张掖市龙首山红砂种群结构和分布格局研究

对张掖市龙首山天然红砂分布区的红砂种群结构和空间分布格局进行了研究。根据年龄大小结构图和存活曲线以及静态生命表分析了红砂种群动态,用扩散系数C,负二项分布中的K值,平均拥挤度m^*,丛生指数I,Cassie指标CA和聚块性指标(m^*/m)6个分布指数对格局类型进行了判断,并根据双向轨迹方差法分析了种群格局规模。结果表明,红砂种群的自然更新状况良好,各龄级苗木均有分布。种群的年龄结构接近于增长型,表现为中龄级(10cm<d≤30cm)丰富;种群存活曲线趋向于DeeveyⅠ型,种群目前处于较为稳定的状态;种群的聚集强度为0.831 8,分布格局类型为聚集分布;种群有两种空间格局规模,分别为4m×4m和8m×8m。     

城市绿地中臭椿更新苗空间点格局及种间关联分析

[目的]探究城市绿地中臭椿更新苗的数量特征、存活情况及空间分布格局,为城市绿地生境下乔木的天然更新和人工干扰或促进更新提供理论依据。[方法]运用种群静态生命表,点格局分析法中的双关联函数G(r)、H(r)函数分析臭椿更新苗的生存状况,空间分布格局及各龄级间的空间关联性。[结果]更新苗种群结构存在波动性,存活曲线趋于DeeveyⅡ型,低龄级和中龄级个体数量丰富,个体死亡率和消失率在前期和后期较稳定,中期先减后增,超过第5龄级(8~10cm)后,个体死亡率和消失率出现高峰。[结论]一侧和两侧铺装样地在空间上都呈现出不同程度的聚集分布,聚集强度随尺度距离的增大呈减小趋势,一侧铺装样地在尺度接近3.7m处有转为随机分布的趋势。龄级间,小尺度内多表现为无关联,随着尺度增加呈正显著相关;两侧铺装有正关联的龄级组合比一侧铺装样地多;较大尺度上,用径级代表龄级的更新苗间相关关系越接近,正关联越强。     

基于空间分布的草原化荒漠地区红砂种群水分利用策略研究

[目的]研究区域尺度上荒漠灌木水分适应与分布格局相呼应关系,揭示干旱半干旱地区植物种群对环境响应的过程与机理,为深入理解植物与环境协同进化规律提供依据。[方法]采用点格局分析方法和氢氧稳定同位素示踪技术,分析了红砂(Reaumuria songarica)种群的空间分布格局、水分利用策略。[结果](1)在完全空间随机零模型下,红砂种群在<3 m尺度内均匀分布,在>32 m尺度内聚集分布,种群内部生态关系由竞争向促进转变;消除生境异质性后,种群在>30 m尺度下呈现随机分布,种内生态关系呈现减弱的趋势。红砂种群空间分布格局的形成过程中生境异质性在大尺度上起到了重要作用。(2)随着多年平均降水量的减少,红砂种群的水分利用深度由0—20 cm加深到60—100 cm;红砂种群的密度与多年降水呈现极显著负相关(p<0.01),样地的植被盖度变化主要受草本盖度影响,红砂植被盖度变化不显著。[结论]随着多年平均降水量的减少,红砂种群的分布格局受环境异质性影响。通过增加植株密度,红砂可以利用更深层的土壤水分适应环境胁迫。     

河南伏牛山区天然红豆杉种群结构与动态研究

采用聚集度指标和编制静态生命表的方法,对伏牛山区红豆杉种群的空间格局及其演化动态进行了研究,结果显示:(1)伏牛山区红豆杉种群的空间分布格局总体上呈现聚集分布状态,聚集程度从幼苗阶段到老龄阶段的发育过程中,呈现先降后升的U型变化趋势;(2)不同龄级的红豆杉树存活量差别较大,种群存活曲线属于Deevey-Ⅲ型;(3)幼苗期和幼树期的红豆杉死亡率高,Ⅲ级(3m高)以后死亡率明显下降,种群数量趋于稳定。本研究表明,伏牛山自然保护区天然红豆杉种群呈现明显的衰退趋势,严酷的环境筛致使红豆杉幼苗死亡率高可能是该种群衰退的主要原因,但树木资源缺乏保护而被滥伐或盗伐、生境被破坏等影响也不容忽视。施行严格的封育政策并辅以人工繁育措施,是保护和恢复该宝贵资源的当务之急。     

