高寒草甸生态系统艾虎种群能量动态的研究

动物种群能流的研究具有重要的意义。为阐明食肉动物与食草动物能量的相互关系,我们于1982年4—10月在青海省门源县海北高寒草甸生态系统定位站地区,测定了艾虎对食物的消化率和同化率,同时统计其密度,初步估计通过其种群的能量流。 艾虎全年平均摄入干物质为0.125克/克体重/日;摄入总能为0.709大卡/克体重/日,同化能、粪便和尿的排出能分别占其80.18％、14.58％和5.25％。全年摄入能为1.157×10~5大卡/公顷,通过种群能流为0.917×10~5大卡/公顷/年。 上述结果表明,通过艾虎种群的能量流是比较少的。因此,保护艾虎,增加其数量,是高寒草甸生态系统改造的任务之一。     

高寒草甸冷季牧场牦牛和藏羊粪中植物种子密度和多样性

为明确高寒草甸冷季牧场牦牛粪和藏羊粪中种子含量,研究了天祝东祁连山高寒草甸冷季牧场不同放牧时期牦牛粪和藏羊粪中可萌发植物种子的密度数量和多样性。结果表明,高寒草甸冷季牧场的同一放牧时期,牦牛粪中种子的物种数高于藏羊粪;种子密度牦牛粪低于藏羊粪,放牧初期和末期差异不显著,放牧中期差异显著。放牧初期和末期牦牛粪中种子的Shannon指数显著高于藏羊粪,放牧中期差异不显著。牦牛粪中的种子物种数为:末期初期中期;藏羊粪为:初期末期中期。单位重量牦牛粪中的种子数量变化规律是:末期初期中期,藏羊粪为:中期末期初期。牦牛粪中所含莎草科的植物种子最多,而藏羊粪中则以杂类草为主。高寒草甸冷季牧场不同放牧时期草地状况的不同,使得草地贮草量和种子在草层内的分布不同,加之牦牛和藏羊各自采食习性、单口采食量的差异,以及牦牛和藏羊消化道对种子的消化率不同,最终导致牦牛和藏羊粪便中的种子密度、种类和多样性存在差异。     

高寒草甸生态系统中牦牛体重和采食量动态模型的研究

高寒草甸生态系统中牦牛体重和采食量动态模型的研究黄大明（清华大学生物科学与技术系,北京１０００８４）赵松岭（兰州大学,兰州７３００００）Ｄｙｎａｍｉｃｍｏｄｅｌｓｏｆｙａｋｌｉｖｅｗｅｉｇｈｔａｎｄｉｔｓｉｎｔａｋｅｉｎａｌｐｉｎｅｍｅａｄｏｗｅｃｏ...     

高寒草甸生态系统牲畜种群的线性规划模型和最优化利用策略

本文研究了高寒草甸生态系统牲畜种群的线性规划模型和最优利用策略。以门源马场牧场的实际数据作为模型的一个例子,分别提出了藏羊、改良羊和牦牛的最优种群结构和最优出栏方案。在改良羊、藏羊、牦牛和马为主的牧场上,改良羊是牧场上的主要牲畜,牦牛和马保持其数量下限,藏羊全部淘汰。在藏羊、牦牛和马为主的牧场上,藏羊是牧场上的主要牲畜,牦牛和马保持其数量下限。按照线性规划模型方案经营,可提高经济收益,并减轻冬舂草场上牲畜的过多采食。价格分析说明青海省现行的畜产品价格体系需要调整。     

不同降水梯度下草地生态系统地表能量交换

通过对不同降水梯度下的蒙古中部针茅草原(KBU)、内蒙古羊草草原(NM)、海北高寒灌丛草甸(HB)和当雄高寒草甸草原(DX)4个草地生态系统的能量通量连续4-5 a的测定,分析了影响青藏高原和蒙古高原草地生态系统生长季中地表能量交换的主要因素。研究表明:相对于KBU、NM和DX,HB高寒灌丛草甸NDVI(0.58)和土壤含水量(28.3%)最大,因而地表短波反射率(αk)最低(0.12),从而获得了最大的净辐射(Rn)。KBU、NM和DX 3个草地生态系统生长季中αk随着植被的生长而降低,在生长季末期,随着植被的凋落而增加;HB的αk季节变化趋势与其它生态系统相反。从蒙古高原(KBU和NM)到青藏高原(HB和DX),随着降水量的增加,波文比(β)逐渐减小(2.25-0.53),即生态系统与大气的能量交换从显热(H)占主导转变为潜热(LE)占主导。植被状况对草地生态系统与大气之间能量交换的季节动态有重要的调控作用,在NDVI较低的时候,4个生态系统H/Rn都大于LE/Rn,LE/Rn随着NDVI的增加而增加,而H/Rn呈现出与LE/Rn相反的季节变化趋势。     

