南京老山国家森林公园朴树种群动态

运用相邻格子法对南京老山国家森林公园朴树(Celtis sinensis)种群(以下简称老山朴树种群)进行野外调查,以定量方法研究其种群结构特征。编制种群静态生命表,并绘制存活曲线、死亡率曲线、消失率曲线和4个生存函数曲线,同时结合时间序列预测模型研究老山朴树种群的数量动态。结果表明,种群各龄级个体数虽然存在波动,但整体呈增长趋势,存活曲线属DeeveyⅡ型,分别在第Ⅰ和第Ⅶ龄级出现2个死亡率高峰。第1个峰值的出现主要是由于种内竞争激烈,第2个峰值伴随种群进入生理死亡年龄而出现。生存分析结果表明,朴树种群至第Ⅵ龄级时,生存率仅为0.5%,累计死亡率高达99.5%;危险率曲线与死亡率和消失率曲线变化情况基本一致,反映朴树种群生长发育过程具有前期薄弱、中期稳定、后期衰退的特点。时间序列预测结果表明,在未来的2～6 a内,老山朴树种群呈增长趋势。对幼苗及幼林进行人工抚育管理将有助于老山朴树种群的天然更新。     

庞泉沟自然保护区华北落叶松种群生命表与谱分析

以种群生命表及生存分析理论为基础,将林木依胸径大小分级,以林木径级结构代表年龄结构,采用分段匀滑技术,编制庞泉沟自然保护区华北落叶松种群特定时间生命表,绘制死亡率曲线、消失率曲线、存活曲线、生存函数曲线,分析种群数量特征;同时结合谱分析方法,分析华北落叶松种群数量的动态变化.结果表明:(1)华北落叶松种群年龄结构表现为稳定型,但林下幼苗、幼树相对较少.(2)华北落叶松种群死亡率和消失率曲线变化趋势基本一致,均出现两个高峰,一个出现在第11、12龄级阶段,另一个出现在第15龄级阶段;存活曲线趋于Deevey-Ⅱ型.(3)4个生存函数曲线表明,华北落叶松种群具有前期稳定、中后期锐减和末期衰退的特点.(4)种群动态的谱分析显示,华北落叶松种群动态除受基波影响外,还存在着明显的小周期波动,在第7龄级这一小周期波动与华北落叶松的高生长有关;在15龄级这一小周期波动与华北落叶松进入生理衰退期有关.     

濒危兰科植物流苏石斛的种群数量动态

运用静态生命表、生殖力表和Leslie矩阵模型,研究了云南西双版纳地区流苏石斛两个种群——A种群(21°58′N,101°13′E,保护区之外)和B种群(21°54′N,101°17′E,保护区内)的种群数量动态.结果表明:种群存活曲线表现为Deevey-型.A、B种群均表现出幼龄个体死亡率高,中龄级个体数量少,说明中龄阶段曾受到较大的人为干扰.种群的净增长率(Ro)、内禀增长率(rm)和周限增长率(λ)都较低,表现为衰退种群,Leslie矩阵模型分析表明在未来25年种群各龄级的个体数及种群总数均表现出持续下降趋势.种群下降可能是由于当地人为的采挖和严重的生境破碎化所导致.图2表4参16     

兰州市郊红砂种群数量动态与分布格局

对兰州市南北两山天然分布的红砂种群数量动态和空间分布格局进行研究。利用地径回归得到红砂种群年龄结构,编制静态生命表,进行生存分析及谱分析,计算红砂种群年龄结构动态指数,以揭示种群数量动态特征;采用扩散系数、负二项指数、平均拥挤度、聚块性指数、扩散型指数、丛生指数、Cassie指数和Green指数8个分布指标判断红砂种群时空尺度上的格局类型。结果表明,南北两山红砂种群密度、盖度适宜,动态指数均大于0,呈现增长型,并存在明显的周期性;种群以中幼龄植株为主体,各龄级的死亡率基本平稳,但在第Ⅱ过渡到第Ⅲ龄级时,出现死亡高峰,存活曲线趋于Deevey-Ⅲ型。种群时空异质性明显,阳坡的红砂种群呈现聚集分布,阴坡则多呈现均匀分布;不同发育阶段红砂种群分布格局呈现明显递变规律,幼龄阶段聚集度高,随着年龄增大,聚集性大幅减弱。     

