秦岭南北地区绝对湿度的时空变化及其与潜在蒸发量的关系

基于秦岭南北地区1960—2011年的气象观测资料,分别利用绝对湿度计算公式和Penman-Monteith公式估算大气绝对湿度和潜在蒸发量,并进一步分析了绝对湿度的空间分布规律、时空变化特征及其与潜在蒸发量变化的响应关系。结果表明:(1)秦岭南北地区绝对湿度由南向北顺次递减,具有较好的海拔地带性和纬度地带性。季节平均湿度以夏季为最大,冬季最小。(2)近52年绝对湿度除巴巫谷地表现出不显著下降趋势外,其它子区均呈现出增加趋势。1986年和1998年是湿度变化的转折点,1960—1986年以微弱下降为主,此后直至1998年震荡上升,1998年以后呈下降趋势。(3)年尺度和春、秋两季,除巴巫谷地外,湿度和潜在蒸发量均表现出显著的负相关关系;而在夏季和冬季,除汉水流域和巴巫谷地不显著正相关以外,其它区域也均为负相关。年度和春、秋两季两个指标负相关的紧密程度随着区域的南移而逐渐减弱。1960—2011年间,年度和季节尺度潜在蒸发和绝对湿度呈反向变化趋势;而在1960—1989年间,两者同向变化;1990—2011年间,年度和春、冬两季潜在蒸发上升,而同期的绝对湿度则是先上升再下降。(4)实际蒸发量的增加导致空气中水汽含量(湿度)增加,反过来抑制了水面蒸发(潜在蒸发量)。秦岭以北、秦岭南坡、汉水流域和巴巫谷地部分地区绝对湿度和潜在蒸发量为互补关系,由北向南随着水分限制作用的不断减弱两者逐渐转化为不显著的正相关关系。     

1960-2011年陕西省年内降水分配非均匀性特征及预测

根据陕西省19个气象站点1960-2011年逐日降水资料,利用反距离加权插值、气候趋势系数、M-K突变检验、Morlet小波分析、相关分析、合成分析和R/S分析等方法对陕西省年内降水集中度和集中期变化特征及其未来变化趋势进行分析.结果表明:1960-2011年,陕西省年内降水集中度为0.44 ～0.66,总的分布特征是南北高、中部低,而年内降水集中期变化于18.32 ～22.37旬,地域差异较小;年内降水集中度呈增加趋势,而年内降水集中期呈提前趋势,且二者的变化趋势均存在明显的区域差异;年内降水集中度在1974年发生减小突变,而年内降水集中期在1962年发生推后突变;年内降水集中度和集中期的变化并没有一个固定周期,而是大、中、小多种周期尺度相互嵌套,具有较强的时频局部特征;年降水量与年内降水集中度在全省表现出一致的正相关,而与年内降水集中期除在陕北的横山呈微弱的负相关外,在其他地区均呈正相关;多水年与少水年降水集中度的空间分布均呈南北高、中间低的特征,而多水年和少水年的降水集中期空间分布差异较大;年内降水集中度和集中期的未来变化趋势将与过去52年的变化趋势保持一致.     

南京城市街区湿球温度时空变化特征及其影响因子

全球气候变化和局地城市热岛加剧了城市热胁迫问题,但针对城市街区的研究仍不多见。湿球温度指示气温和湿度的综合效应,能更准确地反映人体热舒适度。本研究以南京市江北新区为对象,在不同时段、季节和天空状况下,基于移动观测方法获取气温、相对湿度和地理信息等数据,分析了街区尺度湿球温度的时空分布特征;结合天空状况、地表覆盖和城市形态指标(天穹可见度),探究了城市街区湿球温度的影响机制。结果表明: 1)南京城市街区湿球温度的时空特征与气温较为一致;与水汽压相比,气温对湿球温度的变化起主导作用;该地区湿球温度的极端高值主要是由于气温和水汽压协同增长所致。2)天穹可见度在白天与湿球温度呈显著正相关,夜间为负相关关系。植被覆盖比率的增加能够降低湿球温度,不透水面则呈现相反的作用。阴天条件下,湿球温度明显降低并且空间分布更均匀。3)植被和不透水面对湿球温度的水平尺度效应存在昼夜和季节差异,并且在夜间这一效应对天空状况更敏感;与植被相比,冬季夜间不透水面的影响范围比夏、秋季更大;两者对湿球温度的水平尺度效应与气温一致。研究结果可为改善和优化城市街区热环境、缓解城市热胁迫提供有效的科学支持和理论依据。     

