Variability in soil properties at different spatial scales (1 m-1 km) in a deciduous forest ecosystem     

Charles T. Garten Jr.  Sanghoon Kang  Deanne J. Brice  Jizhong Zhou 《Soil biology & biochemistry》2007,39(10):2621-2627

The purpose of this research was to test the hypothesis that variability in 11 soil properties, related to soil texture and soil C and N, would increase from small (1 m) to large (1 km) spatial scales in a temperate, mixed-hardwood forest ecosystem in east Tennessee, USA. The results were somewhat surprising and indicated that a fundamental assumption in geospatial analysis, namely that variability increases with increasing spatial scale, did not apply for at least five of the 11 soil properties measured over a 0.5-km² area. Composite mineral soil samples (15 cm deep) were collected at 1, 5, 10, 50, 250, and 500 m distances from a center point along transects in a north, south, east, and westerly direction. A null hypothesis of equal variance at different spatial scales was rejected (P?0.05) for mineral soil C concentration, silt content, and the C-to-N ratios in particulate organic matter (POM), mineral-associated organic matter (MOM), and whole surface soil. Results from different tests of spatial variation, based on coefficients of variation or a Mantel test, led to similar conclusions about measurement variability and geographic distance for eight of the 11 variables examined. Measurements of mineral soil C and N concentrations, C concentrations in MOM, extractable soil NH₄-N, and clay contents were just as variable at smaller scales (1-10 m) as they were at larger scales (50-500 m). On the other hand, measurement variation in mineral soil C-to-N ratios, MOM C-to-N ratios, and the fraction of soil C in POM clearly increased from smaller to larger spatial scales. With the exception of extractable soil NH₄-N, measured soil properties in the forest ecosystem could be estimated (with 95% confidence) to within 15% of their true mean with a relatively modest number of sampling points (n?25). For some variables, scaling up variation from smaller to larger spatial domains within the ecosystem could be relatively easy because small-scale variation may be indicative of variation at larger scales.  相似文献   

Soil distribution in valleys according to stream order     

Brice Mourier  Christian Walter  Philippe Merot 《CATENA》2008,72(3):395-404

While much research has been done on predicting the occurrence of waterlogged soils in small catchments, we need to improve our knowledge of the extension of these soils in large catchments. The aim of this study is to analyse the extent of soils with redoximorphic features in the valley bottomland domain as a function of the stream order.This study concerns a 10,000 km² catchment (River Vilaine, Armorican massif, north-western France) where valley bottomland soils commonly associated with hydromorphic characteristics cover up to 20% of the basin area. To describe the catchment organisation, we used the stream order classification of Strahler to test the behaviour of the topographic index in a large range of landscape morphological settings. Two methods were used to define the extent of the hydromorphic zone (HZ) in each valley bottomland according to stream order: (i) A field study based on mapping the HZ according to the occurrence of redoximorphic features along 60 transects; (ii) a modelling approach linking a DEM-derived topographic index to the digitized stream network of the River Vilaine.In view of the topographic factors, progressive valley widening may represent an enhancing factor of HZ extent. Thus, simple topographic index modelling predicts an increase in waterlogging in high-order channel settings (orders 6–7). By contrast, field mapping suggests that HZ extent remains stable with increasing order and decreases significantly for high-order settings (orders 6–7). Therefore, topographic index modelling appears effective in upper catchment settings (1st, 2nd and 3rd order). On the contrary, modelling efficiency is limited in high-order settings where the indices prove to be inappropriate: in such contexts, interactions between adjacent hillslope and HZ are of secondary importance. Along the longitudinal profile of the catchment, soil material near the streams shifts from having a colluvial origin in low-order to an alluvial origin in high-order settings. In high-order settings, the fine-scale valley bottomland topography and the spatial organisation of deposits control waterlogging duration and possibly play a major role in HZ extent. Finally, the integration of stream order data should considerably improve the efficiency of modelling the spatial distribution of soils over large catchments.  相似文献   

Foliar application of benzovindiflupyr shows non‐fungicidal effects in wheat plants          下载免费PDF全文

Dmitry Kuznetsov  Alexandre Brice Cazenave  Odile Rambach  Philippe Camblin  Mafalda Nina  Jörg Leipner 《Pest management science》2018,74(3):665-671

BACKGROUND

The fungicide benzovindiflupyr belongs to the class of succinate dehydrogenase inhibitors (SDHIs). Certain SDHIs have shown plant physiological effects, so‐called secondary effects, that appeared to be related to the plant water status. Therefore, the effect of benzovindiflupyr on transpiration of leaves and whole wheat plants was studied under controlled conditions. Furthermore, wheat yield trials under controlled and natural drought stress in the field were conducted.

