西藏色季拉山川滇高山栎种群的空间格局与调节

川滇高山栎是青藏高原具有代表性的常绿阔叶树种,在藏东南林区大面积连续分布,对高山峡谷地带的水土保持和水源涵养具有重要的防护作用和较大的生态效益.采用聚集度指标、以空间推时间法的Logistic方程和种群调节的乘幂函数拟合分别对西藏色季拉山川滇高山栎种群的空间分布格局、增长与调节规律进行了研究.结果表明,川滇高山栎幼苗多呈聚集分布,随着演替的进展,川滇高山栎种群的聚集强度减小;川滇高山栎种群增长的环境容纳量为15.2085m2hm-2,内禀增长率为0.614;种群最大增长速率出现在胸断面积9.66m2hm-2处,种群在平均胸断面积46.23cm2(均胸径7cm)~198.723cm2(均胸径15.91cm)阶段自疏强度最大.川滇高山栎种群聚集强度随演替过程逐渐减弱,是种群在有限的环境容量中自疏和自我调节特征的明显表现.Logistic方程即反映了生物种群增长速度的变化和环境容量限制的时滞效应这一重要特征,种群调节的幂函数拟合则有效刻画了生物种群在大量繁殖之后,随着个体增大,个体间资源竞争增强,种群内部出现优胜劣汰的自我调节过程.图4表2参32     

Energy,population, and agricultural productivity in Iran

Solar energy feeds all life on this planet's surface. The energy of the Sun can be tapped and converted to the different forms of energy by renewable energy systems, such as solar power plants, photovoltaic systems, and plants. Land is needed for food production, which is the most globally important activity. With increasing population, the required area is determined by consumption and production patterns. The world is globally divided into poor and rich areas of production and consumption, which have large differences. Iran's energy and food production and consumption are studied and compare with poor and rich examples. It is concluded that available agricultural land is limited and currently declining per capita due to population growth. The expansion of irrigated crop area, high-quality seed, and modern farming techniques can marginally improve agricultural productivity and provide relative self-sufficiency in grain production. Much of the growth in Iran's renewable energy is attributed to hydroelectricity power plants. Solar energy, wind, hydro and geothermal energy are also potential forms of sustainable energy in Iran.     

Conserving Slow-Growing, Long-Lived Tree Species: Input from the Demography of a Rare Understory Conifer, Taxus floridana

Abstract:  Although land preservation and promotion of successful regeneration are important conservation actions, their ability to increase population growth rates of slow-growing, long-lived trees is limited. We investigated the demography of Taxus floridana Nutt., a rare understory conifer, in three populations in different ravine forests spanning its entire geographic range along the Apalachicola River Bluffs in northern Florida (U.S.A.). We examined spatial and temporal patterns in demographic parameters and projected population growth rates by using four years of data on the recruitment and survival of seedlings and established stems, and on diameter growth from cross-sections of dead stems. All populations experienced a roughly 10-fold increase in seedling recruitment in 1996 compared with other years. The fates of seedlings and stems between 8 and 16 mm differed among populations. The fates of stems in two other size classes (the 2- to 4-mm class and the 4- to 8-mm class) differed among both populations and years. Individual stems in all populations exhibited similarly slow growth rates. Stochastic matrix models projected declines in all populations. Stochastic matrix analysis revealed the high elasticity of a measure of stochastic population growth rate to perturbations in the stasis of large reproductive stems for all populations. Additional analyses also indicated that occasional episodes of high recruitment do not greatly affect population growth rates. Conservation efforts directed at long-lived, slow-growing rare plants like Taxus floridana should both protect established reproductive individuals and further enhance survival of individuals in other life-history stages, such as juveniles, that often do not appear to contribute greatly to population growth rates.     

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     

Indigenous Uses, Population Density, and Conservation of Threatened Medicinal Plants in Protected Areas of the Indian Himalayas

Abstract:  For 10 years I monitored the population density of threatened medicinal plant species in seven protected areas in the Indian Himalayas. I also documented the indigenous uses of threatened medicinal plants through interviews with 138 herbal healers (83 Tibetan healers and 55 Ayurvedic healers) residing in the buffer zone villages of these protected areas. To assess the population status of threatened medicinal plant species, I sampled the 10 major habitat types in the protected areas. In all, I found 60 threatened medicinal plant species during the study period, of which 54 species occurred in the sampling plots. Twenty-two percent of threatened medicinal plant species were critically endangered, 16% were endangered, and 27% were vulnerable. Thirty-two threatened medicinal plant species were endemic to the Himalayan region. The density of threatened medicinal plant species varied with protected areas. The Valley of Flowers protected area had the highest number of threatened medicinal plant species. The "moist" habitat type was richest in these species among all 10 habitat types sampled. Arnebia euchroma (Royle ex Benth.) Johnston and Ephedra gerardiana Wall. ex Stapf. were the most common threatened medicinal plant species. The indigenous groups of healers used these threatened species in curing about 45 different ailments. Based on my findings, I believe that to ensure the long-term sustainability of threatened medicinal plants, medicinal-plant conservation areas should be established.     

