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Abstract
Bush flies, Musca vetustissima attracted to a human, and arthropod fauna attracted to fresh cattle dung in 24 hours, were sampled every 2 weeks for 2 years (1980–1982) near Alice Springs in central Australia. Substantial rain fell in both summers, but it was more prolonged in the second. The bush fly occurred and bred throughout the year, although its abundance was usually low. The only major increase in bush fly abundance occurred after the first summer's rainfall caused the growth of new herbage. This was followed by increased feeding on dung by adult flies and intensified breeding. Bush fly abundance was low in the second summer, despite evidence of a long period of continuous breeding. A variety of dung-feeding and predatory beetles and also mites was almost always present, although numbers were usually low. The introduced dung beetles Euoniticellus intermedius and Onthophagus gazella numerically dominated samples. Dung fauna abundance also increased after significant rainfall, particularly in the second summer. Dissections of the dung beetles showed that they bred at these times.  相似文献   

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两种女贞光合作用季节特性研究   总被引:6,自引:0,他引:6  
孙存华  孙存玉 《生态学报》1997,17(5):525-529
以徐州自然条件下生长的常绿女贞和落叶女贞为材料,在不同季节测定了它们的叶绿素含量、光合速率、呼吸速率、光合作用的最适温度。结果表明,两种女贞各测定的生理指标都有季节特性。在自然条件下,两种女贞的光合速率皆为夏季最高,冬季最低,与叶绿素含量变化相一致。在冬季常绿女贞的净光合速率接近于零,而落叶女贞的净光合速率为负值,但仍保持较高的呼吸强度。光合作用的最适温度测定结果表明,常绿女贞适应环境温度变化的能  相似文献   

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Three species are recognized as additions to the British montane lichen flora:Catillaria gilbertiisp. nov.,Halecania bryophilasp. nov., andH. micaceasp. nov. All three have so far been recorded only from the mica-schist mountains of the Central Highlands of Scotland.  相似文献   

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连惟能 《昆虫学报》1963,(5):664-669
本文报告了1959年2月—1960年1月间在上海龙华郊区进行的三种(虫非)蠊季节消长的观察结果, 各种(虫非)蠊的季节消长有所不同, 美洲大蠊与凹缘大蠊开始出现于4月, 7月下旬达高峰, 11月后消失, 中华地鳖出现于3—12月间, 最高峰是在8月中旬。 最后对(虫非)蠊的季节消长特点与温度的影响问题进行了初步的讨论。  相似文献   

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观察了南岭黄檀(Dalbergia balansae Prain)主干、思茅黄檀(D.szem aoensisPrain)枝条形成层活动的周期,次生韧皮部的季节变化和筛管寿命。结果表明:1.形成层均为叠生型。2. 南岭黄檀形成层于4 月末开始分裂,11月初停止活动。韧皮部于11 月初完成分化,木质部到12月才完成分化。思茅黄檀形成层于4 月中旬到10 月下旬活动,11 月下旬韧皮部和木质部都已完成分化。3. 具功能韧皮部区在秋季最宽,达400—600 μm ;2—4 月最窄,仅为200—370μm ,此时筛管分子仍具P-蛋白质,筛板孔开放。4. 南岭黄檀、思茅黄檀的筛管寿命分别为8—12 个月和9—11 个月。5. 形成层休眠时韧皮薄壁组织细胞中有淀粉与草酸钙结晶积累,形成层活动时量渐减少,夏季很少或无  相似文献   

