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31.
在安徽省2009年和2014年沙化土地监测成果的基础上,分析了沙化土地动态变化以及变化原因,结合安徽省沙化区域自然地理条件和社会经济条件,指出安徽省防治土地沙化中存在的主要问题,并针对沙化土地治理提出相应对策。 相似文献
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Around 20,000 samples are analysed each year for the presence of antibacterial residues in Danish finisher pigs, and between zero and five samples are detected positive above the maximum residue level (MRL). The intention was to develop a risk-based surveillance programme involving fewer samples while ensuring equal sensitivity. Therefore, risk indicators were searched for. Data were obtained from the Danish slaughterhouse database covering the period from July 2010 to December 2012. Residues were found or suspected in 17 incidents. In nine of these, the farmer had called in to prevent the pigs from being slaughtered. Hence, eight suspect cases were found through the surveillance programme, and two of these were above MRL. For these eight case herds, the number of pigs slaughtered and the number in which each of the following lesions were found were included in a statistical analysis: chronic pleuritis, tail bite, chronic pericarditis, chronic pneumonia, chronic peritonitis, osteomyelitis, abscess in hindquarters, abscess in leg/toe and abscess in forequarters. Only chronic pleuritis was associated with the presence of residues. Next, data from all herds delivering pigs for slaughter to the same abattoir were included covering a 3-month period prior to the residue finding. The prevalence of chronic pleuritis was on average 1.7 times higher in the eight case herds compared to all other herds. In two herds, the prevalence was significantly higher (P ≤ 0.05), and in one herd substantially higher, but only borderline significant (P = 0.1). In the remaining herds, the prevalence did not differ from the other herds delivering pigs to the abattoir. This indicates that chronic pleuritis might be considered as a risk indicator for use in surveillance. Other risk indicators/factors – reported in the cases where the farmers called in – were inadequate marking of treated animals and incorrect use of medication dispensers. These factors are not suited for use in surveillance and should be dealt with otherwise. 相似文献
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David A. Keith Corinna Orscheg Peter J. Clarke Steven J. Kennelly Todd R. Soderquist Michael Bedward 《Biological conservation》2009,142(7):1469-1479
The pace and magnitude of biodiversity loss has led to wide recognition that efforts to conserve individual species must be complemented by assessment and planning at community and ecosystem levels. Emerging protocols for assessing the conservation status of communities include as central criteria the current extent, historical reduction and contemporary rate of decline in geographic distribution. Estimation of these parameters is confronted by methodological challenges, data limitations and uncertainties that may vary from case to case. We describe an approach to these issues comprising five steps: (1) classification of the community using an analysis of data from systematic ground surveys; (2) mapping to produce a contemporary baseline distribution (1980s); (3) interpolation to produce a historical distribution (pre-European settlement); (4) interpretation of satellite imagery to update the distribution (various dates up to 2004) and (5) assessment of change in extent over historical and contemporary time scales incorporating plausible bounds of uncertainty around best estimates. The bounds can be based on areas for which image interpretation produces uncertain diagnosis of clearing and differences between credible alternative base maps of the same area. We demonstrated the approach using a case study of Coolibah-Black Box Woodland, a declining semi-arid woodland community in Australia and found that 61% (plausible range 50-67%) of the woodland community had been cleared since European settlement and that during 1998-2004 the community continued to decline on average by 135.3(±21.7) km2 each year, or 1.7(±0.3)% of each previous year’s distribution, apparently accelerating in recent years. Strengths of the approach include the use of biological data (cf. remote sensing) to distinguish the target assemblage from others, the use of historical and contemporary base lines to examine change over different time scales, and the use of bounded estimates to incorporate uncertainty into the assessment. 相似文献
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基于冠层光谱的锦橙叶片磷素营养监测研究 总被引:2,自引:0,他引:2
以盆栽蓬安100号锦橙施肥调控试验为基础,利用田间冠层光谱信息探索建立植株磷素营养监测技术与方法。通过采集蓬安100号锦橙95个单株样本的冠层光谱信息和室内检测分析叶片磷含量,随机选取76个作为建模样本,19个为检验样本,运用多种光谱预处理方法和偏最小二乘法(Partial least square method,PLS)及内部交叉验证方法建立校正模型与模型检验。结果表明,经多种光谱预处理方法的建模结果比较,冠层原始反射光谱经二阶求导和SNV处理后建立的蓬安100号锦橙叶片磷含量冠层光谱监测模型预测能力和稳健性最佳,其主成分数4个,能表达全波段63%的信息;校正模型相关系数为0.90,偏差Bias=2.45E-10,且RMSEC和RMSEP均最小。模型检验预测的决定系数R2=0.85。因此,利用二阶导数及标准归一化(Standard normal variate transformation,SNV)预处理的田间冠层光谱信息快速无损监测蓬安100号锦橙叶片磷含量具有一定的可行性。 相似文献
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T. Hesthagen H. M. Berger B. M. Larsen R. Saksgård 《Water, air, and soil pollution》1995,85(2):641-646
The Norwegian Monitoring Programme for Long-Range Transported Air Pollutants started in 1980. The biological part of this programme includes besides invertebrate studies in streams, (i) fish community status in lakes by means of interviews, test-fishing in lakes by using standard gill-net series, recruitment studies of brown trout in inland streams, and juvenile stock assess and monitoring of fish kills in salmon rivers. Damaged fish stocks are recognized within a land area of 51,500 km2 in southern Norway and 30 km2 in northern Norway. At least 6,000 lake-dwelling fish stocks have either been lost or are at various stages of reduction. Brown trout (Salmo trutta) is the most widespread and abundant species of fish in Norwegian watersheds, and is also most severe affected by acidification. More recently, there are some indications of an increase in the abundance of brown trout in some areas. However, analysis of age structure in lakes, and fry densities in streams in such areas revealed large annual variations in recruitment rate, which indicates unstable water chemical conditions. Atlantic salmon (Salmo salar) is virtually extinct in 25 rivers in southernmost, southwestern and western Norway. 相似文献