Catastrophic Reproductive Failure, Terrestrial Survival, and Persistence of the Marbled Salamander

Abstract:  Wide variation in reproductive success is common among amphibians that breed in seasonal ponds, but persistence of adults can buffer against these fluctuations, particularly for long-lived species. We hypothesized that the frequent episodes of catastrophic failure of the marbled salamander ( Ambystoma opacum ) enhance the importance of high terrestrial survival. At Rainbow Bay in South Carolina reproductive success was poor (<1 metamorph/breeding female) in nearly half of the 22 years that the species bred. Complete failure occurred in 6 of 22 years. To study catastrophic failure, we adapted an age-structured, individual-based model with density-dependent growth and survival of larvae. The model was based on extensive data from local field studies and experiments. With consistently good survival in the pond stages, the simulated population required survival probabilities in the upland stages (juveniles and adults) near 0.5/year to persist and near 0.8/year to achieve the increases observed. Catastrophic failure, occurring randomly with probability 0.5/year, created additional fluctuations in the population, raised the thresholds of survival required for persistence, and caused extinction under conditions that were otherwise favorable. The marbled salamander at Rainbow Bay is not at great risk of extinction because of catastrophic failure, but the risk increases dramatically if life span is decreased or frequency of failure is increased. Any reduction in terrestrial survival will have deleterious consequences by reducing the breeding populations at equilibrium, even if it does not jeopardize persistence. Our model provides assessments of risk that can be applied to poorly studied species with similar life histories, such as the endangered flatwoods salamander ( A. cingulatum ).     

广东人口粮食动态模型的建立及土地生产力分析

对我省的人口发展和粮食生产进行了系统的分析和研究,结果表明广东人口将在2005年底达到8000万人,比过去人口的增长速度明显加快;而粮食生产却不容乐观,到2015年最多只能达到年产2670万t的水平,人均粮食约280 kg,比目前水平略低。从长远来考虑,我省的粮食问题将更显不足,而耕地又逐年减少,故提高土地利用率和生产水平是目前迫切需要解决的实际问题。     

Regional Consequences of Local Population Demography and Genetics in Relation to Habitat Management in Gentiana pneumonanthe

Abstract:  A joint demographic and population genetics stage-based model for a subdivided population was applied to Gentiana pneumonanthe , an early successional perennial herb, at a regional (metapopulation) scale. We used numerical simulations to determine the optimal frequency of habitat disturbance (sod cutting) and the intensity of gene flow among populations of G. pneumonanthe to manage both population viability and genetic diversity in this species. The simulations showed that even small populations that initially had near-equal allele frequencies could, if managed properly through sod cutting every 6 to 7 years, sustain their high genetic variation over the long run without gene flow. The more the allele frequencies in the small populations are skewed, however, the higher the probability that in the absence of gene flow, some alleles will be lost and within-population genetic variation will decrease even under proper management. This implies that although local population dynamics should be the major target for management, regional dynamics become important when habitat fragmentation and decreased population size lead to the loss of local genetic diversity. The recommended strategy to improve genetic composition of small populations is the introduction of seeds or seedlings of nonlocal origin.     

青海三江源区植被退化对土壤养分和微生物区系的影响

采用化学分析法、微生物平皿分离计数和形态鉴定技术研究了青海三江源地区天然与退化植被下的土壤养分和微生物生态特征。结果表明,随着三江源地区天然草地植被退化,土壤有机质含量急剧下降,退化高山草甸土的有机质平均含量为14.85gkg-1,较天然高山草甸土的平均含量降低54.3%,较高山草原土和沼泽化草甸土分别降低74.5%和90.7%,其他养分含量也有不同程度的降低,土壤养分状况明显恶化.不同类型植被下土壤微生物区系特征变化显著,退化高山草甸土的细菌、真菌、放线菌(GA)平均数量分别为8.8×106、9.5×103、8.1×105cfug-1,较天然高山草甸土降低65.8%、46.6%、57.3%,较高山草原土降低37.1%、23.3%、62.6%,较沼泽化草甸土降低90.3%、48.1%、69.6%;退化草地土壤微生物组成较天然草地更为简单,退化高山草甸土的真菌种类数明显降低,土壤放线菌组成趋于简单化,其小单孢菌和其他菌属所占比例明显低于天然草地.三江源高寒湿地生态系统中土壤养分与微生物数量之间存在密切关系,土壤全磷对微生物数量影响最大.     

