SURFACE WAX DEPOSITS ON FOLIAGE OF PICEA PUNGENS AND OTHER CONIFERS

Epicuticular waxes of five cultivated varieties of Picea pungens and six other species of conifers were examined directly with a scanning electron microprobe. The quality, quantity, and distribution patterns of surface wax deposits varied between species, within species, within plants, and within individual leaves. Two basic types of wax were observed, structural and amorphous. Structural wax is associated with glaucousness and the blue foliage color in Picea pungens and other species. The degree of occlusion of the stomatal pore by surface waxes also varied from heavily occluded to completely free of wax. Wax in the epistomatal chamber may be another resistance barrier to gas exchange by conifer needles.     

两种女贞光合作用季节特性研究

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     

SEASONAL CHANGES IN BODY-WEIGHT OF OYSTERCATCHERS HAEMATOPUS OSTRALEGUS

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.     

水稻叶片衰老过程中氨肽酶活性的变化

水稻叶片中存在着氨肽酶,其最适反应pH和最适反应温度分别为8.2℃和40℃,酶促反应的产物量在最初30min内与时间呈直线相关。 水稻叶片衰老过程中叶绿素和蛋白质含量下降,而氨肽酶比活上升;用植物激素延缓或促进叶片衰老蛋白质降解的同时也抑制或促进了氨肽酶比活的上升,说明氨肽酶在水稻叶片衰老蛋白质降解过程中起一定的作用。根据水稻叶片衰老过程中大分子化合物和叶片外部形态的变化,可将叶片衰老过程划分为缓衰期、急衰期和竭衰期。     

名古屋风景林凋落物和凋落叶养分含量季节动态的研究

对日本名古屋市的三个风景林－日本柳形（Cryptomeria japonica)林,日本米槠（Quercus cuspidata)林和常绿落叶阔叶混交林的凋落物和凋落叶养分含量的动态变化及养分贮量进行了研究。日本柳杉林、日本米槠林和常绿落叶阔叶混林的年凋落量分别为7309kg.hm^-2、5790kg.hm^－2和5325kg.hm^-2,日本柳杉林的主要凋落高峰发生在9月,次要凋落高峰发生在3月,而日本米槠林和常绿落叶阔叶混交林的凋落高峰分别发生在5月和11－12月。台风引起大量枝叶凋落。日本柳杉林、日本米槠林和常绿叶阔叶混交林凋落物的5种养分年贮量分别为224.22kg.hm^-2、119.33kg.hm^-2和133.21kg.hm^-2。凋落物养分中N、K和Ca的量大于P和Mg。凋落叶的养分量占养分年贮量的63．19％－79．06％。落叶树种凋落叶养分浓度的季节变化大于常绿树种。     

泡泡刺叶磷酸烯醇式丙酮酸羧化酶季节性聚态变化

以不同季节的泡泡刺为研究对象,利用电氏物活性染色技术发现,在５月（春季）的电泳图谱上未出现磷酸烯醇式丙酮酸送终化酶（ＰＥＰＣ）,７月（夏季）的ＰＥＰＣ分子量４７３ＫＤ,为四聚体,９月（秋季）的ＰＥＰＣ以聚体和四聚体两种形式存在,分子量分别大约是１９２ＫＤ的４７３ＫＤ。泡泡刺水同季节叶片δ＾１３Ｃ值为－２４‰～－２５‰,其解剖结构无“Ｋｒａｎｚ”结构,５月和７月叶片中苹虹酸（Ｍａｌ）含量不具有昼夜波     

西双版纳热带季节雨林林窗内幼树叶生长与虫食动态

 研究了西双版纳热带季节雨林6种乔木幼树在林窗中的叶生长与叶虫食动态。6种幼树叶生长主要在雨季(5～10月),在旱季雾凉期(11～2月)叶停止生长。阳性树种旱季干热期(3～4月)开始叶生长,顶极树种至5月雨季初才开始叶生长。表明雾凉期低温抑制两类树种叶生长,干热期水分不足抑制顶极树种叶生长。叶生长同步性(每两个月的叶生长量变异系数C．V．)顺序为：望天树(Shorea chinensis,1.42)>金钩花(Pseuduvaria indochinensis,1.41)>八宝树(Duabanga grandiflora, 1.02)>云南石梓(Gmelina arborea,0.98)>团花树(Anthocephalus chinensis,0.84)和铁刀木(Cassia siamea,0.84)。旱季造成一些种类幼树出现落叶高峰,严重叶虫食也导致云南石梓在7～8月出现落叶高峰。叶虫食主要出现在雨季,团花树和云南石梓在干热期叶生长能减少昆虫取食,但此时铁刀木叶同步生长却不能降低食叶昆虫危害。6种幼树叶生长量年进程与叶虫食量年进程间存在正相关,其中望天树、金钩花、八宝树和团花树分别达到显著(p<0.05)或极显著(p<0.01)水平。望天树和金钩花在雨季初叶同步生长能减轻叶虫食。食叶昆虫偏爱取食幼叶,6种幼树平均幼叶的虫食量占总虫食量的72.9％,幼叶虫食速率平均为成熟叶的4.3倍。     

