武汉东湖的磷-浮游植物动态模型

本文报道了东湖的一个富营养化模型。这个模型按照1年的时间标度描述东湖藻类的生长和磷循环,其状态变量包括浮游植物磷、藻类生物量、正磷酸盐、碎屑磷和沉积物磷。模型校准和检验结果表明,模型对于系统给定状态的描述是令人满意的,并且对于系统的强制函数的改变能给予合理的响应。根据东湖富营养化工程治理的初步设想,利用模型进行了东湖污水截流前后的水质预报,同时考查了截流后移出沉积物或引灌江水对于改善其水质的效果。模型所提供的各种预报可供拟定东湖治理方案时参考。     

A PERSPECTIVE ON PHOTOSYNTHESIS IN THE OLIGOTROPHIC OCEANS: HYPOTHESES CONCERNING ALTERNATE ROUTES OF ELECTRON FLOW1

Many regions of the open, oligotrophic oceans are depleted of nutrients, especially nitrogen and iron. The biogenesis and the functioning of the photosynthetic apparatus may be specialized and tailored to the various marine habitats. In this minireview, we discuss some new findings with respect to photosynthetic processes in the oceans. We focus on findings that suggest that some cyanobacteria may route electrons derived from the splitting of H₂O to the reduction of O₂ and H⁺ in a water‐to‐water cycle, and that other cyanobacteria that fix nitrogen during the day are likely missing PSII and enzymes involved in the fixation of inorganic carbon. Both of these proposed “variant” forms of photosynthetic electron flow provide new insights into ways in which marine phytoplankton satisfy their energetic and nutritive requirements.     

杉木人工林单叶至冠层光合作用的扩展与模拟研究

根据野外条件下杉木（Ｃｕｎｎｉｎｇｈａｍｉａ ｌａｎｃｅｏｌａｔａ（Ｌａｍｂ．）Ｈｏｏｋ．）针叶光合作用的测定结果。考虑到光合作用对光的非线性响应特性,及其与叶所处的实际冠层环境变量和冠层的空气动力学特性的相关,以筒化的林冠辐射传输模型为基础,结合不同部位和年龄针叶的光响应曲线,实现了叶室测量结果向冠层环境的调整,并进行了冠层光合作用模拟的初步研究。经过调整后的冠层光合作用平均比未经过调整的值高１     

IN SEARCH OF A PHYSIOLOGICAL BASIS FOR COVARIATIONS IN LIGHT‐LIMITED AND LIGHT‐SATURATED PHOTOSYNTHESIS1

The photosynthesis‐irradiance (PE) relationship links indices of phytoplankton biomass (e.g. chl) to rates of primary production. The PE curve can be characterized by two variables: the light‐limited slope (α^b) and the light‐saturated rate (P^b_max) of photosynthesis. Variability in PE curves can be separated into two categories: that associated with changes in the light saturation index, E_k (=P^b_max/α^b) and that associated with parallel changes in α^band P^b_max (i.e. no change in E_k). The former group we refer to as “E_k‐dependent” variability, and it results predominantly from photoacclimation (i.e. physiological adjustments in response to changing light). The latter group we refer to as “E_k‐independent” variability, and its physiological basis is unknown. Here, we provide the first review of the sporadic field and laboratory reports of E_k‐independent variability, and then from a stepwise analysis of potential mechanisms we propose that this important yet largely neglected phenomenon results from growth rate–dependent variability in the metabolic processing of photosynthetically generated reductants (and generally not from changes in the oxygen‐evolving PSII complexes). Specifically, we suggest that as growth rates decrease (e.g. due to nutrient stress), reductants are increasingly used for simple ATP generation through a fast (<1s) respiratory pathway that skips the carbon reduction cycle altogether and is undetected by standard PE methodologies. The proposed mechanism is consistent with the field and laboratory data and involves a simple new “twist” on established metabolic pathways. Our conclusions emphasize that simple reductants, not reduced carbon compounds, are the central currency of photoautotrophs.     

