Sociological and demographic characteristics of a recently found arsi gelada population in ethiopia

A new population of gelada baboons isolated from other known gelada populations living on the opposite side of the Rift Valley was found in 1989 in the Arsi region of Ethiopia (Mori &Belay, 1990). Subsequent observations were conducted on the new gelada population in three study periods of 16 to 55 days over three consecutive years, 1994–1996. When we compare this population with other well studied northern populations, densities were lower, band size was smaller and the ratio of juveniles to adult females was lower. Based onOhsawa andDunbar's (1984) criteria these results suggest that this population exploits the harshest environment among known gelada populations. This may be due to the severe effect of the dry season at low altitude in the study site. Band size was small in the study site. Association rates of units were low, and each unit behaved more independently than those of northern populations. Age-sex composition of units changed drastically between consecutive study periods, indicating unstable unit structure. Moreover, there seems to be a tendency in this population whereby several adult males easily invade and are incorporated into a unit but the unit is expected to thereafter divide. The phenomenon can be explained by two factors: (1) Each unit fed rather independently in this area, where units fed intensively on both plateau and the slope of the cliff; and (2) Males may be incorporated in a unit for defense against leopards. As the units were vary small in size and unstable as compared with the Semien gelada units, the traditional concept of a stable gelada unit formed by blood related females, does not seem to fit this population.     

哈尔滨郊区人为鼠疫疫源地鼠类种群动态分析

根据黑龙江省哈尔滨市郊区人为鼠疫疫源地1952～1996 年达乌尔黄鼠密度监测资料,建立了黄鼠密度的自回归模型D_t=0.1374+1.130 2D_t-1-0.4754D_t-2+0.8033D_t-3-0.4680D_t-4 , 对1997～2000 年的密度进行了预测。1952～1980 年, 人工捕黄鼠率极为显著地影响黄鼠密度(P<0.001)。在该地区, 1982～1996年共捕啮齿动物6种, 其中黄鼠和大仓鼠为野外优势种, 褐家鼠为室内优势种, 其余为常见种。大仓鼠、黑线仓鼠、黑线姬鼠均与夜行鼠总捕获率正相关(P<0.01),逐步回归模型为总捕获率=0.5219+1.1733 大仓鼠+10312 黑线仓鼠+ 1.1273小家鼠+ 0.9242 褐家鼠(P<0.0001)。黄鼠密度与捕获率不相关(P>0.10)。     

云南元江干热河谷半萨王纳植被的植物群落学研究

采用Ｂｒａｕｎ－ Ｂｌａｎｑｕｅｔ 植物群落学研究的理论与方法, 对云南元江中上游干热河谷分布的植被进行考察研究, 把各处取得较典型的１１０ 个样地记录按确限度的原则由下而上归类成１５ 个群丛、５ 个群属、２ 个群目和１ 个群纲, 建立了元江干热河谷萨王纳植被群纲—群目—群属—群丛分类系统综合表和１５ 个群丛表, 以全面深入反映全干热河谷植物群落各级分类单位中各植物种类组成的多优度、存在度、盖度系数、生活型和生长型等特征及其群落结构、生态环境和种型类别。在此基础上, 根据群落的种类组成、结构和生态特征, 确定元江干热河谷植被为萨王纳中“河谷型半萨王纳植被”, 主要是“树萨王纳”和“灌萨王纳”, 肉质刺灌丛属于灌萨王纳。     

Structure,dynamics and disturbance regime of temperate broad-leaved forests in Japan

Abstract. Structure, diversity and dynamics of five Japanese temperate old-growth forests were compared, differing from each other in, i.a., climate, dominant tree type, topography, disturbance regime. The forests were Aya, Ogawa, Kanumazawa Riparian, Kanumazawa upland and Senju. A permanent plot (1–6 ha) was established in each forest and trees were censused several times at intervals of two years. Mean annual recruitment rates and mortality rates in these forests were both in the range of 0.5 to 4.6 %/yr at the community level. Analyses of the structure and dynamics of populations showed that the underlying process was different among the forests. Some forests experienced compositional shifts in their canopies, others had a constant canopy composition but appeared to lack effective regeneration in recent years. The recruitment rate appeared to be strongly affected by competitive undergrowth vegetation such as dwarf bamboo which has been controlled by natural disturbance or human impact. It is likely that the forests with mostly low recruitment rates had a low species diversity. The current variation in structure, diversity and dynamics of the studied forests might have been determined not only by physical conditions (e.g. climate) but also by chance factors (e.g. disturbance, outbreak of deer population).     

