Coupling of seagrass (Cymodocea nodosa) patch dynamics to subaqueous dune migratio

The coupling between patch dynamics - described by the patch growth (horizontal and vertical), patch mortality, and life-history of Cymodocea nodosa (Ucria) Aschers., and the disturbance caused by the migration of subaqueous dunes over the plants was examined in a shallow NW Mediterranean bay (Alfacs Bay) where this species maintains a patchy cover. C. nodosa shoots survived substantial burial rates (up to 2.4 mm/day) by growing vertically at rates proportional to, albeit four-fold slower than, burial rates. Patch death was caused by erosion as large subaqueous dunes migrated pass the plant patch. Patch growth was fastest over the progressing slope of the dunes ( similar to 2.5 m year super(-1)) and flowering was also stimulated by sand accretion. The time interval between the passage of consecutive dunes, which sets the time window available for patch development, ranged between 2 and 6 years. This time interval allowed C. nodosa to recolonize bare substrata, with patch formation occurring about half a year after the disturbance, and also allowed established shoots to complete their life-cycle and produce seeds and thus enable subsequent recolonization. The time windows available for patch development also set an upper limit to patch size of about 26 m. Significant cross correlations between dune topography and patch dynamics and plant flowering frequency provide evidence that the spatial heterogeneity in the vegetation is closely associated with the disturbance imposed by the migration of sand dunes. The migration of subaqueous dunes maintains C. nodosa in a continuous state of colonization involving spatially asynchronous patch growth and subsequent mortality, which is ultimately responsible for the characteristic patchy landscape of this Bay. 

Vortex dynamics in the studies of looping in tropical cyclone tracks

This paper proposes criteria for predicting the tendency of looping in tropical cyclone tracks using the approach of vortex dynamics. We model the asymmetric structure of a cyclone by a system of vortex patches. The evolution of such system of vortices is simulated by the method of contour dynamics. A new set of exact analytic formulas for contour dynamics calculations is derived, which is shown to be more computationally effective. Based on point-vortex models, we derive analytic formulas for the criteria of looping in a cyclone track. From numerical experiments, the simulated trajectories obtained from the point-vortex system and vortex patch system agree quite well. Hence, the looping criteria obtained from the point-vortex system can be applied by forecasters to stay alert for tendency of looping in a cyclone track. To demonstrate the applicability of the proposed criteria, the trajectory of Typhoon Yancy (9012), whose field data are available from ''TCM-90'', is simulated. The case study shows that the asymmetric structure similar to the pattern of a beta gyre is responsible for its recurvature when Yancy landed Fujian Province, China on 20 August 1990.

北京地区植被景观的空间分布特征

本文利用地理信息系统(GIS)技术、景观生态学理论和方法、分形理论以及统计分析方法对北京地区植被景观的空间分布特征进行了分析，并对景观格局和景观多样性的分析方法进行了探讨，结果表明： (1)对几乎所有的斑块类型，其斑块大小的分布都不是对称的，而是右偏的。4种概率分布（Г—分布、对数正态分布、Weibull分布和（负）指数分布）都只能刻划部分斑块类型，并且服从对数正态分布的斑块类型最多，服从（负）指数分布的斑块类型最少。 (2)随着斑块面积的增加，边界效应越来越小，而斑块形状越来越不紧凑。 (3)分形分析识别出本地区植被景观中的两个尺度域：一个是斑块面积小于(大约)2.7km2，另一个是斑块面积大于(大约)2.7km2。两个域中的斑块复杂程度有很大差异，后一个域中的斑块明显比前一个域中的斑块复杂，并且随着斑块面积的增加，斑块形状越来越复杂。 (4)用斑块数作为多度指标时，该景观的斑块类型一多度分布服从（截断）对数正态分布和（截断）负二项分布，不服从对数级数分布和几何分布。用斑块面积作为多度指标时，该景观的斑块类型一多度分布服从对数正态分布、Weibull分布和Г—争布，不服从正态分布。从而该景观的斑块类型一多度分布不是对称的，也是右偏的。在4个优势度／多样性模型中，“生态位优先占领”模型和Zipf-Mandelbrot模型可以较好地刻划该景观的斑块类型一多度关系。 (5)样本大小对多样性测度有直接的影响。如果这种影响比较小，就说明测度指标比较稳定。三个丰富度指数中，Ri比R2和R3更稳定;五个多样性性指数中，D和Di最稳定，OD最不稳定，因此，OD是用于景观多样性监测的理想指标;五个均匀度指数中，Jgi最稳定。根据设计的3种计算临界样方数量（即多样性测度指标达到稳定时的样方数量）方法的计算结果，上述几个最稳定的测度指标在通常情况下只需要几个样方(即总抽样面积为数百km2)就达到稳定状态。 (6)斑块类型数目随面积的增加而增加。根据四个评价指标的评价结果，认为双曲线对该景观的斑块类型一面积关系的拟合效果最好。 (7)样本较大（对于一阶刀切估计，大于30个样方;对于二阶刀切估计，大于60个样方）时，刀切法能够给出斑块类型数目(NPT)较好的估计;样本较小（小于30个样方）时，Mingoti和Meeden提出的经验贝叶斯方法能够对NPT给出比刀切法和自助法更好的估计。斑块类型一面积曲线外推虽然也能给出NPT较好的估计，但这种方法需要慎重使用，不能外推得很远。 (8)列联表分析表明，该植被景观中的斑块类型与土壤类型、岩石类型、海拔高度和坡向各因子之间均存在显著的相关性。植被景观多样性与岩石类型多样性和地形多样性之间也均呈显著的正相关关系，即植被景观多样性随岩石类型多样性和地形多样性的增加而增加。但植被景观多样性与土壤类型多样性之间不存在显著的线性相关或秩相关关系，这可能是由于二者的分类体系不吻合。植被景观多样性与总的道路密度和第二类道路密度之间均呈显著的负相关关系，而与第一类和第三类道路密度之间的关系都不显著。这反映出景观样本单元(10kmxlOkm)的尺度对应于第二类道路的影响尺度。而道路密度在一定程度上反映了人类活动的强度，因此，在10kmxlOkm这个尺度上，人类活动愈剧烈，景观多样性就愈小。

