Identification of an H1N1 subtype of swine influenza virus and serological analysis

To investigate the epizootic of swine influenza virus(SIV), 60 nasal swabs were collected from a clinical cases of pig farm in Tai'an City, Shandong Province of China in April 2017. SIV was isolated by inoculating into 10-day-old Special Pathogen Free embryonated eggs and the whole genome was sequenced. An H1N1 subtype SIV was isolated and designated as A/swine/Shandong/TA04/2017(H1N1). Phylogenetic analysis showed that apart from the polymerase A(PA) fragment belonging to the 2009 pandemic H1N1 branch, seven genome segments belonged to avian-like H1N1 influenza virus lineage. The cleavage site sequence of the hemagglutinin(HA) protein was PSIQSR↓G, which is a typical molecular biological characteristic. Five potential N-glycosylation sites(N14, N26, N277, N484 and N543) were found in the HA gene. To further investigate the epidemiology of SIV in this farm, the 995 serum samples were assessed with EAH1N1 2009 pandemic H1N1 and H3 N2 antigens. The results showed that the total positive rate was 65.43%. The positive rates of single virus infection detected by EAH1N1, 2009 pdmH1N1 and H3 N2 for serum HI(Hemagglutination inhibition) were 48.35, 30.85 and 7.47%, respectively. The results showed that SIV in Shandong Province has been reassorted in some segments and the SIV-positive rate was high on the SIV outbreak farm. These data provide evidence of an epizootic of SIV.     

Scale of heterogeneity of forage production and winter foraging by elk and bison

The relationship between fine-scale spatial patterns of forage abundance and the feeding patterns of large ungulates is not well known. We compared these patterns for areas grazed in winter by elk and bison in a sagebrush-grassland landscape in northern Yellowstone National Park. At a fine scale, the spatial distribution of mapped feeding stations in 30 m × 30 m sites was found to be random where there were no large patches devoid of vegetation. In areas similar to the mapped sites, the underlying spatial distribution pattern of biomass was also determined to be random. At a broad scale, forage biomass differed among communities across the northern range but forage quality did not. These results suggest that ungulates are feeding randomly within forage patches (fine scale) but may select feeding sites based upon forage abundance at broader, landscape scales. Contrary to what has been suggested in other systems, ungulates were not overmatching at finer scales.     

The effects of agricultural fields and human settlements on the use of rivers by wildlife in the mid-Zambezi valley,Zimbabwe

After the eradication of the Tse-Tse fly in the Mid-Zambezi valley, human settlements and fields extended mainly along the main rivers. In order to investigate the consequences of this human development on wildlife diversity we monitored three rivers of the Mid-Zambezi valley in Zimbabwe: Angwa, Manyame and Kadzi. The rivers were divided in segments of 200 m which were checked for spoors in order to assess the number of species and the number of individuals that used the segments. Human settlements were also recorded. We used a GIS to define the spatial characteristics of the fields present along the rivers, and related them to the distribution and abundance of wild species spoors in the river beds and banks. Our results show that the number of species in one segment of the river decreased with the increasing size of the field area bordering the segment. For all the major ungulate species, the numbers of individuals recorded per segment decreased with increasing field area. A similar trend was observed for small and medium-sized carnivores, though they were in lower numbers when present. Our analyses thus confirm that the extension of human agriculture in wildlife areas has an impact on most wild species, but we also define some threshold value of field size above which there seem to be an acceleration of the decrease in wildlife density and diversity: 3.2 ha for medium and small herbivores and carnivores; only the elephant seem to tolerate larger field area with a threshold value of 32 ha.This revised version was published online in May 2005 with corrections to the Cover Date.     

晋西昕水河流域生态经济型防护林体系景观格局动态分析

本文以晋西昕水河流域为典型实例，概述了流域生态经济型防护林体系建设背景。依据流域内各类型区在不同时段的土地利用结构和生态经济特征，进行流域生态经济型防护林体系景观格局变化分析，表明了流域内景观多样性和异质性不断增加的发展趋势，以及确定各区主要发展方向，实行综合开发与治理的必要性，并提出了相应的流域生态经济型防护林体系动态调控途径。     

Pocono mesic till barrens in retreat: topography,fire and forest contagion effects

