Effects of Detectability on Estimates of Geographic Range Size in Bignonieae

Abstract: Extinction risk has not been evaluated for 96% of all described plant species. Given that the Global Strategy for Plant Conservation proposes preliminary conservation assessments of all described plant species by 2010, herbarium specimens (i.e., primary occurrence data) are increasingly being used to infer threat components from estimates of geographic range size. Nevertheless, estimates of range size based on herbarium data may be inaccurate due to collection bias associated with interspecific variation in detectability. We used data on 377 species of Bignonieae to test the hypothesis that there is a positive relationship between detectability and estimates of geographic range size derived from herbarium specimens. This relationship is expected if the proportion of the true geographic range size of a species that is documented by herbarium specimens is given by the product of the true geographic range size and the detectability of the species, assuming no relationship between true geographic range size and detectability. We developed 4 measures of detectability that can be estimated from herbarium data and examined the relationship between detectability and 2 types of estimates of geographic range size: area of occupancy and extent of occurrence. Our results from regressing estimates of extent of occurrence and area of occupancy on detectability across genera provided no support for this hypothesis. The same was true for regressions of estimated extent of occurrence on detectability across species within genera. Nevertheless, regressions of estimated area of occupancy on detectability across species within genera provided partial support for our hypothesis. We considered 3 possible explanations for this mixed outcome: violation of the assumption of no relationship between true geographic range size and detectability; the relationships between estimated geographic range size and detectability may be an artifact of a negative relationship between estimated area of occupancy and the sampling variance of detectability; detectability may have had 2 opposite effects on estimated species range sizes: one determines the proportion of the true range of a species documented by herbarium specimens and the other determines the distribution of true range size for the species actually observed with herbarium data. Our findings should help improve understanding of the potential biases incurred with the use of herbarium data.     

Territory characteristics and coexistence with heterospecifics in the Dartford warbler <Emphasis Type="Italic">Sylvia undata</Emphasis> across a habitat gradient

The study of successional gradients may help to understand the relative influence of habitat structure and competition on territory characteristics. Here, we evaluate the effects of vegetation cover, conspecific and heterospecific densities, and distance to the nearest neighbor on territory size, shape, and overlap in insectivorous birds. We studied these effects along a gradient of postfire habitat regeneration in which foliage cover and densities of focal species varied several-fold. We delineate 197 territories (minimum convex polygons) of the shrub-dwelling Dartford warbler (Sylvia undata) and 255 of the syntopic Sardinian (Sylvia melanocephala), subalpine (Sylvia cantillans) and melodious (Hippolais polyglotta) warblers at three plots in NE Catalonia (Spain and France) in 1987–2005. After accounting for the effect of the number of locations used to delineate polygons, generalized linear mixed models (GLMM) showed a reduction in territory area of the Dartford warbler as conspecific density increased and distance to nearest neighbor decreased, in accordance with the contender pressure hypothesis for territory size regulation. Heterospecific density was not included in the final model of territory size and the effect of habitat structure was marginal. Territory roundness was positively correlated with its size and with conspecific density, probably in relation to energetic constraints, and negatively with heterospecific density. Territorial exclusion was almost complete among Dartford warblers, whereas interspecific territory overlap was extensive and tended to increase with heterospecific density and with structural diversity along the gradient. Our results support the hypothesis that Mediterranean warbler coexistence derives from ecological segregation and not from interspecific territoriality.     

Optimal investment in sons and daughters when parents do not know the sex of their offspring

Optimal parental investment usually differs depending on the sex of the offspring. However, parents in most organisms cannot discriminate the sex of their young until those young are energetically independent. In a species with physical male–male competition, males are often larger and usually develop sexual ornaments, so male offspring are often more costly to produce. However, Onthophagus dung beetles (Coleoptera; Scarabaeidae) are highly dimorphic in secondary sexual characters, but sexually monomorphic in body size, despite strong male–male competition for mates. We demonstrate that because parents provide all resources required by their offspring before adulthood, O. atripennis exhibits no sexual size dimorphism irrespective of sexual selection pressure favoring sexual dimorphism. By constructing a graphic model with three fitness curves (for sons, daughters, and expected fitness return for parents), we demonstrate that natural selection favors parents that provide both sons and daughters with the optimal amount of investment for sons, which is far greater than that for daughters. This is because the cost of producing small sons, that are unable to compete for mates, is far greater than the cost of producing daughters that are larger than necessary. This theoretical prediction can explain sexual dimorphism without sexual size dimorphism, widely observed in species with crucial parental care such as dung beetles and leaf-rolling beetles, and may provide an insight into the enigmatic relationship between sexual size dimorphism and sexual dimorphism.     

