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41.
To estimate potential impact of climate change on wheat fusarium ear blight (FEB), simulated weather for the A1B climate change scenario was input into a model for estimating FEB in central China. In this article, a logistic weather‐based regression model for estimating incidence of wheat FEB in central China was developed, using up to 10 years (2001–2010) of disease, anthesis date and weather data available for 10 locations in Anhui and Hubei provinces. In the model, the weather variables were defined with respect to the anthesis date for each location in each year. The model suggested that incidence of FEB is related to number of days of rainfall in a 30‐day period after anthesis and that high temperatures before anthesis increase the incidence of disease. Validation was done to test whether this relationship was satisfied for another five locations in Anhui province with FEB data for 4–5 years but no nearby weather data, using simulated weather data obtained employing the regional climate modelling system PRECIS. How climate change may affect wheat anthesis date and FEB in central China was investigated for period 2020–2050 using wheat growth model Sirius and climate data simulated using PRECIS. The projection suggested that wheat anthesis dates will generally be earlier and FEB incidence will increase substantially for most locations.  相似文献   
42.
目前全球变暖已经致使地球上生物群系的格局发生了显著的变化。高纬度地区的植物生长由此变得更加活跃,而热带地区植物生长的趋势仍然是一个具有争论的问题。西双版纳热带植物园地处中国西南地区,20世纪70年代以来,这里气候发生了显著的变化,其气温以每10年0.18℃的速度上升。本研究利用西双版纳热带植物园中的48种热带植物(28科)的株高生长数据(1974~2003年)来分析其对西双版纳区域气候变化的长期变化响应,通过对株高与气候因子的相关分析选出对植物株高生长影响最大的气候因子。结果表明,植物在研究期间的株高生长年间波动比较强烈,但没有表现出明显的趋势;植物的株高生长主要受到干热季(3、4月份)的日照时数(负)与月均最低气温(正)所影响,而干热季正是这些植物每年开始萌叶的时期;另外,降雨并没有对引种植物株高生长产生显著的影响;从2个关键因子的长期变化趋势来看,西双版纳气候变化将有利于保护植物的生长,进而将有利于植物园内热带植物的保护与保存。  相似文献   
43.
The wildlife populations of Northern Central African Republic experienced precipitous declines during the 1970s and 1980s. While anecdotes coming out of the region indicate that the wildlife populations remain under serious threat, little is known about their status. An aerial sample count was carried out in the Northern Central African Republic at the end of the dry season in June 2005 and covered an 85,000 km2 complex landscape containing national parks, hunting reserves and community hunting areas. Results show a dramatic decline of wildlife since the previous survey in 1985. In 20 years, large mammals’ numbers decreased by 65%, probably because of poaching and diseases brought by illegal cattle transhumance. Elephant (Loxodonta africana) and Buffon kob (Kobus kob) populations showed the greatest decline (over 80% each), while buffalo (Syncerus caffer), roan antelope (Hippotragus equinus) and Giant Lord’s Derby Eland (Taurotragus derbianus) populations seem stable or increasing over these last 20 years. The analysis of the wildlife population distribution by status of the different types of protected areas (national parks, hunting areas) showed that individual encounter rates of elephant and buffalo were lower in national parks than in neighbouring hunting areas, while those for roan, giraffe (Giraffa camelopardalis) and Buffon kob were higher in the national parks.  相似文献   
44.
There is strong correlative evidence that human-induced climate warming is contributing to changes in the timing of natural events. Firm attribution, however, requires cause-and-effect links between observed climate change and altered phenology, together with statistical confidence that observed regional climate change is anthropogenic. We provide evidence for phenological shifts in the butterfly Heteronympha merope in response to regional warming in the southeast Australian city of Melbourne. The mean emergence date for H. merope has shifted −1.5 days per decade over a 65-year period with a concurrent increase in local air temperatures of approximately 0.16°C per decade. We used a physiologically based model of climatic influences on development, together with statistical analyses of climate data and global climate model projections, to attribute the response of H. merope to anthropogenic warming. Such mechanistic analyses of phenological responses to climate improve our ability to forecast future climate change impacts on biodiversity.  相似文献   
45.
