Population dynamics of Dremomys pernyi and Callosciurus erythraeus in protective and non-protective pine forests at different ages

Four pine forests (6–10, 11–15, 16–20, and 31–40 year-old) located in the Cangshan Mountain and Erhai Lake National Reserve and 7 pine forests (1–5, 6–10, 11–15, 16–20, 21–30, 31–40, and more than 50 year-old) located in the non-protective area near the national reserve were selected. Three replications of each forest was set and a total of 33 sites were investigated. At each site, we quantified 6 habitat variables (species richness, abundance, and percentage of grasses and shrubs coverage respectively at the bottom layer of forests) within randomly determined 5 m × 5 m areas. One hundred cages were set in five lines at each site to trap small mammals, whose species and numbers were recorded. Dominance of Dremomys pernyi and Callosciurus erythraeus in small mammal communities, time niche breadth, and time niche overlap between the two small mammals were calculated, respectively. Step-wise regression was used to analyze the relationship between small mammals and habitat factors. Our results indicated that D. pernyi occurred earlier than C. erythraeus in protective pine forests. D. pernyi was captured in 6–10 year-old forest initially, and C. erythraeus was captured in 16–20 year-old forest initially. D. pernyi and C. erythraeus were captured in the 31–40 and 21–30 year-old forests initially in the non-protective area, respectively. Populations of D. pernyi and C. erythraeus in the 31–40 year-old protective forests were 3 and 3.75 times of those in the same-aged non-protective forests, respectively. Shrubs significantly influenced the populations of the two small mammals. The population of D. pernyi was positively correlated with the density of shrubs; the population of C. allosciurus erythraeus was positively correlated with the coverage of shrubs, and negatively correlated with the coverage of grasses. D. remomys pernyi and C. allosciurus erythraeus were important for pine forests to scatter pine seeds. Human activities in the nonprotective pine forests decreased the vegetation heterogeneity at the bottom layer of pine forests, postponed the occurrence of D. pernyi and C. erythraeus, and decreased the populations of the two small mammals. __________ Translated from Zoological Research, 2006, 27(1): 29–33 [译自: 动物学 研究]     

珀氏长吻松鼠和赤腹松鼠在保护区与非保护区各年龄松林内的种群动态

2004年6~7月,在云南省大理白族自治州苍山和洱海国家自然保护区选取4种年龄段(6~10、11~15、16~20、31~40年)的松林和保护区周围的非保护区选取7种年龄段(1~5、6~10、11~15、16~20、21~30、31~40、50年以上)的松林,每种松林设3个重复,共33个样地,在样地内随机选取3个5m×5m的样方,调查并记录样方内草本植物和灌木的种类、数量、覆盖度。在每个样地按5条样线布笼100个捕捉小兽,每天检查捕获的种类和数量。计算珀氏长吻松鼠和赤腹松鼠在小兽群落中物种优势度、时间生态位宽度、两种小兽的时间生态位重叠度;用逐步回归分析两种松鼠与松林栖境因子的关系。上述结果表明,在保护区珀氏长吻松鼠出现的时间早于(6~10年的松林开始捕获到)赤腹松鼠(16~20年的松林内开始捕获到);在非保护区,分别在31~40年和21~30年的松林内才捕到珀氏长吻松鼠和赤腹松鼠。保护区31~40年的松林内珀氏长吻松鼠和赤腹松鼠种群数量分别是同年龄段非保护区松林的3倍和3·75倍。松林底层的灌木对两种小兽的种群数量有重要影响。珀氏长吻松鼠种群数量与灌木密度呈正相关;赤腹松鼠种群数量与灌木覆盖度呈正相关,而与草本植物覆盖度呈负相关。非保护区树底植被的异质性降低,延迟了两种松鼠在松林里建立种群的时间。     

赤腹松鼠采食选择的季节性变化

2008年9月至2010年8月,对广西宜州龙江河畔赤腹松鼠采食选择的季节性变化进行分析.赤腹松鼠对榕树的采食量最大,约占总采食量的36.53%,食物采食选择的种类存在显著差异(P<0.05),各季节采食的种类无显著变化(P>0.05);取食偏好分析、食物生态位宽度和重叠度结果表明,夏季的生态位宽度最大,为4.1545,秋季的生态位宽度最小,为3.5001,夏季和秋季的生态位重叠度最大,为0.9882,夏季和冬季的生态位重叠度最小,为0.9343.     