不同粒径垃圾焚烧飞灰重金属分布和浸出性质

对烟气净化系统飞灰(以下简称飞灰)按粒径进行分级,研究了飞灰重金属含量、形态分布和浸出毒性随粒径的变化,讨论了不同粒径的飞灰对重金属总量和浸出总量的贡献率.结果表明:飞灰中粒径>154 μm和<30 μm的颗粒较少,粒径为38.5～74 μm的颗粒约占总量的50%.除Ni和Cr外,重金属含量随飞灰粒径的减小呈增加趋势,且主要表现在酸溶态Cd,Zn,Pb,Cu和有机结合态Pb以及晶形氧化铁态Pb,Zn含量的增加.随着飞灰粒径的减小,Cr,Ni,Zn,Hg和Pb的浸出量也呈逐渐增加趋势,其中Zn,Hg和Pb的表现尤为突出.尽管细颗粒上的重金属对飞灰的重金属总量贡献不大,但高浸出率使细颗粒飞灰对重金属浸出总量仍具有较大贡献,尤其是Pb,Zn和Hg,在占飞灰质量8%的粒径<30 μm的飞灰中,富集了约40%的水溶性Pb,Zn和Hg.      

鲁西北地区现状农业土地资源劳动力承载力模拟

传统农区农业劳动力的出路问题是中国目前面临的一个重要经济和社会问题,论文从农业土地资源劳动力承载力评价角度,对这一问题进行了探讨。提出了最小劳均耕地面积、农业土地资源劳动力承载力、规模种植压力指数和农业土地资源劳动力承载力指数的概念及模型,在建立模型分析农业土地资源劳动力承载能力的基础上估算劳动力的剩余。结果如下:在现实收入水平下,鲁西北地区最小劳均耕地面积为0.39hm₂,而实际劳均耕地面积为0.34hm₂;在现实收入水平下,鲁西北地区约有53.3×104个劳动力需要转移,剩余劳动力约占农林牧渔业总劳动力的14.9％;规模种植压力指数K=1.18>1,表明耕地处于正压力状态(承受压力)。说明目前鲁西北地区单位农林牧渔业劳动力所拥有的耕地规模较小,致使劳动生产率难以提高,农民收入增加缓慢,要大力提高农业劳动生产率,必须缩减从事农业的劳动力规模,寻求剩余劳动力转移的有效途径。     

南京冬季市区和郊区气溶胶中PAHs浓度的昼夜特征及粒径分布

为了研究南京市区与郊区气溶胶中多环芳烃(PAHs)污染状况和分布特征,利用气-质联用仪(GC-MS)分析了2010年1月1～10日日间和夜间分别在南京大学和南京信息工程大学采集的气溶胶样品,得到南京市区与郊区17种PAHs浓度,总浓度分别为41.36～220.35 ng.m-3和45.10～200.86 ng.m-3,其中约66%～67%分布于细粒子(Dp≤2.1μm)中.研究发现,南京市区和郊区气溶胶中PAH总浓度均处于较高的水平;但两者昼夜变化趋势不同,即市区PAH总浓度日间高于夜间,郊区PAH总浓度日间低于夜间.主导风向的改变和高压天气系统对PAH浓度变化影响较大;在市区其影响主要表现在细粒子部分,而郊区主要表现在粗粒子部分.市区和郊区不同环数的PAHs粒径分布不同;2～3环PAHs,郊区含量高于市区;而4～6环PAHs,市区含量高于郊区.高环数(4～6环)PAHs在粗模态出现较大浓度峰可能是由于南京地区粗模态气溶胶中碳含量较高.市区和郊区相似的特征比值说明两者的PAHs具有相同污染来源,主要为生物质及煤的燃烧和汽车尾气,表明南京市区PAHs受到郊区工业源排放影响较大.     

南京冬季雾霾过程中气溶胶粒子的微物理特征

2007年冬季南京雾外场试验获得了雾霾转换过程的大气气溶胶和雾滴尺度谱分布同步观测资料,根据能见度和含水量将雾霾过程划分为雾、轻雾、湿霾、霾4个不同阶段,进而分析了不同阶段粗、细气溶胶粒子的微物理特征.结果表明,4个阶段的主要发生顺序为霾←→轻雾—→湿霾—→雾—→湿霾—→轻雾←→霾,雾前湿霾阶段持续时间长于雾后.尺度2μm的粗粒子数浓度、表面积浓度和体积浓度在雾阶段均显著大于其他3个阶段,其中霾阶段浓度最低.雾滴表面积浓度和体积浓度尺度谱分布为双峰或多峰型,而轻雾、湿霾和霾阶段粗粒子谱均为单峰型.尺度0.010μm的细粒子表面积浓度谱形在雾和湿霾阶段、轻雾和霾阶段分别相似,雾和湿霾阶段数浓度占优势的尺度范围分别为0.04～0.13μm和0.02～0.14μm,轻雾及霾阶段数浓度优势粒子尺度范围均为0.02～0.06μm.从霾、轻雾、湿霾到雾的转换过程中,以0.060～0.090μm为界,小粒子减少,大粒子增多.雾霾演变过程中气溶胶粒子数浓度与均方根直径呈显著负相关关系,雾阶段气溶胶粒子数浓度最低、平均尺度最大.     

