Nitrogen pools and fluxes in grassland soils sequestering carbon

Carbon sequestration in agricultural, forest, and grassland soils has been promoted as a means by which substantial amounts of CO2 may be removed from the atmosphere, but few studies have evaluated the associated impacts on changes in soil N or net global warming potential (GWP). The purpose of this research was to ( 1) review the literature to examine how changes in grassland management that affect soil C also impact soil N, ( 2) assess the impact of different types of grassland management on changes in soil N and rates of change, and (3) evaluate changes in N2O fluxes from differently managed grassland ecosystems to assess net impacts on GWP. Soil C and N stocks either both increased or both decreased for most studies. Soil C and N sequestration were tightly linked, resulting in little change in C: N ratios with changes in management. Within grazing treatments N2O made a minor contribution to GWP (0.1-4%), but increases in N2O fluxes offset significant portions of C sequestration gains due to fertilization (10-125%) and conversion (average = 27%). Results from this work demonstrate that even when improved management practices result in considerable rates of C and N sequestration, changes in N2O fluxes can offset a substantial portion of gains by C sequestration. Even for cases in which C sequestration rates are not entirely offset by increases in N2O fluxes, small increases in N2O fluxes can substantially reduce C sequestration benefits. Conversely, reduction of N2O fluxes in grassland soils brought about by changes in management represents an opportunity to reduce the contribution of grasslands to net greenhouse gas forcing

RothCUK - a dynamic modelling system for estimating changes in soil C from mineral soils at 1-km resolution in the UK

We describe the development and application of an integrated data and modelling system for estimating soil carbon (C) fluxes from mineral soils caused by changes in climate, land use and land management at 1-km resolution in the UK (RothCUK). The system was developed with the aim of improving methods for United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol accounting and integrates national scale data sets of soil properties, land use and climate with the Rothamsted carbon model (RothC). A preliminary estimate of soil C fluxes because of land use change (LUC) over the period 1990–2000 is presented as an example application of the system. RothCUK shows LUC to be a net source of CO2 from 1990 to 2000 although the RothC estimate was smaller (6488 kt C) than the estimate from the single exponential model (SEM) method currently used to calculate C fluxes due to LUC for the UK National Greenhouse Gas Inventory (mean: 9412 kt C). Based on previous studies, an uncertainty range in our estimates of ±50–100% seems plausible. In agreement with the SEM, RothCUK suggests that the largest single contributor to soil C fluxes from LUC was conversion of grassland to arable land. Differences between the results may be attributed to differences in the two models and the assumptions and underlying data used in making the calculations. The RothCUK system provides a powerful method for estimating changes in soil C stocks, enabling areas and management systems with particularly large changes in soil C stocks to be located at fine resolution

Simulação pelo modelo century da dinâmica da matéria orgânica de um Argissolo sob adubação mineral e orgânica Simulation of organic matter dynamics in an Argisol under mineral and organic fertilization with the century model

