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21.
Black dot and other fungal blemishing diseases were assessed on tubers from crops in eastern England in 1987 and 1988, and in 1989 and 1990 from crops throughout Great Britain. Black dot was found on tubers in crops from all areas of the country, and was most common in those from eastern and southern England. The disease was scarce on most Scottish crops, but occasionally some were severely affected. In 1988 there was no consistent relationship between the amounts of disease on the seed and subsequent ware crop. On average, the disease was more prevalent in irrigated crops and where the interval between successive potato crops was short. In 1990 treating seed tubers with fungicide had no effect on subsequent levels of disease. Few crops were unaffected by silver scurf, and it was most common in crops from southern and eastern England. In the national survey common scab was the most prevalent disease, black scurf was less common and skin spot and powdery scab uncommon except in some Scottish crops.  相似文献   
22.
Samples collected in 1994 and 1995 from commercial crops of chickpeas and lentils growing in the agricultural region of south-west Western Australia were tested for infection with alfalfa mosaic (AMV) and cucumber mosaic (CMV) viruses, and for members of the family Potyviridae using enzyme-linked immunosorbent assay (ELISA). In 1994 no virus was detected in the 21 chickpea crops tested but in 1995, out of 42 crops, AMV was found in two and CMV in seven. With lentils, AMV and/or CMV was found in three out of 14 crops in 1994 and 4 out of 13 in 1995, both viruses being detected in two crops in each year. Similar tests on samples from chickpea and lentil crops and plots growing at experimental sites, revealed more frequent infection with both viruses. No potyvirus infection was found in chickpeas or lentils in agricultural areas either in commercial crops or at experimental sites. However, bean yellow mosaic virus (BYMV) was detected along with AMV and CMV in irrigated plots of chickpeas and lentils at a site in Perth. When samples of seed from infected crops or plots of chickpeas and lentils were germinated and leaves or roots of seedlings tested for virus infection by ELISA, AMV and CMV were found to be seed-borne in both while BYMV was seed-borne in lentils. The rates of transmission found through seed of chickpea to seedlings were 0.1–1% with AMV and 0.1–2% with CMV. Seed transmission rates with lentil were 0.1–5% for AMV, 0.1–1% for CMV and 0.8% for BYMV. Individual seed samples of lentil and chickpea sometimes contained both AMV and CMV. With both species, infection with AMV and CMV was sometimes found in commercial seed stocks or seed stocks from multiplication crops of advanced selections nearing release as new cultivars. Seed-borne virus infection has important practical implications, as virus sources can be re-introduced every year to chickpea and lentil crops or plots through sowing infected seed stocks leading to spread of infection by aphid vectors, losses in grain yield and further contamination of seed stocks.  相似文献   
23.
A boat survey was conducted from 5 to 26 June 1993 to estimate the abundance of the Amazon river dolphin ( Inia geoffrensis ) and the tucuxi ( Sotalia fluviatilis ) along ca . 120 km of the Amazon River bordering Colombia, Peru, and Brazil. Two survey methods were used: line transects during 5 d and strip transects during 15 d. The line transects were used to estimate the abundance of both species in the main channels of the Amazon at distances greater than 200 m from river banks and islands, and strip transects were used to estimate abundance in the remainder of the habitat. A total of 29 sightings was obtained using line transects, including 8 of Inia , 15 of Sotalia , and 6 with both species present. The total number of sightings made while using strip transects was 143, including 78 of Inia , 51 of Sotalia , and 14 with both species present. The distributions of sightings with respect to distance from the nearest bank were not significantly different between the two species. Based on the results from the two methods, we estimate that there are 346 (CV = 0.12) Inia and 409 (CV = 0.13) Sotalia in the study area. Overall, the mean group size for Inia was 2.9 individuals and for Sotalia was 3.9 individuals. Inia density (dolphin/km2) was highest in tributaries (4.8), followed by areas around islands (2.7) and along main banks (2.0); while Sotalia density was highest in lakes (8.6), followed by areas along main banks (2.8) and around islands (2.0). These are among the highest densities measured to date for any cetacean.  相似文献   
24.
