首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
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.  相似文献   

2.
The cyclicity of population dynamics of abundance has been analyzed in sympatric adult populations of three odonate species monitored for long time (1980–2010) in the Lake Chany basin (Western Siberia). The spectra of odonate population dynamics have been constructed for the first time and shown to be species-specific: each species has its own population cycles, and if the cycles are similar, interspecific differences manifest themselves in the relative power of these cycles. These differences provide for separation of species in time, reducing the stress of competition between them. The population rhythms of all studied species show synchronicity with natural rhythms that are important to them, such as fluctuations of climatic parameters (2–3 year cycles) and hydrological parameters of Lake Chany (2–4-year cycles).  相似文献   

3.
The paper is devoted to the ecology of the Pied Flycatcher in Southern Karelia, where climate warming has had almost no effect on the weather in spring, the season especially important for birds. During the 30-year observation period, the local population has been characterized by variable breeding phenology, high fecundity, and relatively stable abundance. This appears to be related to the broad norm of reaction of this species to the action of external factors, which allows the birds to flexibly respond to changes in the unstable spring weather and adjust the timing and rates of their seasonal activities.  相似文献   

4.
The decline of spruce stands in Belarus has been analyzed in relation to the dynamics of climatic variables. The results show that this process is correlated with the amount of precipitation, moisture deficit, index of aridity, relative air humidity, and evapotranspiration. Frosts at the onset of the growing season enhance tree die-off, while increase in cloud cover has a favorable effect on the state of spruce stands. Damage to trees occurs mainly in areas with elevated and convex topography and slopes of southwestern aspect, increasing on steeper slopes. The level of die-off is most closely correlated with conditions of the previous year, which is explained by the impact of biological factors (pest insects and phytopathogens) on tree stands already affected by water stress. The decline of spruce stands on a mass scale is also observed in neighboring regions of Russia and counties of East Europe, which is evidence for a low adaptability of spruce to current climate change, including the increasing frequency and severity of dry periods.  相似文献   

5.
Variability of the length of the white area on the outermost quill feathers of the great tit from two cities in the Middle Ural has been investigated. Dynamics of the average length of the white area in the birds from the city of Asbest reproduced the dynamics observed in the city of Yekaterinburg with a one-year lag in the females and a two-year lag in the males. Phenotypic changes in the great tit population did not occur simultaneously in the whole population, but rather moved along the living range with a certain velocity (50–60 km/year for the females and 25–30 km/year for the males). The results obtained are discussed in view of the concepts of population biology.  相似文献   

6.
The dispersal, population dynamics, and ecological features of the European roe deer at the northern limit of species distribution and also their visits, wintering, and breeding outside the range boundary are discussed. A significant increase in the abundance of roe deer in the northern part of the range and their largescale expansion beyond the historical distribution limit have taken place during the past decade. However, their spread in Karelia and Arkhangelsk oblast is strictly limited, depending primarily on snow depth and duration. Hunting the roe deer as a game species in the region is possible only in the south of Pskov oblast, where habitat conditions are most favorable for it.  相似文献   

7.
The population of foxes in the central regions of Yakutia has grown by a factor of four to five during the period from 2000 to 2011–2012, following an increase in the abundance of voles from the genus Microtus. A total of 130 carcasses of foxes taken in 2007–2012 have been examined. Age- and sex-related variation in morphological features has been described. The demographic structure of the population has been studied by estimating animal age from annual layers in the recording structures. Changes in female fertility and involvement in reproduction depending on age and feeding conditions have been analyzed. Changes in the composition of fox diet caused by long-term population depression in the mountain hare and their effect on the dynamics of fox abundance have been revealed. Age- and sex-related characteristics of the condition factor in foxes and sex-related differences in their dietary preferences have been demonstrated.  相似文献   

8.
Demographic structure and its seasonal dynamics have been studied in colonies of narrow-skulled voles (Lasiopodomys gregalis Pall.) in Northern Kulunda. Three types of colonies have been distinguished: (I) true colonies (large, complex families), (II) simple families (nuclear or incomplete), and (III) all-male colonies. Changes in their sex, age, and functional composition (based on animal migration activity) during the breeding season have been analyzed.  相似文献   