RESULTS

Transpiration of detached wheat leaves was reduced by benzovindiflupyr in a dose‐dependent manner. Similarly, whole‐plant transpiration decreased for several days following application of this fungicide. In 16 field trials under drought stress conditions that were classified as disease‐free, treatment of wheat plants at the flag leaf stage or at heading with benzovindiflupyr showed a grain yield increase (+5.2%; P ≤ 0.01) that was partially attributed to an increased thousand‐grain weight.

CONCLUSIONS

Water saving during pre‐anthesis as a result of benzovindiflupyr application may be associated with better seed setting and filling under dry field conditions in wheat. The results of this research provide new insights into secondary effects of SDHIs that lead directly to yield improvements. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

Trypanosomiasis challenge estimation using the diminazene aceturate (Berenil) index in Zebu in Gabon     

Cossic  Brieuc G. A.  Adjahoutonon  Brice  Gloaguen  Pierre  Dibanganga  Gui Lov  Maganga  Gael  Leroy  Pascal  MacLeod  Ewan T.  Picozzi  Kim 《Tropical animal health and production》2017,49(3):619-624

A longitudinal study was conducted within a cattle ranch in Gabon to determine the diminazene aceturate (Berenil) index (DAI) in a group of Zebu, raised under low tsetse density; this measure providing an assessment of trypanosomiasis risk. The objective was to evaluate the trypanosomiasis pressure thus informing trypanosomiasis control methods and cattle management. Twenty female adult Zebu were monitored for 24 weeks during the dry season. Blood samples were collected on a weekly basis and subjected to parasitological and haematological analysis (n?=?480), using the buffy-coat method and the packed cell volume value (PCV), respectively, infected animals were treated with a single intramuscular injection of diminazene aceturate (8 mg/kg). Twenty-nine single infectious events were recorded and a DAI of 1.45 was calculated. Two trypanosome species were identified: Trypanosoma congolense (96.2%) and Trypanosoma vivax (3.8%). The mean PCV value of the infected animals was lower (26.6) compared to non-infected animals (32.0). This study shows that DAI may be a useful tool to assess trypanosomiasis. However, this is a time-consuming method that may be improved by using randomly selected sentinel animals to adapt the chemoprophylactic schemes, hence decreasing the costs and the drug resistance risk.

  相似文献   

Timing and magnitude of C partitioning through a young loblolly pine (Pinus taeda L.) stand using 13C labeling and shade treatments     

Warren JM  Iversen CM  Garten CT  Norby RJ  Childs J  Brice D  Evans RM  Gu L  Thornton P  Weston DJ 《Tree physiology》2012,32(6):799-813

