云南不同海拔花椒园昆虫群落结构及动态

调查了4种不同海拔花椒园昆虫群落组成及结构的周年变化,应用群落特征参数及主分量分析方法分析了昆虫群落特征及其在时间过程中的主导因素和时间格局.结果表明,随着海拔的逐渐上升,昆虫群落中种类数量逐渐减少,种群数量相对增加,群落多样性、丰富度及均匀度等指数逐渐下降,随时间的变化而波动的趋势逐渐明显,主导昆虫群落变化的最主要因子由天敌亚群落的物种数和个体数量综合因子逐渐转向害虫亚群落的物种数和个体数量综合因子.     

重度砍伐后极小种群野生植物崖柏群落结构动态

砍伐导致濒危植物种群个体数量减少, 群落结构改变, 加剧物种灭绝风险。崖柏(Thuja sutchuenensis)为典型极小种群野生植物, 森林砍伐是导致其种群数量急剧下降的主要原因。但是, 到目前为止, 有关崖柏种群及其群落对砍伐的响应鲜有报道。本研究以重度砍伐后的崖柏群落为研究对象, 基于对崖柏群落固定样地的调查和两次复查, 对比分析了伐后崖柏种群径级结构、种群生存力、物种多样性及其群落结构动态等特征。结果表明: 崖柏残存群落伐后13年崖柏种群个体数量增加了22.58%, 其中幼苗幼树占85.71%, 而崖柏种群生存率下降25.43%, 种群死亡密度和危险率分别增加了24.12%和28.62%。崖柏群落物种丰富度和Shannon-Wiener指数分别增加96.43%和33.35%。研究结果表明, 砍伐使崖柏种群生存力及其在群落中的优势度持续下降, 崖柏占优势的针阔混交林有向阔叶林演替的趋势, 崖柏种群受到严重威胁, 亟需采取紧急保护措施。     

纸房沟流域植被恢复区乔木林昆虫群落结构及动态分析

2008年4～11月通过对纸房沟流域乔木林恢复区昆虫进行调查,结果表明:昆虫种类数以自然乔木林最高,混交林次之,单纯林分较低,个体数量以柳树林昆虫数量最高,其次为混交林和刺槐林,自然乔木林变化幅度最小.昆虫群落多样性指数高低次序均为自然乔木林＞混交林＞单纯林分,均匀度以单纯林和混交林的昆虫群落变化幅度较大,自然乔木林变化幅度最小.群落的优势度与均匀度值的变化呈相反趋势.主分量分析表明,林分类型不同的昆虫群落,其主导因素和时间格局不同,且结构越复杂,主导因素和时间格局越明显;相反,则主导因素和时间格局分化不明显;植食性昆虫类群在各林分中均为优势类群,自然乔木林的天敌种类数和个体数量明显高于其它林分,通过排序不同功能类群在各林分昆虫群落变化的不同时期占主导因素.并探讨了植物群落与昆虫多样性间的生态关系,为植被恢复和森林害虫的自然生态调控提供依据.     

黄河三角洲潮间带柽柳灌丛的格局及结构动态研究

采用聚集度指标与种群结构动态量化法, 分析了黄河三角洲潮间带柽柳灌丛的分布格局与结构动态变化。结果表明: (1)在潮间带, 柽柳种群从幼苗、小灌木至中灌木都服从集群分布, 大灌木为随机分布; 柽柳个体幼苗多生长在母体周围, 以母体为中心进行繁衍, 随着径级的增加, 种群个体间的竞争增加, 聚集度减小, 逐渐呈现随机分布。(2)柽柳种群结构呈纺锤型; 高度级失稳率指数显示幼苗和小灌木有很高的衰退速率, 随着群落的演替发展, 龄级较大的柽柳优势地位将被削弱。(3)种群动态预测表明, 种群明显处于衰退的早期阶段, 中小灌木的个体数量减少, 大灌木个体数增加,达到数量高峰; 虽然群落在短时期内会保持稳定, 但大灌木(或老龄个体)的数量大幅减少后, 柽柳种群将面临重度衰退。     