CO2-fluxes in different plant communities of a high-Arctic tundra watershed (Western Spitsbergen)

Abstract. There is little information on (1) whether the net carbon balance is positive or negative in different habitats in high Arctic ecosystems such as Spitsbergen today, and (2) what effect a cloudier, cooler summer could have on carbon balance. To provide data on this subject CO₂-flux measurements in different plant communities were made in the high-Arctic coastal tundra of Spitsbergen, using a mobile macro-cuvette system based on infrared gas analysis. The study area was situated on the exposed west coast, where westerly winds produce precipitation daily in the form of rain, drizzle and fog. During the cold and cloudy measurement period in 1996, light and surface temperatures were limiting for primary producers, resulting in low size and low physiological activity of the plants. Net CO₂-flux measurements showed carbon fluxes from soil to atmosphere in most of the communities even during the brightest hours of the day, when mean photon flux density was 325 mmol m^-2 s^-1. Calculations based on spatial distribution of the plant communities and soils in the watershed combined with C-flux measurements revealed information on daily carbon loss. For instance, the Drepanocladus community, covering 21 % of the catchment area, was responsible for 42.6 % of the catchment carbon loss. Only two of nine investigated plant communities, the Racomitrium and a Salix-Saxifraga community on debris, both adapted to frequent fog situations, were able to compensate for respiratory CO₂-losses under the prevailing low light conditions during daytime. Since there were no significant sunny periods in this area in the summer of 1996, the habitats of the investigated coastal tundra finished the season with a marked carbon loss due to increased cloudiness.     

Theoretical considerations on the C-D effect in self-thinning plant populations

A model for describing the competition–density (C-D) effect in self-thinning populations was developed on the basis of the following three basic assumptions: (1) the growth of mean phytomass follows a general logistic equation; (2) final yield is independent of initial population density; and (3) there exists a functional relationship between actual and initial population densities at any given time. The resultant equation takes the same reciprocal form as the reciprocal equation of the C-D effect derived from Shinozaki–Kira's theory (i.e., the logistic theory of the C-D effect), which deals with the density effect in nonself-thinning populations. However, one of the two time-dependent coefficients is quite different in mathematical interpretation between the two reciprocal equations. The reciprocal equation for self-thinning populations is essentially the same as the reciprocal equation assumed in the derivation of the functional relationship between actual and initial population densities. The establishment of the reciprocal equation is supported by the empirical facts that the reciprocal relationship between mean phytomass and population density is discernible in not only nonself-thinning populations but also in self-thinning populations. The present model is expected to systematically interpret underlying mechanisms between the C-D effect, which is observed at a time constant among populations with various initial densities, and self-thinning, which is observed along a time continuum in a given population. Received: August 5, 1998 / Accepted: January 7, 1999     

Parasitic systems and the structure of parasite populations

 The analysis of population systems is carried out on the basis of the spatial and functional classification of populations developed by V.N. Beklemishev. The population system is a functional part of a particular community. Steady interrelationships between population systems of different species within the community (referred to as ”community links”) appear to be a prerequisite for the formation of a complex of population systems. A prominent example of this is the parasitic system. The parasitic system is the population system of a parasite with all the connected populations of its hosts. The complexity of a parasitic system depends on: (1) peculiarities of the life cycle of the parasite, since its population system is the organizing component of the parasitic system and (2) subdivision of the environment for the parasites. The first trait is discussed from the standpoint of the phase structure of populations, which is clearly seen in parasites. The second one comprises the organization of the parasites’ environment according to the scale of variability (interspecies, interpopulation or intrapopulation) of hosts. These make it possible to recognize spatial and functional parts in the framework of the parasitic system. A critical review of the terminology is presented together with a list of the pertaining vocabulary. Received: 15 January 1998 / Accepted: 15 October 1998     

Study on Age and Bunch Structure of Four Stipa Species in Inner Mongolia Plateau

The age status of four Stipa L. species, S. baicalensis Roshev., S. grandis P. Smim., S. krylovii Roshev., and S. klemenzii Roshev. in Inner Mongolia plateau was analyzed using a transect sampling method. The ontogeny of Stipa species was divided into five stages: the seedling, juvenile, reproductive, presenile, and senile. Dynamics of the population age speetra were determined mainly by the appearance of new individuals and their death rate. The survival rate of the seedlings was very low while that of file adults was high. The considerable longevity of bunch life allowed the old individuals to accumulate in the population. Both S. grandis and S. krylovii had higher proportion of seedlings than others. The proportion of the juveniles and the reproductives in the population decreased from S. baicalensis community to S. klemenzii community, but the old individuals including the preseniles and the seniles showed a reverse pattern. The aging process occurred in bunch level was characterized by the fragmentation of bunch and the within-bunch- self-thinning of the tillers. The process of within-bunch-self-thinning can be described by power equation Y: aXb. Meanwhile as a response to enviroument changes especially to the fluctuation of annual precipitation and its seasonal distribution both the numbers of reproductive shoots and vegetative shoot mass within a bunch were variable.     

宋朝中国人的姓氏分布与群体结构分化

姓氏是一种十分有用的文化遗传因子,它的传递方式类似于Ｙ染色体的表现。１０００年前宋朝（公元９６０￣１１７９年）中国人姓氏频率的分布,是一组十分吻合Ｋａｒｌｉｎ－ＭｃＧｒｅｇｏｒ的中性等位基因分布理论的随机数据。１６个省区的姓氏种类丰度的相对参数α和迁移率的相对参数ｖ的分析,反映了这一时期的中国人群的迁移和人群间混合的程度。姓氏遗传距离和现状聚类图的分析,表明在１０００年前的宋朝中国人群已经形成了南