粤北2座饮用水源地水库的富营养化与浮游植物群落动态

粤北地区的水库以山地型水库为主,其中有不少担负着饮用水源的功能。为了解粤北地区水源地水库的富营养化状态与浮游植物种群的动态变化,于2011年的枯水期（2―3月）和丰水期（6―7月）对花山和白水礤2座中型水库进行了采样调查,对水库的营养盐和浮游植物种群进行了分析。结果表明：2座水库均为贫营养型;浮游植物在枯水期和丰水期的种类变化不大,共鉴定出的浮游植物6门37种（属）,以硅藻为主要优势种群,优势种为小环藻（Cyclotella sp.）和颗粒直链藻（Melosira granulata）。同时,枯水期和丰水期2座水库浮游植物的丰度和生物量都比较低,其值分别为0.65×106～1.95×106cells.L-1、0.11 mg.L-1和0.73×106～8.9×106cells.L-1、0.05～0.50 mg.L-1。在浮游植物种群动态中,2座水库浮游植物丰度和生物量的季节变化主要表现为硅藻丰度和生物量的变化,低浓度的氮、磷营养盐限制是影响这2座贫营养水库浮游植物动态变化主要因素。     

三峡水库香溪河库湾氮磷分布状况及沉积物污染评价

为了解三峡大坝蓄水完成之后香溪河库湾水体及沉积物中氮、磷的分布状况以及沉积物污染水平,2013年4月对三峡水库香溪河库湾进行调查采样,测定表层水及沉积物中氮磷含量和形态组成。结果表明,香溪河库湾表层水总磷(TP)含量范围为0.20~0.51 mg·L~(-1),总氮(TN)含量范围为0.54~2.25 mg·L~(-1),TP主要由磷酸盐(PO_4~(3-))组成,TN主要由硝酸盐(NO_3~-)以及氨氮(NH_4~+)组成,TP在空间上呈现从河口向库尾逐渐升高的分布格局,TN分布从河口向库尾逐渐降低。香溪河库湾沉积物中TP含量变化范围为642~1 189 mg·kg~(-1),TN含量变化范围为867~1 718 mg·kg~(-1),沉积物TP含量分布呈现上游高下游低,沉积物TN分布趋势呈现中间高,两头低。沉积物中TP主要由无机磷(IP)组成,有机磷(OP)所占比例较小,其中IP由钙磷(Ca-P)、铁铝磷(Fe/Al-P)组成,三者含量:Ca-POPFe/Al-P,且沉积物TP含量空间变化受到三者影响(P0.05)。采用单一因子标准指数法对香溪河库湾沉积物中TN、TP污染水平进行评价,结果表明,表层沉积物中TN、TP最低级别污染指数平均值为2.0和1.6,表层沉积物中TN、TP污染指数均超过最低污染水平,且TP的严重级别污染指数达到0.5以上。三峡水库三期蓄水完成以后,香溪河库湾表层水体中氮磷含量较初期蓄水有所升高,各样点沉积物中氮磷含量表现出相同的趋势,沉积物中不稳定磷释放对水体富营养化具有影响,香溪河库湾的表层沉积物已经受到一定的污染,磷污染水平较高。     

镉、汞、铅和石油烃复合污染对渤海湾常见渔业资源生物的影响初探(Effects of the Combined Pollution of Cd, Hg, Pb and Petroleum Hydrocarbons on Common Fishery Species in the Bohai Bay)

