小麦条锈病典型越夏区孢子传输的数值模拟

在阿坝和陇南越夏区使用HYSPLIT-4沉降模型对条锈病菌孢子进行连续多年的数值模拟,并使用ArcGIS 9进行叠加计算,得出越夏区孢子传播的沉降概率分布。结果表明:在风场合适的条件下,陇南越夏区的条锈病孢子可以传播到黄淮冬麦区、长江中下游及华北平原冬麦区的部分地区影响其秋苗感病,而阿坝越夏区对其影响甚微;根据模拟结果推测陇南越夏区的条锈病菌可对关中地区的秋苗发病有直接影响;阿坝和陇南地区均可以为四川盆地和陕西南部冬繁区提供冬繁菌源;阿坝和陇南越夏区之间可以进行很好的菌源交流,进一步证明了前人关于西北和川西北越夏区连成一片的论断。     

利用GIS和RS确定长白山自然保护区森林景观分布的环境范围

在对遥感数据进行景观分类和对环境因子进行空间表达基础上,在地理信息系统的支持下,确定长白山自然保护区森林景观分布的环境(包括年均温、年降水量、坡度和坡向)范围．结果表明。从苔原、岳桦、云冷杉到阔叶红松林,最适海拔高度范围依次为1780-2212、1705-1956、1042-1625、823-1184m;最适温度范围分别为-4．75～-2．40℃、-3．42～-2．07℃、-1．49-1．39℃、0．71-2．37℃;最适降水范围分别为1034～1110、1014-1060、883-1017、824-925mm;长白山自然保护区的森林景观主要分布在平、缓坡地上,并与坡向关系密切。苔原在各个坡向上均有分布。且在各个坡向上分布面积的变化不大;岳样、云冷杉林、阔叶红松林、山杨白样林主要呈现北、西北向分布,其次为东北、西向分布;落叶松林主要为东北向分布。其次为东和北向分布;疏林主要为西向分布,其次为西南、西北和南向分布;风倒区主要为西、西南、西北向分布。     

中国农作物生产碳足迹及其空间分布特征

基于中国1993—2013年的农业统计数据,采用生命周期评价、重心模型以及GIS等方法分析农作物生产碳排放及碳足迹的时序变化、碳足迹重心的移动轨迹、碳排放和碳足迹的空间分布特征以及影响碳排放的主导因素.结果表明: 研究期间,中国农作物生产碳排放量(GHGe)、单位播种面积碳足迹(CFs)和单位耕地面积碳足迹(CFc)均显著增加,而单位产量碳足迹(CFy)和单位产值碳足迹(CFv)显著减少.CFs重心一直分布在河南,且逐渐移向西南;CFc重心位于湖北或河南,并向西北方向移动;CFy重心位于陕西或河南,且整体移向东南;CFv重心始终在河南,并逐渐移向西南.GHGe和碳足迹存在显著的省域差异,GHGe具有南北低、中部高的特点,CFs是东西两翼高、中间低,CFc高值区主要集中在中部及东部沿海省份,CFy在西北-东南方向上表现为“高-低-高”,CFv在西北-东南方向上则是由高走低.农业生产过程中不同投入占农作物碳足迹的比例以化肥最为突出,化肥投入构成中以氮肥和复合肥所占比例较大.通过分析GHGe与各影响因素的关联度,得出化肥尤其是磷肥和氮肥、灌溉以及农田N₂O排放是导致GHGe显著增加的主导因素,并据此提出发展低碳农业的对策建议.     

丁香属植物的地理分布及其起源演化

木犀科丁香属植物主要分布在中国、朝鲜、日本以及欧洲东南部。中国是丁香属的自然分布中心,丁香主要分布在中国西南、西北、华北、东北等地区。根据植物区系的演化规律,作者认为丁香属起源于中国西南,并以此为中心主要沿中国西南-西北-华北-东北-朝鲜半岛-日本和中国西南-中亚-欧洲的路径散布。近缘种之间存在着遥远的地理隔离,中国原产的华丁香与分布在我国西北及中亚的花叶丁香、欧洲特有种欧洲丁香均为近缘种,表明欧洲丁香的散布与中国西北的种类有着密切的联系。近年分子生物学试验表明羽叶性状是演化中的过渡类型,在研究该属系统演化中具有重要作用。化石记录华北紫丁香在中新世时的华中地区已有存在,说明该属至少在中新世时完成了由西南向华中的演化、辐射。     