COMBINATION OF FLOW CYTOMETRY AND SINGLE CELL ABSORPTION SPECTROSCOPY TO STUDY THE PHYTOPLANKTON STRUCTURE AND TO CALCULATE THE CHL A SPECIFIC ABSORPTION COEFFICIENTS AT THE TAXON LEVEL1

The phytoplankton community structure of a hypertrophic lake was quantitatively determined with the aid of flow cytometry. The flow cytometry signals were calibrated to obtain cell‐specific information, such as the chl a content and the biovolume per cell. The reliability of this method was tested with laboratory cultures. The results of the phytoplankton structure in a hypertrophic lake with respect to chl distribution in the different algal groups obtained by flow cytometry were compared with the results from HPLC pigment fingerprinting. Both methods yield the percentage contribution of the different algal groups to total chl a. The chl a specific absorption coefficient of the phytoplankton (a^*_Phy) was determined via visible (VIS) spectroscopy of samples taken from a hypertrophic lake (Auensee) in 2003. The results indicated that a^*_Phy of the total cell suspension is dependent on the phytoplankton structure as well as on environmental factors. The linear relationship between a^*_Phy at 675 nm and the product of the chl a content per cell and the biovolume offered the possibility to normalize phytoplankton absorption spectra to acquire the taxon‐specific a^*_Phy. The estimated a^*_Phy (675 nm) values were used to normalize single cell absorption spectra at this wavelength to obtain the a^*_Phy between 400 and 750 nm for representatives of the major algal groups. Our measurements show that the absorption coefficient for the whole phytoplankton community varies within the season. Finally, we used the a^*_Phy and the chl a distribution to calculate the light absorption of each algal group in the hypertrophic lake.     

EFFECTS OF ULTRAVIOLET RADIATION ON PHOTOSYNTHESIS IN THE SUBTROPICAL MARINE DIATOM,CHAETOCEROS GRACILIS (BACILLARIOPHYCEAE)1

Acclimation to ambient ultraviolet radiation (UVR) was examined in a subtropical marine diatom, Chaetoceros gracilis Schutt. Short-term exposure to UVR (<24 h) reduced the efficiency of photosynthetic energy conversion, carbon fixation, activity of 1,5-bisphosphate carboxylase-loxygenase (RUBISCO), and the rapid turnover of the putative Dl reaction center (32 kda) protein, whereas longer-term exposure to ambient UVR (24–48 h) revealed a steady-state acclimation, defined as recovery of carbon fixation and RUBISCO activity to rates equivalent to treatments without exposure to UVR. The turnover of D1 and chlorophyll a (Chl a) remained high during exposure to UVR. Efficiency of energy conversion by photosystem II, measured with double flash (pump and probe) fluorometry, increased by 24% in cells acclimated to UVR. Acclimation to UVR had no detectable effect on the functional absorption cross-section or cellular concentrations of Chl a, Chl c, or total carotenoids. However, the maximum rate of carbon fixation was reduced by UVR on a Chl a basis but remained unaffected on a per-cell basis. Response to UVR exposure in this subtropical diatom has two components: a short-term inhibitory response and a longer-term acclimation process that ameliorates the inhibition of carbon fixation.     

A PHYLOGENETIC APPROACH TO THE ESTIMATION OF PHYTOPLANKTON TRAITS1

The quantitative characterization of the ecology of individual phytoplankton taxa is essential for model resolution of many aspects of aquatic ecosystems. Existing literature cannot directly parameterize all phytoplankton taxa of interest, as many traits and taxa have not been sampled. However, valuable clues on the value of traits are found in the evolutionary history of species and in common correlations between traits. These two resources were exploited with an existing, statistically consistent method built upon evolutionary concepts. From a new data set with >700 observations on freshwater phytoplankton traits and a qualitative phytoplankton phylogeny, estimates were derived for the size, growth rate, phosphate affinity, and susceptibility to predation of 277 phytoplankton types, from evolutionary ancestors to present‐day species. These estimates account simultaneously for phylogenetic relationships between types, as imposed by the phylogeny, and approximate power‐law relationships (e.g., allometric scaling laws) between traits, as reconstructed from the data set. Results suggest that most phytoplankton traits are to some extent conserved in evolution: cross‐validation demonstrated that the use of phylogenetic information significantly improves trait value estimates. By providing trait value estimates as well as uncertainties, these results could benefit most quantitative studies involving phytoplankton.     