蚜虱净对苜蓿田节肢动物群落结构及动态的影响

以物种丰富度(S)、个体数量(N)、香农指数(Shannon’sindex,H′)和均匀度指数(E)作为多样性指标,研究了蚜虱净对苜蓿田节肢动物群落结构和季节动态的影响.结果表明:蚜虱净对天敌亚群落物种数的影响大于害虫亚群落,使总群落和害虫亚群落的优势集中性显著增加,但5月底施药对传粉蜜蜂类亚群落的优势集中性无显著影响.喷药初期,蚜虱净显著降低了蚜虫、蓟马等害虫数量,7d后蚜虫、蓟马等种群数量迅速回升,40d后超过对照;施药初期天敌亚群落的物种数大幅减少,多样性和均匀度指数较低,7d后天敌的物种数逐渐回升,到后期与对照田基本一致,但个体数量一直未恢复至对照水平.     

氮磷养分共同添加促进退化典型草原恢复的机制

土壤养分含量降低是我国草原退化的主要原因之一,养分添加是退化草原恢复的有效措施,但过量养分添加会导致物种多样性降低。为了探讨适宜的养分添加量以及养分添加促进退化草原恢复的机制,本研究选择内蒙古典型草原的退化群落,通过氮(N)磷(P)养分共同添加梯度试验,研究了退化典型草原在群落、功能群和物种3个组织水平上对养分添加的响应。结果表明: 在群落水平,养分添加显著促进了退化典型草原生物量,但没有降低物种多样性;群落生物量随养分添加水平表现为饱和曲线响应,在12.0 g N·m^-2、3.8 g P·m^-2水平趋于饱和;物种多样性在低养分添加水平(N<9.6 g·m^-2、P<3.0 g·m^-2)较对照显著增加,在其余养分添加水平未发生显著变化。在功能群水平,随着养分添加量的增加,多年生根茎禾草在群落中优势度增加,生物量和密度均显著提高;一年生植物生物量和密度在高养分水平添加下显著增加,多年生丛生禾草和杂类草无显著变化。在物种水平,6个物种对养分添加响应不同,羊草通过增加种群密度和个体大小显著增加了种群生物量;大针茅、冰草和糙隐子草种群生物量没有显著变化;星毛委陵菜和黄囊苔草分别因为降低个体大小和种群密度减少了种群生物量。养分添加作为草原恢复的措施,可以显著增加退化草原生物量和物种多样性,降低植物群落中退化指示种,增加多年生根茎禾草。     

放牧后自然恢复沙质草地土壤节肢动物群落结构与多样性

以中国科学院奈曼沙漠化研究站为依托,对不同放牧强度后自然恢复沙质草地土壤节肢动物群落进行了调查,分析了土壤节肢动物群落结构及其多样性变化,探讨了植被和土壤环境对土壤节肢动物群落的影响.结果表明: 无牧草地土壤动物种类丰富,个体数量较多,多样性最高;中牧后恢复草地土壤动物个体数量少,但主要类群较多,分布较均匀,多样性较高;重牧后恢复草地土壤动物主要类群少,但个体数量多,多样性较高;而轻牧后恢复草地土壤动物分布均匀性最差,多样性最低.植物个体数、高度及盖度和土壤酸碱度是影响不同放牧强度后恢复草地土壤动物种类和个体数量分布的主要因素.说明沙质草地经过12年的围封可以一定程度上恢复土壤动物群落,而放牧干扰对土壤动物群落的负面影响是长期的.     

黄土高原南部麻栎不同群落类型乔木种群结构及演替模拟

由于对黄土高原南部麻栎天然次生林的群落稳定机制缺乏了解,以不同群落类型麻栎天然次生林为研究对象,通过样地监测及时间序列模型预测的方法,重点研究了不同群落类型中重要乔木的种群结构动态,并根据不同群落类型重要乔木种群的年龄结构数据,用时间序列模型预测未来20、30、40和50年的种群发展趋势。结果表明：（1）不同群落类型中各重要乔木种群生存能力均较好,但松栎混交林中的槲栎种群及麻栎纯林中的茶条槭种群生存能力欠佳;（2）除麻栎纯林中杜梨种群及栎阔混交林中槲栎种群,其余乔木种群的存活曲线皆呈Deevey-Ⅲ型;（3）不同麻栎群落类型中各个重要值较高的乔木种群幼龄级个体数量相对丰富,时间序列分析表明,在未来20、30、40和50年中,不同群落类型中各重要乔木种群均可持续发育,并未出现衰退迹象。同时麻栎纯林具有向混交林演替的趋势,说明未来对不同类型麻栎林经营均应以顺应自然演替规律的近自然经营方式为主。研究结果可为促进次生林持续经营及恢复提供理论依据。     