不同松林内马尾松毛虫种群动态的特征

通过对1992-2001年5种不同混交林型的马尾松林内各代幼虫发生量,受害面积和有虫株率的系统调查,研究了各种不同林型的松林对马尾松毛虫种群动态的影响。结果表明,不同树种混交的马尾松林对马尾松毛虫的种群动态有较大的影响。马尾松毛虫在马尾松纯林中发生量多,为害最严重。暴发周期最短;在与杉木等混交的马尾松林中发生次之;而在与阔叶树混交的马尾松林中平均每株虫口数少,发生与危害率及有虫株率均较其它林型小,不易引起松毛虫暴发为害。     

Population dynamics of small mammals at Mlawula, Swaziland

Population density, biomass and composition of a small mammal community in an Acacia nigrescens savanna were studied over 12 months from August 2000. The community consisted of Mus minutoides (A. Smith 1834), Mastomys natalensis (A. Smith 1834), Lemniscomys rosalia (Thomas 1904), Crocidura hirta (Peters 1952), Steatomys pratensis (Peters 1846); and on one occasion, Graphiurus murinus (Desmarest 1822) was caught. M. minutoides was the dominant species in the site. Species richness was found to vary significantly with the time of the year. The density of M. minutoides was significantly high in winter and low in the other seasons, the ratio of males to females was found to be equal, and pregnant females were caught from November to May. The biomass of small mammals in the area (also density and numbers) was generally low (mean biomass 212 g ha^?1). The occurrence of new individuals in catches remained high throughout the study, suggesting a high mortality or emigration rate or a combination of the two.     

黄山松种群结构与动态研究

以“空间代替时间”的方法,以种群径级结构代替年龄结构,采用静态生命表和生存分析的方法,探讨了天柱山国家森林公园黄山松种群结构和动态规律。结果表明,随海拔升高,黄山松种群密度增大,径级分布范围减小,种群存活曲线由Deevey-Ⅱ型之间过渡到Deevey—Ⅰ型,种群由稳定型过渡为增长型。表明由低海拔向高海拔,黄山松种群处于不同的演替和发展阶段。     

Population dynamics: Limits of predictability

Problems related to the complex pattern of ecosystem dynamics are discussed. Examples of studies on the complex population dynamics are considered, including those of plankton populations in a spatially heterogeneous environment and of an agroecosystem invaded by pests resistant to Bt toxins produced by genetically modified insecticidal crops.     

Population dynamics of insects associated with Rumex obtusifolius in different habitats

The effect of different habitats on insect communities associated with Rumex obtusifolius was studied in detail. Study sites were selected for their variety of environmental characteristics (vegetation and habitat): shaded woodland, disturbed wasteland and pasture. The results of this study were that insect populations associated with R. obtusifolius responded differently to the different habitats. The observed differences in population dynamics among the insects showed quite clearly their responses to different habitats. There was also a pattern of time partitioning in the exploitation of the host‐plant among the insect species observed. Philaenus spumarius at nymphal stage had a peak density on approximately 20 June, Apion frumentarium and Apion spp. (Apion species other than A. frumentarium) had a peak density on approximately 30 June and Aphis rumicis had a peak density on approximately 28 July. This pattern of shift in time for peak population density (time‐shift) among the insects sharing a common host‐plant may guarantee each insect the opportunity to exploit the plant to a maximum.     

三化螟种群动态分析及防治

分析了 1 980～ 2 0 0 0年三化螟种群数量变动情况 ,发现年度间的变动不一致 ,有明显间歇性。认为冬春气候 (气温、雨量 )、耕作制度、天敌因素等与三化螟为害密切相关 ,并提出科学实用的防治方法     