基于模型数据融合的长白山阔叶红松林碳循环模拟

 充分、有效地利用各种陆地生态系统碳观测数据改善陆地生态系统模型, 是当前我国陆地生态系统碳循环研究领域亟待解决的重要问题之一。该研究以2003~2005年长白山阔叶红松林的6组生物计量观测数据和涡度相关技术测定的碳通量数据为基础, 利用马尔可夫链-蒙特卡罗方法对陆地生态系统模型的关键参数(即碳滞留时间)进行了反演, 进而预测了长白山阔叶红松林生态系统碳库、碳通量及其不确定性。反演结果表明, 长白山阔叶红松林叶凋落物和微生物碳的平均滞留时间最短, 为2~6个月; 其次是叶和细根生物量碳, 二者的平均滞留时间为1~2 a; 慢性土壤有机碳的平均滞留时间为8~16 a; 碳在木质生物量和惰性土壤有机质库中的滞留时间最长, 平均滞留时间分别为77~109 a和409~1 879 a。模拟结果显示, 碳库和累积碳通量模拟值的不确定性将随着模拟时间的延长而增大。当气温升高10%和20%时, 长白山阔叶红松林总初级生产力年总量将分别增加6.5%和9.9%, 净生态系统生产力(NEP)年总量的变化取决于土壤温度的变化。若土壤温度保持不变, NEP年总量将分别增加11.4%~21.9%和17.6%~33.1%; 若土壤温度也相应升高10%和20%, NEP年总量的增幅反而下降甚至低于原来的水平。假设气候和植被保持在2003~2005年的状态, 2020年长白山阔叶红松林NEP年总量为(163±12) g C·m^–2·a^–1, 土壤呼吸年总量为(721±14) g C·m^–2·a^–1。马尔可夫链-蒙特卡罗方法是反演模型参数、优化模拟结果和评估模拟结果不确定性的有效方法, 但今后仍需在惰性土壤碳滞留时间的估计、驱动数据和模型结构的不确定性分析、模型数据融合方法方面进行深入研究, 以进一步提高碳循环模拟的准确性。     

A MODEL APPROACH FOR SIZE-SELECTIVE COMPETITION OF MARINE PHYTOPLANKTON FOR FLUCTUATING NITRATE AND AMMONIUM1

Phytoplankton size-selective competition for fluctuating nutrients was studied with the use of a numerical model, which describes nitrate and ammonium uptake, nitrate reduction to ammonium, and growth as a function of cell she under fluctuating nitrogen limitation. The only size-dependent parameter in the model was the cell nutrient quota. Related to this, the cell surface area per biomass was negatively correlated to cell volume, and the vacuole volume per biomass ratio was positively correlated to cell volume. Simulations showed an inverse correlation between the maximum specific growth rate and cell size under steady-state conditions. With nitrate as the limiting nitrogen source, nitrogen quotas were always higher than with ammonium at the same specific growth rate. Net passive transport of ammonium due to unspecific diffusion of ammonia across the plasma membrane decreased the affinity for ammonium, whereas the affinity for nitrate was not influenced. Transient state-specific ammonium uptake was not dependent on cell size. However, small algae always have the highest specific growth rate in ammonium-controlled systems according to our model. Transient state nitrate uptake rate was positively correlated to cell size because larger algae have a higher vacuole volume per biomass, in which nitrate can be stored. Despite their lower maximum growth rate, larger algae became dominant during simulations under fluctuating nitrate supply when amplitude of and the period between nitrate pulses were high enough. Results from model simulations were qualitatively validated by earlier observations that large diatoms become dominant under fluctuating conditions when nitrate is the main nitrogen source.     

北美CHIHUAHUAN荒漠啮齿动物群落动态 IV.群落变量的模拟(英文)

利用ＭｏｎｔｅＣａｒｌｏ方法模拟了北美ＣＨＩＨＵＡＨＵＡＮ荒漠啮齿动物群落变量的总和、月间和年间变动情况及统计学特征,这些变量是：物种数、生物量、物种多样性和均匀性。模拟产生的１００００个样本显示这４个变量的平均值是８９１,１５４４ｋｇ／ｈｍ２,１５８和０７３。真实群落４个变量的所有值均在模拟群落变量的９５％置信区间内。模拟群落物种数、生物量和物种多样性有相同的年间变动规律。物种数和生物量有相同的季节变动规律。当零假设为这些变量均服从正态分布时,Ｘ２检验及偏度和峭度说明,在９５％的显著性水平上,物种数有９６２个样本,生物量有１０９个样本,物种多样性有５５２９个样本,均匀性有６６５４个样本服从正态分布,即在９５％的显著性水平上,没有一个变量是服从正态分布的。结果说明,当样本含量较小时,我们不能用（平均数＋１９６×标准误）的公式来计算     