2001-2020年新疆阿勒泰地区归一化植被指数时空变化特征及其对气候变化的响应

气候变化是干旱区植被变化的重要驱动因素,探究干旱区气候与植被关系的时空变化,有助于理解生态系统演化特征。基于MODIS-NDVI与CRU数据集中气候数据（降水、平均气温、最高气温、最低气温、水汽压及潜在蒸散）,采用Sen+Mann-kendall、Hurst指数及相关分析法,在不同时间尺度评价了阿勒泰地区NDVI的时空变化特征及其对气候变化的响应。结果表明：（1）在年尺度上,植被NDVI整体呈上升趋势,但存在弱反持续特征。区域内植被退化现象严重（12.11%）,植被改善区域与退化区域呈破碎化分布。（2）月尺度与季尺度上,NDVI与降水、气温、极端气温、水汽压和潜在蒸散呈正相关,其中降水因素在季尺度上的相关性高于月尺度。（3）不同土地利用方式下NDVI与气候因子的滞后效应表现为短期正效应与长期负效应。     

2000-2016年秦岭山地植被覆盖变化地形分异效应

利用2000-2016年MODIS NDVI数据,采用趋势分析及地形差异修正法,探讨秦岭山地植被覆盖变化在南北坡、不同海拔以及不同坡度坡向下的空间分异性。结果表明：近17年来,秦岭山地植被覆盖度良好,整体呈上升趋势,南北坡、不同海拔、不同坡度、不同坡向下植被覆盖度有所差异,植被变化趋势也不同。（1）就南北坡而言,近17年来秦岭南坡植被覆盖度上升趋势大于北坡,南坡植被覆盖以上升趋势为主,而北坡以稳定为主。（2）不同的海拔高度上秦岭山地植被覆盖变化在存在分异性：低海拔区域呈减少趋势,中海拔区呈明显的上升趋势,2000 m以上的高海拔区域北坡的植被覆盖度较为稳定,而南坡的2500到3100 m区域内有较明显的减小趋势。（3）从坡度来看,随着坡度的增加秦岭山地植被覆盖度由减少转为增加再转为稳定,南北坡植被变化分异性不明显。（4）不同坡向上,秦岭南北坡植被覆盖度变化差异明显,由阴坡转为阳坡时,北坡植被覆盖有明显的增长趋势,而南坡则不明显,植被覆盖度减小区在南北坡的分布呈相反趋势,分别分布在南坡的阳坡以及北坡的阴坡。     

松嫩平原潜在蒸散量的时空变化特征

利用松嫩平原及周边地区72个气象站1961—2003年逐日气象资料,应用Penman-Monteith方程计算潜在蒸散量,采用气候倾向率、Mann-Kendall突变检验、累积距平法,对松嫩平原地区潜在蒸散量变化进行定量分析,并应用ArcGIS软件的空间分析功能对研究区潜在蒸散量的空间分布特征进行分析.结果表明:1961—2003年,松嫩平原年均潜在蒸散量在330~860 mm,总体呈减小趋势,空间分布总体特征为西南高、四周低,呈环带状向西南方向增加;年潜在蒸散量的气候倾向率为-0.21 mm.a-1;年潜在蒸散量在1982年达最大值,形成突变点,而后下降,至1995年降至最低,此后呈增加趋势;春、夏、秋、冬季潜在蒸散量的气候倾向率分别为-0.19、0.01、-0.05、0.03 mm.a-1,表明春、秋季潜在蒸散量呈微弱减小趋势,夏、冬呈微弱增加趋势.     