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油页岩废渣地12种木本植物光合作用的季节变化   总被引:11,自引:0,他引:11       下载免费PDF全文
研究了引种在油页岩工业废渣地12种木本植物冬、夏季光合作用特征,根据此评价引种植物的光合作用效率,测定的主要参数包括净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)。结果表明:1) 冬、夏季各项测定指标差异很大,PnTrGs均是夏季高于冬季,而且,夏季平均PnTrGs值要比冬季均值分别高60.9%、77.7%和85.7%,但水分利用效率(WUE)却是冬季高于夏季26.8%~77.2%。2) Pn日变化节律冬、夏季有异,夏季较多的种出现“双峰型”,而冬季较多出现“单峰型”。但也有例外,樟树(Cinnamomum camphora)冬、夏季均出现“单峰”;油榄仁(Terminalia bellirica)、红胶木(Tristania conferta)和柚木(Tectona grandis)冬、夏季均出现“双峰”;海南蒲桃(Syzygium cumini)则冬季为“双峰”,夏季为“单峰”。3) 若某一植物种在冬、夏季都表现出有较高的Pn日均值,相对于另一种植物其中有一季有较高的Pn,说明前者更适应当地环境生长。据此,以冬、夏季Pn日均值的平均值高低排序,评价参试植物在当地自然光照条件下的光合作用效率高低,树种的排序为:大叶相思(Acacia auriculiformis)、油榄仁、铁刀木(Cassia siamea)、云南石梓(Gmelina arborea)、柚木、红胶木、樟树、海南红豆(Ormosia pinnata)、铁冬青(Ilex rotunda)、海南蒲桃、双翼豆(Peltophorum ptetocarpum)和海南翅萍婆(Pterygota alata)。  相似文献   

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菜区趋光性昆虫包含10目47科173种,以鳞翅目和鞘翅目的数量最大,分别占总类数的54.33%和20.81%.3月中旬~5月上旬、10月上旬~12月中旬间物种数出现两个高峰,且后者明显高于前者.物种多样性在4月上旬~5月上旬、9月份、11月下旬~翌年1月份较高,其变化同物种数和个体数量有关.不同季节均以鞘翅目、同翅目和鳞翅目的优势集中性较高.  相似文献   

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SEASONAL CHANGES IN BODY-WEIGHT OF OYSTERCATCHERS HAEMATOPUS OSTRALEGUS   总被引:1,自引:0,他引:1  
P. J. Dare 《Ibis》1977,119(4):494-506
The body-weights of Oystercatchers Haematopus ostralegus wintering in Morecambe Bay, north-west England, showed marked seasonal changes between late summer and late winter, with considerable differences apparent between adult and immature birds. An attempt is made to relate these changes to recorded seasonal variations in prey biomass and to the annual cycles of breeding, moult and migration of the Oystercatcher. The mean weight of females invariably exceeded the mean weight of males in samples collected on the same dates, regardless of age. Adults returned from northern breeding areas in very lean condition, with mean weights ranging from 526 g in males to 540 g in females. Mean weight then increased progressively, due mainly to fat deposition, to a peak in March (up to 662 g in males and 675 g in females) around the time of their main departures for breeding. Heaviest birds then exceeded 800 g. Birds migrating to Iceland in spring would need to be of above average weight in March to make the shortest crossing (850 km, 13 h), via Scotland, while Oystercatchers of 700 g and over could probably make a direct flight (1500 km, 25 h) from Morecambe Bay in favourable weather. Breeding weights of British Oystercatchers were similar to those of post-breeders returning to Morecambe Bay in late August. The mean weights of first-year Oystercatchers arriving in August were very low, 449 g in males and 478 g in females. Their weights, and those of second- and third-year immatures, then rose rapidly in autumn, with some fat deposition, and reached mean values ranging between 551 g (males) and 597 g (females) by November-December. Mean weight then fell by 10–17% from December to March returning close to or below the September levels, whereas adults gained a further 6% during these winter months. Summer and autumn weight gains, and the major moult of adults and older immatures, occurred when the biomass of their two staple mollusc preys, Mytilus edulis (mussel) and Cardium edule (cockle), was maximal. Winter loss in mean weight of immatures corresponded with declining prey biomass, suggesting either that they were less efficient than adults in coping with deteriorating winter food supplies, or that they had no need to accumulate further (premigratory) fat reserves. The autumnal increases in mean weight of immatures are interpreted as an adaptation for withstanding adverse feeding conditions in winter. The Oystercatcher appears to be the only wader species in Britain in which adults increase, rather than lose, weight during the winter. This may be a consequence of an early breeding season, but it may be regarded also as a measure of the success Oystercatchers have achieved by specializing on a difficult but plentiful prey source.  相似文献   

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ARTHROPOD SPECIES IN SOYBEANS IN SOUTHEAST QUEENSLAND   总被引:1,自引:1,他引:0  
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1987-1988年,在西双版纳大勐龙曼养光的季节雨林内,按3个时期,在林缘及林心的5个固定样地采虫,对蝽类昆虫的种类,数量及其变动和群落结构等进行了初步研究。1.季节雨林水平结构内,林缘样地的蝽类科、属、种、个体数及多样性指数明显大于林心样地。2.季节雨林垂直结构不同层次的蝽类,以中层的科、属、种、个体数及多样性指数占明显优势,特别是1.5-2米的草本层与幼灌层的交错空间内,种类与数量最多,最丰富。  相似文献   

