Crown morphology of Norway spruce from usual tree measurements     

李长胜  孙剑峰  徐永芳 《林业研究》1998,9(1):8-12

Intr0ducti0nNorwayspruce(PiceaabiesKarst)is0l1eoflI1e111ostimportal1tc011iferinFra11ce.lnl99l,tI1etotaIareaofNorwaysprLICewasestimatedt0be723000I11112.ItsvoIUmewasl27Inilli0I1m3.Tl1eanl1uaIvoILl111eiI1crc-mentwas5.74millionm3.ltiswideIyacceptedII1atIargeri11itialspacingssI1ouldbeusednow.l111940's,thedensity0ftl1epIantatiol1rangedfr0m5000to10000stems/hm2.Nowtl1einitiaIdensityvariesbetweenI000to250Ostems/I1m2.TI1eIargestspacit1g111aybe650~800stems/hm2.S0ithasasignifica11cetostLldyt…  相似文献   

Behaviour and Impact of Cow Slurry Beneath a Storage Lagoon: 1. Groundwater Contamination 1975–1982     

Withers  Paul J. A.  McDonald  Hamish G.  Smith  Kenneth A.  Chumbley  Colin G. 《Water, air, and soil pollution》1998,107(1-4):35-49

The chemical and biological composition of groundwater sampled from a 76 m deep borehole situated 80 m from an unlined, earth-banked lagoon excavated in Upper Chalk and continuously used to store liquid cow manure was regularly monitored from August 1975 to January 1982 for signs of pollution. The lagoon became self-sealing 3 months after the start of filling in 1975, but was further enlarged and re-filled in autumn 1976, and emptied by dragline in September 1978 and 1980. No significant changes in groundwater composition were detected in the period August 1975 to December 1978. In January 1979, significant numbers of Escherichia coli and a large, rapid increase in concentrations of ammonium-nitrogen (NH₄-N), phosphorus (P), potassium (K), sodium (Na), chloride (Cl) and sulphate (SO4) were detected in the groundwater. Nutrient concentrations fluctuated at elevated levels throughout 1979 but decreased during 1980. Additional bacterial and chemical (NH₄-N, P and K) contamination was recorded in January 1981 and subsequent months. The contamination was considered to have occurred as a result of fissure flow through the unsaturated zone of the Upper Chalk following repeated disruption of the self-sealing layer during emptying of the lagoon by dragline in September 1978 and 1980. The results indicate that unlined, earth-banked slurry storage lagoons need to be carefully managed to avoid biological and chemical pollution of Chalk aquifers.  相似文献   

The Global Exposure of Forests to Air Pollutants     

David Fowler  J. Neil Cape  Mhairi Coyle  Chris Flechard  Johan Kuylenstierna  Kevin Hicks  Dick Derwent  Colin Johnson  David Stevenson 《Water, air, and soil pollution》1999,116(1-2):5-32

The tall, aerodynamically rough surfaces of forests provide for the efficient exchange of heat and momentum between terrestrial surfaces and the atmosphere. The same properties of forests also provide for large potential rates of deposition of pollutant gases, aerosols and cloud droplets. For some reactive pollutant gases, including SO₂, HNO₃ and NH₃, rates of deposition may be large and substantially larger than onto shorter vegetation and is the cause of the so called "filtering effect" of forest canopies. Pollutant inputs to moorland and forest have been compared using measured ambient concentrations from an unpolluted site in southern Scotland and a more polluted site in south eastern Germany. The inputs of S and N to forest at the Scottish site exceed moorland by 16% and 31% respectively with inputs of 7.3 kg S ha^-1 y and 10.6 kg N ha^-1 y^-1. At the continental site inputs to the forest were 43% and 48% larger than over moorland for S and N deposition with totals of 53.6 kg S ha^-1 y^-1 and 69.5 kg N ha^-1 y^-1 respectively. The inputs of acidity to global forests show that in 1985 most of the areas receiving > 1 kg H⁺ ha^-1 y^-1 as S are in the temperate latitudes, with 8% of total global forest exceeding this threshold. By 2050, 17% of global forest will be receiving > 1 kg H^-1 ha^-1 as S and most of the increase is in tropical and sub-tropical countries. Forests throughout the world are also exposed to elevated concentrations of ozone. Taking 60 ppb O₃ as a concentration likely to be phytotoxic to sensitive forest species, a global model has been used to simulate the global exposure of forests to potentially phytotoxic O₃ concentrations for the years 1860, 1950, 1970, 1990 and 2100. The model shows no exposure to concentrations in excess of 60 ppb in 1860, and of the 6% of global forest exposed to concentrations > 60 ppb in 1950, 75% were in temperate latitudes and 25% in the tropics. By 1990 24% of global forest is exposed to O₃ concentrates > 60 ppb, and this increases to almost 50% of global forest by 2100. While the uncertainty in the future pollution climate of global forest is considerable, the likely impact of O₃ and acid deposition is even more difficult to assess because of interactions between these pollutants and substantial changes in ambient CO₂ concentration, N deposition and climate over the same period, but the effects are unlikely to be beneficial overall.  相似文献   