基于综合气象干旱指数的1961—2012年阿勒泰地区干旱时空演变特征

基于阿勒泰地区7个气象站1961—2012年的逐日气温、降水等气象资料,运用趋势分析法、M-K突变检验法、小波分析法并结合ArcGIS软件,探究了阿勒泰地区干旱的时空演变特征.结果表明： 综合气象干旱指数能较好地反映阿勒泰地区干旱状况.研究期间,阿勒泰地区虽然年和四季的干旱频次和不同等级干旱覆盖范围都呈减少趋势,但是旱情仍较为严重,年和季节的干旱发生频繁,且多年存在重旱和特旱发生在整个阿勒泰地区;秋季和冬季的干旱频次分别在1997和1983年发生减少突变,夏季的干旱频次首先在1962年发生增加突变,随后在1991年发生减少突变,年均和春季的干旱频次无突变发生;年和四季的干旱频次都存在明显的周期性.干旱频次和不同干旱等级在空间上的分布表明,东部清河县旱情较为严重,中部阿勒泰市、富蕴县、布尔津县、福海县旱情次之,西部地区的哈巴河和吉木乃县的旱情较轻.     

基于综合气象干旱指数的1961—2012年阿勒泰地区干旱时空演变特征

基于阿勒泰地区7个气象站1961—2012年的逐日气温、降水等气象资料,运用趋势分析法、M-K突变检验法、小波分析法并结合Arc GIS软件,探究了阿勒泰地区干旱的时空演变特征.结果表明:综合气象干旱指数能较好地反映阿勒泰地区干旱状况.研究期间,阿勒泰地区虽然年和四季的干旱频次和不同等级干旱覆盖范围都呈减少趋势,但是旱情仍较为严重,年和季节的干旱发生频繁,且多年存在重旱和特旱发生在整个阿勒泰地区;秋季和冬季的干旱频次分别在1997和1983年发生减少突变,夏季的干旱频次首先在1962年发生增加突变,随后在1991年发生减少突变,年均和春季的干旱频次无突变发生;年和四季的干旱频次都存在明显的周期性.干旱频次和不同干旱等级在空间上的分布表明,东部清河县旱情较为严重,中部阿勒泰市、富蕴县、布尔津县、福海县旱情次之,西部地区的哈巴河和吉木乃县的旱情较轻.     

基于SPEI指数的长江中下游流域干旱时空特征分析

基于长江中下游流域1961—2015年129个气象站点的逐日气温和降水数据,利用标准化降水蒸散指数(SPEI),对长江中下游流域近55年年尺度及各季节干旱变化趋势、站次比、强度和频率进行了分析,并探讨了干旱和区域气温、降水变化及ENSO的关系。结果表明:(1)在区域尺度,近55年长江中下游流域年尺度、春季和秋季呈干旱化趋势,春季干旱化趋势显著;夏季和冬季呈湿润化趋势。空间变化上,对于年尺度,汉江流域、中游干流区及洞庭湖流域以干旱化趋势为主,鄱阳湖流域、下游干流区和太湖流域以湿润化趋势为主;春季和秋季分别有96.90%和92.25%的站点呈干旱化趋势;夏季和冬季分别有82.95%和72.87%的站点呈湿润化趋势。(2)年尺度、春季和秋季干旱站次比及强度均呈增加趋势,春旱站次比与强度增加趋势显著;夏季和冬季干旱站次比和强度均呈下降趋势。(3)年尺度和春季干旱频率在21世纪初均达到最高,年尺度、春季和夏季干旱频率从20世纪90年代到21世纪初均呈增加趋势。(4)春、秋季干旱化趋势与降水量的减少及气温的上升相关,夏、冬季降水量的增加使得夏、冬季呈湿润化趋势。冬季SOI和次年春季干旱相关性极显著,冬季发生拉尼娜事件时,次年春季更易发生干旱。     