根茎克隆植物羊草分株种群对去叶干扰的生长对策

克隆植物具有多种不同于非克隆植物的生长和繁殖策略。本研究首先综述了这些生长与繁殖策略之中，与我们的实验研究相关的尤其是对于去叶干扰适应策略的四个方面，包括克隆整合、克隆分株大小与密度之权衡( tradeoff)过程、碳水化合物贮备与利用、营养繁殖和芽种群(bud population)调节等。预测克隆植物选择什么样的对策以及某种对策发生作用的条件及程度如何，对克隆植物生态学研究者来说，将是富有挑战意味的课题。 羊草(Leymus chinensis (Trin,) Tzvel.)是禾本科的一种多年生根茎型克隆植物，常常处于由放牧或刈割造成的去叶干扰( defoliation)的胁迫下。在我们的第一个实验（2002年）中，考察了去叶干扰和根茎切割( rhizome severing)是否影响根茎本身和分株地上部分的生长、以及营养繁殖芽的数量特征。同时我们检验如下的假设：直接受到去叶干扰的分株除了会受益于可能的补偿作用之外，还会受益于克隆整合作用，即与之保持根茎联系的未受去叶处理的分株将转移碳水化合物或养分给受去叶干扰的分株，使之得以尽快恢复光合组织。实验结果显示：单次去叶干扰影响根茎生长和芽的产生，而对地上部分的生长影响甚微。只有重度去叶干扰才显著影响营养繁殖芽的产生，而轻度去叶干扰作用不明显。所以，当去叶强度不大时，补偿作用机制将弥补植物由于去叶干扰而受到的损失。我们的实验并未检测到克隆整合的发生，可能的原因是本实验持续的时间不足够长或者是由于根茎中的碳水化合物贮备在去叶干扰发生后发挥了作用，缓解了去叶干扰对羊草分株生长及芽生产的所造成的冲击。 在第二个实验（200 3年）中，为了考查相继数次的去叶干扰是否能够启动羊草分株间的克隆整合，以及启动克隆整合所需达到的去叶干扰的频次，我们将实验样方设计为两部分：核心区( Core section)和外围区(Periphery section)。不同频次的去叶处理（0去叶，作为对照; 1次去叶;3次去叶;5次去叶）仅施加于实验样方的核心区。结果表明，经历3次和5次去叶处理的样方外围区的生物量及水溶性碳水化合物( wsc)含量均明显少于经历1次去叶处理及0去叶处理的样方外围区，这意味着克隆整合在3次去叶和5次去叶两种处理中发生了，而在其它两种处理中没有发生。此外，分株的大小一数目之权衡可能在基株(genet)水平上发生，因此，一个克隆植物基株，当部分分株受到去叶干扰后，将增加其分株数目，但优先增加未受到去叶干扰部分的分株数目。我们将羊草的这种行为视为克隆基株试图逃避干扰的“逃逸行为”( escaping behavior)。 同时在实验中，我们监测了实验样方核心区分株的wsc浓度，目的是查明羊草枝条与根茎中wsc浓度随时间的变化格局及其对去叶干扰的响应，意在发现羊草枝条地上、地下部分和根茎中wsc浓度的时间变化之间的联系。在生长旺季，对照处理（即O去叶处理）的wsc浓度显著降低，这是由于植物在此时期的高生长速率和高呼吸速率所致;相比之下，其它经历去叶干扰的三个处理中羊草wsc浓度降低不如对照处理那么明显和迅速，甚至在高频次去叶处理中还有所上升，其原因大概是由于去叶而使叶面积减小，引起枝条的总呼吸下降所致。羊草枝条中最终的wsc浓度没有受到单次去叶处理的显著影响，却很可观地受到相继数次去叶干扰（3次和5次去叶处理）的影响。去叶干扰可能加速了碳水化合物在气温降低时自地上向地下的转移。枝条的地下部分wsc浓度比地上部分更稳定。在地上部分受到去叶干扰后，根茎中的wsc必然向上输出到地上枝条，而强烈的生长会消耗wsc，但可能的克隆整合（通常在相对频繁的去叶干扰条件下发生）将在一定程度上缓解这种wsc消耗。 在此实验中，我们还监测了羊草平均每分株所拥有的芽的数目，包括每分株分蘖节芽（tiller bud）数目和根茎芽(thizomatous bud)数目。从平均每分株芽数目的时间动态来看，各种去叶处理之间的差异程度不大，这主要是羊草在受到去叶干扰后补偿作用的贡献。与对照处理相比，受不同频次去叶干扰的三个处理的根茎芽具有相对于分蘖节的更强的增长优势。去叶干扰对根茎芽生长的促进作用大于对分蘖节芽的促进作用。我们认为这种反应是羊草克隆基株的一种逃避干扰的适应性努力，可视为一种“逃逸行为”，也可看作克隆植物觅养行为(foraging behavior)的一种特殊形式。芽的增长在中等频度的去叶干扰条件下最强，似乎同样符合中度干扰理论。有趣的是，特定频度的去叶干扰可能会造成芽种群中两大类型芽之间比例（根茎芽／分蘖节芽）的振荡现象（Oscillation）。 最后展望了对于羊草今后应继续开展的工作主要集中在两大方面：一是有性繁殖与无性繁殖之间在不同生境或不同干扰条件下的权衡关系;二是处于不同斑块对比度( patch contrast)的生境中的羊草克隆分株之问的生理整合，及其强度与斑块对比度的定量关系。