Os modelos de simulação são ferramentas essenciais para o entendimento da dinâmica da matéria orgânica do solo e da transformação de seus compartimentos em solos tropicais. Os objetivos deste estudo foram: (a) simular por meio do modelo Century os efeitos de sistemas de produção de milho sob adubação orgânica e mineral sobre a dinâmica da matéria orgânica em um Argissolo Vermelho-Amarelo, e (b) comparar os estoques de C orgânico total (COT), N total (NT) e dos compartimentos de C medidos por meio de métodos de laboratório e estimados pelo modelo Century na camada superficial (0-20 cm). A área em estudo, sob Floresta Atlântica (FA) até o ano de 1930, foi cultivada com milho e feijão por aproximadamente 50 anos, até à instalação do experimento no ano de 1984. Os tratamentos constaram de combinações entre três doses de adubo mineral, correspondentes a de 0, 250 e 500 kg ha-1 da fórmula 4-14-8, e duas doses de adubo orgânico (esterco bovino com palha de soja e feijão), nas doses de 0 e 40 m³ ha-1. Os métodos de laboratório incluíram determinações do COT, do NT, do C da biomassa microbiana (C MIC), representando o compartimento ativo, e do C da fração leve (C FL), referenciando o compartimento lento. O compartimento passivo foi obtido por diferença. A parametrização do modelo Century foi realizada a partir dos dados obtidos no experimento e na literatura, enquanto as simulações da dinâmica do COT, NT e dos compartimentos ativo de C lento e passivo incluíram as mudanças no uso da terra ocorridas de 1930 a 2050. O modelo Century estimou diminuição nos estoques de COT, NT e dos compartimentos de C desde a derrubada da FA até o início do experimento e apenas nos tratamentos com adubação orgânica foi observada recuperação desses estoques. O CmIC e o C FL foram mais sensíveis às mudanças no manejo do que o COT, o que indica a importância desses compartimentos no estudo da dinâmica da matéria orgânica, especialmente em solos tropicais. Os estoques de COT, NT e dos compartimentos de C (lento e passivo), simulados pelo modelo Century, foram similares aos estoques medidos. Os estoques de COT (em Mg ha-1 de C), medidos e simulados pelo modelo Century, foram bem correlacionados (R² = 0,93; p < 0,01), assim como para o C do compartimento ativo (R² = 0,84; p < 0,05), lento (R² = 0,87; p < 0,05) e passivo (R² = 0,91; p < 0,05). Também para os estoques de NT (em Mg ha-1 de N), medidos e simulados pelo modelo Century, houve alta correlação (R² = 0,93; p < 0,01). O modelo Century demonstrou bom desempenho para simular a dinâmica da matéria orgânica em solos tropicais ácidos.<br>Simulation models are essential instruments to understand soil organic matter dynamics and the turnover of its pools in tropical soils. The objectives of this study were: (a) simulate the effects of maize production systems under organic and mineral fertilization on soil organic matter dynamics of an Ultisol using the Century model; (b) to compare total carbon (TOC) and total nitrogen stocks (TN) and the carbon pools (C) measured in the laboratory and estimated by the Century model for the surface soil layer (0-20 cm). The study area had been part of the Atlantic Forest (FA) until 1930. After that it had been used for maize/bean production up to 1984, when the field experiment was set up. The treatments included a combination of three levels of mineral fertilizer at doses of 0, 250 and 500 kg ha-1 of the 4-14-8 formula and two levels of organic fertilizer (animal manure with soybean and bean straw) at doses of 0 and 40 m³ ha-1. Laboratory determinations included TOC and TN, microbial biomass C representing the active C pool and carbon of the light fraction representing the slow C pool. The passive C pool was determined by difference. The Century model was parameterized with data from the present experiment and from literature, whereas the simulations of the dynamics of TOC, TN and the active, slow, and passive pool included land use changes between 1930 and 2050. The Century model estimated a decrease in TOC, TN and the different carbon pools between the slash and burn of the Atlantic Forest until the establishment of the field experiment. Only in the treatments with organic fertilization it was observed a recovery of these pools. Biomass carbon and the carbon of the light fraction were more sensitive to changes in management than TOC. This highlights the relevance of these pools in studies of organic matter dynamics, particularly in tropical soils. Measured and simulated values of TOC (in Mg ha-1 of C) were well correlated (R² = 0.93; p < 0.01). This was also observed for the active (R² = 0.84; p < 0.05), the slow (R² = 0.87; p < 0.05) and the passive (R² = 0.91; p < 0.05) C pools. Both measured and simulated values of TN (in Mg ha-1 of N) were well correlated (R² = 0.93; p < 0.01). The Century model showed a good performance to simulate soil organic matter dynamics in tropical soils

Geomorphic classification of rivers and streams

deuxième éditionInternational audienceThis chapter discusses general philosophies of classifications in fluvial geomorphology, and reviews examples of geomorphic classification systems. It explores uses and limitations of classifications as a tool in fluvial geomorphology and river management. Buffington and Montgomery emphasize the distinction between descriptive and process‐based classifications, noting that descriptive classifications can be quantitative and process‐based classifications can be qualitative. Distinctions between mountain torrents and lowland rivers are perhaps the oldest form of river classification. A wide range of geomorphic river classification schemes have been proposed since the late 19th century, reflecting the diversity of environmental settings, the variety of potential approaches to ordering complex natural systems, the intellectual framework of the field and the diverse purposes for which the systems were developed. Classification can focus on spatial features such as river patterns, floodplains, in‐channel features, which can be separated according to a set of parameter

Multicenter International Study of the Consensus Immunoscore for the Prediction of Relapse and Survival in Early-Stage Colon Cancer