丝栗栲种群生命过程及谱分析

以种群生命表及生存分析理论为基础，编制丝栗栲种群静态生命表，绘制存活曲线，死亡率曲线，亏损度曲线，死亡密度函数曲线。积累死亡函数曲线和危险率函数曲线，分析种群生命过程。结果表明，丝栗栲有2个死亡高峰，存活曲线趋于Deevey-Ⅱ型。并应用谱分析方法研究丝栗栲种群动态，结果表明，在丝栗栲种群自然更新过程中存在着明显的周期性。     

麻城枳椇种群结构及动态分析

为了阐明枳椇天然种群的年龄结构和发展趋势,保护现有资源,对麻城五脑山枳椇天然种群进行样地调查,分析了种群龄级动态,编制了种群静态生命表,进行了时间序列预测.结果表明:枳椇种群龄级结构动态指数V_(pi)=51.58%0,呈增长型;环境筛的抑制出现在第Ⅳ龄级,其后种群动态趋向稳定;存活曲线介于Deevey-Ⅱ型和Deevey-Ⅲ型之间,更接近Deevey-Ⅱ型;时间序列分析表明,由于林下更新层幼苗数量较大,种群具有较强增长和恢复能力.研究表明,枳椇种群的生长发育符合其自身生物学特性,种子库充足,种群处于稳定增长型.种群保护应避免景区建设对种群更新造成干扰.     

天山云杉的种群动态

选择我国新疆境内天山山脉从西到东处于不同经度位置5个地区(昭苏、巩留、乌苏、乌鲁木齐和哈密)的天山云杉林进行垂直样带调查,采用静态生命表法,分析5个地区天山云杉种群的存活曲线和死亡率曲线,为天山云杉种群数量统计和生态保护提供依据.结果表明:其存活曲线为DeeveyⅡ型,表明天山云杉种群处于动态稳定状态;5个地区天山云杉种群均有两个死亡率曲线高峰,死亡高峰主要出现在幼年时期、近成熟前期、成年阶段和老年期.种群的死亡强度和死亡高峰在时间格局上各地区有明显的差异.图2表6参31     

采伐后各演替阶段红松种群结构和动态特征

研究阔叶红松林皆伐后各演替阶段红松种群结构和动态特征可以更好地理解生态系统的演替规律及其维持生物多样性的作用机制,为林区可持续经营提供理论依据。以分布于小兴安岭地区凉水国家级自然保护区内原始红松林采伐后形成的4个不同演替阶段的次生林为对象,根据全体乔木和红松的种群静态生命表、存活曲线、生存函数和动态指数以及对其时间序列预测,进行种群结构和动态特征分析。1)在次生演替序列中,在先锋群落和中期群落,全体乔木和红松第Ⅰ龄级的株数均较多,分别为1 486 plant·hm^-2和467 plant·hm^-2,占总株数的77.032%和94.341%。2)全体乔木在先锋群落第Ⅳ-Ⅴ龄级死亡率(q_x)最高,达到0.934;而在稳定群落第Ⅲ-Ⅳ龄级的死亡率最低,仅有0.032。红松在先锋群落第Ⅱ-Ⅲ龄级死亡率最高,达到了0.911;而在顶极群落第Ⅲ-Ⅳ龄级死亡率最低,仅有0.065%。3)红松和全体乔木的存活曲线均更接近于Deevey-Ⅱ型。4)从反映红松和全体乔木整体年龄结构动态的V_pi和V_pi′     

南京南郊马尾松种群动态及种内竞争模型的应用

通过对南京南郊马尾松(Pinus massoniana)种群年龄结构的统计,绘制该种群的静态生命表。结果表明,该马尾松种群年龄结构属衰退型;存活曲线为凸形曲线,属Deevey-A型;死亡率和消失率变化规律一致,均在第11龄级(47~49 a)时取得极大值,分别达0.625和0.981。对群落Hegyi竞争指数的计算表明,种内竞争是马尾松种群衰退的主要原因:种内竞争指数占总竞争指数的85.8%,种内平均单木竞争指数为1.71,而种间竞争指数仅占总竞争指数的14.2%。非线性回归结果表明,用林振山种内竞争模型拟合南京南郊马尾松种群数量的衰退规律可以达到较高优度,判定系数为0.759,此地马尾松种群固有出生率为0.105,环境对马尾松的最大容量为31株·(400 m2)-1。模型稳定性分析表明,马尾松种群虽然处于衰退阶段,但种群不会退出该地区,并将在未来很长时间保持群落优势种的地位,种群密度最终将衰退至9.396株·(400 m2)-1的稳定状态。     