Game Vertebrate Densities in Hunted and Nonhunted Forest Sites in Manu National Park, Peru

Manu National Park of southern Peru is one of the most renowned protected areas in the world, yet large-bodied vertebrate surveys conducted to date have been restricted to Cocha Cashu Biological Station, a research station covering <0.06 percent of the 1.7Mha park. Manu Park is occupied by >460 settled Matsigenka Amerindians, 300-400 isolated Matsigenka, and several, little-known groups of isolated hunter-gatherers, yet the impact of these native Amazonians on game vertebrate populations within the park remains poorly understood. On the basis of 1495 km of standardized line-transect censuses, we present density and biomass estimates for 23 mammal, bird, and reptile species for seven lowland and upland forest sites in Manu Park, including Cocha Cashu. We compare these estimates between hunted and nonhunted sites within Manu Park, and with other Neotropical forest sites. Manu Park safeguards some of the most species-rich and highest biomass assemblages of arboreal and terrestrial mammals ever recorded in Neotropical forests, most likely because of its direct Andean influence and high levels of soil fertility. Relative to Barro Colorado Island, seed predators and arboreal folivores in Manu are rare, and generalist frugivores specializing on mature fruit pulp are abundant. The impact of such a qualitative shift in the vertebrate community on the dynamics of plant regeneration, and therefore, on our understanding of tropical plant ecology, must be profound. Despite a number of external threats, Manu Park continues to serve as a baseline against which other Neotropical forests can be gauged.