动物单种群动态的ALLEE效应的数学模型及其解的性态

本文根据单种群动态ALLEE效应的特点,引入一个适当的数学模型,并对其解的振动性、有界性和渐近稳定性进行了研究。     

等电点时氨基酸数学模式探讨

本论文从氯基酸各种离子在溶液中的分布出发,对中性氨基酸,酸性氨基酸,碱性氨基酸等电点时的特性进行了数学分析,从而解释了氨基酸等电点时的行为。     

PHOTOSYNTHESIS OF THE RED ALGA GASTROCLONIUM COULTERI (RHODOPHYTA) IN RESPONSE TO CHANGES IN TEMPERATURE,LIGHT INTENSITY,AND DESICCATION1

Previously reported transplantation experiments in the field showed that Gastroclonium coulteri (Harvey) Kylin could survive above its normal intertidal range (0.0–0.5 m above MLLW), except during periods of daytime low tides in spring. Net photosynthetic rate measurements in the laboratory were performed to determine which physical factors might determine the upper boundary for this species in the intertidal zone. Maximum net photosynthesis occurred between 15 and 20° C, but remained positive between 4 and 35° C. The air temperature extremes observed in the field were 2° C (only seen once) and 26° C. Net photosynthesis increased as expected with light intensity to the highest value obtainable in the laboratory, 1400 μEin m^?2 s^?1. Plants collected from the field under higher light intensity (up to 2000 μEin m^?2 s^?2) also showed high rates of photosynthesis. Neither the temperature nor light levels observed in the field were directly damaging to photosynthesis. Desiccation, however, resulted in a sharp decrease in both photosynthesis and respiration. G. coulteri fully recovered from successive daily treatments of about 35% desiccation, but not from successive treatments of 50% desiccation. One exposure to 70% desiccation allowed no recovery of photosynthetic capacity.     

EFFECTS OF SMALL-SCALE TURBULENCE ON PHOTOSYNTHESIS,PIGMENTATION, CELL DIVISION,AND CELL SIZE IN THE MARINE DINOFLAGELLATE GOMAULAX POLYEDRA (DINOPHYCEAE)1

Several experiments were conducted to understand better the physiological mechanisms underlying growth inhibition of the dinoflagellate Gonyaulax polyedra Stein due to small-scale turbulence shear. To measure photosynthetic ¹⁴C uptake, a “phytoplankton wheel” device for rotating cultures in closed bottles was used. Turbulence was quantified biologically in the bottles by comparing growth inhibition with that in cultures with constant shear between a fixed cylinder and an outer concentric rotating cylinder (a stable Couette flow). At saturating irradiances, particulate photosynthesis (P_sat) or photosynthesis per unit chlorophyll (P^B_sat) were not inhibited completely at the highest turbulence level (26.6 rad.s^?1), and photosynthesis was less sensitive than growth. Photosynthesis per cell (P^C_sat) was increased by turbulence. In three experiments on the effects of turbulence on photosynthesis versus irradiance curves, the slope of the curve, α, for particulate photosynthesis at limiting irradiances did not change. Photosynthesis per unit chlorophyll per unit irradiance (α^B) decreased at high (but not intermediate) turbulence levels. Photosynthesis per cell per unit irradiance, α^C, increased with turbulence, suggesting an increase in photosynthetic efficiency in turbulent cultures. In two of the three experiments, respiration rates increased with turbulence, and in one experiment excretion of photosynthetically fixed ¹⁴C was not affected by motion. Ratios of accessory pigments to chlorophyll a did not change with turbulence, but pigments per cell and per dry weight increased with turbulence. These findings suggest little or no disruption of the photosynthetic apparatus. When turbulence was applied for 1 week, β-carotene increased while peridinin and diadinoxanthin decreased, suggesting inhibition of synthesis of these latter pigments by prolonged turbulence. Since cell numbers did not increase or decreased during turbulent 72–h incubations, cell division was inhibited and also the cells were very much enlarged. Increases in α^C per cell suggest that, in the sea, photo synthetic metabolism can persist efficiently without cell division during turbulent episodes. After turbulence ceases or reaches low levels again, cells can then divide and blooms may form. Thus, blooms can come or go fairly rapidly in the ocean depending on the degree of wave- and wind-induced turbulence.     

