Changes in the sex structure of pine populations related to temperature anomalies

The results of ten-year observations on fluctuations in the sex of individual trees and the sex structure of tree stands in two insular pine forests in the south of Central Siberia are presented. It is noted that the ratio of sex types of pine trees has markedly changed since 1998–1999. Significant correlations between the sex structure of stands and anomalies of the annual average air temperature have been recorded since the early 1990s. The male generative sphere of pine has changed to the greatest extent. Periodicity and delay in the change of shoot sexualization in response to changes in temperature are discussed.     

Monitoring of Orchid Populations in a Unique Area of Their Concentration in the Middle Urals

The abundance, density, structure, and dynamics of the populations of 11 rare orchid species are characterized on the basis of observations carried out in the eastern foothills of the Middle Urals from 1991 to 2002. The pattern of changes in the age structure of populations belonging to different ecobiomorphs is revealed. The concept of vegetatively oriented and generatively oriented age spectra of populations is proposed.     

The State of Protected Forest Communities in the European Forest–Steppe Zone of Russia and Prospects for Their Reconstruction: A Case Study of Specially Protected Areas of Penza Oblast

The structure of most forest communities in the European forest–steppe, including protected areas, has been disturbed. The adverse consequences of these disturbances include the incomplete age structure of the populations of cenosis-forming species and the irreversibility of successions. The conservation of biodiversity in the structurally disturbed communities is impossible without human intervention, which must be aimed at restoring their age heterogeneity with regard to their specific ecological features.     

Population structure and dynamics of Monotarsobius curtipes (Myriapoda, Chilopoda) at the northern periphery of the species range

Studies on the population structure and dynamics of the stone centipede Monotarsobius curtipes C. Koch in soils of the northern Kola Peninsula have shown that, with respect to abundance and biomass, this species is a dominant of the soil macrofauna and, in particular, of the trophic group of zoophages. Life in high northern latitudes does not disturb the sex and age structure of populations but limits the reproductive activity of these centipedes. Specific biological features of M. curtipes at the northern periphery of its range include the absence of repeated breeding, completion of several developmental (age) stages within a short growing season, and long ontogeny involving several winterings.     

Comparative Assessment of the State of Populations of the Ural Endemic Lagotis uralensisSchischk. in the Gradient of Altitudinal Zonality

The endemic species Lagotis uralensisis characterized with regard to the stages of ontogeny, population structure and dynamics, and the ways of species adaptation to growing in the form of small isolated populations in high mountains.     

Intrapopulation Variation and Interpopulation Phenetic Differentiation of Chum Salmon (Oncorhynchus keta Walbaum) in Populations of the Northern Sea of Okhotsk Region

The results of phenetic studies on chum salmon populations from the rivers flowing into Taui and Yama bays, Sea of Okhotsk, are discussed. The heterogeneity of samples with respect to the frequency of a certain phene in females is not necessarily revealed when this frequency is analyzed in males. Statistically significant heterogeneity with respect to phene frequencies is observed in all chum salmon populations, whether the corresponding data are analyzed by years or throughout the observation period. This population heterogeneity is accounted for by specific phenetic features of each chum salmon population, although in different years it manifests itself in the frequencies of different phenes. The phenes distinguished on the head of fish contribute most significantly to interpopulation differences.     

Ecological Analysis of Spleen Hypertrophy in Cyclomorphic Rodents Taking into Account the Type of Ontogeny

The functional approach at the level of physiological functional groups (PFGs) reflecting two types of ontogeny was used to analyze spleen hypertrophy in five species of rodents. In addition to a wide variation of spleen weight, its hypertrophy was observed: in bank voles (Clethrionomys glareolus), the spleen weight was as great as 3.5 g versus the normal value of 100–150 mg. The variation range of the relative spleen weight was estimated. For example, in the dominant species, C. glareolus, this range was considerable (from 2 to 125). A distinct relationship with the types of animal ontogeny was revealed. The genus specificity of the phenomenon—its occurrence in three species of Clethrionomys voles and absence in Microtus voles and mice—was determined in the study region. The animals with normal and hypertrophied spleens did not differ from each other significantly in their vital activity (at least, with respect to the parameters studied). The voles with hypertrophied spleens normally reproduced, and the hypertrophy was asymptomatic. These findings suggest that the populations have adapted to a damaging factor (or factors) in the course of a prolonged coevolution. This parameter is regarded as the indicator of the presence of a damaging factor in the population.     