城市森林中火炬树的更新特性

[目的]对天津市城市森林中火炬树的更新苗特性进行调查,为生物入侵后的生态恢复提供依据。[方法]对天津市城市森林中火炬树的更新特性进行年际调查,并与已有的火炬树天然更新研究数据进行对比,经5种聚集强度指数的表征,探究城市森林中火炬树更新苗的数量特征、径级结构和空间格局的年际变化等。[结果](1)火炬树更新苗全年密度在3~8株/m2之间波动,1年生幼苗个体数占绝大多数,龄级结构呈现典型金字塔型,种群属于增长型,更新能力旺盛;(2)处于低地径级和低高度级的火炬树更新苗占总体的绝大多数;(3)火炬树更新苗呈现典型的聚集分布。[结论]城市森林内火炬树更新能力旺盛,入侵性仍然显著,需采取有效措施进行监测与防治。     

石羊河下游不同立地类型黑果枸杞种群结构及数量动态研究

以黑果枸杞为优势种的天然灌木群落是石羊河下游的重要植被建群种之一，为揭示该地区黑果枸杞种群动态变化特征，探索其生态价值，基于对石羊河下游不同生境黑果枸杞天然种群的样地调查，对其年龄结构、静态生命表、动态指数、存活曲线进行了分析研究。结果表明，不同立地类型黑果枸杞种群均表现为新苗和幼龄个体丰富，中老龄个体少；种群在Ⅲ龄级时死亡率最高，种群亏损率与死亡率保持一致。各样地种群动态指数基本为正值，说明黑果枸杞种群整体处于稳定增长的发育状态。盐碱地、覆沙地和砾石地黑果枸杞的存活曲线均接近于Deevey-Ⅲ型，固定/半固定沙地的存活曲线为Deevey-Ⅱ型。不同立地类型黑果枸杞种群的4个生存函数变化除局部有差异外整体趋势较为一致，各样地中黑果枸杞种群累积死亡率F(t)和危险系数λ(t)在Ⅰ龄级向Ⅲ龄级过渡时呈现逐渐增大的趋势，生存率S(t)和死亡密度函数f(t)随龄级呈单调递减的趋势。总体上黑果枸杞种群呈现出前期增长、中期稳定、后期衰退的特征。     

濒危植物急尖长苞冷杉种群生命表分析

急尖长苞冷杉是我国二级保护植物,处于易危状态.在西藏色季拉山,对急尖长苞冷杉种群全面调查的基础上,以种群生命表及生存理论为基础,编制色季拉山阳坡、阴坡及总体急尖长苞冷杉种群特定时间生命表,分别绘制存活曲线、死亡率曲线、亏损率曲线,以及积累死亡率函数、死亡密度甬数和危险率函数曲线,并分析种群动态变化.结果表明:生长在阳坡、阴坡及总体的急尖长苞冷杉种群各龄级个体数量均随年龄增长呈直线下降趋势,生境对种群的结构和动态有较大影响,幼苗死亡率阴坡大于阳坡,老龄个体死亡率阳坡大于阴坡;生长在阳坡种群的存活曲线属Deevey-Ⅱ型中的B3亚型,生长在阴坡种群的存活曲线属Deevey-Ⅲ型,总体种群的存活曲线也属Deevey-Ⅲ型;三个生命表中引入的几个函数都能较好地说明了种群的结构和动态变化.研究结果可为该资源的管理及持续利用提供理论依据.     

西鄂尔多斯4种荒漠植物种子萌发对水分条件的响应

研究了不同土壤水分处理对霸王、沙冬青、长叶红砂及蒙古扁桃这4种荒漠植物种子萌发和幼苗生长的影响。结果表明,土壤含水量显著地影响着种子萌发和幼苗生长。霸王种子在6%的土壤含水量下萌发率和萌发指数最高,活力指数和幼苗生物量也最大,幼苗生长良好。沙冬青种子在12%的土壤含水量、长叶红砂和蒙古扁桃种子在16%的土壤含水量下萌发和生长良好。种子萌发策略反映了物种对荒漠水分条件不同的适应机制,并影响种群的更新和扩展。     

