effects of temperature and precipitation on labile N concentrations, suggesting destabilization of soil N and the potential for soil N loss under increased temperature and intensified precipitation. Fertilizer and vetch use might mitigate some of the effects of temperature by accelerating microbial N transformations, with vetch having a larger effect than fertilizer (0.35 vs. 0.15, Table 1). No-till can reduce some of the effects of precipitation on soil labile N by maintaining soil structure. Our study suggests that fertilizer, vetch cover crop, and no-till might help improve function and resilience of agroecosystems in relation to soil N cycling. Soil N stabilization in cropping systems can be enhanced by adjusting agricultural management

Variation in Bacterial Community Structure Under Long-Term Fertilization, Tillage, and Cover Cropping in Continuous Cotton Production

Agricultural practices alter the structure and functions of soil microbial community. However, few studies have documented the alterations of bacterial communities in soils under long-term conservation management practices for continuous crop production. In this study, we evaluated soil bacterial diversity using 16S rRNA gene sequencing and soil physical and chemical properties within 12 combinations of inorganic N fertilization, cover cropping, and tillage throughout a cotton production cycle. Soil was collected from field plots of the West Tennessee Agriculture Research and Education Center in Jackson, TN, United States. The site has been under continuous cotton production for 38 years. A total of 38,038 OTUs were detected across 171 soil samples. The dominant bacterial phyla were Proteobacteria, Acidobacteria, Actinobacteria, Verrucomicrobia, and Chloroflexi, accounting for ~70% of the total bacterial community membership. Conventional tillage increased alpha diversity in soil samples collected in different stages of cotton production. The effects of inorganic N fertilization and conventional tillage on the structure of bacterial communities were significant at all four sampling dates (p \u3c 0.01). However, cover cropping (p \u3c 0.05) and soil moisture content (p \u3c 0.05) only showed significant influence on the bacterial community structure after burn-down of the cover crops and before planting of cotton (May). Nitrate-N appeared to have a significant effect on the structure of bacterial communities after inorganic fertilization and at the peak of cotton growth (p \u3c 0.01). Structural equation modeling revealed that the relative abundances of denitrifying and nitrifying bacteria were higher when conventional tillage and vetch cover crop practices were applied, respectively. Our results indicate that long-term tillage and fertilization are key factors increasing the diversity and restructuring the composition of bacterial communities, whereas cover cropping may have shorterterm effects on soil bacteria community structure. In this study, management practices might positively influence relative abundances of bacterial functional groups associated with N cycling. The bacteria functional groups may build a network for providing N and meet microbial N needs in the long term

Global warming reduces leaf-out an flowering synchrony among individuals

The temporal overlap of phenological stages, phenological synchrony, crucially influences ecosystem functioning. For flowering, among-individual synchrony influences gene flow. For leaf-out, it affects interactions with herbivores and competing plants. If individuals differ in their reaction to the ongoing change in global climate, this should affect population-level synchrony. Here, we use climate-manipulation experiments, Pan-European long-term (>15 years) observations, and common garden monitoring data on up to 72 woody and herbaceous species to study the effects of increasing temperatures on the extent of leaf-out and flowering synchrony within populations. Warmer temperatures reduce in situ leaf-out and flowering synchrony by up to 55%, and experiments on European beech provide a mechanism for how individual differences in day-length and/or chilling sensitivity may explain this finding. The rapid loss of reproductive and vegetative synchrony in European plants predicts changes in their gene flow and trophic interactions, but community-wide consequences remain largely unknown