  1. Freshwater conservation is vital to the maintenance of global biodiversity. Ponds are a critical, yet often under‐recognized, part of this, contributing to overall ecosystem functioning and diversity. They provide habitats for a range of aquatic, terrestrial, and amphibious life, often including rare and declining species.
  2. Effective, rapid, and accessible survey methods are needed to enable evidence‐based conservation action, but freshwater taxa are often viewed as “difficult”—and few specialist surveyors are available. Datasets on ponds are therefore limited in their spatiotemporal coverage.
  3. With the advent of new recording technologies, acoustic survey methods are becoming increasingly available to researchers, citizen scientists, and conservation practitioners. They can be an effective and noninvasive approach for gathering data on target species, assemblages, and environmental variables. However, freshwater applications are lagging behind those in terrestrial and marine spheres, and as an emergent method, research studies have employed a multitude of different sampling protocols.
  4. We propose the Pond Acoustic Sampling Scheme (PASS), a simple protocol to allow a standardized minimal sample to be collected rapidly from small waterbodies, alongside environmental and methodological metadata. This sampling scheme can be incorporated into a variety of survey designs and is intended to allow access to a wide range of participants, without requiring complicated or prohibitively expensive equipment.
  5. Adoption of this sampling protocol would enable consistent sound recordings to be gathered by researchers and conservation organizations, and allow the development of landscape‐scale surveys, data sharing, and collaboration within an expanding freshwater ecoacoustic community—rather than individual approaches that produce incompatible datasets. The compilation of standardized data would improve the prospects for effective research into the soundscapes of small waterbodies and aid freshwater conservation efforts.
  相似文献   
25.
This study investigates how the ecosystem services (ES) linked to livestock grazing are perceived across countries. A total of 82 case studies collected from 42 countries via survey (53.7% cases from Europe and 46.3% from outside of Europe) have been analysed through a multivariate approach. In all, 18 non-provisioning ES were considered. Overall, the reported impacts of livestock grazing on the different ES were much more positive than negative. Notably, a large proportion of respondents reported either positive or very positive impacts for some cultural ES, namely cultural, historic and natural heritage (84%), knowledge systems and educational values (77%), landscape values (74%), and for some supporting and regulating ES, namely habitat provision (66%), nutrient cycling (65%), and bush encroachment/fire control (66%). Based on multiple regression analysis, geographic origin, stakeholder type and species category, as well as protection status of the grazing area, had significant effects on the perception of the impacts. Respondents reported those impacts as more positive in Europe, in protected areas and where several species were present in the grazing area. A significantly larger proportion of respondents reported recognition of ES provided by the grazing livestock population in European countries (40.9%) compared with non-European countries (23.7%). Based on the survey responses it appears that in non-European countries absence of formal recognition, especially by policy makers, is a major challenge for the continued provision of ES in grazing systems. In Europe, where such recognition is already often included in legislation, the long-term sustainability of related policies and incentives to provide such services is viewed as a major issue by the respondents.  相似文献   
26.
1993年生效的《生物多样性公约》(CBD,the Convention on Biological Diversity)将获取与惠益分享(ABS,access and benefit sharing)作为其三大目标之一。2010年在CBD缔约方大会第10次会议(COP-10)上达成了《生物多样性公约关于遗传资源获取与公平和公正地分享其利用所产生惠益的名古屋议定书》(简称"《名古屋议定书》"),标志着获取与惠益分享议题取得了实质性进展。随后又组织召开了3次政府间委员会会议,《名古屋议定书》于2014年10月在韩国平昌召开COP-12期间生效,并在2014年10月13-17日召开了《名古屋议定书》缔约方大会第1次会议(COP/MOP-1)。本文系统总结和梳理了获取与惠益分享议题产生背景、关键议题争论的焦点、谈判历程和发展动态,深入分析了欧盟、非洲集团、瑞士等主要国家集团和非政府组织(NGOs)、工商界等非国家行为体(NSAs)在获取与惠益分享国际谈判中的立场、策略和作用,讨论了《名古屋议定书》对发展中国家和发达国家的利益体现、影响以及中国面临的挑战。  相似文献   
27.