浑善达克沙地境内沙地榆的自然更新

对不同生境下浑善达克沙地榆(Ul mus pumila L.var.sabulosa J.H.Guo Y.S.Li)林下幼苗的密度、生长情况及林缘、单株下幼苗扩散分布进行了野外调查研究,运用种群生态学方法及数理统计方法分析了其更新规律。结果表明,浑善达克沙地榆幼苗的密度为流动沙丘半固定沙地固定沙地;固定沙地、流动沙丘幼苗生长较差且流动沙丘幼苗死亡现象严重,半固定沙地幼苗生长较好更适于沙地榆的更新;幼苗主要集中分布于距林缘20m范围内,20m外幼苗密度显著降低;风向对浑善达克沙地榆的分布有较大的影响。     

土壤水分胁迫对红砂幼苗生长和渗透调节物质的影响

[目的]探讨干旱与半干旱区受损红砂种群幼苗适宜生长的土壤水分条件,为红砂植被保护、恢复、重建提供理论依据。[方法]采用盆栽试验研究不同土壤水分条件下红砂幼苗生长及渗透调节物质差异。[结果]随土壤水分胁迫程度的加剧,红砂幼苗茎叶总生物量呈明显的减少趋势,其株高呈逐渐降低的变化趋势,而根冠比、根长和根表面积均呈逐步增大的变化趋势,根系生物量呈先增加后减少的变化趋势。随土壤水分胁迫程度的加剧,红砂幼苗茎叶、根组织中脯氨酸含量均表现出明显的增加趋势,而可溶性糖和可溶性蛋白含量的变化相对不明显。[结论]土壤水分胁迫下红砂幼苗可通过调整自身生长和生物量分配来加大根冠比以及通过积累脯氨酸来适应干旱胁迫,维持植株正常生长。     

Estimation of a Finite Population Mean and Total Using Population Ranks of Sample Units

This paper introduces new estimators for population total and mean in a finite population setting, where ranks (or approximate ranks) of population units are available before selecting sample units. The proposed estimators require selecting a simple random sample and identifying the population ranks of sample units. Selection of the sample can be performed with- or without-replacement. The population ranks of the selected units of with-replacement samples are determined among all population units. On the other hand, the ranks of the sample units of without-replacement samples are identified in two different ways: (1) The rank of a sample unit is determined sequentially among the remaining population units after excluding all previously ranked sample units from the population; (2) The ranks are determined among all units in the population. By conditioning on these population ranks, we construct a set of weighted estimators, develop a bootstrap re-sampling procedure to estimate the variances of the estimators, and construct percentile confidence intervals for the population mean and total. We show that the new estimators provide a substantial amount of efficiency gain over their competitors. We apply the proposed estimators to estimate corn production in one of the counties in Ohio.     

Multi-Site Integrated Population Modelling

We examine the performance of a method of integrated population modelling for the joint analysis of different types of demographic data on individuals that exist in, and move between, different sites. The value of the approach is demonstrated by a simulation study which shows substantial improvement in parameter estimation when site-specific census data are combined with demographic data. The multivariate normal approximation to a multi-state mark-recapture likelihood is evaluated, and the performance of a diagonal variance-covariance matrix for the approximation is also examined. The work is motivated by a study of great cormorants. Analysis of the cormorant data suggests that breeders survive better than non-breeders, and also that probabilities of recruitment to breeding have been declining over time for all the colonies of the study. Supplementary material, including notes on the computation of standard errors and extended simulation results, are available online.     

Estimation of Population Mean and Total in a Finite Population Setting Using Multiple Auxiliary Variables

This paper introduces a new sampling design in a finite population setting, where potential sampling units have a wealth of auxiliary information that can be used to rank them into partially ordered sets. The proposed sampling design selects a set of sampling units. These units are judgment ranked without measurement by using available auxiliary information. The ranking process allows ties among ranks whenever units cannot be ranked accurately with high confidence. The ranking information from all sources is combined in a meaningful way to construct strength-of-agreement weights. These weights are then used to select a single sampling unit for full measurement in each set. Three different levels of sampling design, level-0, level-1, and level-2, are investigated. They differ in their replacement policies. Level-0 sampling designs construct the sample by sampling with replacement, level-1 sampling designs constructs the sample without replacement of the fully measured unit in each set, and level-2 sampling designs construct the sample without replacement on the entire set. For these three designs, we estimate the first and second order inclusion probabilities and construct estimators for the population total and mean. We develop a bootstrap resampling procedure to estimate the variances of the estimators and to construct percentile confidence intervals for the population mean and total. We show that the new sampling designs provide a substantial amount of efficiency gain over their competitor designs in the literature.     