异迟眼蕈蚊在不同植物上的生长发育及种群参数

【目的】异迟眼蕈蚊Bradysia difformis Frey的幼虫取食为害作物的地下部分,影响作物的品质,为了明确韭菜、蚕豆、生菜、白菜和甘蓝5种植物对异迟眼蕈蚊生长发育以及繁殖的影响。【方法】本试验采用室内人工饲养测定的方法,研究了5种不同植物对异迟眼蕈蚊生长发育,繁殖力和存活率的影响,并统计了其对异迟眼蕈蚊种群参数的影响。【结果】结果表明:卵到蛹的发育历期依次为甘蓝、白菜、韭菜、生菜、蚕豆;5种植物对雌雄虫寿命影响不显著,对雌虫产卵量以及蛹重均有影响,其中在韭菜上的产卵量最大,甘蓝最少,在韭菜上蛹最重,生菜上蛹最轻;异迟眼蕈蚊的存活率随着生长发育降低,总体在韭菜上的存活率高于其他寄主植物,在生菜上的存活率均最低。统计分析不同植物对异迟眼蕈蚊种群参数的影响,净增殖率和内禀增长率在韭菜上最大而在甘蓝上最小;平均世代周期在蚕豆上最短,甘蓝上最长;种群加倍时间在韭菜上最短,而在甘蓝上最长。【结论】由此可知,异迟眼蕈蚊均可以在韭菜,蚕豆,生菜,白菜和甘蓝上完成生长发育及繁殖,其对5种植物的适应性依次为:韭菜、蚕豆、白菜、甘蓝和生菜。     

柞蚕微孢子虫孢子分离纯化方法

柞蚕微粒子病是柞蚕Antheraea pernyi(Guérin-Méneville)的主要胚胎传染性病害,病原为柞蚕微孢子虫Nosema pernyi(Wenet Ding),其病原分离提纯技术研究对于柞蚕微粒子病的防治具有重要意义。本文利用差速离心和Percoll密度梯度离心法研究了柞蚕微孢子虫孢子的分离纯化方法,结果表明,采用不连续密度梯度分离纯化柞蚕微孢子虫孢子的效果比单一浓度的效果好,以浓度为25%、50%、75%、100%不连续梯度,15000r/min离心30min分离纯化得到的柞蚕微孢子虫孢子纯净度高。     

Population dynamics of hypolimnetic rotifers in the Pluss-see (North Germany)

The hypolimnetic rotifer populations of the Pluss-see (Keratella hiemalis, Filinia terminalis, Filinia hofmanni) show similar patterns of changing population parameters indicating that they respond to particular environmental signals in the same way.     

Carbon storage and fluxes in ponderosa pine forests at different developmental stages

We compared carbon storage and fluxes in young and old ponderosa pine stands in Oregon, including plant and soil storage, net primary productivity, respiration fluxes, eddy flux estimates of net ecosystem exchange (NEE), and Biome‐BGC simulations of fluxes. The young forest (Y site) was previously an old‐growth ponderosa pine forest that had been clearcut in 1978, and the old forest (O site), which has never been logged, consists of two primary age classes (50 and 250 years old). Total ecosystem carbon content (vegetation, detritus and soil) of the O forest was about twice that of the Y site (21 vs. 10 kg C m^?2 ground), and significantly more of the total is stored in living vegetation at the O site (61% vs. 15%). Ecosystem respiration (R_e) was higher at the O site (1014 vs. 835 g C m^?2 year^?1), and it was largely from soils at both sites (77% of R_e). The biological data show that above‐ground net primary productivity (ANPP), NPP and net ecosystem production (NEP) were greater at the O site than the Y site. Monte Carlo estimates of NEP show that the young site is a source of CO₂ to the atmosphere, and is significantly lower than NEP(O) by c. 100 g C m^?2 year^?1. Eddy covariance measurements also show that the O site was a stronger sink for CO₂ than the Y site. Across a 15‐km swath in the region, ANPP ranged from 76 g C m^?2 year^?1 at the Y site to 236 g C m^?2 year^?1 (overall mean 158 ± 14 g C m^?2 year^?1). The lowest ANPP values were for the youngest and oldest stands, but there was a large range of ANPP for mature stands. Carbon, water and nitrogen cycle simulations with the Biome‐BGC model suggest that disturbance type and frequency, time since disturbance, age‐dependent changes in below‐ground allocation, and increasing atmospheric concentration of CO₂ all exert significant control on the net ecosystem exchange of carbon at the two sites. Model estimates of major carbon flux components agree with budget‐based observations to within ± 20%, with larger differences for NEP and for several storage terms. Simulations showed the period of regrowth required to replace carbon lost during and after a stand‐replacing fire (O) or a clearcut (Y) to be between 50 and 100 years. In both cases, simulations showed a shift from net carbon source to net sink (on an annual basis) 10–20 years after disturbance. These results suggest that the net ecosystem production of young stands may be low because heterotrophic respiration, particularly from soils, is higher than the NPP of the regrowth. The amount of carbon stored in long‐term pools (biomass and soils) in addition to short‐term fluxes has important implications for management of forests in the Pacific North‐west for carbon sequestration.     