Risk factors for Salmonella enterica subsp. enterica contamination in French broiler-chicken flocks at the end of the rearing period     

N. Rose  F. Beaudeau  P. Drouin  J. Y. Toux  V. Rose  P. Colin 《Preventive veterinary medicine》1999,39(4):1158

Broiler-chicken are often Salmonella carriers. However, these bacteria are responsible for major food-borne human infection, in which poultry-meat products are frequently implicated. In order to prevent Salmonella spread during the slaughtering process, control measures should be implemented at the farm level to reduce the prevalence before slaughtering. The objective of this study was to identify the risk factors for Salmonella contamination in French commercial broiler flocks at the end of the rearing period. A prospective study was carried out in 1996 and 1997 on 86 broiler flocks located in western France. The Salmonella status of the flocks was assessed by means of litter swabs and dust samples analyzed with classical bacteriological methods. Sixty flocks (70%) had at least one contaminated environmental sample and were classified as Salmonella-contaminated flocks. Logistic regression was used to assess association of managerial practices, general hygiene and results of environmental Salmonella recovery, with the odds that the flock itself would be Salmonella-contaminated at the end of the rearing period. Salmonella contamination of the house before placing day-old chicks and the Salmonella contamination of day-old chicks were significantly related to Salmonella contamination of the flock at the end of the rearing period. The risk for Salmonella contamination of the flock was increased when feed trucks parked near the entrance of the change room and when feed meal, instead of small pellets, was provided at the start.  相似文献   

Differences in early developmental rate and yolk conversion efficiency in offspring of trout with alternative life histories          下载免费PDF全文

Travis E. Van Leeuwen  Shaun S. Killen  Neil B. Metcalfe  Colin E. Adams 《Ecology of Freshwater Fish》2017,26(3):371-382

Partial migration, in which some individuals of a population migrate while other individuals remain resident, is generally associated with ontogenetic shifts to better feeding areas or as a response to environmental instability, but its underlying mechanisms remain relatively unknown. Brown trout (Salmo trutta) exhibit partial migration, with some individuals remaining in freshwater (freshwater resident) while others undertake an anadromous migration, where they spend time at sea before returning to breed in freshwater (migrant). We reared full‐sibling groups of offspring from freshwater‐resident and anadromous brown trout from the same catchment in the laboratory under common garden conditions to examine potential differences in their early development. Freshwater‐resident parents produced eggs that were slower to hatch than those of anadromous parents, but freshwater‐resident offspring were quicker to absorb their yolk and reach the stage of exogenous feeding. Their offspring also had a higher conversion efficiency from the egg stage to the start of exogenous feeding (so were larger by the start of the fry stage) than did offspring from anadromous parents despite no difference in standard metabolic rate, maximal metabolic rate or aerobic scope. Given these differences in early development, we discuss how the migration history of the parents might influence the migration probability of the offspring.  相似文献   

A Marine λ-Oligocarrageenan Inhibits Migratory and Invasive Ability of MDA-MB-231 Human Breast Cancer Cells through Actions on Heparanase Metabolism and MMP-14/MMP-2 Axis     

Rmi Cousin  Hugo Groult  Chanez Manseur  Romain Ferru-Clment  Mario Gani  Rachel Havret  Claire Toucheteau  Grgoire Prunier  Batrice Colin  Franck Morel  Jean-Marie Piot  Isabelle Lanneluc  Kvin Baranger  Thierry Maugard  Ingrid Fruitier-Arnaudin 《Marine drugs》2021,19(10)