云南普洱紫花三叉白及昆虫群落多样性研究

为探究云南普洱紫花三叉白及昆虫群落结构及多样性,掌握昆虫群落多样性发展变化的时空动态,进一步明确紫花三叉白及害虫的种类和发生时间,为害虫防控提供理论参考依据,本研究采用棋盘式取样法,通过定时定点和大范围随机普查的方法,于2016年对云南省普洱市紫花三叉白及标记的样点进行了系统调查。调查期间共调查到节肢动物76种,分属于4纲12目56科。其中植食性节肢动物亚群落46种,分属于34科;捕食类节肢动物亚群落14种,分属于10科;寄生性节肢动物亚群落8种,分属于8科;中性节肢动物亚群落8种,分属于6科。其中科数及物种数最多为双翅目,个体数量最多的为膜翅目。对昆虫群落的多样性指数分析结果表明:双翅目昆虫群落丰富度最高,蜘蛛目优势度指数最高,多样性指数与均匀度均是膜翅目最高。时间上,6月物种数与多样性指数均最大,4月个体数量最多。不同类群分析结果为,植食性节肢动物群落物种数量最多,天敌亚群落的物种数量时间动态相对比较稳定。通过黄板及扫网采集,物种数量的变化趋势与总群落变化趋势基本保持一致,总群落个体数与物种数的变化基本由黄板与扫网采集到的类群主导。通过调查及分析可知,紫花三叉白及节肢动物群落物种数量变化基本由植食类类群主导,节肢动物群落的稳定性较高,天敌亚群落的物种数量时间动态相对比较稳定,非天敌亚群落的群落多样性与个体数量的变化趋势基本一致;物种丰富度与物种均匀度变化趋势基本一致;优势集中性与优势度随时间变化趋势基本一致。进入雨季之后,个体数量有较大幅度的降低,而持续性降雨与暴雨天气是导致个体数量迅速减少的重要因素。     

有机管理对柑橘园节肢动物群落多样性恢复的作用

比较了有机管理、常规管理和自然园3种不同管理方式下柑橘树冠层节肢动物群落多样性。结果表明：常规管理的柑橘园转有机管理后,柑橘园节肢动物群落的物种组成增加了1目、24科、130种;害虫类群的个体数量减少,而天敌类群的个体数量增加;在有机管理方式下,节肢动物群落的多样性指数、均匀度及优势集中性指数等全年的波动幅度介于自然园和常规管理区之间;有机管理区节肢动物群落的丰富度、多样性指数、均匀度及优势集中性指数等指标与自然园相比无显著差异,而与常规管理之间差异显著。有机管理方式能够提高和恢复柑橘园节肢动物群落的多样性,有助于实现对柑橘害虫的生态控制。     

Redescription and taxonomic status of Sinodiaptomus valkanovi , a common limnoplanktonic calanoid copepod in Japan, with comparison to the closely related S. sarsi

The limnoplanktonic calanoid copepod Sinodiaptomus valkanovi (Diaptomidae: Diaptominae) is redescribed in detail from Japan, where it commonly occurs in ponds and reservoirs especially around the Seto Inland Sea. The species has been referred to as a subspecies of S. sarsi outside Japan due to lack of subsequent morphological comparisons. Sinodiaptomus valkanovi is easily distinguishable from S. sarsi by having longer antennules in both sexes, a short projection on the right antennule segment 15 of the male, and a thumb-like posterodistal basal projection of the male left leg 5. These characters do not show significant variation, indicating differentiation at the species level. S. valkanovi is restricted to Japan, in contrast to the wide-range of it S. sarsi in Asian waters. The Bulgarian population, from which the species was originally described, and the North American population, which was formerly recorded as S. sarsi, are considered to have been introduced from Japan with aquatic plants such as water lilies.     