1961-2010年桂林气温和地温的变化特征

关于气温变化特征已有大量研究,但是关于地温变化及其与气温的关系研究还较少.以亚热带湿润地区的广西桂林气象站为研究对象,分析了1961-2010年桂林气温和0-80 cm各层地温的年代和季节变化趋势、地气温差变化、气候突变和异常年份以及气温和地温关系.结果表明:气温与各层地温有很好的相关性.各年、季平均气温和各层平均地温大部分呈显著的升高趋势,但气温和地温的增温速率不一致,即升温存在非对称性;年均气温低于各层地温1.3-2.1℃,气温的增温速率和增温幅度分别为0.184℃/10 a和0.8℃,高于除0 cm外其它各层地温的变化;气温、5-40 cm地温在冬季的增温最多,0 em和80cm地温分别在秋季和夏季的增温最多;春、夏季,随着土壤深度的增加,地温呈减小趋势,春季气温小于0-15 em而大于20-80 cm地温,夏季气温小于0-40 cm而大于80 em地温;秋、冬季,随着土壤深度的增加,地温呈增加趋势,秋、冬季气温小于各层地温;气候变暖背景下,年平均、四季气温比除0 em外其它各层地温的响应更快.近50年来,各层地温和气温的温差减小了0.1-0.4℃(0 em地温和气温温差除外),这主要是因为气温的增加幅度要大于地温,且随着土壤深度的增加,地气温差的减小幅度加大.桂林年均地温和四季气温、地温大多无气候突变现象,仅有年均气温和夏季80 em地温分别在1997和1977年出现气候突变.春季气温和5-80 cm各层地温的异常偏低年较一致;秋季气温和40、80 cm地温的异常偏低年相同;夏、冬季气温和地温的异常年份对应性较差;而年均气温和各层地温的异常偏高年较一致.     

Functional characterization of powdery mildew resistance gene MlIW172, a new Pm60 allele and its allelic variation in wild emmer wheat

Wild emmer wheat (Triticum dicoccoides, WEW) is an immediate progenitor of both the cultivated tetraploid and hexaploid wheats and it harbors rich genetic diversity against powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt). A powdery mildew resistance gene MlIW172 originated from WEW accession IW172 (G-797-M) is fine mapped in a 0.048 centimorgan (cM) genetic interval on 7AL, corresponding to a genomic region spanning 233 kb, 1 Mb and 800 kb in Chinese Spring, WEW Zavitan, and T. urartu G1812, respectively. MlIW172 encodes a typical NLR protein NLR^IW172 and physically locates in an NBS-LRR gene cluster. NLR^IW172 is subsequently identified as a new allele of Pm60, and its function is validated by EMS mutagenesis and transgenic complementation. Haplotype analysis of the Pm60 alleles reveals diversifications in sequence variation in the locus and presence and absence variations (PAV) in WEW populations. Four common single nucleotide variations (SNV) are detected between the Pm60 alleles from WEW and T. urartu, indicative of speciation divergence between the two different wheat progenitors. The newly identified Pm60 alleles and haplotypes in WEW are anticipated to be valuable for breeding powdery mildew resistance wheat cultivars via marker-assisted selection.     

Studies of primate protein variation and evolution: Microelectrophoretic detection

Genetic variation at 16 protein and enzyme loci in Cercopithecus aethiops and several other primate species has been surveyed, using cellulose acetate microelectrophoresis. Resolution of several standard variant proteins is comparable to that achieved on starch gel or polyacrylamide gel. Although both intraspecific and interspecific variation was observed for some loci, the data generally support the concept that extracellular proteins are more likely to be polymorphic within a species, while intracellular proteins generally vary between species, if at all. These methodologies are particularly appropriate for screening multiple-locus variation in large numbers of samples; their relevance to studies of molecular evolution and evaluation of theories of kin selection is discussed.This research was supported in part by California State Agricultural Experiment Station Funds to the University of California, Berkeley, and the Wenner Gren Foundation.     

长白山阔叶红松林土壤氮化亚氮和甲烷的通量研究

采用静态箱／气相色谱分析方法对长白山阔叶红松林两个处理的N2O和CH4通量进行了研究．结果表明,凋落物对土壤N2O排放和CH4吸收的影响是显著的,影响程度分别是36．9％和23．4％．两个处理的N2O排放通量季节变化趋势相似：夏季(6～8月)的排放通量最高,春季(3～5月)次之,秋(9～11月)冬(12～1月)两季较低．其日变化趋势也相似：最大值都出现在18：00,最小值都出现在12：00和14：00．CH4吸收通量的季节变化趋势也很相似：夏秋两季的吸收通量明显高于春冬两季的吸收通量．其日变化趋势也相似：从14：00开始持续上升到18：00达到最大值,然后持续下降到早晨6：00达到通量的最小值．研究还发现,长白山阔叶红松林土壤的N2O排放和CH4吸收间存在着一种负线性相关关系．     