高寒草甸生态系统——小哺乳动物能量动态的研究 Ⅱ.通过高原鼠兔种群能流的初步估计

本文对栖息于高寒草甸优势种小哺乳动物--高原鼠兔(Ochotona curzoniae)种群的密度、食物的摄入、消化和同化、平均每日代谢率(ADMR)、每日能量收支(DEB)、种群的生产量(P)和呼吸量(R)进行了长期研究的基础上,按照 A=P+R的途径,估计了通过高原鼠兔种群的能流。     

系统发育多样性对青藏高原高寒草甸的稳定性影响

生物多样性较高的草地生态系统能够充分利用生态环境资源,提升生态系统的多功能性。本文以青藏高原高寒草甸生态系统为研究对象,基于多元线性回归和结构方程模型,阐明系统发育多样性、物种多样性和环境因素对高寒草甸生态系统稳定性的影响。结果表明：高寒草甸系统发育多样性、物种多样性和环境因素与生态系统稳定性之间均存在正相关关系,且具有尺度依赖性。小样方尺度高寒草甸通过物种多样性(丰富度指数)和环境因素对生态系统稳定性产生影响,作用系数分别为0.237和0.221。系统发育多样性主要受到物种多样性影响,作用系数为0.812(P<0.001)。大样方尺度生态系统稳定性主要受到环境因素、物种多样性影响,作用系数分别为0.364和0.246(P<0.05)。随着样方尺度的增大,高寒草甸的系统发育多样性、物种多样性和环境因素对生态系统稳定性的影响逐渐增强,且环境因素的作用效应逐渐占据主要地位。因此,应充分注重系统发育多样性和物种多样性在维持高寒草甸生态系统稳定性的作用。     

青藏高原区退化高寒草甸植被和土壤特征

高寒草甸约占青藏高原草地的46.7%,是我国草地生态系统重要的组成部分。近年来,在气候变化和人为活动的影响下,高寒草甸生态系统退化严重,植被和土壤均呈现出不同的退化趋势。在大空间尺度上表现为草地覆盖度下降,杂草类植被增加,土壤退化甚至沙化;在微观尺度上,退化高寒草甸的土壤粒径、土壤微生物和土壤酶也发生改变。本研究从高寒草甸物种多样性、植物群落结构、植被生物量、土壤物理性质、土壤微生物、土壤酶和土壤养分等方面,分析了高寒草甸生态系统退化过程中植被和土壤的变化特征,提出当前研究中存在的一些不确定性和有待深入研究的问题,为全面了解高寒草甸的退化机制和规律、有效干预高寒草甸生态系统和恢复生态功能提供科学依据。     

"生态系统的能量流动"一节的教学设计

“问题导学法”是一种以教材为依据 ,通过学生对问题进行分析、探究来获得知识和发展能力的一种课堂教学模式 ,这种教学法注重学生主体地位的发挥和能力的培养 ,充分体现了“以学生为中心”的教学理念。教师的作用主要体现在如何设计问题和组织教学。笔者在“生态系统的能量流动”一节的教学中成功运用了此方法 ,收到了良好的教学效果。1　教材内容分析生态系统的能量流动是生态系统的基本功能之一 ,能量流动的结构基础是食物链和食物网 ,生态系统中能量的输入和输出涉及到生物新陈代谢过程中光合作用和呼吸作用的知识 ,能量在各个营养级上…     

短期围封对西藏北部高寒草甸土壤线虫群落的影响

为了解放牧对高寒草甸的影响,以及围封对高寒草甸的恢复作用,2013年5月、8月、10月,分别对藏北短期围封高寒草甸和自由放牧高寒草甸不同深度土层的土壤线虫群落及土壤理化性质等进行了调查。调查结果表明,3a围封提高了土壤全氮、磷、钾及土壤有机质含量,土壤保水能力也明显提高;围封使土壤线虫个体密度下降,但物种多样性和丰富度却提高了;围封使土壤线虫群落中的植食性线虫所占比重呈下降趋势,食真菌线虫比重加大。短期围封有利于高寒草甸生态系统的正向演替,使之向更稳定的方向发展,同时,土壤线虫数量对土壤理化性质变化有明显的响应,通过土壤线虫群落的群落特征可以反映放牧干扰及围封对高寒草甸生态系统的影响。     