Background: The prognostic value of Immunoscore was evaluated in Stage II/III colon cancer (CC) patients, but it remains unclear in Stage I/II, and in early-stage subgroups at risk. An international Society for Immunotherapy of Cancer (SITC) study evaluated the pre-defined consensus Immunoscore in tumors from 1885 AJCC/UICC-TNM Stage I/II CC patients from Canada/USA (Cohort 1) and Europe/Asia (Cohort 2). METHODS: Digital-pathology is used to quantify the densities of CD3+ and CD8+ T-lymphocyte in the center of tumor (CT) and the invasive margin (IM). The time to recurrence (TTR) was the primary endpoint. Secondary endpoints were disease-free survival (DFS), overall survival (OS), prognosis in Stage I, Stage II, Stage II-high-risk, and microsatellite-stable (MSS) patients. RESULTS: High-Immunoscore presented with the lowest risk of recurrence in both cohorts. In Stage I/II, recurrence-free rates at 5 years were 78.4% (95%-CI, 74.4−82.6), 88.1% (95%-CI, 85.7−90.4), 93.4% (95%-CI, 91.1−95.8) in low, intermediate and high Immunoscore, respectively (HR (Hi vs. Lo) = 0.27 (95%-CI, 0.18−0.41); p < 0.0001). In Cox multivariable analysis, the association of Immunoscore to outcome was independent (TTR: HR (Hi vs. Lo) = 0.29, (95%-CI, 0.17−0.50); p < 0.0001) of the patient’s gender, T-stage, sidedness, and microsatellite instability-status (MSI). A significant association of Immunoscore with survival was found for Stage II, high-risk Stage II, T4N0 and MSS patients. The Immunoscore also showed significant association with TTR in Stage-I (HR (Hi vs. Lo) = 0.07 (95%-CI, 0.01−0.61); P = 0.016). The Immunoscore had the strongest (69.5%) contribution χ2 for influencing survival. Patients with a high Immunoscore had prolonged TTR in T4N0 tumors even for patients not receiving chemotherapy, and the Immunoscore remained the only significant parameter in multivariable analysis. CONCLUSION: In early CC, low Immunoscore reliably identifies patients at risk of relapse for whom a more intensive surveillance program or adjuvant treatment should be considered

International validation of the consensus Immunoscore for the classification of colon cancer: a prognostic and accuracy study

Contains fulltext : 193579.pdf (publisher's version ) (Closed access)BACKGROUND: The estimation of risk of recurrence for patients with colon carcinoma must be improved. A robust immune score quantification is needed to introduce immune parameters into cancer classification. The aim of the study was to assess the prognostic value of total tumour-infiltrating T-cell counts and cytotoxic tumour-infiltrating T-cells counts with the consensus Immunoscore assay in patients with stage I-III colon cancer. METHODS: An international consortium of 14 centres in 13 countries, led by the Society for Immunotherapy of Cancer, assessed the Immunoscore assay in patients with TNM stage I-III colon cancer. Patients were randomly assigned to a training set, an internal validation set, or an external validation set. Paraffin sections of the colon tumour and invasive margin from each patient were processed by immunohistochemistry, and the densities of CD3+ and cytotoxic CD8+ T cells in the tumour and in the invasive margin were quantified by digital pathology. An Immunoscore for each patient was derived from the mean of four density percentiles. The primary endpoint was to evaluate the prognostic value of the Immunoscore for time to recurrence, defined as time from surgery to disease recurrence. Stratified multivariable Cox models were used to assess the associations between Immunoscore and outcomes, adjusting for potential confounders. Harrell's C-statistics was used to assess model performance. FINDINGS: Tissue samples from 3539 patients were processed, and samples from 2681 patients were included in the analyses after quality controls (700 patients in the training set, 636 patients in the internal validation set, and 1345 patients in the external validation set). The Immunoscore assay showed a high level of reproducibility between observers and centres (r=0.97 for colon tumour; r=0.97 for invasive margin; p<0.0001). In the training set, patients with a high Immunoscore had the lowest risk of recurrence at 5 years (14 [8%] patients with a high Immunoscore vs 65 (19%) patients with an intermediate Immunoscore vs 51 (32%) patients with a low Immunoscore; hazard ratio [HR] for high vs low Immunoscore 0.20, 95% CI 0.10-0.38; p<0.0001). The findings were confirmed in the two validation sets (n=1981). In the stratified Cox multivariable analysis, the Immunoscore association with time to recurrence was independent of patient age, sex, T stage, N stage, microsatellite instability, and existing prognostic factors (p<0.0001). Of 1434 patients with stage II cancer, the difference in risk of recurrence at 5 years was significant (HR for high vs low Immunoscore 0.33, 95% CI 0.21-0.52; p<0.0001), including in Cox multivariable analysis (p<0.0001). Immunoscore had the highest relative contribution to the risk of all clinical parameters, including the American Joint Committee on Cancer and Union for International Cancer Control TNM classification system. INTERPRETATION: The Immunoscore provides a reliable estimate of the risk of recurrence in patients with colon cancer. These results support the implementation of the consensus Immunoscore as a new component of a TNM-Immune classification of cancer. FUNDING: French National Institute of Health and Medical Research, the LabEx Immuno-oncology, the Transcan ERAnet Immunoscore European project, Association pour la Recherche contre le Cancer, CARPEM, AP-HP, Institut National du Cancer, Italian Association for Cancer Research, national grants and the Society for Immunotherapy of Cancer