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991.
Modelling site quality and individual-tree growth in pure and mixed Pinus brutia stands in north-east Greece 总被引:1,自引:0,他引:1
Marc Palahí Timo Pukkala Dimitrios Kasimiadis Konstantinos Poirazidis Aristotelis C. Papageorgiou 《Annals of Forest Science》2008,65(5):501-501
992.
Banana monocultures (Musa spp., AAA, Cavendish sub-group cv. Grande Naine) can have a detrimental impact on the environment. In these agro-systems, pesticide treatments can lead to surface and groundwater pollution, as is the case in the tropical insular conditions of the French West Indies. Using models to design alternative cropping systems is of growing interest but most of the research work has been concentrated on annual crops and most often in temperate climate. A specific model called SIMBA was built to assess environmental risks under a large range of cropping techniques and to help design more sustainable cropping systems. SIMBA simulates banana-cropping systems at field level over several cropping cycles. It includes sub-models that simulate soil structure, water balance, root nematode populations, yield, and economic outputs with a sound balance between representing the major phenomena well and keeping the model simple to reduce the parameterization costs in a large range of conditions. Agro-environmental indicators generated by the model make it possible to assess the major potential environmental impacts. The model has been developed and calibrated in Guadeloupe and Martinique and is used to draw up practical recommendations for farmers and for virtual experiments of agro-technological innovations or field management strategies. The structure of SIMBA is presented and a methodology is proposed for designing sustainable banana-based cropping systems using the model. SIMBA has been evaluated in a broad range of cropping systems in Guadeloupe by comparing model estimates to data collected in field experiments and surveys. Simulations lead to trends in rotation-based cropping systems characterized by systems that can be considered as intensive for profit evaluation, and combinations of frequent replanting, low nematicide application, no ploughing, and low fertilization level, for environmental evaluation. Simulations performed to optimize the replanting decision rule showed that relatively frequent replanting is good for profit while low frequency replantations (over four banana cycles) give a better environmental evaluation. 相似文献
993.
Vincent Le Guen Jean Guyot Carlos Raimundo Reis Mattos Marc Seguin Dominique Garcia 《Crop Protection》2008,27(12):1498-1503
The resistance of the MDF 180 Hevea brasiliensis cultivar to South American leaf blight caused by Microcyclus ulei has been studied under both controlled conditions of inoculation, and under natural infestation in the Brazilian state of Bahia. Inoculated isolates on this cultivar in most cases developed sporulating lesions and produced conidiospores, but at a moderate level, characteristic of a race non-specific, partial resistance. The teleomorph of M. ulei has never been reported on this cultivar, either in controlled conditions or in natural infestation, whereas it is commonly observed on other susceptible cultivars. This type of resistance has seldom been described for other pathosystems. MDF 180 resistance having also endured for more than 30 years in areas very conducive to the disease can, therefore, be described as a durable resistance. Rubber productivity of this cultivar is not sufficient to allow planting on industrial scale, but its resistance characteristics make it a good progenitor candidate for rubber tree resistance breeding programs. 相似文献
994.
Timber harvesting and fuelwood collection have dramatically reduced the total amount of forestland around the world, including in China. To understand how timber harvesting and fuelwood collection activities affect use by wildlife, we examined giant panda (Ailuropoda melanoleuca) use within Wolong Nature Reserve, Sichuan Province, southwest China. We evaluated giant panda use of habitat by observing the presence/absence of panda feces in 913 field plots. Newly harvested areas (0-10 years) had the lowest frequency of feces presence (3%), while unharvested forests had the highest (36%). Feces presence is influenced by bamboo cover, overstory and midstory composition, slope, aspect and distance to human activity. Results suggest that timber harvesting and fuelwood collection have important impacts on the use of forested habitats and panda use is reduced for several decades after harvests. However, as the forest regenerates, panda habitat may begin to recover after a period of at least 37 years. This has potential implications for the long-term conservation of panda habitats and suggests that if forestland is maintained via the Natural Forest Conservation Program (China’s logging ban), habitats that were previously harvested may eventually regenerate and increase the potential for the species long-term survival. 相似文献
995.
Park EK Watanabe T Gee SJ Schenker MB Hammock BD 《Journal of agricultural and food chemistry》2008,56(2):333-336
A simple, sensitive, and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determining urinary creatinine was developed and used to evaluate 24 h urine samples collected during an exposure study. Urine (1 microL) was diluted with methanol and then directly applied to LC-MS/MS. Under electrospray ionization (ESI) conditions, the transition molecules of creatinine and creatinine- d3 were observed at m/ z 114 > 44 and m/ z 117 > 47, respectively. The retention time of creatinine was 0.59 min. The linear range was 1-2000 ng/mL, with a detection limit in urine of 1 ng/mL. LC-MS/MS and colorimetric end-point methods were significantly associated ( R2 = 0.8785, p < 0.0001). The LC-MS/MS method to determine creatinine in 24 h urine samples had shorter retention times, was more sensitive, reliable, reproducible, simple, selective, and used a smaller sample size than other LC-MS/MS or commercial methods. 相似文献
996.
997.
Pablo Modernel Valentin Picasso Martin Do Carmo Walter A. H. Rossing Marc Corbeels Pablo Soca Santiago Dogliotti Pablo Tittonell 《Grass and Forage Science》2019,74(4):636-649
Droughts in southern South America affect grazing systems in many ways. They reduce biomass productivity; decrease livestock feed intake, weight and reproductive performance; increase farmers’ costs; and reduce farm income. It was hypothesized that simple grazing management variables affect the resilience of grazing systems to droughts at the paddock and farm scales. The effects of grazing management on herbage and animal production were assessed at paddock level, and how technological and structural variables relate to the production and economic performances at farm level. Results of a grazing experiment controlling herbage allowance at paddock level showed that resistance of herbage accumulation and animal live weight to drought was significantly higher for paddocks with higher pre‐drought herbage allowance than for those managed to low herbage allowance treatments. A strong positive linear relationship was found between pre‐drought herbage height and resistance of herbage accumulation rate (p < .01). In a longitudinal study of nine farms in Uruguay, resistance of cow pregnancy rate to drought was positively correlated with cow pregnancy rate (r = .72, p = .02) and farm net income (r = .78, p = .02), and negatively correlated with sheep‐to‐cattle ratio (r = ?.80, p = .01). These correlations suggest that farms with higher incomes and low proportions of sheep in the herd withstand drought better (in terms of pregnancy rate). Four common regional production strategies were identified that react differently when farmers face drought, and these results can aid farmers in those regions to design more resilient mixed livestock farming systems and can inform policymakers about effective strategies for mitigating drought impacts in the region. 相似文献
998.
Causes of color changes in wood during drying 总被引:3,自引:0,他引:3
The forest industry operates in a dynamic and global market where change and competition are the rule rather than the 相似文献
999.
与肠道有关的健康问题,如慢性肠炎,正不断成为世界各地广为认可的疾病.荷兰研究人员发现一种天然的饲料原料与额外添加的维生素和矿物质联合使用是对抗母鸡慢性肠炎的一种有前途的方法. 相似文献
1000.