西双版纳望天树种群结构与动态研究

本文采用空间代替时间和相邻格子样方法阐明了望天树种群的结构类型和群落演替模式,结果表明其种群结构类型可分为初始增长型（类型Ｉ）,增长型种群前期类型（类型Ⅱ）,增长型种群（类型Ⅲ）和稳定性种群（类型Ⅳ）．其群落演替模式遵从类型Ⅰ─类型Ⅱ─类型Ⅲ─类型Ⅳ模式,即具有更新镶嵌和循环的特点．探讨了群落演替过程中伴生种的变化规律,并就望天树种群的合理保护和群落重建提出了建议．     

蒲洼农业生态系统能流的稳定性及其动态

在研究生态系统结构及功能的基础上,本文基于１９７５－１９９０年的数据,对蒲洼农业生态系统能流的稳定性及其动态进行了分析。通过建立能流模型,由李雅普诺夫稳定性原理,得出该生态系统能流的平衡态具有渐近稳定性。动态数学模拟表明,目前该系统的能量流动正从不稳定状态向稳定和平衡态过渡,这一过程大约需要７ａ时间。     

POST MORTEM STABILITY AND STORAGE IN THE COLD OF BRAIN ENZYMES

Tyrosine hydroxylase (TH), glutamate-decarboxylase (GAD) and choline acetyltransferase (CAT) were estimated in the striatum of rat brains kept at 20°C or 4°C for various periods of time up to 48 h after death. At 20°C TH and GAD activities decreased up to 4&50% of controls after 48 h; CAT activity was not affected. Maintenance of dead animals at 4°C completely (GAD and CAT) or partially (TH) prevented the decrease in enzyme activities. In a second series of experiments, TH, G A D and CAT activities were measured in striata (tissue or homogenate) stored immediately after death at different temperatures (4°C; -35°C; -70°C) for various time intervals up to 3 months. Storage of striata at 4°C induced a rapid decrease of all enzyme activities with time (GAD > CAT > TH). TH, GAD and CAT activities in striata kept at -35°C or -70°C were fairly stable. However, CAT activity was slightly decreased when the dissected striata were not homogenized; GAD activity was substantially reduced after 3 months at -35°C. Stability of TH, GAD and CAT activities were confirmed in homogenates of human caudate nucleus stored at -70°C for 1 month. If human enzymes behave similarly to the rat enzymes the following conclusions should be drawn: (1) brains should be obtained at autopsy within 8 h after death; (2) placement of dead bodies in the refrigerator should be done as soon as possible; (3) dissected brain structures (preferably as homogenates) should be stored at -70°C.     

WITHIN- AND BETWEEN-GENERATION EFFECTS OF TEMPERATURE ON THE MORPHOLOGY AND PHYSIOLOGY OF DROSOPHILA MELANOGASTER

We investigated the effects of developmental and parental temperatures on several physiological and morphological traits of adult Drosophila melanogaster. Flies for the parental generation were raised at either low or moderate temperature (18°C or 25°C) and then mated in the four possible sex-by-parental temperature crosses. Their offspring were raised at either 18°C or 25°C and then scored as adults for morphological (dry body mass, wing size, and abdominal melanization [females only]), physiological (knock-down temperature, and thermal dependence of walking speed), and life history (egg size) traits. The experiment was replicated, and the factorial design allows us to determine whether and how paternal, maternal, and developmental temperatures (as well as offspring sex) influence the various traits. Sex and developmental temperature had major effects on all traits. Females had larger bodies and wings, higher knock-down temperatures, and slower speeds (but similar shaped performance curves) than males. Development at 25°C (versus at 18°C) increased knock-down temperature, increased maximal speed and thermal performance breadth, decreased the optimal temperature for walking, decreased body mass and wing size, reduced abdominal melanization, and reduced egg size. Parental temperatures influenced a few traits, but the effects were generally small relative to those of sex or developmental temperature. Flies whose mother had been raised at 25°C (versus at 18°C) had slightly higher knock-down temperature and smaller body mass. Flies whose father had been raised at 25°C had relatively longer wings. The effects of paternal, maternal, and developmental temperatures sometimes differed in direction. The existence of significant within- and between-generation effects suggests that comparative studies need to standardize thermal environments for at least two generations, that attempts to estimate “field” heritabilities may be unreliable for some traits, and that predictions of short-term evolutionary responses to selection will be difficult.     