Relationship between laying dates of black kites Milvus migrans and spring temperatures in Italy: rapid response to climate change?

Many Holarctic bird species have been shown to be laying progressively earlier in response to global warming. Most studies have been conducted on small-bodied species at northern latitudes. In Italy, black kite Milvus migrans populations are concentrated near large pre-Alpine lakes, whose water temperatures have been increasing steadily in recent decades. Annual black kite laying dates have become 10–11 days earlier during the last nine years. This shift was related to temporal variations in spring air temperatures, with earlier laying in warmer springs. The progressive advancement in laying dates was not associated with an increase in population level productivity, despite the fact that productivity declined with laying date at the individual territory level within years. Avian response to climate change may be occurring more rapidly than previously thought, even in relatively long-lived species, and not only at the most northern latitudes or highest elevations. Because this change has occurred so rapidly, and because laying dates match annual variations in spring temperatures, the response must be facultatively driven by prevailing conditions, rather than genetic in response to natural selection.     

Increased variance in temperature and lag effects alter phenological responses to rapid warming in a subarctic plant community

Summer temperature on the Cape Churchill Peninsula (Manitoba, Canada) has increased rapidly over the past 75 years, and flowering phenology of the plant community is advanced in years with warmer temperatures (higher cumulative growing degree days). Despite this, there has been no overall shift in flowering phenology over this period. However, climate change has also resulted in increased interannual variation in temperature; if relationships between phenology and temperature are not linear, an increase in temperature variance may interact with an increase in the mean to alter how community phenology changes over time. In our system, the relationship between phenology and temperature was log‐linear, resulting in a steeper slope at the cold end of the temperature spectrum than at the warm end. Because below‐average temperatures had a greater impact on phenology than above‐average temperatures, the long‐term advance in phenology was reduced. In addition, flowering phenology in a given year was delayed if summer temperatures were high the previous year or 2 years earlier (lag effects), further reducing the expected advance over time. Phenology of early‐flowering plants was negatively affected only by temperatures in the previous year, and that of late‐flowering plants primarily by temperatures 2 years earlier. Subarctic plants develop leaf primordia one or more years prior to flowering (preformation); these results suggest that temperature affects the development of flower primordia during this preformation period. Together, increased variance in temperature and lag effects interacted with a changing mean to reduce the expected phenological advance by 94%, a magnitude large enough to account for our inability to detect a significant advance over time. We conclude that changes in temperature variability and lag effects can alter trends in plant responses to a warming climate and that predictions for changes in plant phenology under future warming scenarios should incorporate such effects.     

INTERACTION OF CHLOROPLAST AND VACUOLES IN CHLAMYDOMONAS

The abundance of phycoerythrin-containing cyanobacteria and picoeukaryotes in water samples from the Scripps Institution of Oceanography pier have been followed at least weekly for more than two years using flow cytometry. These cyanobacteria show a seasonal cycle with generally lower cell numbers during the winter, a "bloom" as water temperatures increase, and higher cell numbers during the summer. However the population abundance appears to be more variable and the magnitude of the annual change in cell number is less than reported for coastal Massachusetts by Waterbury et al. (1986). Isolates have been obtained from pier samples and genetic characterization using rpoC1 (RNA polymerase) sequence data is in progress. The PUB:PEB chromophore ratios of isolates assayed using fluorescence excitation spectra range from about 0.4 (low PUB) to 0.7 (mid-PUB) for isolates grown under white light. The physiological and genetic characterization of isolates is being used to examine the similarities and differences of cyanobacterial populations from different coastal regimes. Similarly a picoeukaryote has been isolated that has a flow cytometric signature similar to the natural population. It appears to be a small nonmotile prasinophyte.     