通过对1996～2005年渤海湾近岸海域海水镉、汞、铅和石油烃浓度变化的分析,发现海水中镉浓度呈明显上升趋势,汞、铅和石油烃则无明显变化趋势.加速生命试验法模型(Accelerated Life Testing model)的研究显示,1996～2005年渤海湾近岸海域海水镉、汞和铅平均浓度均已超过其对渤海湾常见渔业资源生物的安全浓度.镉、汞、铅和石油烃对生物的长期致死率鱼类分别为4.5%、16.3%、0.0%和12.0%,甲壳类为0.4%、7.9%、0.3%和6.6%,双壳类为10.5%、0.2%、0.2%和2.3%.效应加和模型(Independence Action model)的估算表明,在镉、汞、铅和石油烃组成的复合污染条件下,渤海湾常见鱼类、甲壳类和双壳类的长期死亡率分别为29.7%、14.6%和12.9%,其种群增长率分别降低约6.4%、14.6%和12.9%.与镉、汞、铅和石油烃单种污染物暴露相比,其复合污染导致的渤海湾常见渔业资源生物种群(鱼类、甲壳类和双壳类)增长率的降低更明显.因此,复合污染是导致渤海湾渔业资源衰退的重要因素。     

Invasion, Disturbance, and Competition: Modeling the Fate of Coastal Plant Populations

Abstract:  Wetland habitats are besieged by biotic and abiotic disturbances such as invasive species, hurricanes, habitat fragmentation, and salinization. Predicting how these factors will alter local population dynamics and community structure is a monumental challenge. By examining ecologically similar congeners, such as Iris hexagona and I. pseudacorus (which reproduce clonally and sexually and tolerate a wide range of environmental conditions), one can identify life-history traits that are most influential to population growth and viability. We combined empirical data and stage-structured matrix models to investigate the demographic responses of native ( I. hexagona ) and invasive ( I. pseudacorus ) plant populations to hurricanes and salinity stress in freshwater and brackish wetlands. In our models I. hexagona and I. pseudacorus responded differently to salinity stress, and species coexistence was rare. In 82% of computer simulations of freshwater marsh, invasive iris populations excluded the native species within 50 years, whereas native populations excluded the invasive species in 99% of the simulations in brackish marsh. The occurrence of hurricanes allowed the species to coexist, and species persistence was determined by the length of time it took the ecosystem to recover. Rapid recovery (2 years) favored the invasive species, whereas gradual recovery (30 years) favored the native species. Little is known about the effects of hurricanes on competitive interactions between native and invasive plant species in marsh ecosystems. Our models contribute new insight into the relationship between environmental disturbance and invasion and demonstrate how influential abiotic factors such as climate change will be in determining interspecific interactions.     

Exploring Population Dynamics Patterns in a Rare Fish, Zingel asper, through Capture-Mark-Recapture Methods

Abstract:  We performed a capture-mark-recapture study on one of the last populations of Zingel asper , an endemic percid species of the Rhône River basin in France. The distribution of Z. asper has decreased dramatically during the last century. We sampled three sites in suitable habitats in the Beaume River. No impact of individual tagging on survival was found. The demography of the population was analyzed using capture-recapture methods that allow the estimation of survival, recruitment, and demographic growth rates. Annual survival rates were low (0.35–0.50). The level of transience was high (5% to 25%), suggesting that a significant number of individuals were highly mobile or shifted to suboptimal habitats. Seniority rates suggested random highly variable recruitment between years. The three sites had similar variation patterns in all demographic parameters, indicating broad spatial covariation in population dynamics. We found some local differences in demographic parameters, which could be linked to local habitat quality. Individual tagging allowed for the estimation of demographic parameters that improved our understanding of Z. asper population dynamics and revealed mechanisms that may affect population persistence, such as stochastic recruitment, low survival, and frequent dispersal. The fragmentation of habitat through river damming inhibits dispersal and represents a threat to the persistence of Z. asper in the Rhône basin. Our results offer evidence of the importance of dispersal in nonmigratory fishes and confirm the usefulness of individual tagging methods in rare fish demography.     

Demographic Characteristics of Extinction in a Small, Insular Population of House Sparrows in Northern Norway

Abstract:  In conservation ecology there is an urgent need for indicators that can be used to predict the risk of extinction of populations. Identifying extinction-prone populations has been difficult because few data sets on the demographic characteristics of the final stage to extinction are available and because of problems in separating out stochastic effects from changes in the expected dynamics. We documented the demographic changes that occurred during the period prior to extinction of a small island population of House Sparrows ( Passer domesticus ) after the end of permanent human settlement. A mark-recapture analysis revealed that this decline to extinction was mainly due to increased mortality after closure of the last farm that resulted in a negative long-term-specific growth rate. No change occurred in either the structural composition (breeding sex ratio and age distribution) of the population or in female recruitment. No male, however, recruits were produced on the island after the farm closure. Based on a simple, stochastic, density-dependent model we constructed a population prediction interval (PPI) to estimate the time to extinction. The 95% PPI slightly overestimated the time to extinction with large uncertainty in predictions, especially due to the influence of demographic stochasticity and parameter drift. Our results strongly emphasize the importance of access to data on temporal variation that can be used to parameterize simple population models that allow estimation of critical parameters for credible prediction of time to extinction.     