基于SLEUTH模型的上海城市增长预测

基于SLEUTH模型,利用1989-2005年高分辨率土地利用数据,模拟4种土地资源保护情景下,2006-2035年上海的城市增长,以及城市化对城市景观格局的影响.结果表明:在各种情景下,城市土地利用类型的面积均呈增长趋势,增量随着保护等级的提高而逐渐减少;城市增长方式主要是边缘增长,扩散增长和道路影响增长出现在郊区,增长主要发生在西北方向,西南和东南方向次之;城市化显著影响城市景观格局,并存在阶段性;早期阶段城市化导致景观破碎化,斑块密度增加,景观多样性和异质性提高;后期阶段,城市化将导致景观多样性和异质性降低,城市景观趋于均质化,加大农田和绿地景观的保护等级将减缓城市化降低景观多样性和增加均质化的趋势.     

互花米草海向入侵对土壤有机碳组分、来源和分布的影响

在江苏盐城新洋港互花米草(Spartina alterniflora)盐沼选择光滩(MF),互花米草入侵la(SAF-1),3a(SAF-3),5a(SAF-5)和12a(SAF-12)样地,采集0-20 cm表层土壤样品,分别测定土壤有机碳(SOC)、顽固性有机碳(RC)和活性有机碳(LC)含量,碳氮比(C/N),土壤有机碳和顽固性有机碳的δ13C值,分析互花米草海向入侵过程中土壤有机碳组分、分布及来源变化.结果表明:(1)SOC、RC、LC含量分别介于0.82-7.60 mg/g,0.58-4.02 mg/g和0.23-3.58 mg/g,由海向陆呈递增趋势:SAF-5＞SAF-12＞SAF-3＞MF＞SAF-1.入侵12 a的SAF-12样地表土SOC储量最大,年均碳汇积累速率为1.8 t/hm2.(2)互花米草来源SOC、RC和LC含量分别为0.06-3.01 mg/g、0.04-1.06 mg/g和0.03-2.00 mg/g,各占5.75％-47.40％、6.77％-31.77％和3.20％-64.40％.互花米草来源SOC、RC、LC由海向陆均呈递增趋势:SAF-12＞SAF-5＞SAF-3＞ SAF-1＞ MF.(3)互花米草植物来源SOC、RC、LC含量、比例与入侵时间显著正相关(P＜0.01).互花米草入侵对LC的影响较大,对RC的影响较小.(4)随着入侵时间的增长,互花米草来源有机碳的输入显著改变了土壤SOC组分.以上结果表明,短期内互花米草海向入侵能够提高土壤碳汇能力.     

长孢假小蜜环菌，一种孢子杆状的亚洲产新种

根据形态和分子系统发育证据,描述采自我国西南的新种长孢假小蜜环菌Pseudoarmillariella bacillaris.与假小蜜环菌属Pseudoarmillariella已知分布于北美-中美洲和大洋洲的2个物种相比,该新种的突出特征是担孢子杆状.在亚洲发现假小蜜环菌属真菌,表明该属的地理分布范围与过去已知的相比要广泛得多.     

浙江天童木本植物叶片性状空间变异的地统计学分析

探究叶片性状的空间变异性和环境关联性有助于我们理解植物对环境的适应策略和群落建构机制。该研究以浙江天童5 hm²大型动态样地所有胸径≥1 cm的木本植物为对象, 测定了20 253株个体的单叶面积、比叶面积和叶片干物质含量, 土壤总氮、总磷、总碳、pH值、体积含水率、容重和腐殖质, 以及海拔、坡度和凹凸度等; 并用地统计学等方法分析了叶片性状的空间变异性及其与环境因子的相关性。结果表明: 1)单叶面积的空间变异最大, 比叶面积次之, 叶片干物质含量最小。三者在0-5.16 m空间范围内表现出较弱的空间自相关, 其半变异函数的最优模型分别为高斯模型、指数模型和指数模型。2)叶片性状空间变异具有方向性, 单叶面积空间变异在东北-西南方向上最大, 在西北-东南方向上最小; 比叶面积和叶片干物质含量的空间变异均在西北-东南方向最大, 在东北-西南方向最小。3)单叶面积与地形因子显著负相关(r = -0.12, p < 0.0001); 比叶面积与土壤养分显著负相关(r = -0.16, p < 0.0001), 叶片干物质含量与土壤养分显著正相关(r = 0.13, p < 0.0001)。4)东北-西南方向上, 地形因子对单叶面积、比叶面积和叶片干物质含量空间变异的影响大于土壤养分; 西北-东南方向上, 地形因子对单叶面积空间变异的影响相对较大, 而土壤养分对比叶面积和叶片干物质含量空间变异的影响较大。总之, 在研究样地内, 植物叶片性状随空间距离和方向存在很大的变异性, 叶片性状与地形因子、土壤养分的关联性间接表明了环境过滤对群落构建的影响。     