Tests for trend are important in analyzing data where the binary response in ordered categories is of interest. An example is in toxicology where the response in various dose groups is observed. For testing an association between the dose and the response the approach from Cochran and Armitage is widely used. However the result of this test is highly dependent on the scores assigned to the dose groups. Various dose assignments can lead to different outcomes. As an alternative the isotonic regression, a nonparametric method, is proposed. The outcome of this approach is independent of the quantification of the dose. Both methods (Cochran‐Armitage test and isotonic regression) are compared within a simulation study to an isotonic version of the Pearson's Chi‐squared test and the Wilcoxon rank sum test.  相似文献   
46.
Abstract  Over the last three decades, special-purpose "entomological" radars have contributed much to the development of our understanding of insect migration, especially of the nocturnal migrations at altitudes of up to ˜ 1 km that are regularly undertaken by many important pest species. One of the limitations of early radar studies, the difficulty of maintaining observations over long periods, has recently been overcome by the development of automated units that operate autonomously and transmit summaries of their observations to a base laboratory over the public telephone network. These relatively low-cost Insect Monitoring Radars (IMRs) employ a novel "ZLC" configuration that allows high quality data on the migrants' flight parameters and identity to be acquired. Two IMRs are currently operating in the semi-arid inland of eastern Australia, in a region where populations of migrant moths (Lepidoptera) and Australian plague locusts Chortoicetes terminifera (Orthoptera) commonly originate, and some examples of outputs from one of these units are presented. IMRs are able to provide the data needed to characterize a migration system, i.e. to estimate the probabilities of migration events occurring in particular directions at particular seasons and in response to particular environmental conditions and cues. They also appear capable of fulfilling a "sentinel" role for pest-management organisations, alerting forecasters to major migration events and thus to the likely new locations of potential target populations. Finally, they may be suitable for a more general ecological monitoring role, perhaps especially for quantifying year-to-year variations in biological productivity.  相似文献   
47.
研究了鸡骨常山属(Alstonia)3个种的核形态,其中盆架树(A.rostrata)的核型属首次报道,3个种的体细胞染色体数目均为2n=42,且糖胶树(A.scholaris)和鸡骨常山(A.yunnanensis)的染色体数目同前人报道的2n=44不同。盆架树的间期核和有丝分裂前期染色体分别为棒状前染色体型和中间型,核型公式为2n=42=3M+21m+18sm,核型不对称性类型为2A型。糖胶树的间期核和有丝分裂前期染色体分别为球状前染色体型和中间型,核型公式为2n=42=14m+24sm+4st,核型不对称性类型为3A型。鸡骨常山的间期核和有丝分裂前期染色体分别为复杂染色体中央粒型和中间型,核型公式为2n=42=5m+37sm,核型不对称性类型为3B型。根据核形态结果,结合形态学特征和已有的细胞学资料,初步讨论了该属几个种的系统位置及演化趋势。  相似文献   
48.