The dynamics of rapid changes in carbon (C) partitioning within forest ecosystems are not well understood, which limits improvement of mechanistic models of C cycling. Our objective was to inform model processes by describing relationships between C partitioning and accessible environmental or physiological measurements, with a special emphasis on short-term C flux through a forest ecosystem. We exposed eight 7-year-old loblolly pine (Pinus taeda L.) trees to air enriched with (13)CO(2) and then implemented adjacent light shade (LS) and heavy shade (HS) treatments in order to manipulate C uptake and flux. The impacts of shading on photosynthesis, plant water potential, sap flow, basal area growth, root growth and soil CO(2) efflux rate (CER) were assessed for each tree over a 3-week period. The progression of the (13)C label was concurrently tracked from the atmosphere through foliage, phloem, roots and surface soil CO(2) efflux. The HS treatment significantly reduced C uptake, sap flow, stem growth and fine root standing crop, and resulted in greater residual soil water content to 1 m depth. Soil CER was strongly correlated with sap flow on the previous day, but not the current day, with no apparent treatment effect on the relationship. Although there were apparent reductions in new C flux belowground, the HS treatment did not noticeably reduce the magnitude of belowground autotrophic and heterotrophic respiration based on surface soil CER, which was overwhelmingly driven by soil temperature and moisture. The (13)C label was immediately detected in foliage on label day (half-life = 0.5 day), progressed through phloem by Day 2 (half-life = 4.7 days), roots by Days 2-4, and subsequently was evident as respiratory release from soil which peaked between Days 3 and 6. The δ(13)C of soil CO(2) efflux was strongly correlated with phloem δ(13)C on the previous day, or 2 days earlier. While the (13)C label was readily tracked through the ecosystem, the fate of root C through respiratory, mycorrhizal or exudative release pathways was not assessed. These data detail the timing and relative magnitude of C flux through various components of a young pine stand in relation to environmental conditions.  相似文献   

Effects of intravenous, low-dose ketamine-diazepam sedation on the results of hematologic, plasma biochemical, and coagulation analyses in cats     

Reynolds BS  Geffré A  Bourgès-Abella NH  Vaucoret S  Mourot M  Braun JP  Trumel C 《Journal of the American Veterinary Medical Association》2012,240(3):287-293

  相似文献   

Development of thermal insulating and sound absorbing agro-sourced materials from auto linked flax-tows     

Nemr El Hajj  Brice Mboumba-MamboundouRose-Marie Dheilly  Zoheir AbouraMalek Benzeggagh  Michèle Queneudec 《Industrial Crops and Products》2011,34(1):921-928

The aim of this paper is to develop a green composite using only flax fiber material for thermal insulations and sound absorbing using flax-tows and thus enhance the less noble part of the flax plant. The Lin-K process is a simple patented manufacturing process used to develop these self-linked materials. Thermal conductivity, absorbing acoustic coefficient, hydric properties and the effect of several parameters on these performances are reviewed. The use of fine flax-tows leads to extract more organic substances of the inner fibers during the microwave treatment which improves the mechanical performances and reduces the thermal conductivities of these materials. The environment has very significant effects on thermal stability and durability of these materials.  相似文献   

Spatial pattern dynamics of oak mortality and associated disease symptoms in a California hardwood forest affected by sudden oak death     

Maggi Kelly  Desheng Liu  Brice McPherson  David Wood  Richard Standiford 《Journal of Forest Research》2008,13(5):312-319

Sudden oak death is a disease affecting coastal forests in California and southern Oregon. The spatial pattern of disease dynamics is important for forest and landscape pathology; in this work we investigated the interaction across landscape scales of disease symptomology in coast live oaks, Quercus agrifolia, (trunk bleeding, presence of beetles, and presence of the fungus Hypoxylon thouarsianum) and tree mortality through time. We used two-dimensional spatial analysis tools with data gathered in point-centered-quarter format in 2001 and 2004 to quantify the population density of the disease through time; to examine the spatial pattern of tree mortality across scales through time; and to examine the spatial co-occurrence of disease symptoms with crown mortality through time. Early in the study period dead trees were strongly clustered at smaller scales (~300 m) and after three years this clustering was less pronounced. Bleeding on trees occurred in clusters away from dead trees, particularly in 2004, likely indicating a new cohort of infected trees. The presence of H. thouarsianum was strongly related to overstory mortality through time. Beetle-infested trees co-occurred with mortality in 2001. By 2004, they occurred throughout the forest, and were less strongly correlated with overstory tree mortality, suggesting a future peak of tree mortality.  相似文献   

Diversity and Current Spatial Distribution of Wild-Edible Fruit Trees Species in the Lama Forest Reserve in Benin     

Symphorien Agbahoungba  Achille Ephrem Assogbadjo  Eric Etchikinto Agoyi  Brice Sinsin 《International Journal of Fruit Science》2019,19(1):13-28

  相似文献   

Effects of historical and current disturbance on forest biomass in Minnesota     

Brice B. Hanberry  Hong S. He 《Landscape Ecology》2015,30(8):1473-1482

  相似文献