广州市空气微生物含量及其变化规律研究

用JWL-IIB新型固体撞击式空气微生物采样仪对广州市18个监测点的空气微生物含量及其月和季节变化势态进行了观察和研究。结果表明：广州市区室外空气微生物年平均含量为2,298cfu／m^3,室内空气微生物年平均含量为1,792cfu／m^3。各功能区的室外空气微生物平均含量（cfu／m^3）大小顺序为：垃圾压缩站（4,573）〉商业步行街（3,835）〉交通枢纽（1,580）〉居民住宅小区（1,413）〉工业厂区（1,197）〉中心公园（1,187）;室内空气微生物含量（cfu／m^3）大小顺序为：交通枢纽（2,511）〉旅游三星酒店（1,699）〉地铁站（1,167）。一年中,市区各监测点室外空气微生物月平均含量变化范围在1,073～4,096cfu／m^3,其中3月份的空气微生物平均含量最高,可达4,096cfu／m^3,而10月份的空气微生物平均含量最低仅为1,073cfu／m^3。四季中,各监测点室外空气细菌和真菌平均含量（cfu／m^3）变化均表现为春季（3,716）〉夏季（2,300）〉冬季（1,816）〉秋季（1,553）。可为广州市区公共场所的卫生防疫和环境治理提供科学依据。     

Genetic variation, predator-prey interactions and food web structure

Food webs are networks of species that feed on each other. The role that within-population phenotypic and genetic variation plays in food web structure is largely unknown. Here, I show via simulation how variation in two key traits, growth rates and phenology, by influencing the variability of body sizes present through time, can potentially affect several structural parameters in the direction of enhancing food web persistence: increased connectance, decreased interaction strengths, increased variation among interaction strengths and increased degree of omnivory. I discuss other relevant traits whose variation could affect the structure of food webs, such as morphological and additional life-history traits, as well as animal personalities. Furthermore, trait variation could also contribute to the stability of food web modules through metacommunity dynamics. I propose future research to help establish a link between within-population variation and food web structure. If appropriately established, such a link could have important consequences for biological conservation, as it would imply that preserving (functional) genetic variation within populations could ensure the preservation of entire communities.     

Phenotypic variation and stress resistance in core and peripheral populations of Hordeum spontaneum

The phenotypic variation and response of plants to water stress were studied in a field trial in populations of wild barley, Hordeum spontaneum Koch. from Israel and Turkmenistan. Populations from the species distributional core and periphery were compared and contrasted for phenotypic variation in 16 phenological and morphological traits. The peripheral populations (six) were found to be phenotypically more variable and more resistant to water stress than core populations (12). The association of water-stress resistance with high phenotypic variability gives support to the hypothesis that populations that are genetically more variable are better adapted or pre-adapted to environmental changes and are thus valuable for conservation.     

Intra- and interspecific variation in genome size in Lathyrus (Leguminosae)

2C nuclear DNA amounts for 24 species of Lathyrus (section Lathyrus ) were determined using flow cytometry. A greater than two-fold variation was observed, ranging from 10.2 pg in L. basalticus to 24.2 pg in L. latifolius. In general, the perennial species had greater DNA amounts than the annuals. Significant intraspecific variation was observed in five species of Lathyrus (from 10.1% in L. annuus to 28% in L. tingitanus). A positive correlation was observed between DNA values obtained by flow cytometry and those previously determined by microdensitometry. Finally, the distribution of DNA amounts in species within section Lathyrus appears to be continuous.     