毛乌素沙地克隆植物沙鞭生长对AM真菌生态分布的影响

从毛乌素沙地沙鞭群落间隔空地沙鞭根状茎延伸方向设置样地,2007年5月、7月和10月在0-10、10-20、20-30、30-40和40-50 cm共5个土层分别采集土壤样品,研究了AM真菌时空分布及沙鞭侵入间隔空地前后对AM真菌分布的影响。结果表明,沙鞭能与AM真菌形成良好共生关系,菌根结构为中间型(I-型),AM真菌定殖率和孢子密度有明显的时空分布规律,并与土壤因子密切相关。随采样时间后延AM真菌定殖率先增后降,最大值出现在7月份;孢子密度先降后增,最大值出现在10月份。土壤采样深度对AM真菌定殖和孢子密度有显著影响,AM真菌最高定殖率和最大孢子密度均出现在0-20 cm浅土层。孢子密度仅与泡囊定殖率显著正相关。土壤速效N与菌丝和总定殖率极显著负相关;土壤温度与泡囊、丛枝、菌丝和总定殖率显著和极显著正相关,与孢子密度显著负相关;土壤湿度与丛枝、菌丝和总定殖率显著正相关,与孢子密度显著负相关。克隆植物沙鞭的生长对土壤AM真菌活动和分布有很大影响,沙鞭入侵前后样地中AM真菌孢子密度和定殖率变化显著。     

基于GIS和地统计学的黄泛区土壤磷空间变异——以周口为例

土壤中的磷是衡量土壤肥力的重要指标,其含量的高低对土壤理化性质、植物生长以及微生物的活动等都有重要影响.本文以周口黄泛区土壤为例,通过土样采集和室内试验分析,运用地统计分析及GIS空间模拟等方法,分析土壤全磷和速效磷的空间分布特征.结果表明: 研究区土壤全磷和速效磷含量比较高,且表层(0～20 cm)含量均高于第二层含量(20～40 cm).两层土壤全磷和速效磷均属于中等程度变异,并且速效磷的变异程度高于全磷;两层土壤全磷为中等程度的各向异性,最适模型为高斯模型,表层具有较强的空间相关性,第二层则具有中等的空间相关性. 两层土壤速效磷的各向异性均较弱,最适模型为线性模型,两层均呈现较弱的空间相关性. 两层全磷含量从西南到东北方向呈现缓慢上升的变异趋势,而从西北到东南方向呈逐渐下降的变异趋势. 表层速效磷含量在西南到东北方向先升后降,在东南到西北方向呈先降后升的变异趋势;第二层速效磷含量在西南到东北方向上呈现先降后升的趋势,而在西北到东南方向则呈上升趋势.表层土壤全磷含量较高,第二层含量属于中等水平;表层速效磷含量较高,而第二层含量较低.土地利用方式、耕作制度和施肥等人为因素是影响该区土壤磷分布趋势和空间变异的主要因素.     

麦红吸浆虫随气流远距离扩散的轨迹分析

为了解麦红吸浆虫Sitodiplosis mosellana (Géhin)种群随气流远距离扩散的可能性和扩散方向, 本研究于2010年5月在河南省洛阳市洛宁县, 利用系留气球携带取样器调查了麦红吸浆虫种群在5~75 m高空的分布以及活动节律, 应用HYSPLIT-4大气扩散模型模拟了2010年以洛宁县(34.35°N, 111.52°E)为起始点, 空中不同高度层麦红吸浆虫种群的扩散轨迹, 以及2007年麦红吸浆虫种群在我国北方麦区的扩散轨迹。结果表明: 在成虫发生期, 麦红吸浆虫在空中5, 45, 50和65 m 4个高度层种群密度较大, 表现出了明显的成层效应。2010年河南洛宁迁入的种群来自西南方的河南南阳地区, 迁出种群能够随气流进入东北方向的河南省宜阳县境内。2007年麦红吸浆虫种群能够随小麦发育期的先后, 随西南气流逐步向东北方向扩散。成虫随气流扩散是麦红吸浆虫种群远距离扩散的一种重要方式。研究结果有助于了解我国麦红吸浆虫远距离扩散方式, 同时对优化发生动态监测和综合治理提供参考。     