目的:了解坦克部队官兵在野外驻训期间的膳食营养状况,为指导合理膳食提供参考依据。方法:膳食调查采用称重法,能量消耗采用生活观察法,体格检查指标包括体重和皮褶厚度。结果:每日人均禽肉、鱼虾、蔬菜等摄入水平未达到"军人食物定量"标准,而植物油摄入量则超过军标要求;VB1、VC、铁、锌、硒、碘等摄入量未达到"军人营养素供给量"标准要求;三大产能营养素供能比例不合理,脂肪摄入偏高,碳水化合物偏低;多数官兵野外驻训7 d后体重和皮褶厚度降低。结论:该部队在野外驻训期间膳食结构不够合理,部分营养素摄入量未达到军标要求,应调整膳食结构,改善官兵的营养状况。  相似文献   
28.
Although whale sharks (Rhincodon typus) have been documented to move thousands of kilometres, they are most frequently observed at a few predictable seasonal aggregation sites. The absence of sharks at the surface during visual surveys has led to the assumption that sharks disperse to places unknown during the long ‘off-seasons’ at most of these locations. Here we compare 2 years of R. typus visual sighting records from Mafia Island in Tanzania to concurrent acoustic telemetry of tagged individuals. Sightings revealed a clear seasonal pattern with a peak between October and February and no sharks observed at other times. By contrast, acoustic telemetry demonstrated year-round residency of R. typus. The sharks use a different habitat in the off-season, swimming deeper and further away from shore, presumably in response to prey distributions. This behavioural change reduces the sharks'' visibility, giving the false impression that they have left the area. We demonstrate, for the first time to our knowledge, year-round residency of unprovisioned, individual R. typus at an aggregation site, and highlight the importance of using multiple techniques to study the movement ecology of marine megafauna.  相似文献   
29.
Abstract: Aerial surveys have been used to estimate abundance of several wild bird species including wild turkeys (Meleagris gallopavo). We used inflatable turkey decoys at 3 study sites in the Texas Rolling Plains to simulate Rio Grande wild turkey (M. g. intermedia) flocks. We evaluated detectability of flocks and errors in counting flock size during fixed-wing (Cessna 172) aerial surveys using logistic and linear regression models. Flock detectability was primarily influenced by flock size and vegetative cover, and errors in counting flock size were primarily influenced by size of flocks. We conducted computer simulations to evaluate the accuracy and precision of fixed-wing aerial surveys and examined power to detect trends in population change. Our simulations suggested abundance estimates from fixed-wing aerial surveys may be underestimated by 10-15% (2.0-4.8% CV). Power analyses suggested that fixed-wing aerial surveys can provide sufficient power (>0.80) to detect a population change of 10-25% over a 4-5-year period. We concluded fixed-wing aerial surveys are feasible on ecoregion scales.  相似文献   
30.
ABSTRACT We designed a novel approach to determining extent of distribution and area of occupancy for wolverines (Gulo gulo) by using aerial surveys of tracks in snow and hierarchical spatial modeling. In 2005 we used a small, fixed-wing aircraft with pilot and one observer to search 575 of 588 survey units for wolverine tracks in approximately 60,000 km2 of boreal forest in northwestern Ontario, Canada. We used sinuous flight paths to scan open areas in the forest in the 100-km2 survey units. We detected tracks in 138 (24%) of the 575 sampled units. There was strong evidence of occurrence (probability of occurrence >0.80) in 30% of the 588 survey units, weak evidence of occurrence (0.50–0.80) in 12%, weak evidence of absence (0.20–0.50) in 15%, and strong evidence of absence (< 0.20) in 43%. Wolverine range comprised 59% of the study area and area of occupancy was 33,400 km2. With information on probability of occurrence and core areas of occupation for wolverines in our study area, resource managers and others can examine factors that influence wolverine distribution patterns and use this information to formulate best management practices that will maintain wolverines on the landscape in the face of increasing resource development. Comparing future survey results with those of our 2005 survey will provide an objective way to assess the efficacy of management practices.  相似文献   
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