THE DEVELOPMENT AND CYTOLOGY OF THE EPIBIOTIC PHASE OF PHYSODERMA PULPOSUM

Lingappa , Yamuna . (U. Michigan, Ann Arbor.) The development and cytology of the epibiotic phase of Physoderma pulposum. Amer. Jour. Bot. 46(3) : 145-150. Illus. 1959.—Physoderma pulposum, a chytrid parasite on Chenopodium album L. and Atriplex patula L., has a zoosporangial epibiotic phase. The latter consists of extramatrical sporangia and intramatrical bushy rhizoids, both enclosed in large protruding galls. The sporangia are subspherical, up to 350μ in diameter, and may produce hundreds of planospores. If planospores settle on the host surface, they develop narrow germ tubes which penetrate the epidermal cells and develop into rhizoids. The planospore body, however, remains on the host surface and develops into a mature epibiotic sporangium in about 20-25 days at 16°C., 12-15 days at 20-25°C., or 6-8 days at 30°C. During development, its nucleus and daughter nuclei divide mitotically with intranuclear spindles until the sporangium contains several hundred nuclei. This is followed by progressive cleavage which delimits the planospore rudiments. When mature sporangia are placed in fresh water, the planospores are quickly formed within 1 hr. at 25°C. and begin to swarm within the sporangia. They escape in large numbers through an opening formed by the deliquescence of a papillum in the sporangial wall. The planospores are subspherical or elongate, 3-5 × 4-6 μ, and each has an eccentric orange-yellow refractive globule and a flagellum 18-22 μ in length. The electron micrographs of the flagella indicate that the flagella are absorbed from tip backward during encystment of the planospores. By periodic inoculation of the host plants with planospores from epibiotic sporangia, as well as from germinating resting sporangia, generation after generation of epibiotic sporangia have been obtained for 4 years. This proves the existence of a eucarpic, epibiotic, ephemeral zoosporangial phase in P. pulposum. Field observations on the duration and sequence of development of the fungus indicate that the endobiotic resting sporangial phase always follows the epibiotic phase. The results of infection experiments also indicate that the epi- and endobiotic phases belong to one and the same fungus, P. pulposum.     

THE EFFECT OF SHORT PERIODS OF HIGH TEMPERATURE DURING DAY AND NIGHT PERIODS ON PEA YIELDS

Karr , E. J. (Ohio State U., Columbus), A. J. Linck , and C. A. Swanson . The effect of short periods of high temperature during day and night periods on pea yields. Amer. Jour. Bot. 46(2) : 91-93. Illus. 1959.—The effect of high temperatures during periods of relatively short duration (3-4 days) at various stages following anthesis at the first bloom node was studied in relation to yield of peas at this node. Except for the periods of differential temperature treatments, the plants were maintained in a standard environment room (24°C., light, 12 hr.; 15°C., darkness, 12 hr.). Three different temperature regimes during the treatment periods were studied: high day temperature—standard night temperature (32°—15°C.) ; standard day temperature—high night temperature (24°—30°C.) ; and high day and night temperatures combined (32°—30°C.). The data reveal the existence of a relatively well-defined thermal-sensitive period, with maximal sensitivity to high day temperatures occurring at about 9-11 days from full bloom, and maximal sensitivity to high night temperatures occurring about 6-9 days from full bloom. High night temperatures proved more critical, resulting in a maximal reduction of 25% in yield, as opposed to about 8% for high day temperatures. The effect of high day and night temperatures combined tended to be roughly additive.     

江苏海岸带水域浮游动物的种类组成和分布

调查江苏海岸带水域(119°15′—123°30′E,31°40′—35°15′N),分析鉴定1980年8、11月和1981年2、5月浮游动物样品。结果如下: 1.初步鉴定浮游动物98种,其中水螅水母类29种、管水母类4种、栉水母类2种、枝角类1种、桡足类46种、糠虾类6种、磷虾类2种、樱虾类4种、浮游腹足类1种、毛颚类8种及浮游幼虫多类。 2.浮游动物的种类组成是以暖温性近岸低盐种为主的。真刺唇角水蚤。(Labidocera euchaeta)、中华哲水蚤(Calanus sinicus)、中华假磷虾(Pseudeuphausia sinica)、强壮箭虫(sagittacrassa)等是组成调查区浮游动物的主要种类。 3.浮游动物生物量,5月最高,平均达195毫克/米~3。11月最低,平均为85毫克/米~3。8月的和2月的分别为146毫克/米~3和106毫克/米~3。 4.浮游幼虫的数量,8月高最,平均达188个/米~3。2月最低,平均不到1个/米~3。5月的和11月的分别为6个/米~3和3个/米~3。 5.江苏海岸带水域能有3个全国有名的渔场存在、这和该区具有形成渔场的饵料基础——浮游动物资源丰富是分不开的。 6.不同生态类群浮游动物的时空分布基本上反映了江苏海岸带水域各个季节水文状况的基本特征。     