SEASONAL PATTERNS OF LEAF PHOTOSYNTHETIC CAPACITY IN SUCCESSIONAL NORTHERN HARDWOOD TREE SPECIES

Seasonal patterns of leaf photosynthetic capacity and conductance were determined for deciduous hardwood tree species in natural habitats in northern lower Michigan. Leaves of bigtooth aspen and red oak at the top of the canopy had higher maximum CO₂ Exchange Rate (CER) (10–15 μmol m ² s ¹) than leaves of sugar maple, red maple, red oak, and beech growing in the understory (4–5 μmol m ² s ¹). In all leaves, CER measured at light-saturation increased to a maximum near the completion of leaf expansion in early June, was constant until mid-September, and then rapidly declined until leaf death. A similar pattern was seen for CER measured in low light (1.5% full sun). Respiration rate in the dark was highest in young leaves and decreased during leaf expansion; a relatively constant rate was then maintained for the rest of leaf lifespan. The seasonal pattern of the initial slope of the light response of CER paralleled the pattern of light-saturated CER. The initial slope in midsummer ranged from values of 37 to 44 μmol/mol for species in the understory to 51 and 56 μmol/mol for red oak and bigtooth aspen, respectively, at the top of the canopy. Leaf conductance was constant throughout most of leaf lifespan, with some decline occurring in autumn. Leaves at the top of the canopy had higher conductances for water vapor (2–5 mm/s) than leaves in the understory (1–2 mm/s). All species maintained leaf intercellular CO, mole fractions (c,) near 200 uML/L until autumn, when c, increased during leaf senescence.     

HYMENAEA和COPAIFERA幼树叶内倍半萜类化合物昼夜和季节性变化

运用气相色谱对在温室栽培的Hymenaea courbaril和Copaifera officinalis及C. pubiflora幼树叶内倍半萜类化合物昼夜和季节性变化进行了分析测定。Hymenaea和Copaifera这二个属植物叶内具有基本相同的一组倍半萜类化合物,对认为具有生态意义的它的主要成分:石竹烯(caryophyllene),α,β-瑟林烯(selinene)和树脂含量进行了分析统计。在三个季节和昼夜的资料中,这二个属植物的石竹烯、α,β-瑟林烯和树脂含量昼夜变化是很小的,而在植株间(遗传型)和不同的季节里它们有明显而有意义的变化。     

野生鲇鱼生长激素分泌的季节变化及其神经内分泌调控

采用离体垂体碎片灌流孵育系统 ,将处于性腺退化期野生鲇鱼垂体切成约 1mm3 的碎片 ,用M 199冲洗之后放入灌流柱的两层Cytodex -Ⅲ微载体之间 (温度为 19± 1℃ )。每 5分钟收集一管灌流液 ,- 2 5℃贮存待测GH。采用鲤鱼GH放射免疫测定方法 (cGHRIA)测定鲇鱼垂体碎片灌流液以及血清和垂体中的GH含量。结果表明 :促黄体素释放激素类似物 [desGly10 (D Ala6)LHRHethylamide ,LHRH A]不能显著刺激离体垂体碎片基础GH分泌 ,注射LHRH A后不能显著提高血清基础GH水平 ;注射DA能显著提高鲇鱼血清基础GH水平 ,APO能以剂量依赖方式显著刺激垂体碎片基础GH分泌。雌、雄鲇鱼血清GH水平在 6月达到峰值 ,垂体GH水平在 3月和 7月份各出现一个峰值 ,各个季节雌鱼垂体和血清GH水平均显著高于雄鱼。鲇鱼血清和垂体GH水平与生殖周期有密切联系。     

SEASONAL AND INDIVIDUAL VARIATION IN LEAF QUALITY OF TWO NORTHERN HARDWOODS TREE SPECIES

Seasonal trends in five traits of sugar maple (Acer saccharum Marsh.) and yellow birch (Betula allegheniensis Britt.) leaves thought to influence feeding by herbivores were measured from 17 May through 19 September, 1979. Total nitrogen and water contents declined and toughness increased through the growth season. These seasonal changes were more pronounced in sugar maple than in yellow birch. Total polyphenol contents and tanning coefficients of leaf extracts from both species reached a season high by the end of May and changed very little after that date; these patterns differ from those reported by several other investigators. Sugar maple leaf extracts exhibited much higher tanning coefficients than did those of yellow birch, a finding which is consistent with current plant defense theory. Significant differences in total polyphenol content and tanning coefficients were found between individual trees in yellow birch, but not sugar maple. The relationship between successional status, leaf quality traits, and variability in these traits in forest trees is discussed.     

祁连山区青海云杉林冠层叶面积指数的反演方法

叶面积指数(Leaf area index, LAI)是陆地生态系统的一个十分重要的结构参数。随着空间精细化模型的发展和基于过程的分布式模拟技术的应用, 对LAI的区域估算显得越来越重要, 但目前尚缺乏有效的估算手段。该项研究以青海云杉(Picea crassifolia)林为研究对象, 利用LAI-2000冠层分析仪、鱼眼镜头法和经验公式法对林冠层LAI进行了测定, 观测值分别为1.03~3.70、0.48~2.26和2.27~8.20, 显然, 仪器测定值偏低。针对针叶的集聚效应导致仪器测定值偏低的现象, 利用跟踪辐射与冠层结构测量仪(TRAC)测定的青海云杉林聚集系数计算调整系数, 对鱼眼镜头法获取的LAI值进行订正。根据高分辨率的遥感数据反演青海云杉林的植被指数与LAI的关系, 最后获得了较合理的该地区林冠层LAI的空间分布图。