安徽省宣州扬子鳄饲养种群繁殖现状分析

对１９９３ ～１９９８ 年安徽省扬子鳄繁殖研究中心内的亲代与子代鳄的繁殖情况进行了统计研究,结果表明：扬子鳄亲代卵的平均受精率为（７５．６６±２．２９） ％ ,子一代为（６９ ．２４ ±５ ．１２） ％ ,经ｔ 检验,两者差异显著;亲代产卵孵化幼鳄的平均畸形率为（０．３０ ±０．２０） ％ ,而子一代产卵幼鳄平均畸形率为（１ ．８５±０．９５） ％ ,经ｔ 检验,两者差异显著．但受精卵幼鳄孵化率在两代间差异不显著．通过饲养种群的家系和有效群体大小分析,作者认为造成子代鳄的繁殖率下降和畸形率上升的原因与近亲繁殖有关．对扬子鳄的遗传保护研究提出了建议．     

关中-天水经济区人口-经济-生态协调发展研究

在经济迅速发展的背景下,我国人口、经济和生态的矛盾日益突出。选择关中-天水经济区为研究对象,基于变异系数的协调函数模型对其人口-经济-生态协调度进行了测算。结果表明：1）1999—2008年,关中-天水经济区各地市人口-经济-生态协调度整体呈现上升的趋势,总体由失调状态转向勉强协调,其中天水市呈直线上升趋势,咸阳、宝鸡、铜川3市的协调度在波动中有所增加,西安市变化幅度不大;2）人口、经济、生态3个子系统的变化都会影响到整个系统的变化,西安市生态子系统协调度的下降,制约了整个系统的协调发展;3）协调度在空间上表现为关中-天水经济区中部地市的协调度较高,渭南和天水市的协调度始终处于该地区的较低水平。     

桂西南喀斯特区域群落主要环境因子及稳定性对飞机草入侵的影响

为揭示桂西南喀斯特区域群落主要环境因子及稳定性对飞机草（Eupatorium odoratum）入侵的影响,本文通过对群落生存状况、土壤环境因子的调查分析,研究群落的稳定性特征,探讨不同植物群落对外来入侵种飞机草生长扩散的影响。结果发现：植物群落内本地种盖度、群落高度等与飞机草的盖度和多度呈极显著的负相关关系,说明本地种的生长能对飞机草的入侵产生显著影响,其中光因子可能是影响飞机草生长的主导因子和限制因子;本地物种多样性对飞机草的盖度和多度影响也较显著,说明本地种多样性能有效抵御飞机草入侵;人为干扰对飞机草的盖度和多度则呈极显著的正相关关系,说明干扰能促进飞机草的入侵;土壤速效氮含量、土壤含水量、有机质含量和与飞机草的盖度和多度的关系均呈显著负相关关系,可能是由于群落内肥水充裕程度与调节飞机草生长的主导因子光水平呈负相关关系造成的。群落的稳定性与飞机草的盖度和多度呈极显著的相关关系,说明稳定性较高的群落更能有效的抵御飞机草的入侵,稳定性较低的群落更容易受到飞机草的入侵。     

Small Populations and Offspring Sex-Ratio Deviations in Eagles

Abstract:  Stochastic variation of sex ratio has long been appreciated as a potential factor driving small populations to extinction, but it is not the only source of sex-ratio bias in small populations. We examined whether some consequences of sex allocation could affect extinction risk in small populations of size-dimorphic birds such as eagles. We report variations in sex ratio at fledging from a long-term study of a declining population of Spanish Imperial Eagles ( Aquila adalberti ). Nestling sex-ratio deviation apparently was mediated by age of breeders, whereas territory quality had no obvious effect. Adult–adult pairs produced the same proportion of both sexes in high- or low-density situations, but pairs with at least one member in nonadult plumage class produced more males. As the population declined over a period of years, the proportion of breeders with immature plumage increased; consequently, the proportion of fledgling males increased. However, when population density was high, the proportion of breeders with immature plumage decreased and more female offspring were produced. This relationship between population density, composition of breeder age, and fledgling sex ratios allowed us to make predictions of extinction risk due to nonstochastic deviations of sex ratio in small, declining populations. In the study population, on the basis of the Vortex simulation results, an estimated reduction of 42.5% in predicted mean time to extinction was attributed solely to biased sex ratio.