The Pocono mesic till barrens (PMTB) are a unique assemblage of fire-maintained shrub communities that support numerous rare species. Historically these barrens covered a large area in the vicinity of Long Pond, Pennsylvania, USA. However, due largely to regional fire suppression instituted in the early 1960s, over 70% of the area covered by barrens succeeded to fire-intolerant forest that does not support the rare species. We investigated the influence of forest proximity on barrens succession across three geomorphic types during periods of high fire frequency and fire suppression, testing the hypothesis that forest processes such as seed rain, shading, and detrital enrichment of soils enhances barrens succession through a contagion effect. Evidence of a forest contagion effect should be shown by increased rates of barrens succession with increasing proximity to the nearest forest edge. In order to detect a forest contagion effect, barrens persistence and barrens succession were modeled in proximity zones of 0-50 m, 50-100 m, 100-200 m, and greater than 200 m from the nearest forest edge. We used existing GIS data layers for fire, geomorphology, and vegetation distribution in 1938, 1963, and 1992. The layers were modified and overlain using ArcView software to determine persistence and succession rates for each unique combination of layers in each proximity zone from 1938 to 1963 (pre-fire suppression) and 1963 to 1992 (post-fire suppression). ANCOVA results indicate that proximity to the nearest forest edge significantly affected barrens persistence rates in both time periods, but succession rates were significantly affected in 1938 to 1963 only. Twenty-eight percent of the 1938 barrens succeeded to forest by 1963; 56% of the 1963 barrens became forest by 1992. Results support previous findings that barrens persistence is enhanced by increased fire frequency, and that barrens persist longer where they overlie flat glacial till than on other geomorphology types.     

排水工程对三江平原湿地流域的影响分析

在三江平原别拉洪河流域地形图、土地利用图和排水工程建设资料的基础上,利用地理信息系统进行流域景观制图,并根据排水工程建设量将该流域划分出4个排水分区。利用景观结构分析软件FRAGSTATS分别计算了各分区2个时期(1967年和2005年)的多种景观结构指标。结果表明:排水工程之前,除了旱地无排区的其它3个排水区域,自然湿地覆盖率均达到90%以上,且呈大块连续状分布,结构比较简单,自然状态保存完好;排水渠大量修建之后,沼泽地因排水基本消失,草甸及其它沼泽类型也大片被排干,取而代之的是以大面积的旱地和水田为基质,湿地以小的斑块体镶嵌其中的流域景观,景观结构破碎化严重并趋于复杂化。最后提出下一步的研究工作。     

城市慢行空间美景度评价 ——以贵阳市小车河沿河河谷慢行空间为例

以贵阳市小车河沿河河谷慢行空间为研究对象,通过实地调查选取能够较好地反映慢行空间景观特征与景观效果的20处景观样点作为评价对象,运用基于心理物理模式的美景度评价法计算景观样点的美景度值,再通过景观要素分解量化得到景观要素评值,运用回归分析建立慢行空间美景度评价模型,进而对慢行空间美景度进行评价.结果表明,形态优美、具有...     

翅形态特征在重阳木斑蛾成虫性别鉴定中的应用

为了明确重阳木斑蛾的翅形态特征在其性别鉴定中的作用,探索雌雄难于区分的成虫的数值鉴定方法。采用图像处理与分析技术,通过爱普生扫描仪获取重阳木斑蛾前翅图,利用BugShape v1.0软件提取雌雄成虫翅的轮廓特征,利用tpsDig2软件获取翅脉交叉点位置特征,并利用独立样本t检验和标志点空间普氏叠加和扭曲分析,以明确此类特征在该成虫雌雄鉴定中的作用。结果表明,重阳木斑蛾成虫左右前翅轮廓特征在同一性别中差异不显著。仅利用左前翅数据进行分析时,翅面积、短轴长度、等效圆半径、偏心率、球状性和圆形度在两个性别中存在极显著差异,周长和长轴长度的差异达到显著水平,而紧凑度和叶状性差异不显著。使用左右前翅作为数据集进行分析时,除紧凑度和叶状性差异仍不显著外,其余参数均达到极显著水平。雌雄前翅轮廓特征作为指标来判别性别时正确率为100%,但存在左右翅相互错判现象。翅膀内部翅脉交叉点的空间位置在个体间存在较大差异,主要表现在相对于翅的横向方向变异大。雌雄间的差异主要存在于外缘附近的翅脉交叉点。结论:通过前翅的轮廓特征可以区分重阳木斑蛾雌雄成虫的差异。翅脉交叉点空间位置在雌雄间和个体间存在一定的变异。     

基于GIS与马尔可夫模型的渭河盆地景观动态变化研究

基于1988年与2003年两期TM影像,综合遥感与GIS技术以及景观生态学理论,深入分析了渭河盆地景观变化的数量和空间特征以及由此所引起的一系列生态环境效应,主要表现在:耕地、园地与城镇建设用地面积显著增加,林地、水体和未利用地面积呈减少趋势,城镇建设用地的增加是以侵占大量农田为代价的,而园地与耕地的增加则主要是通过开荒的方式。景观形状趋于复杂,破碎度降低,异质性下降,景观类型有向单一化或非均衡化方向发展的趋势,表明人类的开发活动增强,这样必然导致景观稳定性下降,因而降低了景观抗干扰的能力。最后采用马尔可夫模型对景观的变化趋势进行了预测。