Photosynthesis drives anomalies in net carbon-exchange of pine forests at different latitudes

The growth rate of atmospheric CO₂ exhibits large temporal variation that is largely determined by year‐to‐year fluctuations in land–atmosphere CO₂ fluxes. This land–atmosphere CO₂‐flux is driven by large‐scale biomass burning and variation in net ecosystem exchange (NEE). Between‐ and within years, NEE varies due to fluctuations in climate. Studies on climatic influences on inter‐ and intra‐annual variability in gross photosynthesis (GPP) and net carbon uptake in terrestrial ecosystems have shown conflicting results. These conflicts are in part related to differences in methodology and in part to the limited duration of some studies. Here, we introduce an observation‐driven methodology that provides insight into the dependence of anomalies in CO₂ fluxes on climatic conditions. The methodology was applied on fluxes from a boreal and two temperate pine forests. Annual anomalies in NEE were dominated by anomalies in GPP, which in turn were correlated with incident radiation and vapor pressure deficit (VPD). At all three sites positive anomalies in NEE (a reduced uptake or a stronger source than the daily sites specific long‐term average) were observed on summer days characterized by low incident radiation, low VPD and high precipitation. Negative anomalies in NEE occurred mainly on summer days characterized by blue skies and mild temperatures. Our study clearly highlighted the need to use weather patterns rather than single climatic variables to understand anomalous CO₂ fluxes. Temperature generally showed little direct effect on anomalies in NEE but became important when the mean daily air temperature exceeded 23 °C. On such days GPP decreased likely because VPD exceeded 2.0 kPa, inhibiting photosynthetic uptake. However, while GPP decreased, the high temperature stimulated respiration, resulting in positive anomalies in NEE. Climatic extremes in summer were more frequent and severe in the South than in the North, and had larger effects in the South because the criteria to inhibit photosynthesis are more often met.     

Population dynamics of the chydorid cladocera of a Southern Michigan Marl Lake

The seasonal population dynamics are described for 21 chydorid species in two shallow Scirpus subterminalis beds of Lawrence Lake, Michigan, USA. Six species were rare; four species were predominantly abundant. The dynamics of the populations followed no consistent pattern among the species. However, each species, with one exception, may follow the same pattern from year to year. Eight species overwintered under the ice as parthenogenetic individuals. Populations of Alonella excisa may be greatly reduced during the summer months because of competition with A. exigua.     

Population dynamics and control of Triatoma infestans

Analysis of field populations of Triatoma infestans (Hemiptera: Reduviidae), after a 3-year study, shows that population growth rate is affected by both density-dependent and density-independent mortality. Although an equilibrium exists, apparently as a consequence of a density dependent-mechanism, population density fluctuates throughout the year because of the effect of monthly mean minimum temperature as a density-independent source of mortality. Simulation studies based on Moran curves shows that high population densities have an approximately constant extinction probability (around 0.20), independently of the season the population starts growing. However, at very low population densities, the extinction probability depends strongly on the season when the population begins to grow. Very low density populations beginning in winter or autumn have the highest extinction probability. The outcome of the simulation studies coincides with results observed in field populations affected by insecticide application at different seasons.     

Brief report: Population dynamics of free-ranging rhesus monkeys in different ecological conditions in India

Data are presented on group size, composition, and reproductive rates of nine free-ranging rhesus monkey groups inhabiting different habitats in India, based on 7,300 observation hours spread over 1975–1980. Analysis suggests that groups increased in size irrespective of the habitat occupied.     

穴蚁蛉的自然种群动态

本文主要报道了穴蚁蛉 Myrmeleon(Morter) sagax(Walker)幼虫的野外自然种群数量动态。穴蚁蛉 1年发生 1代 ,在自然界其幼虫 3～ 5月份数量平稳略有下降 ,5、6月间数量迅速下降 ,6月初数量最少 ;7～ 9月份数量迅速上升 ,而后下降 ;新一代穴蚁蛉幼虫 (蚁狮 )在 6月份出现。其种群 ,秋季以 1龄幼虫数量为多 ,冬季主要以 2龄幼虫为主越冬 ,春季以 3龄蚁狮占优势。春季野外采集来的蚁狮 ,在每日光照 14小时、每周两饲 (每次饲 1头米蛾 Corcyra cephalonica成虫 )的条件下饲养 ,结果发现 ,采集回时处于 3龄期的蚁狮比自然界大约提前 1个月结茧化蛹和羽化 ;而采集回时处于 2龄期的蚁狮则和自然界中的情况基本一致。