Soil microbial populations in deep floodplain soils are adapted to infrequent but regular carbon substrate addition

This is the final version of the article. Available from Elsevier via the DOI in this record.Floodplain soils provide an important link in the land-ocean aquatic continuum. Understanding microbial activity in these soils, which can be many metres deep, is a key component in our understanding of the role of floodplains in the carbon (C) cycle. We sampled the mineral soil profile to 3 m depth from two floodplain sites under long-term pasture adjacent to the river Culm in SW England, UK. Soil chemistry (C, nitrogen (N), phosphorus (P), soil microbial biomass (SMB), moisture content) and soil solution (pH, dissolved organic C (DOC) and N, nitrate, ammonium, water extractable P) were analysed over the 3 m depth in 6 increments: 0.0–0.2, 0.2–0.7, 1.0–1.5, 1.5–2.0, 2.0–2.5, and 2.5–3.0 m. 14 C-glucose was added to the soil and the evolution of 14 CO 2 measured during a 29 d incubation. From soil properties and 14 C-glucose mineralisation, three depth groups emerged, with distinct turnover times extrapolated from initial k 1 mineralisation rate constants of 2 h (topsoil 0.0–0.2 m), 4 h (subsoil 0.2–0.7 m), and 11 h (deep subsoil 1.0–3.0 m). However, when normalised by SMB, k 1 rate constants had no significant differences across all depths. Deep subsoil had a 2 h lag to reach maximal 14 CO 2 production whereas the topsoil and subsoil (0.2–0.7 m) achieved maximum mineralisation rates immediately. SMB decreased with depth, but only to half of the surface population, with the proportion of SMB-C to total C increasing from 1% in topsoil to 15% in deep subsoil ( > 1.0 m). The relatively large SMB concentration and rapid mineralisation of 14 C-glucose suggests that DOC turnover in deep soil horizons in floodplains is limited by access to biologically available C and not the size of the microbial population.Natural Environment Research Council (NERC)Biotechnology and Biological Sciences Research Council (BBSRC

Mapping mean total annual precipitation in Belgium, by investigating the scale of topographic control at the regional scale

Accurate precipitation maps are essential for ecological, environmental, element cycle and hydrological models that have a spatial output component. It is well known that topography has a major influence on the spatial distribution of precipitation and that increasing topographical complexity is associated with increased spatial heterogeneity in precipitation. This means that when mapping precipitation using classical interpolation techniques (e.g. regression, kriging, spline, inverse distance weighting, etc.), a climate measuring network with higher spatial density is needed in mountainous areas in order to obtain the same level of accuracy as compared to flatter regions. In this study, we present a mean total annual precipitation mapping technique that combines topographical information (i.e. elevation and slope orientation) with average total annual rain gauge data in order to overcome this problem. A unique feature of this paper is the identification of the scale at which topography influences the precipitation pattern as well as the direction of the dominant weather circulation. This method was applied for Belgium and surroundings and shows that the identification of the appropriate scale at which topographical obstacles impact precipitation is crucial in order to obtain reliable mean total annual precipitation maps. The dominant weather circulation is determined at 260°. Hence, this approach allows accurate mapping of mean annual precipitation patterns in regions characterized by rather high topographical complexity using a climate data network with a relatively low density and/or when more advanced precipitation measurement techniques, such as radar, aren't available, for example in the case of historical data

How can we realize sustainable development goals in rocky desertified regions by enhancing crop yield with reduction of environmental risks?

This is the final version. Available from MDPI via the DOI in this record. Data Availability Statement: The data utilized in the study is available from the authors, on reasonable request.To meet the sustainable development goals in rocky desertified regions like Guizhou Province in China, we should maximize the crop yield with minimal environmental costs. In this study, we first calculated the yield gap for 6 main crop species in Guizhou Province and evaluated the quantitative relationships between crop yield and influencing variables utilizing ensembled artificial neural networks. We also tested the influence of adjusting the quantity of local fertilization and irrigation on crop production in Guizhou Province. Results showed that the total yield of the selected crops had, on average, reached over 72.5% of the theoretical maximum yield. Increasing irrigation tended to be more consistently effective at increasing crop yield than additional fertilization. Conversely, appropriate reduction of fertilization may even benefit crop yield in some regions, simultaneously resulting in significantly higher fertilization efficiency with lower residuals in the environment. The total positive impact of continuous intensification of irrigation and fertilization on most crop species was limited. Therefore, local stakeholders are advised to consider other agricultural management measures to improve crop yield in this region.National Natural Science Foundation of ChinaNatural Environment Research Counci

Periodic relations between terrestrial vegetation and climate factors across the globe