9.
The results of long-term bird censuses in the Ilmen State Reserve are presented. Analysis of dynamic processes in the forest ornithocomplexes has shown that factors influencing changes in the abundance of birds in multispecies communities have unequal effects on different species. It has been found that the abundance dynamics of some species is correlated with spring meteorological parameters and the timing of phenological phases.  相似文献   

10.
Adaptive strategies of cyclomorphic rodent populations (Rodentia) under extreme conditions of droughts (in 1975 and 2010) have been analyzed on the basis of functional–ontogenetic approach. The following features of these strategies have been revealed: minimization of metabolic processes, block of sexual maturation, intergenerational crossing, prolongation of breeding period, and species-specific features in the dynamics of intrapopulation processes. Profound changes in the level of long-term oscillations of abundance after the drought have been noted in different species. Evidence is provided for the possibility of extremely rapid population rearrangements on an evolutionary scale that are fixed in a series of generations.  相似文献   

11.
Quantitative data of winter bird censuses in forest habitats of the Ilmen Nature Reserve (1986–2010) have been analyzed with regard to changes in the monthly average, maximum, and minimum temperatures and precipitation in the period from December to February. No warming trend has been revealed in the reserve over the study period, The dynamics of bird population structure in winter has proved to be independent of weather conditions, despite significant interannual fluctuations. The most significant factors of long-term dynamics of abundance of wintering birds include population density in the previous nesting period, the seed yield of the main food plants, and local migration of wintering species.  相似文献   

12.
长江近口段沿岸刀鲚生物量的时间格局   总被引:1,自引:0,他引:1  
为了解长江刀鲚Coilia nasus资源的变动状况,探讨沿岸水域对刀鲚资源的保育作用,于2002~2013年间用定制张网对长江靖江段沿岸鱼类作了每月2~3个样本的采集。分析结果显示,12a采集的369份样品中,刀鲚的出现频率达94.6%,分别占总渔获数量和重量的5.18%和5.46%。刀鲚平均CPUEN和CPUEW有16.7±19.9尾和106.6±109.5g,是沿岸鱼类群聚的优势种或次优势种。但其年资源量并不稳定,最高的2010年是最低2002年的5.4陪。平均体长123.6±37.0mm,平均体重仅7.5±8.2g。0+龄组占78.9%,1+龄组占20.7%,2+龄仅出现在4、5月份,且仅占当月个体数的3.0%,幼体是沿岸刀鲚群体的主要组成成分。从0+龄个体的月度体长分布看,当年孵化的幼鱼大多栖息在河岸水域,沿岸生境在维持刀鲚幼鱼资源上具有重要作用。分析显示,4月1日至6月30日的长江禁渔期虽可保护约42.6%的幼鱼个体,但从保护效果看,还因适当延长沿岸水域的禁渔时间。维护沿岸水域的生境完整性,也是保护长江刀鲚幼鱼资源的重要措施。  相似文献   

13.
The effect of rise in spring air temperature on the breeding phenology and reproductive success of the Song Thrush in the Voronezh Nature Reserve have been studied over the periods of 1987 to 1990 and 2008 to 2012. The results show that relatively high air temperatures provide for earlier arrival of the birds from wintering grounds, earlier and more synchronous breeding of the majority of nesting pairs, and an increase in clutch size and proportion of pairs producing two broods per season. Predation pressure on bird nests decreases under such conditions, which markedly improves reproductive success. Climate warming is conducive to increasing breeding productivity of the Song Thrush population as a whole.  相似文献   

14.
Chromosome aberration frequency in relation to population dynamics and demographic parameters was studied for six years in a bank vole population in the Middle Urals. The frequencies of structural chromosome aberrations, chromatid gaps, aneuploidy, and polyploidy in males and females and in animals of different ages did not differ significantly. In the breeding period, the frequencies of structural aberrations and changes in chromosome number increased in the somatic cells of voles. Highly significant differences between the levels of chromosome instability in different years manifested a tendency toward a negative correlation with population size.  相似文献   

15.
The data on the dynamics of population size and species composition of wasps from the families Pompilidae, Sphecidae, and Vespidae were obtained in the course of long-term studies carried out in successional pine forests of the Berezinskii Biosphere Reserve. The abundance and species diversity of wasps were significantly higher in a polewood forest (40 years) than in a young forest (20 years) and mature moss forest (70 years). In an overgrown ride in the moss pine forest, the composition of dominant wasp species remained relatively stable during the seven-year period of observations, although the number of species and their abundance varied significantly from year to year, depending on the weather.  相似文献   