DIURNAL RHYTHM AND TURNOVER OF TRYPTOPHAN HYDROXYLASE IN THE PINEAL GLAND OF THE RAT

Tryptophan hydroxylase in the pineal gland of the rat was found to undergo a diurnal rhythm in activity with an elevated activity at night. The rhythm was abolished in constant light. Cycloheximide (15 mg/kg, i.p.), administered both at night and during the day, caused a rapid decay in activity suggesting that tryptophan hydroxylase was subject to a rapid turnover in vivo. The primary site of control appeared to be at the level of translation since actinomycin D had no effect. Some relevant properties of the enzyme were studied. Thiol-containing compounds were shown to substantially protect pineal tryptophan hydroxylase from inactivation at 0°C but provided little protection at higher temperatures. The inactivation process appeared to be independent of oxygen. The activity of the enzyme, lost after ageing at 0°C. could be recovered by incubation with dithiothreitol under anaerobic conditions. Fresh enzyme, or enzyme inactivated at 37°C could not be activated by this process. A re-examination of the action of p-chlorophenylalanine (PCPA) on pineal tryptophan hydroxylase revealed that an irreversible inactivation occurred within 6h (25% of initial activity) followed by a recovery within 24 h. The rapid turnover of the enzyme is the probable reason for the failure of previous studies to observe an irreversible inhibition of this enzyme by PCPA.     

Plant phenological variation related to temperature in Norway during the period 1928–1977

First flowering was observed in some native herbaceous and woody plants in Norway at latitudes of ∼58°N to nearly 71°N from 1928 to 1977. For woody plants, the timing for first bud burst was also often observed. Generally, there were highly significant correlations (0.1% level) between the timing of nearly all spring–early summer observations in plants and gridded mean monthly temperatures for the various phenophases (up to 65% of the variance was accounted for, less so for the autumn phenophases). Analyses by a low pass Gaussian smoothing technique showed early phenophases in the warm period of the early 1930s, delayed phases for most sites and species in colder periods in the early 1940s, mid-1950s, late 1960s and also towards the end of the study period in the late 1970s, all in approximately 10- to 12-year cycles. The study thus starts in a relatively early (warm) period and ends towards a late (cooler) period, resulting in mainly weak linear trends in phenophases throughout the total period. The end of the observation period in 1977 also predates the strongly increasing “earliness” in phenology of plants in most Norwegian lowland areas due to global warming. The strong altitudinal and latitudinal variations in Norway, however, do cause regional differences in trends. The study showed a tendency towards earlier spring phenophases all along the western coast from south to north in the country. On the other hand, the northeasternmost site and also the more continental sites in the southeast showed tendencies to weak trends for later phenophases during the 50 years of these field observations.     

THE EFFECT OF HYPERTHERMIA UPON OXYGEN CONSUMPTION AND UPON ORGANIC PHOSPHATES, GLYCOLYTIC METABOLITES, CITRIC ACID CYCLE INTERMEDIATES AND ASSOCIATED AMINO ACIDS IN RAT CEREBRAL CORTEX

The influence of hyperthermia on cerebral blood flow, cerebral metabolic rate for oxygen and cerebral metabolite levels was studied by increasing body temperature from 37° to 40°C and 42°C in rats under nitrous oxide anaesthesia maintained at constant arterial CO₂ tension. The metabolic rate for oxygen increased by 5-6% per degree centigrade. At 42°C the increase in cerebral blood Row was comparable to that in the metabolic rate. The increased temperatures were not accompanied by changes in organic phosphates (phosphocreatine, ATP, ADP or AMP) or in lactate/pyruvate ratio. There was an increase in the tissue to blood glucose concentration ratio. At steady state, there was an increase in glucose-6-phosphate but no other changes in glycolytic metabolites or citric acid cycle intermediates, and the only change in amino acids studied (glutamate, glutamine, aspartate, alanine and GABA) was an increase in glutamate concentration.