Population dynamics of the Bwindi mountain gorillas

Mountain gorillas are critically endangered, with just a few hundred animals remaining in each of two populations: in Bwindi Impenetrable National Park in south-western Uganda and the nearby Virunga Volcanoes on the borders of Uganda, Rwanda and the Democratic Republic of Congo. While the life-history and population dynamics of the Virunga gorillas have been studied extensively, comparable information from Bwindi has not been reported. Such studies are difficult to conduct because gorillas are long-lived, have delayed reproduction, and monitoring known individuals requires habituation of social groups. Bwindi has experienced lower levels of human disturbance than the Virungas, yet its gorilla population has shown little or no growth over the past 20 years, while a subpopulation of study groups in the Virungas have grown by 3-4% per year. Here we show that the lower growth rate at Bwindi may arise mainly from lower fertility than the Virunga study groups, rather than higher mortality. This difference may indicate that the more frugivorous Bwindi gorillas have a slower life-history, or that they are closer to the carrying capacity of their habitat. The study groups at Bwindi had a higher growth rate than the broader population, possibly because they receive veterinary care and better protection from poachers, but further analysis is necessary to understand the complex interactions among human disturbance, ecology, and the gorillas’ population dynamics. Meanwhile, efforts to increase the Bwindi population should place emphasis on reducing human disturbances, improving our understanding of the impact of habitat quality, and ensuring that the gorillas can expand their home ranges into under-utilized areas of the park.     

烟台市人口分析及预测

利用时间序列分析模型和GM(1,1)模型拟合了烟台市人口数量,并对未来4年烟台市人口进行了预测.结果显示,二次滑动平均模型的相对误差波动范围为-0.731%～0.70%,均接近于0,预测精度最高.利用二次滑动平均模型预测未来4年烟台市人口分别为646.395万人、646.445万人、646.495万人和646.545万人,人口有逐年缓慢上升的趋势.     

Limited-Information Modeling of Loggerhead Turtle Population Size

We attempt to estimate the size of a population of female loggerhead turtles. In traditional capture-recapture experiments to estimate the size of an animal population, individual animals are tagged and the information about which individuals are captured repeatedly is crucial. For these loggerhead turtle data, information about individual turtles is not available. Rather, we observe only the counts of successful and failed nestings at a location over a series of days (in our case, three). We view the turtles’ nesting behavior as an alternating renewal process, model it using parametric distributions, and then derive probability distributions that describe the behavior of the turtles during the three days via a 3-way contingency table. We adopt a Bayesian approach, formulating our model in terms of parameters about which strong prior information is available. We use a Gibbs sampling algorithm to sample from the posterior distribution of our random quantities, the most crucial of which is the number of turtles remaining offshore during the entire sampling period. We illustrate the method using data sets from loggerhead turtle sites along the South Carolina coast. We provide a simulation study which illustrates the quality and robustness of the method and investigates sensitivity to prior parameter specification.     

几个抗旱玉米群体引种试验初报

对来自墨西哥国际玉米小麦改良中心（ＣＩＭＭＹＴ）的９个抗旱玉米群体进行引种试验，研究了其９个性状。结果表明，这批群体的散粉至抽丝间隔（ＡＳＩ）都极显著地比广西推广的品种墨白１号（对照）为短。各群体中有一个群体的单株粒重显著高于对照，有５个群体与对照无显著差异。再综合考虑其他性状，认为有希望从这批群体中选育出抗旱性、产量等综合性状较好的群体，在生产中直接应用。     

有机毒物甲磺隆胁迫下根际微生物种群生态的动态变化研究

运用根箱盆栽法进行定期测定土壤中微生物的数量,确定甲磺隆胁迫下,小麦根际土壤微生物种群生态的动态变化。表明甲磺隆胁迫下根际土壤中的细菌、真菌、放线菌数量均大于非根际土壤,并初步分离和鉴定了优势菌群。     

小麦冷温群体研究

通过对小麦群体温度的多年观测，发现自然界存在冷温群体，其冠层温度偏低，叶片功能期较长，源较充足，对灌浆甚为有利。尤其这类群体中的冷型小麦，冷域发达，蒸腾旺盛，净光合率较高，更是利于子位充实。这种类型小支的发现为优良株系、品系、品种的选择提供了重要的理论和实践依据。