木根麦冬的种群数量动态

运用静态生命表、生殖力表和Leslie矩阵模型,研究了木根麦冬种群数量动态过程,揭示了种群各龄级植株的动态规律.结果表明,木根麦冬种群为衰退型种群,种群的净增殖率、内禀增长率和周限增长率较低,种群世代周期偏长,种群不能自我更新.在20 a内种群幼苗数量和总数量将持续快速下降.木根麦冬种群在16～20 a年龄段受到了环境筛的强烈过滤作用. 表3 参6     

青檀天然群落土壤成分及其对青檀生长的影响

对湖北省三潭风景区青檀（Pteroceltis tatarinowii）天然群落土壤主要元素进行测定,并通过因子相关分析,探讨了土壤成分与青檀生长指标之间的相关性,研究结果可为青檀野生资源的保护和合理利用提供科学依据。结果表明,土壤水溶性Ca2＋、Mg2＋平均质量分数为3.598和0.176 g·kg-1,速效钾、全氮、有效磷的平均质量分数分别是133.324 mg·kg-1、4.413 g·kg-1和3.569 mg·kg-1,有机质平均质量分数为3.295%。土壤水溶性Ca2＋与青檀生长指标之间无显著相关关系;土壤可溶性Mg2＋与乔木、灌木的丛生植株数量呈显著正相关,当Mg2＋浓度处于0.191~0.221 g·kg-1之间时,青檀的丛生植株数量大;全氮与青檀乔木平均高度、平均胸径呈极显著正相关,与单生植株数量呈显著负相关;有效磷与乔木平均高度和胸径呈显著正相关;速效钾与乔木丛生植株数量及乔木总数量呈显著正相关;有机质灌木冠幅呈显著正相关。按土壤成分可将青檀群落聚成3类,3个聚类组的土壤水溶性Mg2＋、全氮（TN）、速效钾（TK）、有效磷（TP）、有机质以及青檀乔木植株总数量存在着显著差异。     

Sex-biased maternal expenditure in Rocky Mountain bighorn sheep

Summary We examined maternal energy expenditure in Rocky Mountain bighorn sheep to test the hypothesis (Trivers and Willard 1973) that individual sons in polygynous mammals should obtain a larger maternal subsidy. In accord with theory, males weighed more at birth (an index of relative prenatal expenditure), tended to suckle more between 40 and 100 days of age (an index of relative postnatal expenditure) and imposed greater delays on their mothers' return to estrus in the subsequent breeding season (an index of relative total preweaning expenditure). Mothers rather than offspring appeared to have primary control over postnatal expenditure. The effect of maternal reproductive effort on return to estrus was cumulative over a period of 3–5 years so that ewes making relatively large expenditures gave birth progressively later. Ewe and lamb mortality was associated with late conception in the previous rut. Thus, differential reproductive effort by ewes in this population appeared to entail a fitness cost involving reductions in both offspring and maternal survivorship. Correspondence to: J.T. Hogg at the present address     

Potential effects of environmental contamination on Yuma Myotis demography and population growth.

Unplanned natural and anthropogenic disasters provide unique opportunities for investigating the influence of perturbations on population vital rates and species recovery times. We investigated the potential effects of a major pesticide spill by comparing annual survival rates using mark-recapture techniques on a riparian bat species, Yuma Myotis (Myotis yumanensis). Demography and population dynamics for most bat species remain poorly understood despite advances in mark-recapture estimation and modeling techniques. We compared survival and population growth rates of two roost populations exposed to a large chemical (metam sodium) spill in the upper Sacramento River in Northern California with two roost populations outside the contaminated area from 1992 to 1996. Hypotheses about long-term effects of the spill on female juvenile and adult survival were tested using an information-theoretic approach (AIC). Working hypotheses included effects of age, chemical spill, and time trend on survival. Female adult survival was higher than female juvenile survival across all sites, suggesting stage-specific mortality risks. Model-averaged estimates of female juvenile survival in the contaminated area (0.50-0.74) were lower than in control roosts (0.60-0.78) for each year in the study, suggesting that the spill may have reduced juvenile survival for several years. Female adult survival (0.73-0.89) did not appear to be strongly affected by the spill during the years of the study. There was an increase in survival for both stage-classes across all populations during the study period, which may have been caused by the end of an extended drought in California in the winter of 1993. The spill-affected population was in decline for the first year of the study as indicated by an estimated growth rate (lambda) < 1, but population growth rates increased during the four-year period.     