杭州西湖引水后生态系统中磷循环模型

报道了杭州西湖截污和引灌钱塘江水后的一个富营养化模型。它按照年度描述西湖生态系统中的磷循环。状态变量有浮游植物磷、正磷酸盐、碎屑磷和沉积物磷。模型校准和检验结果表明,对于系统给定的强制函数（引水量和水温等）的改变,模型作出的状态变量的描述是合理的。并且利用该模型模拟在不同引水量及挖泥量下西湖水质变化。模型对引水及挖泥的效益所作出的评估可供综合治理时参考。     

昆虫种群动态模拟方法的一点改进──三化螟种群动态模拟模型的研究

以Ｒｕｅｓｉｎｋ（１９７６）的模型为基础,根据昆虫个体一般不同步地进入下一发育阶段的状况,当昆虫各虫态发育到完成该虫态发育所需要的最低年龄级数后,假定各年龄级的昆虫种群均以一定的概率分布函数值进入下一个发育阶段,同时根据有效积温向前推进。据此,对昆虫种群动态模拟方法作了一点改进。该方法综合了已有的种群模型的优点,因而较Ｒｕｅｓｉｎｋ（１９７６）和ＣｈｉＨｓｉｎ等（１９８５）提出的方法更真实地反映了昆虫种群动态的变化规律。根据三化螟自然种群生命表的资料,分析和确定逐日存活率、逐日发育率和逐日生殖率,对三化螟种群进行逐日动态模拟和预测,同时引入环境因素对种群的控制作用,研究不同环境条件下的种群动态,经验证,模型基本能够反映田间三化螟的发生规律。     

THE ACCLIMATED RESPONSE OF GROWTH,PHOTOSYNTHESIS, COMPOSITION,AND CARBON BALANCE TO TEMPERATURE IN THE PSYCHROPHILIC ICE DIATOM NITZSCHIA SERIATA1

Nitzschia seriata Cleve, a common member of marine bottom ice communities in the Arctic, was grown in unialgal batch cultures to test for compensatory mechanisms for the low temperatures (?1.8° C) typical of its natural habitat. The upper lethal limit for growth was between 12° and 15°C, and the optimum was between 6° and 12° C. The Arrhenius function adequately (R²= 73%) fitted the relationship between growth rate and temperature from – 1.6° up to 10° C, with an average Q₁₀ of 1.9 over the entire range. Light-saturated and light-limited rates of photosynthesis (normalized to chlorophyll a or cell carbon) showed complete compensation from 12° to 4° C. Photosynthetic rates, especially at light saturation, declined rapidly at temperatures below 4° C. Susceptibility to photoinhibition was greatest at the lowest growth temperatures. Cellular composition (chlorophyll a, protein, polysaccharide, and lipid contents) was not systematically related to temperature in any simple way, although cell size (carbon per cell) was maximal at the lowest growth temperature. Dark respiration was unmeasurably low (<0.015 day^?1) at all growth temperatures. The strategy of adaptation in N. seriata may be characterized as optimizing efficiency and compensation, rather than maximization, of growth rate.     

ALGAL PHOTOSYNTHETIC MEMBRANE COMPLEXES AND THE PHOTOSYNTHESIS-IRRADIANCE CURVE: A COMPARISON OF LIGHT-ADAPTATION RESPONSES IN CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA)1

Chlamydomonas reinhardtii was grown at photon flux densities (PFDs) ranging from 47 to 400 μE.m^-2 s^-1. The total cellular content of chlorophyll (Chl) was twice as high in the low light (LL) versus high light (HL) grown cells. On an equal Chl basis, photosystem II (PSII) and cytochrome f (Cyt f) content was higher in HL cells, but photosystem I (PSI) concentration displayed little variation with the light intensity during cell growth. Consequently, there was a shift in the ratio of PSII / PSI and Cyt / PSI from near unity in LL cells to greater than two in HL cells. The functional Chl antenna size of PSII and PSI ranged from 460 and 170 Chl (a + b)in HL-grown cells to 620 and 370 Chl (a+ b)in LL-grown cells, respectively. The initial slope of the Chl-specific photosyn-thesis-irradiance (P-I) curve was similar in LL- and HL-grown cells, but the light saturated rate of photosynthesis was lower under LL. The response to low light was beneficial at the cellular level, since there was an enhancement of photosynthesis in LL. The PFD for the onset of light saturation, 1 was a factor of 2 lower in LL- relative to HL-grown photosythetic membranes. Since growth PFD varied by a factor of ten, photosynthesis shifted from being light-limited in the LL regime to light-saturated in the HL regime. The requirement for balanced absorption of light by the two photosystems constrains the PSII / PSI ratio to near unity when growth is light-limited, but such a constraint does not apply in HL conditions. Instead the concentration of individual electron transport complexes way be related to the pool size necessary for maximum rates of steady-state electron transport. Thus the stoichiometry of electron transport complexes changes in response to growth PFD and this change is correlated with the response flexlbility of algal photosynthesis in diverse light environments.