Sea Otters (Enhydra lutris L.) of Bering Island, the Commander Islands: Age and Sex Composition of Dead Animals and Spatial Distribution

Animal censuses and assessment of mortality in the sea otter subpopulation of Bering Island (the Commander Islands) have shown that indices of seasonal mortality may be used as a criterion for estimating well-being of this animal group. In 1999, the subpopulation of Bering Island entered a phase of stabilization of its spatial, age, and sex structure, with the stabilization process proper taking approximately three years after a peak of mortality. Mortality in the course of this process proved to be relatively high in age groups older than eight years but insignificant among middle-aged reproductive animals. As the age and sex structure of the insular group varies during the year and in different coastal areas, the data obtained by collecting dead animals cannot be used for estimating the structure of the whole population.     

Assessment of the Age Structure of Sable Samples Using Three Methods of Age Determination

The age structure of sable samples has been analyzed on the basis of parameters obtained by three methods of age determination: by annual cementum layers (Klevezal, 1988), canine root canal width (Smirnov, 1960), and the degree of development of the mastication muscles and sagittal crest on the skull (Timofeev and Nadeev, 1955). It has been found that the first two methods produce similar results (r = 0.95) that are suitable for use in the practice of monitoring and commercial game management. The third method is simpler but less accurate and can be recommended only for the preliminary assessment of age ratios in populations. The results of such assessment by the method proposed by Klevezal are sufficiently accurate for a detailed analysis of population structure and dynamics of its reproductive core, but this method is laborious and involves a complicated histological procedure. When large samples are studied for the purposes of monitoring and management planning, the method proposed by Smirnov is preferable.     

Tree Ontogeny and Its Reflection in the Structure and Dynamics of Plant and Soil Covers

Based on the results of our own long-term experiments and the analysis of published data, the process of individual development (ontogeny) of trees and the parameters of ontogenetic stages are described. Changes in the environment-forming (edificatory) role of a tree in the course of ontogeny and upon its completion are characterized. The performance of this role leads to the formation of the following components of biogeocenosis heterogeneity: phytogenic fields of trees, gaps in the tree canopy, and windfall–soil complexes. The data concerning the interrelation of structural transformations of the plant and soil covers in the course of forest vegetation and soil formation on the primary substrate are reviewed.     

Ecomorphological Characteristics of the Marsh Frog Rana ridibunda from the Galich'ya Gora Nature Reserve

Russian Journal of Ecology -     

Dynamics of abundance and population structure of sea otters, <Emphasis Type=Italic>Enhydra lutris</Emphasis> L., on the Commander Archipelago and activity of their migrations between Islands

Fluctuations in the abundance of insular groups of sea otters on the Commander Archipelago are analyzed with regard to changes in meteorological conditions. The main factors responsible for the abrupt decline of the Bering Sea group between 2002 and 2004 are discussed. A statistically significant correlation has been revealed between fluctuations of sea otter abundance and the cycles of solar activity in the period since 1992. Changes in the age and sex structure of the insular groups of sea otters are evaluated.     

Ecological and genetic characteristics of the distribution of <Emphasis Type="Italic">Bradybaena fruticum</Emphasis> Mull. (mollusca,gastropoda, pulmonata) in a forest-steppe landscape

The distribution pattern of the gastropod Bradybaena fruticum has been studied in a forest-steppe landscape. Analysis of the frequencies of polymorphic biochemical and conchological characters has yielded preliminary results on the characteristics of the species population structure whose formation was determined by a set of natural and anthropogenic factors.Translated from Ekologiya, No. 1, 2005, pp. 39–47.Original Russian Text Copyright © 2005 by Snegin.     