Integrated global assessment of the natural forest carbon potential

Forests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system1. Remote-sensing estimates to quantify carbon losses from global forests2–5 are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these estimates. Here we combine several ground-sourced6 and satellitederived approaches2,7,8 to evaluate the scale of the global forest carbon potential outside agricultural and urban lands. Despite regional variation, the predictions demonstrated remarkable consistency at a global scale, with only a 12% difference between the ground-sourced and satellite-derived estimates. At present, global forest carbon storage is markedly under the natural potential, with a total deficit of 226 Gt (model range = 151–363 Gt) in areas with low human footprint. Most (61%, 139 Gt C) of this potential is in areas with existing forests, in which ecosystem protection can allow forests to recover to maturity. The remaining 39% (87 Gt C) of potential lies in regions in which forests have been removed or fragmented. Although forests cannot be a substitute for emissions reductions, our results support the idea2,3,9 that the conservation, restoration and sustainable management of diverse forests offer valuable contributions to meeting global climate and biodiversity targets.EEA Santa CruzFil: Mo, Lidong. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Zohner, Constantin M. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Reich, Peter B. University of Minnesota. Department of Forest Resources; Estados UnidosFil: Reich, Peter B. Western Sydney University. Hawkesbury Institute for the Environment; Australia.Fil: Reich, Peter B. University of Michigan. Institute for Global Change Biology; Estados UnidosFil: Liang, Jingjing. Purdue University. Department of Forestry and Natural Resources; Estados UnidosFil: de-Miguel, Sergio. University of Lleida. Department of Agricultural and Forest Sciences and Engineering; EspañaFil: de-Miguel, Sergio. Joint Research Unit CTFC - AGROTECNIO – CERCA; EspañaFil: Nabuurs, Gert-Jan. Wageningen University and Research; Países BajosFil: Renner, Susanne S. Washington University. Department of Biology; Estados UnidosFil: van den Hoogen, Johan. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Araza, Arnan. Wageningen University and Research; Países BajosFil: Herold, Martin. Helmholtz GFZ German Research Centre for Geosciences. Remote Sensing and Geoinformatics Section; Alemania.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral.; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Crowther, Thomas W. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); Suiz

The global biogeography of tree leaf form and habit

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17–34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling.EEA Santa CruzFil: Ma, Haozhi. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Crowther, Thomas W. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Mo, Lidong. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Maynard, Daniel S. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Maynard, Daniel S. University College London. Department of Genetics, Evolution, and Environment; Reino UnidoFil: Renner, Susanne S. Washington University. Department of Biology; Estados UnidosFil: van den Hoogen, Johan. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Zou, Yibiao. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Liang, Jingjing. Purdue University. Department of Forestry and Natural Resources; Estados UnidosFil: de-Miguel, Sergio. University of Lleida. Department of Agricultural and Forest Sciences and Engineering; EspañaFil: de-Miguel, Sergio. Joint Research Unit CTFC - AGROTECNIO – CERCA; EspañaFil: Nabuurs, Gert-Jan. Wageningen University and Research; Países BajosFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral.; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Zohner, Constantin M. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); Suiz

An integrated low-energy ventilation system to improve indoor air quality and thermal comfort of primary school buildings in the cold climate zone of China