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The structure of tracheids in Lycopodium lucidulum, L. clavatum, and L. tristachyum was studied with the light microscope. Protoxylem development is at least sometimes and possibly always mesarch in indeterminate axes of all three species. Centrifugally formed protoxylem elements are reticulate and discontinuities in the secondary walls of these elements are sometimes conspicuously bordered. Wall thickenings of first formed protoxylem elements consist mainly of indirectly connected rings. Late centripetally formed protoxylem elements and transitional elements have a reticulate secondary wall pattern. The narrowest metaxylem elements have circular bordered pits while in wider metaxylem elements pits are bordered and may vary from circular to scalariform. Pitting is uniseriate to triseriate in tracheids of all three species, and intermittent tetraseriate pitting was occasionally observed in L. lucidulum. Crassulae occur in tracheids of the three species, and in L. clavatum an additional framework, probably representing thickened compound middle lamella, is also present. Pits often appear helically arranged, and in all three species pits are connected by thin areas in the secondary wall. Macrofibrils approximately 0.5 μ wide were observed in tracheids of the three species. In L. clavatum the arrangement of macro-fibrils was predominantly bidirectional.  相似文献   

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本文对三种烟草属植物进行了核型分析。粘烟草Nicotianaglutinosa为二倍体,其核型可简式为:2n=24=10M+10m+4sm(2SAT);内索菲拉烟草N.nesophila和斯托克通氏烟草N.stocktoni可能均为双二倍体,其核型简式,前者为2n=48=6M+20m(2SAT)+18sm+4st,后者为2n=48=14M+12m+18sm+4st。此外,作者对供试材料的染色体基数、倍性及随体等问题进行了初步讨论。  相似文献   

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Tissue nitrogen was assessed monthly for 16 months in five species of perennial macroalgae representing three phyla at one location in Rhode Island Sound. The species showed a remarkable similarity in their pattern of seasonal fluctuation in both nitrate and total nitrogen. The period of greatest accumulation (January through March) coincided with the period of highest concentration of inorganic nitrogen in the water, and for most of these algae it was also the time of-least growth. Conversely, the period of lowest tissue nitrogen (50% of the winter value, May through July) coincided with the period of lowest inorganic nitrogen in the water and highest algal growth. The greatest accumulation of nitrate was found in Laminaria saccharina (L.) Lamour. (80 μmol·g dry wt.?1), four times as much as that measured simultaneously in the other species and 560 times the ambient concentration. By April the concentration of internal nitrate had dropped to nearly undetectable levels, but in August it began to accumulate again—a pattern that was repeated in Chondrus crispus Stackh. In Ascophyllum nodosum (L.) Le Jolis, Fucus vesiculosus L. and Codium fragile subsp. tomentosoides (Van Goor) Silva, the period of negligible internal nitrate level extended from March to December. The greatest concentration of total tissue nitrogen was measured in C. crispus (4.8% dry wt.), double the maximum in L. saccharina (2.3% dry wt.).  相似文献   

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John  Alcock 《Ibis》1969,111(3):308-321
White-throated Sparrows Zonotrickia albicollis, Fork-tailed Flycatchers Muscivora tyrannus and Black-capped Chickadees Porta atricapillus were placed in experimental situations where they could watch a trained companion uncover a hidden mealworm. After a period of watching its companion find the concealed mealworm, the observer bird was isolated visually from the other bird. While in isolation the observer birds approached, touched and pecked at a hidden food tray significantly more often than control birds which had not had an opportunity to observe a trained companion. However, the experimental birds failed to learn from observation alone how to uncover the concealed mealworm. But if rewarded in the presence of the companion bird (by taking a mealworm from it or by uncovering a mealworm as a result of local enhancement), then the observer bird frequently did come to find the prey in isolation. It is suggested that the interaction between observational learning and a bird's reinforced socially facilitated experience could assist in the development and expansion of a bird's behavioural repertoire.  相似文献   

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