Specific Anatomical Features of Vegetative Organs in Some Macrophyte Species under Conditions of Industrial Pollution

Russian Journal of Ecology -     

Natural Movements of Tagged Beavers in Tyva

Ninety-three beavers were tagged in 1998–2000 on the Azas River (Tyva Republic), and 28 returns were obtained within one to two years. The results of the study indicated that, unfavorable environment notwithstanding, most beavers did not move outside their settlements. Animals under two years of age were especially active. Females were more resident, whereas males migrated over longer distances. The section of the Azas River with numerous rapids was not an insuperable obstacle for the animals; genetic exchange between the upper and lower subpopulations was found to occur through this section.     

Experimental Study on the Effects of Population Density of Bloodsucking Mosquito (Aedes communis Deg.) Larvae on Their Biological Characteristics

Results of laboratory experiments on the effects of population density of Aedes communis Deg. larvae on their growth, survival, and sex ratio are presented. At the highest density, larval mortality increased by factors of 1.5 and 2.2, the duration of preimaginal development increased significantly, and the weight of pupae was 11 and 14.7% smaller than in low-density populations. The sex ratio was the same in both cases. The absolute numbers and the biomass of insects per cultivation vessel were greater in high-density populations.     

人口年龄结构、人口迁移与东北经济增长

近些年来,中国东北地区经济增速的迅速下滑引发了广泛关注,与此同时,东北地区的人口老龄化与人口流失局面也在加速发展,为探究二者间的联系,本文在梳理文献的基础上,选择从人口年龄结构和人口迁移的视角切入,利用扩展的索洛模型推导了各变量与人均资本、人均产出间的关系。并通过对地级市面板数据的一阶系统广义矩估计研究了人口年龄结构,人口迁移等变量对东北经济增长的影响及经济增长对人口迁移的反作用,利用交叉项分析探讨了人口因素对东北不同经济发展水平地区的差异化影响。实证发现:1劳动年龄人口占比与东北经济增长成正相关,而人口老龄化与人口净迁出均对东北经济增长产生了不利影响;2相较于一般性的人口流动,户籍人口的净迁出对经济增长的不利影响更突出;3人口年龄结构与人口迁移对发达地区和落后地区产生的影响会有所差异;4东北经济增长存在惯性且符合区域增长收敛理论;5投资率与劳动力参与率这两个变量则未能通过显著性检验。6经济增长也对人口迁移产生了一定的反作用。在此基础上,本文针对性地提出了一些建议:1东北地区应及时科学综合地应对人口老龄化,开发老龄人力资源,调整人口政策,平衡地区间养老压力,发展老龄产业;2东北地区应控制人口流失局面,放宽户籍限制,加快国企改革,形成合理的产业结构与制度环境,留住人才。     

重庆四面山杉木林优势种群径级结构与空间分布格局

种群空间格局分析有利于更好地理解格局形成的潜在生态过程。本研究以重庆四面山杉木林为研究对象,采用单变量和双变量函数分析了样地中杉木林主要种群的空间分布格局以及种群间的空间关联性。结果表明:(1)四面山杉木林共调查到乔木65种、灌木31种、草本20种。杉木种群径级结构呈衰退型,表现为以大树为主,中树次之,无小树;腺萼马银花、元江栲、细枝柃等种群径级结构呈增长型,表现为以小树、中树为主,大树次之。(2)在0~25 m尺度内,杉木种群呈随机分布,栲和元江栲呈聚集分布,而腺萼马银花、细枝柃、光叶山矾和长蕊杜鹃等4个种群则在小尺度下呈聚集分布,随着尺度的增大,呈现出随机分布的趋势。(3)生物学特性以及生境因子的差异导致杉木林主要种群间空间关联差异较大,杉木与元江栲和腺萼马银花种群之间呈负相关,而与光叶山矾、栲和长蕊杜鹃种群呈无相关,因此,在该区杉木纯林的近自然改造上,应优先考虑竞争力强的乡土树种,如长蕊杜鹃、栲、光叶山矾等进行混交。