Indoor air quality (IAQ) and thermal comfort in schools are serious concerns in China because they have significant effects on student health, academic performance and learning productivity. Due to the financial limitations and the requirements of building design regulations, primary school buildings in China are commonly naturally ventilated. However, the applicability of natural ventilation dramatically depends on the suitability of the local climate. On ambient air pollution days and in the cold winter or hot summer seasons, natural ventilation cannot deliver clean air and provide a thermally comfortable environment. Air purifiers have become popular for mitigating indoor air pollution. However, air purifiers are not always efficient and cannot dilute CO2 concentrations in closed spaces. Additionally, some purifiers may generate ozone gases as they remove other air pollutants. Furthermore, many governments have rejected the installation of air purifiers in classrooms because of the power shortages, financial limitations and inadequate space. To solve these issues, an integrated low-energy ventilation (ILEV) system was invented. The system includes four main parts: a solar chimney, natural ventilation, earth-to-air heat exchangers (EAHEs), and a sunspace with plants. These four parts form the ILEV system, which can be employed by primary school buildings in the cold climate zone of China. In the system, fresh air is preheated or precooled to the temperature of the undisturbed soil by EAHEs and is then supplied to the sunspace. The air is cleaned in the sunspace by the plants and is further supplied to the classrooms. Finally, the waste air inside classrooms is released through the solar chimney by stack effects. To explore the performance of the ILEV system, a typical school building located in the cold climate zone of China was selected. The case study building was redesigned to install the ILEV system based on the School Building Design Regulation-2011 (SBDR-2011) and the Public Building Energy Saving Standard-2015 (PBESS-2015). The research methods in this work involve the dynamic thermal modelling (DTM), computer fluid dynamics (CFD) simulations and experimental measurements. The experimental methods were used to explore the abilities of plants to remove air pollutants (PM2.5 and PM10). The DTM provided hourly classroom data regarding the average indoor air temperature, relative humidity, airflow rates, CO2 levels and heat gains throughout the calendar year. The CFD simulations verified the fluidity of the ILEV system and provided a steady state analysis of the internal air flow distribution in classrooms. An energy simulation model created in GBSWARE was used to quantify the energy consumption of the case study building. Revit models of the case study building were used to generate material take-off sheets. These sheets indicate the additional incremental material costs and estimate the payback period of the ILEV system. The simulation results and experimental data indicate that the air temperatures inside the classrooms were maintained in the range of 15°C to 27°C throughout the year. The internal CO2 concentrations averaged approximately 900 ppm in all classrooms. In addition, the indoor PM2.5 and PM10 concentrations were only 48% and 64% of the current PM concentrations in primary school classrooms, respectively. The ILEV system consumed approximately 2% of the energy currently consumed by the cast study primary school buildings. Consequently, over 90% of the CO2 emission was reduced. The payback period of the ILEV system was 9.7 years. Compared to other renewable technologies, the ILEV system only requires 19% of its lifespan to recoup the initial costs and provides economic benefits over 40 years. In summary, a low-energy system was designed to provide clean air and a thermally comfortable indoor environment in the primary school buildings located in the cold climate zone of China. This system can save energy, reduce CO2 emissions and provide significant economic benefits

Sonic Hedgehog Pathway Is Essential for Maintenance of Cancer Stem-Like Cells in Human Gastric Cancer

Abnormal activation of the Sonic hedgehog (SHH) pathway has been described in a wide variety of human cancers and in cancer stem cells (CSCs), however, the role of SHH pathway in gastric CSCs has not been reported. In this study, we investigated the possibility that abnormal activation of the SHH pathway maintained the characteristics of gastric CSCs. First, we identified cancer stem-like cells (CSLCs) from human gastric cancer cell lines (HGC-27, MGC-803 and MKN-45) using tumorsphere culture. Compared with adherent cells, the floating tumorsphere cells had more self-renewing capacity and chemoresistance. The cells expressing CSCs markers (CD44, CD24 and CD133) were also significantly more in tumorsphere cells than in adherent cells. More importantly, in vivo xenograft studies showed that tumors could be generated with 2×104 tumorsphere cells, which was 100-fold less than those required for tumors seeding by adherent cells. Next, RT-PCR and Western blot showed that the expression levels of Ptch and Gli1 (SHH pathway target genes) were significantly higher in tumorsphere cells than in adherent cells. The results of quantitative real-time PCR were similar to those of RT-PCR and Western blot. Further analysis revealed that SHH pathway blocked by cyclopamine or 5E1 caused a higher reduction in self-renewing capacity of HGC-27 tumorsphere cells than that of adherent cells. We also found that SHH pathway blocking strongly enhanced the efficacy of chemotherapeutic drugs in HGC-27 tumorsphere cells in vitro and in vivo but had no significant effect in adherent cells. Finally, we isolated the tumorspheres from gastric cancer specimen, these cells also had chemoresistance and tumorigenic capacity, and SHH pathway maintained the gastric CSLCs characteristics of tumorsphere cells from primary tumor samples. In conclusion, our data suggested that SHH pathway was essential for maintenance of CSLCs in human gastric cancer