Diatoms can be an important exception to temperature–size rules at species and community levels of organization

Climate warming has been linked to an apparent general decrease in body sizes of ectotherms, both across and within taxa, especially in aquatic systems. Smaller body size in warmer geographical regions has also been widely observed. Since body size is a fundamental determinant of many biological attributes, climate‐warming‐related changes in size could ripple across multiple levels of ecological organization. Some recent studies have questioned the ubiquity of temperature–size rules, however, and certain widespread and abundant taxa, such as diatoms, may be important exceptions. We tested the hypothesis that diatoms are smaller at warmer temperatures using a system of geothermally heated streams. There was no consistent relationship between size and temperature at either the population or community level. These field data provide important counterexamples to both James’ and Bergmann's temperature–size rules, respectively, undermining the widely held assumption that warming favours the small. This study provides compelling new evidence that diatoms are an important exception to temperature–size rules for three reasons: (i) we use many more species than prior work; (ii) we examine both community and species levels of organization simultaneously; (iii) we work in a natural system with a wide temperature gradient but minimal variation in other factors, to achieve robust tests of hypotheses without relying on laboratory setups, which have limited realism. In addition, we show that interspecific effects were a bigger contributor to whole‐community size differences, and are probably more ecologically important than more commonly studied intraspecific effects. These findings highlight the need for multispecies approaches in future studies of climate warming and body size.     

Reduced reproductive performance associated with warmer ambient temperatures during incubation in a winter‐breeding,food‐storing passerine

Timing of reproduction can influence individual fitness whereby early breeders tend to have higher reproductive success than late breeders. However, the fitness consequences of timing of breeding may also be influenced by environmental conditions after the commencement of breeding. We tested whether ambient temperatures during the incubation and early nestling periods modulated the effect of laying date on brood size and dominant juvenile survival in gray jays (Perisoreus canadensis), a sedentary boreal species whose late winter nesting depends, in part, on caches of perishable food. Previous evidence has suggested that warmer temperatures degrade the quality of these food hoards, and we asked whether warmer ambient temperatures during the incubation and early nestling periods would be associated with smaller brood sizes and lower summer survival of dominant juveniles. We used 38 years of data from a range‐edge population of gray jays in Algonquin Provincial Park, Ontario, where the population has declined over 50% since the study began. Consistent with the “hoard‐rot” hypothesis, we found that cold temperatures during incubation were associated with larger brood sizes in later breeding attempts, but temperatures had little effect on brood size for females breeding early in the season. This is the first evidence that laying date and temperature during incubation interactively influence brood size in any bird species. We did not find evidence that ambient temperatures during the incubation period or early part of the nestling period influenced summer survival of dominant juveniles. Our findings provide evidence that warming temperatures are associated with some aspects of reduced reproductive performance in a species that is reliant on cold temperatures to store perishable food caches, some of which are later consumed during the reproductive period.     

Climate change, breeding date and nestling diet: how temperature differentially affects seasonal changes in pied flycatcher diet depending on habitat variation

1.?Climate warming has led to shifts in the seasonal timing of species. These shifts can differ across trophic levels, and as a result, predator phenology can get out of synchrony with prey phenology. This can have major consequences for predators such as population declines owing to low reproductive success. However, such trophic interactions are likely to differ between habitats, resulting in differential susceptibility of populations to increases in spring temperatures. A mismatch between breeding phenology and food abundance might be mitigated by dietary changes, but few studies have investigated this phenomenon. Here, we present data on nestling diets of nine different populations of pied flycatchers Ficedula hypoleuca, across their breeding range. This species has been shown to adjust its breeding phenology to local climate change, but sometimes insufficiently relative to the phenology of their presumed major prey: Lepidoptera larvae. In spring, such larvae have a pronounced peak in oak habitats, but to a much lesser extent in coniferous and other deciduous habitats. 2.?We found strong seasonal declines in the proportions of caterpillars in the diet only for oak habitats, and not for the other forest types. The seasonal decline in oak habitats was most strongly observed in warmer years, indicating that potential mismatches were stronger in warmer years. However, in coniferous and other habitats, no such effect of spring temperature was found. 3.?Chicks reached somewhat higher weights in broods provided with higher proportions of caterpillars, supporting the notion that caterpillars are an important food source and that the temporal match with the caterpillar peak may represent an important component of reproductive success. 4.?We suggest that pied flycatchers breeding in oak habitats have greater need to adjust timing of breeding to rising spring temperatures, because of the strong seasonality in their food. Such between-habitat differences can have important consequences for population dynamics and should be taken into account in studies on phenotypic plasticity and adaptation to climate change.     