16.
2010年9月~2012年8月在长江上游攀枝花等9个采样点收集到长薄鳅(Leptobotia elongata Bleeker)样本1 528尾,基于体长频率数据采用世界粮农组织(FAO)开发的FiSAT II软件研究了长江上游长薄鳅的生长与种群参数。估算结果显示长薄鳅的极限体长(L∞)为6561 mm,生长系数(k)为015/a,理论生长起点年龄(t0)为-0048 a。采用Pauly的经验公式估算长薄鳅的自然死亡系数(M)为033(其中长江上游年平均水温为184℃),总死亡系数(Z)、捕捞死亡系数(F)和开发率(E)分别为085、053和062。2010~2011年长江上游长薄鳅年均资源重量和资源数量分别为1321 t和162 862尾,最大可持续产量(MSY)为517 t。经相关估算参数和相对单位补充渔获量分析得出,当前长江上游长薄鳅已处于过度捕捞状态,有必要采取有效保护措施  相似文献   

17.
长江靖江段沿岸似鳊生长及种群参数估算   总被引:2,自引:0,他引:2  
2012年1月~2013年12月连续24个月在长江靖江段沿岸收集似鳊标本2 334尾,采用基于体长频率数据的ELEFAN I技术估算长江近口段沿岸似鳊的生长参数与种群参数。结果表明:似鳊体长(L,cm)与体质量(W,g)幂函数关系为:W=0.0182×L~(2.948)(r=0.9823,n=2334)。Von Bertalanffy生长方程描述的似鳊生长参数为:极限体长(L_∞)=19.25 cm,生长系数(K)=0.2/a,理论生长起点年龄(t_0)为-1.59 a,体质量的生长拐点年龄为3.55 a。采用Pauly的经验公式估算似鳊自然死亡系数(M)为0.556/a。由长度变换渔获曲线法估算出的似鳊总死亡系数(Z)为1.638/a,捕捞死亡系数(F)和开发率(E)分别为1.082/a和0.66/a。2012~2013年长江靖江段沿岸似鳊年均资源重量和资源数量分别为120.59 t和947.4万尾。经相关估算参数和相对单位补充渔获量分析得出,当前长江靖江段沿岸似鳊已处于过度捕捞状态。建议将沿岸水域禁渔期延长至9月(即4~9月),以实现似鳊资源的恢复和可持续发展。  相似文献   

18.
Two alternative ontogenetic pathways regularly effected in the populations of small mammals are analyzed as a manifestation of developmental multiversality. The types of ontogeny in rodents are characterized. These data are reflected in the concept of the functional approach. Multiversality of development in plants and animals is considered. Based on the results of long-term (26-year) observations on the natural populations of six rodent species, the dynamics of relationships between the types of ontogeny, abundance, and basic population parameters are analyzed using an example of a background species (Clethrionomys glareolus). A trigger mechanism of switching to a certain type of ontogeny, the role of environmental factors in actuating this mechanism, and the role of the genotype as a basis of multivalence are discussed. The existence of two developmental variants is regarded as a basis for functional rearrangements providing for a high flexibility of population responses and as a mechanism of population regulation determining the dynamics of rodent fauna. An adaptive population response to a board spectrum of influences, including anthropogenic damage, depends not only on the type and strength of the influence, but also on the functional structure of the population. The concepts described in the paper may explain the significance of critical periods in the life of populations.  相似文献   

19.
The return of willow ptarmigans to the sites in which they nested the previous year has been studied using color banding. No factors influencing the return index have been revealed, except for its dependence in males on the time when spring begins in a given year. In northernYamal, in contrast to the temperate zone, some surviving birds fail to return to their former nesting sites. Polymorphism of individuals with respect to territorial behavioral strategy is proposed for L. lagopus populations at the northern boundary of the species range.__________Translated from Ekologiya, No. 3, 2005, pp. 215–221.Original Russian Text Copyright © 2005 by Tarasov.  相似文献   

20.
The population dynamics of the parasitic gamasid mite Macronyssus corethroproctus (Oudemans, 1902) during the overwintering period of its host, the pond bat Myotis dasycneme (Boie, 1825), has been analyzed. Regression equations have been obtained that describe the dependence of the abundance of mites on the time since the start of overwintering and on host??s sex and body condition.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号