霾与非霾期间汞在不同粒径颗粒物上的分布特征

在我国高速经济增长过程中,霾污染日趋突出,同时大气汞污染也十分严重,而颗粒汞对于汞在大气中的循环演化意义重大.为了探讨霾污染期间汞在不同粒径颗粒物中的分布特征,采用Nano-moudi 12级(6.2~9.9μm、3.1~6.2μm,1.8~3.1μm、1.0~1.8μm、0.56~1.0μm、0.32~0.56μm、0.18~0.32μm、0.10~0.18μm,0.056~0.10μm、0.032~0.056μm、0.018~0.032μm、0.010~0.018μm)大气颗粒物采样器,对上海霾与非霾期间不同粒径大气颗粒物中的汞进行分析.结果表明,颗粒态汞含量与颗粒物含量正相关;采样期间霾天颗粒态汞平均浓度0.31 ng·m-3是非霾天颗粒态汞平均浓度0.11 ng·m-3的2~3倍;霾和非霾天颗粒态汞浓度以及颗粒物质量浓度随粒径分布呈双峰型,霾期间峰值分别出现在0.56~1.0μm粒径段和3.1~6.2μm粒径段,而非霾期峰值分别出现在0.32~0.56μm和3.1~6.2μm粒径段;霾天较非霾天颗粒态汞和颗粒物的粒径分布均出现了向大粒径方向偏移;颗粒态汞主要分布在粒径≤1μm粒子上,能够长时间停留和长距离输送;非霾期间颗粒态汞在颗粒物中的平均含量为0.029 ng·μg-1,而霾期间为0.015 ng·μg-1;霾污染过程中其他污染物迅速成长,而汞成长较慢;霾天积聚核模态粒子中颗粒态汞质量浓度为2.06 ng·m-3,而非霾天为0.55 ng·m-3,积聚态颗粒物的大幅增加,是灰霾形成的主要原因.本地源燃煤等的排放以及风沙扬尘的增加和外地源的输送是导致霾天污染严重的重要原因.     

亚青会期间南京市气溶胶中OC和EC的粒径分布

采用Anderson 9级撞击式采样器和DRI Model 2001A热/光碳分析仪对南京2013年8月10~28日亚青会期间不同粒径段气溶胶中有机碳(OC)和元素碳(EC)的质量浓度进行了观测分析.结果表明,51.55%和54.81%的OC和EC富集于粒径<1.1μm的细粒子中,亚青会期间OC和EC的最大浓度分别位于0~0.43μm和0.43~0.65μm粒径段,占总浓度的比例分别为20.90%±5.02%和22.68%±9.90%.PM1.1、PM1.1~2.1和PM2.1~10中OC和EC的浓度在亚青会期间比亚青会前分别减少了43.44%~56.17%和59.17%~73.55%.亚青会期间OC的谱分布没有变化,均为双峰型分布;EC的谱分布由双峰型变为单峰型.观测期间不同粒径段的EC和OC具有较好的同源性.亚青会前OC和EC主要来自汽车尾气;亚青会期间PM1.1中OC和EC主要来自汽车尾气,PM1.1~2.1和PM2.1~10中OC和EC主要来自汽车尾气和燃煤.     

纳米复合聚硅酸铝的颗粒粒度效应:Al_(13)与氧化硅的相互作用及其混凝特征

为了研究纳米复合聚硅酸铝(PASC)混凝剂的颗粒粒度效应,以实验室提纯的Al13溶液和活化水玻璃为原料,制备一系列不同粒度分布的PASC.以Al-Ferron法测定的铝水解形态表明,在该混凝剂中,Al13作为混凝优势形态具有较好的稳定性.氧化硅聚集度的测定和粒度分析结果表明,活化硅酸的加入能显著提高混凝剂的平均粒度,同时,Si/Al比(物质的量比)是影响平均粒度的主要因素.在活化硅酸不过量的前提下,Si/Al比和混凝剂的平均粒度呈正相关.混凝实验结果表明,在保证电中和能力的前提下,混凝剂的颗粒粒度越大,混凝剂的除浊能力越强.