四川森林植被碳储量的时空变化

利用平均木法建立森林生物量与蓄积量模型,结合四川森林资源二类调查数据,研究了森林碳密度和碳储量的时空变化.结果表明 四川森林碳储量从1974年的300.02 Tg增加到2004年的469.96 Tg,年均增长率1.51%,表明其是CO2的"汇".由于人工林面积的增加,森林植被的平均碳密度从49.91 Mg·hm-2减少到37.39 Mg·hm-2.四川森林碳储量存在空间差异性,表现为川西北高山峡谷区＞川西南山区＞盆周低山区＞盆地丘陵区＞川西平原区.森林碳密度由东南向西北呈现逐渐增加趋势,即盆地丘陵区＜川西平原区＜川西南山区＜盆周低山区＜川西北高山峡谷区.通过分区森林经营与管理将提高四川森林的碳吸存能力.     

A method for the extraction and enumeration of resting spores of Plasmodiophora brassicae from infested soil

A technique is described for the extraction of the resting spores of Plasmodiophora brassicae from soil. After deflocculation, coarse mineral matter was filtered from soil samples and the remainder mixed with 40% sucrose. The mixture was allowed to stand for 2–5 days; this enabled most mineral particles to settle out leaving the spores in suspension. The spores were counted optically on a microscope using Nomarski interference contrast optics, although preliminary studies had indicated that electronic image analysis was a more satisfactory method. Good recovery of spores was achieved from artificially infested soils containing 10⁶ spores/g but the technique can be satisfactorily applied to less heavily infested soils. Clubroot symptoms developed on seedlings dipped in suspensions of spores recovered in this way.     

Wind drift,compensation, and the use of landmarks by nocturnal bird migrants

In this paper we describe fall nocturnal migration at three localities in eastern New York, one adjacent to the Hudson River, the other two 30 km to the west in a topographically more uniform area. Migrants at both study areas moved southwest in winds not out of the west and were, therefore, seemingly unaffected by the river. In west winds, however, birds away from the river moved south-southeast whereas those in the vicinity of the river flew a track west of south paralleling the river. In addition, a relative increase in the number of migrants along the river compared to away was observed in west winds as birds presumably became concentrated near the river. We conclude that on most autumn nights migrants passing through this area have a preferred track direction toward the southwest and in strong winds from the west and northwest they are drifted. Upon reaching the vicinity of the Hudson River, some birds alter their headings yielding a track direction that closely parallels the river resulting in at least a partial compensation for wind drift. No alternative hypothesis is consistent with all the data.     

中国香菇自然种质的rDNA遗传多样性分析

测定了全国范围内的59个野生香菇菌株rDNA的ITS区域的序列。所得序列的总长度在723-727个碱基之间,G+C含量也基本稳定在57.5%左右。用Phylip3.6软件包对59个ITS序列进行DNA数据分析。结果表明59个菌株被划分到3个不同的谱系中,其中谱系Ⅰ包括11个菌株,分布较为均衡,涉及东北、西北、西南和东部沿海等地区的8个省份;谱系Ⅱ包括14菌株,以西北、西南的4个省份为主;谱系Ⅲ包括34个菌株,覆盖范围最广,除东北和西北高原地区外,其它均有涉及。地缘关系分析表明以陕、甘为主的西北高原地区的菌株涉及Ⅰ、Ⅱ两个谱系;以闽、浙、赣和台湾为主的东部沿海地区的菌株涉及Ⅰ、Ⅲ两个谱系;而以云、贵、川为主的西南地区的菌株则覆盖到了所有的3个谱系。这三个地区的香菇遗传多样性最丰富,西南地区尤为突出,是香菇种质资源保护与利用的重点区域。     