Thermal habitat of adult Atlantic salmon Salmo salar in a warming ocean

The year-round thermal habitat at sea for adult Atlantic salmon Salmo salar (n = 49) from northern Norway was investigated using archival tags over a 10 year study period. During their ocean feeding migration, the fish spent 90% of the time in waters with temperatures from 1.6–8.4°C. Daily mean temperatures ranged from −0.5 to 12.9°C, with daily temperature variation up to 9.6°C. Fish experienced the coldest water during winter (November–March) and the greatest thermal range during the first summer at sea (July–August). Trends in sea-surface temperatures influenced the thermal habitat of salmon during late summer and autumn (August–October), with fish experiencing warmer temperatures in warmer years. This pattern was absent during winter (November–March), when daily mean temperatures ranged from 3.4–5.0°C, in both colder and warmer years. The observations of a constant thermal habitat during winter in both warmer and colder years, may suggest that the ocean distribution of salmon is flexible and that individual migration routes could shift as a response to spatiotemporal alterations of favourable prey fields and ocean temperatures.     

Asexual reproduction in scyphistomae of Aurelia sp.: Effects of temperature and salinity in an experimental study

The growth and survival of colonies and individuals within sedentary polyp colonies of moon jellyfish (Aurelia sp.) was investigated at three temperatures and three salinities in laboratory experiments. Growth rates of colonies (number of polyps and number of buds in the colony) and individuals (number of buds per active scyphistomae) significantly increased with temperature, but were not affected by salinity. Survival was high in all treatment combinations indicating a wide tolerance to environmental conditions. However, scyphistomae at the lowest temperature had a greater percentage of larger individuals and slower population growth rate than those at warmer temperatures. These results suggest that the reproductive strategy to maximise production of Aurelia sp. is to increase the size of scyphistomae colonies by asexual budding when conditions are good (warmer temperatures and abundant food generally during spring and summer). Budding activity slows, but the size of scyphistomae increases, during the colder winter period leading up to strobilation, resulting in the production of a greater number of ephyrae. The trigger for strobilation is possibly stressful conditions. However, if trigger conditions do not occur, the colony of scyphistomae can continue to grow and survive through a broad range of conditions spanning many seasons, thus ensuring survival of the population.     

Changes in temperature sensitivity of spring phenology with recent climate warming in Switzerland are related to shifts of the preseason

The spring phenology of plants in temperate regions strongly responds to spring temperatures. Climate warming has caused substantial phenological advances in the past, but trends to be expected in the future are uncertain. A simple indicator is temperature sensitivity, the phenological advance statistically associated with a 1°C warmer mean temperature during the “preseason”, defined as the most temperature‐sensitive period preceding the phenological event. Recent analyses of phenological records have shown a decline in temperature sensitivity of leaf unfolding, but underlying mechanisms were not clear. Here, we propose that climate warming can reduce temperature sensitivity simply by reducing the length of the preseason due to faster bud development during this time period, unless the entire preseason shifts forward so that its temperature does not change. We derive these predictions theoretically from the widely used “thermal time model” for bud development and test them using data for 19 phenological events recorded in 1970–2012 at 108 stations spanning a 1600 m altitudinal range in Switzerland. We consider how temperature sensitivity, preseason start, preseason length and preseason temperature change (i) with altitude, (ii) between the periods 1970–1987 and 1995–2012, which differed mainly in spring temperatures, and (iii) between two non‐consecutive sets of 18 years that differed mainly in winter temperatures. On average, temperature sensitivity increased with altitude (colder climate) and was reduced in years with warmer springs, but not in years with warmer winters. These trends also varied among species. Decreasing temperature sensitivity in warmer springs was associated with a limited forward shift of preseason start, higher temperatures during the preseason and reduced preseason length, but not with reduced winter chilling. Our results imply that declining temperature sensitivity can result directly from spring warming and does not necessarily indicate altered physiological responses or stronger constraints such as reduced winter chilling.