Age-specific survivorship in relation to clutch size and fledging success in California gulls

Summary Data from a natural population of California gulls (Larus californicus) demonstrated that increasing reproductive effort with age was associated with reduced survivorship. Number of offspring fledged but not clutch size was inversely related to adult survivorhip indicating that reproductively induced mortality resulted from the cumulative effects of the entire breeding season. Agerelated increases in fledging success were correlated with increased adult mortality. Young gulls fledged few offspring and had high survival rates. Old gulls tended to fledge more offspring and had low survival rates. However, those old gulls fledging few offspring survived as well as young gulls. Data also invalidate the assumption that survivorship is age-constant in this species.     

Book Reviews

The study focused on the so-called dark coniferous forest belt on the northern slope of Changbai Mountain, at an altitude of 1100 to 1700 m. Forty tree species, 50 shrub species and 165 herb species were recorded in a series of transects. The main impact factors on forest diversity and proposals for sustainable management of this diversity were studied using an altitude and area gradient pattern method. The results showed that the diversity of dark coniferous forest gradually decreased from lower to upper altitude; while the importance value of key species increased. The methodology used to assess attributes for conservation of dark coniferous forest diversity involved measurement of individual trees, number of species, age structure, stand structure, diameter at breast height (DBH), and cumulative wood storage. Different conservation strategies have been developed and are discussed for different parts of the forest.     

Age-dependent survival analyzed with Bayesian models of mark-recapture data

We describe a Bayesian random effects model of mark-recapture data that accounts for age-dependence in survival and individual heterogeneity in capture probabilities and survival. The model is applied to data on the Glanville fritillary butterfly (Melitaea cinxia) collected from a population enclosed in a large cage in the field. The cage population consisted of a mixture of butterflies originating from newly established and old populations in a large metapopulation in the Aland Islands in Finland. The explanatory variables in the model included the effects of temperature, sex, and population type (new vs. old) on capture probabilities, and the effects of age, sex, population type, and day vs. night on survival. We found that mortality rate increased with age, that mortality rate was much higher during the day than during the night, and that the life span of females originating from newly established populations was shorter than the life span of females from old populations. Capture probability decreased with increasing temperature and decreased with increasing mobility of individuals.     

梅州城区植物群落的结构特征

2009年4—10月,采用群落调查法、主成分分析法对梅州城区5种绿地类型65个种植的植物群落进行研究,结果表明：1）各类植物共计43科105属147种（含变种）,其中乔木62种（42．17％）、灌木45种（30．61％）、草本植物31种（21．09％）、藤本植物9种（6．12％）;2）群落垂直结构为乔、灌、草3层复合结构者9个（13．85％）,为乔、草2层结构者34个（52．31％）,乔或草单层结构者12个（18．46％）;3）乔木树种平均胸径16．7cm,其中平均胸径〈10cm者23种（37．09％）,平均胸径10～20cm者29种（46．77％）,平均胸径20～30cm、〉30Cm者分别为5种（均为8．06％）;4）梅州城区植物群落结构的特征,可用乔木高度因子、胸径因子、密度因子及冠幅因子来表述,这4个主因子的方差累积贡献率达到81．55％,可以很好地反映出群落结构的大部分信息;5）梅州市城区乔木层的优势树种是垂榕、大叶榕、大王椰子,次优势种是阿珍榄仁、阴香、海南蒲桃、细叶榕、木棉、麻楝、香樟、洋紫荆,这11个树种分属桑科、棕榈科、使君子科·、樟科、桃金娘科、木棉科、楝科、豆科（云实科）,它们是梅州城市森林的骨干树种和基调树种,决定了梅州城市森林的南亚热带性质的外貌。     

Estimation of birth rate and juvenile mortality from observed numbers of juveniles in a mammal population with normally dispersed reproduction

The increase in the number of juveniles in a mammal population with a normally dispersed reproduction is simulated using a computer. The effect of juvenile mortality and its age-dependency on the recruitment curve is discussed. The maximum number of juveniles is reached before all juveniles are born. The ratio of the period of time between the beginning of the reproduction period and the maximum of juveniles and of births (the coefficient of reduction of the apparent reproduction period) is related to the juvenile mortality rate and the ratio of the maximum number of juveniles to the total number of births. These relationships can be used to estimate the total number of births and the juvenile mortality rate from a series of counts of the juveniles. The simulation model used is programmed in CSMP-III.