This is the final version. Available on open access from MDPI via the DOI in this record. The GLASS LAI data from 1981 to 2014 were acquired from the Chinese National Earth System Science Data Sharing Infrastructure website (http://www.geodata.cn/thematicView/GLASS.html)In this paper, cross-spectrum analysis was used to verify the agreement of periodicity between the global LAI (leaf area index) and climate factors. The results demonstrated that the LAI of deciduous forests and permanent wetlands have high agreement with temperature, rainfall and radiation over annual cycles. A low agreement between the LAI and seasonal climate variables was observed for some of the temperate and tropical vegetation types including shrublands and evergreen broadleaf forests, possibly due to the diversity of vegetation and human activities. Across all vegetation types, the LAI demonstrated a large time lag following variation in radiation (>1 month), whereas relatively short lag periods were observed between the LAI and annual temperature (around 2 weeks)/rainfall patterns (less than 10 days), suggesting that the impact of radiation on global vegetation growth is relatively slow, which is in accord with the results of previous studies. This work can provide a benchmark of the phenological drivers in global vegetation, from the perspective of periodicity, as well as helping to parameterize and refine the DGVMs (Dynamic Global Vegetation Models) for different vegetation types.National Natural Science Foundation of ChinaChina Scholarship Counci

Geomorphically mediated carbon dynamics of floodplain soils and implications for net effect of carbon erosion

This is the final version. Available from Wiley via the DOI in this record. DATA AVAILABILITY: The data that support the findings of this study are openly available in “figshare” at http://doi.org/10.6084/m9.figshare.17263883.v1The fate of organic carbon deposited in floodplain sediments is an important control on the magnitude and direction of the carbon flux from anthropogenically accelerated erosion and channelization of the riverine network. Globally, carbon deposition rates and mean residence time (MRT) within different geomorphic settings remains poorly constrained. We sampled soil profiles to 0.8 m depth from two geomorphic zones: active channel belt (ACB) and lowland floodplain, under long-term pasture adjacent to the river Culm in SW England, UK. We evaluated sedimentation rates and carbon storage using fallout radionuclide 137Cs, particle size and total carbon analyses. Variation in decomposition was assessed via empirical (soil aggregate size, density fractionation combined with natural abundance 13C analysis) and modelling simulation (using the RothC model and catchment implications explored using a floodplain evolution model). Sedimentation and carbon accumulation rates were 5–6 times greater in the ACB than the floodplain. Carbon decomposition rates also varied with geomorphic setting. In floodplain cores, faster decomposition rates were indicated by greater 13C-enrichment and subsoils dominated by mineral-associated soil organic carbon. Whereas, in the ACB, carbon was less processed and 13C-depleted, with light fraction and macroaggregate-carbon throughout the cores, and RothC modelled decomposition rates were 4-fold less than lowland floodplain cores. Including the ACB in floodplain carbon MRT calculations increased overall MRT by 10%. The major differences in the balance of sedimentation and decomposition rates between active and inactive floodplains suggests the relative extent of these contrasting zones is critical to the overall carbon balance. Restoration projects could enhance soil carbon storage by maximizing active floodplain areas by increasing river channel complexity.Natural Environment Research CouncilNatural Environment Research Counci

Contrasting rhizosphere soil nutrient economy of plants associated with arbuscular mycorrhizal and ectomycorrhizal fungi in karst forests

This is the author accepted manuscript. The final version is available from Springer via the DOI in this recordData availability: Requests for data or other materials should be directed to Xinyu Zhang ([email protected]).Purpose Plants growing in the soils of karst forests associate with arbuscular mycorrhizae (AM) or ectomycorrhizae (ECM) to acquire nutrients. We researched how these different mycorrhizal associations affect rhizosphere soil nutrient economy in these calcareous soils. Methods Bulk and rhizosphere soils were sampled beneath 25 AM and 9 ECM plants growing in primary forests at the Puding Karst Critical Zone Observatory. Nutrient contents and potential enzyme activities were analyzed to test the effect of different types of mycorrhizal association on rhizosphere soil nitrogen (N) and phosphorus (P) economies. Results The contents of nitrate-N and available-P were markedly lower in the rhizospheres of ECM plants compared to AM plants. Ectomycorrhizal plants promoted relatively greater investment in N-acquisition enzymes, in contrast, AM plants caused relatively greater investment in P-acquisition enzymes. The decreased pH in the rhizospheres of AM plants likely promoted the greater P availability. Conclusion Our results revealed how plants that form contrasting mycorrhizal associations have fundamentally different effects on rhizospheric nutrient economies in the low fertility karst soils of southwest China. Differentiation in N- and P-acquisition capacity of these plants have implications for species coexistence and the high levels of plant biodiversity observed in these forests.National Natural Science Foundation of ChinaNational Key Research and Development ProgramNatural Environment Research Council (NERC

Unraveling trade‐offs among reforestation, urbanization and food security in the South China Karst Region: How can a hinterland province achieve SDGs?