Sugar-based molecules such as heparins or natural heparan sulfate polysaccharides have been developed and widely studied for controlling heparanase (HPSE) enzymatic activity, a key player in extracellular matrix remodelling during cancer pathogenesis. However, non-enzymatic functions of HPSE have also been described in tumour mechanisms. Given their versatile properties, we hypothesized that sugar-based inhibitors may interfere with enzymatic but also non-enzymatic HPSE activities. In this work, we assessed the effects of an original marine λ-carrageenan derived oligosaccharide (λ-CO) we previously described, along with those of its native counterpart and heparins, on cell viability, proliferation, migration, and invasion of MDA-MB-231 breast cancer cells but also of sh-MDA-MB-231 cells, in which the expression of HPSE was selectively downregulated. We observed no cytotoxic and no anti-proliferative effects of our compounds but surprisingly λ-CO was the most efficient to reduce cell migration and invasion compared with heparins, and in a HPSE-dependent manner. We provided evidence that λ-CO tightly controlled a HPSE/MMP-14/MMP-2 axis, leading to reduced MMP-2 activity. Altogether, this study highlights λ-CO as a potent HPSE “modulator” capable of reducing not only the enzymatic activity of HPSE but also the functions controlled by the HPSE levels.  相似文献   

Density‐ and species‐dependent errors in single‐pass timed electrofishing assessment of riverine salmonids          下载免费PDF全文

Hannele M. Honkanen  Jennifer A. Dodd  Jessica R. Fordyce  Patrick Boylan  Colin E. Adams 《Ecology of Freshwater Fish》2018,27(1):98-102

Electrofishing techniques are widely used for the estimation of the size of stream‐dwelling fish populations for both fishery management and scientific study. In contrast to multiple pass, population depletion methods, single‐pass catch‐per‐unit‐effort (CPUE) methods are less time‐consuming and labour‐intensive. A possible issue with the commonly used fixed total time CPUE protocol is that it does not differentiate between the time spent actively fishing and the time incurred while not actively fishing (e.g. removing fish from nets and navigating the site). This issue is likely related to fish density. This study compared two methods of CPUE electrofishing and tested the hypothesis that time spent handling fish and navigating a site can be a source of error in the commonly used fixed total time electrofishing method. Seventy‐one sites were sampled across three subcatchments in the Foyle catchment in Northern Ireland. We found a difference in the catch per unit time between the two methods and that this difference increased with fish density. The fixed‐time CPUE method also failed to detect a species presence in low‐density sites.  相似文献   

High‐resolution melt and morphological analyses of mealybugs (Hemiptera: Pseudococcidae) from cacao: tools for the control of Cacao swollen shoot virus spread          下载免费PDF全文

Andy Wetten  Colin Campbell  Joël Allainguillaume 《Pest management science》2016,72(3):527-533

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Optimizing resource distribution and crop productivity in hedgerow intercropping by manipulating tree arrangement     

Solomon B. Ghezehei  John Annandale  Colin Everson 《Agroforestry Systems》2016,90(5):861-873

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Environmental and spatial characterisation of bacterial community composition in soil to inform sampling strategies     

Kate L. Baker  Silke Langenheder  Graeme W. Nicol  Dean Ricketts  Kenneth Killham  Colin D. Campbell  James I. Prosser 《Soil biology & biochemistry》2009,41(11):2292-2298

Soil physicochemical properties and microbial communities are highly heterogeneous and vary widely over spatial scales, necessitating careful consideration of sampling strategies to provide representative and reproducible soil samples across field sites. To achieve this, the study aimed to establish appropriate sampling methodology and to determine links between the variability of parameters, utilising two sampling strategies. The first (design 1) involved extracting 25 cores from random locations throughout the field and pooling them into five sets of five cores. The second (design 2) involved a further 25 cores within five 1 m² sub-plots. Sub-samples from each sub-plot were pooled in order to determine between and within sub-plot variability. All samples were analysed independently and as pooled sub-samples. Results indicate that pooling spatially separated samples significantly reduced the variability in pH, compared to individual samples. Pooling samples from a small area resulted in lower within sub-plot variability than between sub-plots for pH and bacterial community composition assessed by terminal-restriction fragment length polymorphism analysis. Following multivariate statistical analysis, a large amount of variation in community composition was explained by soil pH, which is remarkable given the relatively small size of the sampling area and minor differences in pH. Moisture content was also important in determining bacterial communities in the random design (design 1). In the 1 m² sub-plot design (design 2), the spatial location of the plots explained a large degree of the variation in bacterial community composition between plots, which was due to spatial autocorrelation of pH and possible additional environmental parameters. This study emphasises the importance of sampling design for obtaining representative samples from soil.  相似文献