Ivermectin and moxidectin are closely related avermectin/milbemycin anthelmintics and available data suggest that side resistance occurs with these two drugs. However, moxidectin remains effective against many species of ivermectin-resistant worms due to its higher potency. The larval development assay (LDA) is routinely used to diagnose ivermectin resistance in Haemonchus contortus but laboratory diagnosis of moxidectin resistance is hampered by the lack of any validated in vitro tests. The objective of this study was to measure the relative susceptibility/resistance of H. contortus to moxidectin on goat farms in Georgia, and to validate the DrenchRite LDA for detecting resistance to moxidectin. Fecal egg count reduction tests (FECRT) were performed at five different moxidectin dose levels and DrenchRite LDAs were performed in duplicate on nine meat goat farms in Georgia, USA. To improve our ability to make inferences on the relative levels of resistance between farms, FECRT data were first analysed using a linear mixed model, and then Tukey's sequential trend test was used to evaluate the trend in response across dose levels. LDA data were analysed using log-dose logit-response and probit models. Using these statistical results, we were able to rank the nine farms from the least to the most resistant, and to develop a set of criteria for interpreting DrenchRite LDA results so that this assay can be used to diagnose both clinically apparent moxidectin resistance, as well as sub-clinical emerging resistance. These results suggest that our novel approach for examining these types of data provides a method for obtaining an increased amount of information, thus permitting a more sensitive detection of resistance. Based on results of the LDA, moxidectin-resistant farms had resistance ratios, compared with an ivermectin-sensitive farm, ranging from 32 to 128, and had resistance ratios of 6-24 compared with an ivermectin-resistant/moxidectin naive farm. Moxidectin resistance was diagnosed both in Haemonchus and Trichostrongylus on almost half of the farms tested, despite this drug only being used on these farms for 2-3 years.  相似文献   
49.
Plant phenology is in great measure driven by air temperature. To forecast harvest time for ‘Algerie’ loquat accurately, the growing degree days (GDD) needed from bloom to ripening were determined using data from nine seasons. The methods proposed by Zalom et al. (Zalom FG, Goodell PB, Wilson LT, Barnett WW, Bentley W, Degree-days: the calculation and use of heat units in pest management, leaflet no 21373, Division Agriculture and Natural Resources, University of California 10 pp, 1983) were compared as regards their ability to estimate heat summation based on hourly records. All the methods gave remarkably similar results for our cultivation area, although the double-sine method showed higher performance when temperatures were low. A base temperature of 3°C is proposed for ‘Algerie’ loquat because it provides a coefficient of variation in GDD among seasons of below 5%, and because of its compatibility with loquat growth. Based on these determinations, ‘Algerie’ loquat requires 1,715 GDD from bloom to harvest; under our conditions this heat is accumulated over an average of 159 days. Our procedure permits the ‘Algerie’ harvest date to be estimated with a mean error of 4.4 days (<3% for the bloom-harvest period). GDD summation did not prove superior to the use of the number of calendar days for predicting ‘Algerie’ harvest under non-limiting growing conditions. However, GDD reflects the developmental rate in water-stressed trees better than calendar days. Trees under deficit irrigation during flower development required more time and more heat to ripen their fruits.  相似文献   
50.
The breeding population of the sandwich tern (Sterna sandvicensis) on the German North Sea coast has undergone substantial fluctuations throughout the last 100 years. Numbers of breeding birds were fluctuating quite strongly in the first 30 years of the twentieth century. From 1930 to the mid-1950s, a relatively steady decrease occurred. A minimum was reached in 1965 with 2,243 pairs. Around 1970, numbers increased quite markedly up to the mid-1990s and reached a centurial maximum with 10,138 pairs in 1996. Most recently, the numbers have dropped to only 5,681 pairs in 2005, the lowest number over the last 30 years. Some colonies have existed over long periods, others only for short periods, with often substantial and sudden changes. The distribution at sea was studied by transect counts from ships. During the reproductive period, high totals were found between the mainland coast and the islands, up to 30 km from the outer coast/island line. The seaward extent of the sandwich tern distribution coincided quite well with the 20-m depth line. Maximum foraging ranges for single colonies were estimated to be ca. 45 km for Trischen, ca. 35 km for Norderoog and ca. 30 km for both Scharh?rn/Nigeh?rn and Juist. Overall flight ranges for all colonies were estimated at 33.8 km for 95% of the birds. Germany has a high international responsibility for the protection of this species. Only a few colonies exist every year, making this species very vulnerable to anthropogenic disturbance, pollution events and fishing activities.
Stefan GartheEmail:
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