This is the author accepted manuscript. Available on open access from Wiley via the DOI in this recordWhether the world can achieve the United Nations Sustainable Development Goals (SDGs) largely depends on the ability of less-developed areas to cope with multiple socio-economic changes. The challenges that hinterland areas would face during the realization of SDGs has not yet received enough attentions. In this study, a context-based assessment of regional food balances was conducted, considering key challenges related to socio-economic development as well as land use competition under the framework of the shared socioeconomic pathways (SSPs) and the implementation of reforestation. We examined one of the poorest hinterland provinces in China as a case study, projecting its food deficit and exploring the potential threats to and opportunities for SDG realization by 2030, including population growth, urbanization, urban land expansion and reforestation. The projections revealed a crop deficit of 4.9-9.8 million tonnes, corresponding to the food demands of 10.2-20.6 million people. Approximately 76-81% of this deficit was expected to be caused by increased food demand, rather than reforestation policies. Therefore, for this less-developed area with low agricultural productivity and large groups of vulnerable people, population growth and urbanization are likely to result in demands for food that cannot be met locally. In addition, large-scale reforestation projects, while enhancing a number of key ecosystem services, will increase the local food deficit by promoting the abandonment of cropland. This will result in greater reliance on food imports, with potential impacts on SDG realization in other regions. These findings highlight the need for integrated governance across multiple scales to ensure hinterland sustainability.Natural Environment Research Council (NERC)National Natural Science Foundation of Chin

Analysing and simulating spatial patterns of crop yield in Guizhou Province based on artificial neural networks

Supplemental material for this article is available online.This is the author accepted manuscript, the final version is available from SAGE via the DOI in this record.The area of karst terrain in China covers 3.63×106 km2, with more than 40% in the southwestern region over the Guizhou Plateau. Karst comprises exposed carbonate bedrock over approximately 1.30×106 km2 of this area, which suffers from soil degradation and poor crop yield. This paper aims to gain a better understanding of the environmental controls on crop yield in order to enable more sustainable use of natural resources for food production and development. More precisely, four kinds of artificial neural network were used to analyse and simulate the spatial patterns of crop yield for seven crop species grown in Guizhou Province, exploring the relationships with meteorological, soil, irrigation and fertilization factors. The results of spatial classification showed that most regions of high-level crop yield per area and total crop yield are located in the central-north area of Guizhou. Moreover, the three artificial neural networks used to simulate the spatial patterns of crop yield all demonstrated a good correlation coefficient between simulated and true yield. However, the Back Propagation network had the best performance based on both accuracy and runtime. Among the 13 influencing factors investigated, temperature (16.4%), radiation (15.3%), soil moisture (13.5%), fertilization of N (13.5%) and P (12.4%) had the largest contribution to crop yield spatial distribution. These results suggest that neural networks have potential application in identifying environmental controls on crop yield and in modelling spatial patterns of crop yield, which could enable local stakeholders to realize sustainable development and crop production goals.Natural Environment Research Council (NERC)National Natural Science Foundation of ChinaChina Scholarship Counci

Micro-scale interactions between Arabidopsis root hairs and soil particles influence soil erosion

This is the final version. Available from Nature Research via the DOI in this record. Soil is essential for sustaining life on land. Plant roots play a crucial role in stabilising soil and minimising erosion, although these mechanisms are still not completely understood. Consequently, identifying and breeding for plant traits to enhance erosion resistance is challenging. Root hair mutants in Arabidopsis thaliana were studied using three different quantitative methods to isolate their effect on root-soil cohesion. We present compelling evidence that micro-scale interactions of root hairs with surrounding soil increase soil cohesion and reduce erosion. Arabidopsis seedlings with root hairs were more difficult to detach from soil, compost and sterile gel media than those with hairless roots, and it was 10-times harder to erode soil from roots with than without hairs. We also developed a model that can consistently predict the impact root hairs make to soil erosion resistance. Our study thus provides new insight into the mechanisms by which roots maintain soil stability.Leverhulme TrustBiotechnology and Biological Sciences Research CouncilEngineering and Physical Sciences Research Counci

Well-being in residency training: a survey examining resident physician satisfaction both within and outside of residency training and mental health in Alberta

BACKGROUND: Despite the critical importance of well-being during residency training, only a few Canadian studies have examined stress in residency and none have examined well-being resources. No recent studies have reported any significant concerns with respect to perceived stress levels in residency. We investigated the level of perceived stress, mental health and understanding and need for well-being resources among resident physicians in training programs in Alberta, Canada. METHODS: A mail questionnaire was distributed to the entire resident membership of PARA during 2003 academic year. PARA represents each of the two medical schools in the province of Alberta. RESULTS: In total 415 (51 %) residents participated in the study. Thirty-four percent of residents who responded to the survey reported their life as being stressful. Females reported stress more frequently than males (40% vs. 27%, p < 0.02). Time pressure was reported as the number one factor contributing to stress (44% of males and 57% of females). A considerable proportion of residents would change their specialty program (14%) and even more would not pursue medicine (22%) if given the opportunity to relive their career. Up to 55% of residents reported experiencing intimidation and harassment. Intimidation and harassment was strongly related to gender (12% of males and 38% of females). Many residents (17%) rated their mental health as fair or poor. This was more than double the amount reported in the Canadian Community Health Survey from the province (8%) or the country (7%). Residents highly valued their colleagues (67%), program directors (60%) and external psychiatrist/psychologist (49%) as well-being resources. Over one third of residents wished to have a career counselor (39%) and financial counselor (38%). CONCLUSION: Many Albertan residents experience significant stressors and emotional and mental health problems. Some of which differ among genders. This study can serve as a basis for future resource application, research and advocacy for overall improvements to well-being during residency training