苜蓿切叶蜂授粉扩散行为及苜蓿种子增产效应的研究

对苜蓿切叶蜂(Megachilerotundata)为苜蓿授粉的田间群体扩散行为和苜蓿种子增产效应研究表明,以授粉后苜蓿种子增产效应为指标,发现苜蓿切叶蜂以蜂箱为中心向四周扩散,随着距离增大,蜂的扩散及授粉效应逐渐降低。但不同方向其扩散及授粉效应不同,以苜蓿种子产量Y≥50g·m^-2为高效区,50g·m^-2>Y≥30g·m^-2为中效区,30g·m^-2>Y≥15g·m^-2为低效区。在高效区和中效区内,东北方向扩散距离最远,分别为50和60m,其次是东和北;在低效区,向北扩散距离最远,可达100m,其次是东北和西北;西、南、西南和东南扩散距离较短。据此做出了高效区、中效区和低效区的苜蓿切叶蜂授粉扩散行为图,由此可直观地看到3个区的范围.     

土壤来源苏云金芽孢杆菌的形态,δ—内毒蛋白质及其...

94 strains of Bacillus thuringiensis were isolated from soils in southwest and northwest of China. The morphology of cells, spores and parasporal crystals of these strains was investigated under transmission and scanning electro-microscope. Proteins of delta-endotoxins from all strains were analysed by rapid SDS-PAGE. 9 species of insects in Lepidoptera, Coleoptera and Diptera were tested for assay of delta-endotoxins. Some kinds of parasporal crystals were quite different in form and in composition of protein from those reported before. Most of strains were nontoxic to all of 9 species used in bio-assay. Some strains were very effective in species of Coleoptera or Noctuidae.     

Postglacial dispersal of the European rabbit (Oryctolagus cuniculus) on the Iberian peninsula reconstructed from nested clade and mismatch analyses of mitochondrial DNA genetic variation

Nested clade analysis was applied to cytochrome b restriction site data previously obtained on 20 natural populations of the European rabbit across the Iberian Peninsula to test the hypothesis of postglacial dispersal from two main refugia, one in the northeast and the other in the southwest. Apart from historical fragmentation that resulted in geographic discontinuity of two distinct mitochondrial DNA (mtDNA) clades A and B, patterns of haplotype genetic variability have been shaped mostly by restricted gene flow via isolation by distance. The distribution of tip versus interior haplotypes suggests that dispersal occurred from both the southwestern and northeastern groups. Dispersal from the southwest had a north and northwest direction, whereas from the northeast it had mostly a western and southern orientation, with subsequent overlap in a southeastern-northwestern axis across the Iberian Peninsula. The analysis of the pairwise mismatch distribution of a 179-181-bp fragment of the mtDNA control region, for seven of those populations, further supports the idea that major patterns of dispersal were in the direction of central Iberia. Additionally, rabbit populations do not show signs of any significant loss of genetic diversity in the recent past, implying that they maintained large population sizes and structure throughout the ice ages. This is congruent with the fact that the Iberian Peninsula was itself a glacial refugium during Quaternary ice ages. Nonetheless, climatic oscillations of this period, although certainly milder than in northern Europe, were sufficient to affect the range distributions of Iberian organisms.     

XYLEM STRUCTURE AND ECOLOGICAL DOMINANCE IN A FOREST COMMUNITY

The relative dominance of deciduous trees having diffuse, semiring, or ring porous xylem is considered in relation to percent slope, site, vertical stratification within site, and to disturbance. Xylem type relative dominance was calculated on the basis of basal area by a procedure that is generally employed for the determination of species relative dominance. The study area was located within the central hardwoods region of the Eastern Deciduous Forest. On a moisture gradient, the sites were a hydric floodplain, a mesic river terrace and cove, and a xeric hillside spur. There was an increase from lowland to upland sites in absolute number of species having diffuse porous and those having ring porous xylem; however, the data showed no significant difference among the four sites or between the cove's northwest and southwest aspects in the percentages of species having diffuse porous xylem and those having ring porous xylem. In contrast to species number data, relative dominance data showed that diffuse porous species were dominant on the floodplain, on the northwest aspect of the cove, and in lower strata beneath the dominant ring porous upper canopy on the spur and southwest aspect of the cove. Ring porous species were dominant in the upper canopy only on the spur and on the southwest aspect of the cove. Semiring porous species had a high dominance level on the disturbed terrace site, a much lower level of dominance on the less disturbed floodplain, and very low dominance on the relatively undisturbed cove and spur sites. The results demonstrated that sets of closely and distantly related tree species having the same xylem anatomy share some common ecological characteristics, suggesting that xylem structure is a critical character in the adaptation of trees to variations in the environment over small geographical areas.