广东省不同区域农田土壤酸化时空变化及其影响因素

基于广东省1980s、2010年以及2015年3期土壤数据,对全省不同区域农田耕作层土壤pH值的时空变异特征进行分析,并初步探讨了可能导致土壤pH变化的因素.结果表明: 不同时期广东全省土壤pH值空间分布格局变化显著. 全省农田土壤在1980s—2010年间,pH整体下降了0.3,呈酸化趋势,2010—2015年,土壤pH上升了0.09,但不均匀势态有所增强,酸碱分化趋势较明显. 从各区域看,1980s—2010年,各区域土壤均呈现酸化趋势;2010—2015年,珠三角地区农田土壤pH均值上升了0.27,而东、西两翼土壤pH均值分别下降了0.05、0.15,山区土壤pH变化不明显. 分析表明:广东省各地区土壤酸化除受土壤自身及降水等自然因素影响外,酸雨、不合理施肥以及高产作物高复种的种植结构等人为因素也是导致土壤酸化的主要原因;工业化、城市化、矿山开发和测土配方施肥的推广导致局部地区土壤pH值有所上升. 研究结果可为不同区域控制缓解土壤酸化、提高耕地质量提供理论指导.     

Variation in plant functional traits across and within four species of Western Australian Banksia (Proteaceae) along a natural climate gradient

Plant traits are fundamental components of the ecological strategies of plants, relating to how plants acquire and use resources. Their study provides insight into the dynamics of species geographical ranges in changing environments. Here, we assessed the variation in trait values at contrasting points along an environmental gradient to provide insight into the flexibility of species response to environmental heterogeneity. Firstly, we identified how commonly measured functional traits of four congeneric species (Banksia baxteri, B. coccinea, B. media and B. quercifolia) varied along a longitudinal gradient in the South Western Australian Floristic Region. This regional gradient provides significant variation in moisture, temperature and soil nutrients: soil nitrogen content decreases with declining rainfall and increasing temperature. We hypothesized that (i) the regional pattern in trait–environment associations across the species would match those observed on a global scale and (ii) that the direction and slopes of the within‐species relationships would be similar to those across species for each of the measured traits. Along the regional gradient we observed strong shifts in trait values, and cross‐species relationships followed the expected trend: specific leaf area was significantly lower, and leaf N_area and seed dry mass significantly higher, at the drier end of the rainfall gradient. However, traits within species were generally not well correlated with habitat factors: we found weak patterns among populations, either due to the small ecological gradient or perhaps because fine‐scale structuring among populations (at a micro‐evolutionary scale) was low due to high gene flow within species. Understanding how species traits shift as a result of climatic influences, both at the regional (across species) and local (within species) scale, provides insight into plant adaptation to the environment. Such studies have important applications for conservation biology and population management in the face of global change.     

Temporal and spatial variations of stem CO2 efflux of three species in subtropical China

Aims Although stem CO₂ efflux is critical to ecosystem carbon and energy balance and its feedback to future climate change, little information is available on stem CO₂ efflux and its responses to temperature, especially in subtropical China. This study aims to (i) evaluate the temporal and spatial variations of stem CO₂ efflux of three species, including oak (Quercus acutissima Carr.), masson pine (Pinus massoniana Lamb.) and loblolly pine (Pinus taeda Linn.) in subtropical China and (ii) analyze the temperature sensitivity of stem CO₂ efflux in the three species based on 2-year field measurements.Methods We measured stem CO₂ efflux and stem temperature (at 3 cm depth) of the three species using the horizontally oriented soil chamber technique from September 2008 to August 2010. We also conducted a 24-h measurement to examine the diurnal variation of stem CO₂ efflux in three consecutive days in April 2009.Important findings The temporal dynamics of stem CO₂ efflux followed the change of the stem temperature in a 3-cm depth with a bell-shaped curve in the three species. Stem temperature explained 77–85% of the seasonal variations of stem CO₂ efflux over the entire study period in the three species. The temperature sensitivity (Q 10) of stem CO₂ efflux was obviously different among the three species with higher Q 10 value found in oak (2.24) and lower values in the coniferous species (1.76 and 1.63). Our results also showed that the Q 10 values of stem CO₂ efflux in all the three species were lower in the growing season than that in the non-growing season, indicating that the growth and maintenance respiration had different temperature responses. Moreover, we found that the temperature-normalized stem CO₂ efflux (R 10) changed greatly between the growing and non-growing seasons in oak and masson pine, but not in loblolly pine. Additionally, we also found that in the non-growing season, the principal factor responsible for the spatial variation of stem CO₂ efflux among the 15 sampling trees was sapwood volume, whereas in the growing season, stem CO₂ efflux was closely related to annual dry-matter production in the three subtropical species.