Properties of the proton-evoked currents and their modulation by Ca2+ and Zn2+ in the acutely dissociated hippocampus CA1 neurons

The characterization of acid-sensing ion channel (ASIC)-like currents has been reported in hippocampal neurons in primary culture. However, it is suggested that the profile of expression of ASICs changes in culture. In this study, we investigated the properties of proton-activated current and its modulation by extracellular Ca2+ and Zn2+ in neurons acutely dissociated from the rat hippocampal CA1 using conventional whole-cell patch-clamp recording. A rapidly decaying inward current and membrane depolarization was induced by exogenous application of acidic solution. The current was sensitive to the extracellular proton with a response threshold of pH 7.0-6.8 and the pH(50) Of 6.1, the reversal potential close to the Na+ equilibrium potential. It had a characteristic of acid-sensing ion channels (ASICs) as demonstrated by its sensitivity to amiloride (IC50 = 19.6 +/- 2.1 muM). Either low [Ca2+](0) or high [Zn2+](0) increased the amplitude of the current. All these characteristics are consistent with a current mediated through a mixture of homomeric ASIC1a and heteromeric ASIC1a + 2a channels and closely replicate many of the characteristics that have been previously reported for hippocampal neurons cultured for a week or more, indicating that culture artifacts do not necessarily flaw the properties of ASICs. Interestingly, we found that high [Zn2+] (>10(-4) M) slowed the decay time constant of the ASIC-like current significantly in both acutely dissociated and cultured hippocampal neurons. In addition, the facilitating effects of low [Ca2+](0) and high [Zn2+](0) on the ASIC-like current were not additive. Since tissue acidosis, extracellular Zn elevation and/or Ca2+ reduction occur concurrently under some physiological and/or pathological conditions, the present observations suggest that hippocampal ASICs may offer a novel pharmacological target for therapeutic invention. (C) 2004 Elsevier B.V. All rights reserved.

Circulating immunoglobulin A- and immunoglobulin G-secreting hybridoma cells in peripheral blood preferably migrate to female genital tracts. The role of sex hormones

Antigen-specific circulating immunoglobulin-secreting cells (ISC) migrate to various secondary and tertiary lymphoid tissues. To understand the migration of the cells into the genital tract and its regulation by sex hormones, spleen-derived SG2 hybridoma cells secreting immunoglobulin G2b (IgG2b) and Peyer's patch-derived PA4 hybridoma cells secreting polymer IgA were labelled with (3) H-TdR, and intravenously injected into syngeneic mice of both sexes. Using flow cytometry, surface molecular markers of plasma cells, CD38 and CD138, and adhesion molecules, CD49d, CD162, and CD11a were found to be positive in SG2 and PA4 cells, but CD62L, alpha4beta7 and CD44 were not expressed on these cells. The relative distribution indexes (RDIs) of the cells in genital tract and other tissues were measured. The means of RDIs of SG2 and PA4 cells in female genital tissues were 6.5 and 4.5 times as many as the means in male genital tissues, respectively. The treatment of ovariectomized mice with beta-oestradiol significantly increased the RDIs of PA4 cells in cervix and vagina, but decreased the RDIs of SG2 cells in vagina, horn of uterus, uterus and rectum (P <0.05). Progesterone treatment increased the RDIs of PA4 cells in vagina and rectum (P <0.05). The treatment with testosterone significantly increased the RDIs of SG2 and PA4 cells in epididymis and accessory sex glands (P <0.05). These results demonstrate that the female genital tract is the preferable site for the migration of circulating hybridoma cells to the male genital tract, and sex hormones play an important role in regulation of the migration of circulating ISC to genital tracts.

Effects of ginkgo biloba extract on cation currents in rat ventricular myocytes

Ginkgo biloba extract (GBE), a valuable natural product for cerebral and cardiovascular diseases, is mainly composed of two classes of constituents: terpene lactones (e.g., ginkgolide A and B, bilobalide) and flavone glycosides (e.g., quercetin and kaempferol). Its electrophysiological action in heart is yet unclear. In the present study, using whole-cell patch clamp technique, we investigated electrophysiological effects of GBE on cation channel currents in ventricular myocytes isolated from rat hearts. We found that GBE 0.01-0.1% inhibited significantly the sodium current (I-Na), L-type calcium current (I-Ca) and transient outward potassium current (IKto) in a concentration-dependent manner. Surprisingly, its main ingredients, ginkgolide A (GB A), ginkgolide B (GB B) and bilobalide (GB BA) at 0.1 mM did not exhibit any significant effect on these cation channel currents. These results suggested that GBE is a potent non-selective cation channel modulator in cardiaomyocytes. Other constituents (rather than GB A, GB B and GB BA) might be responsible for the observed inhibitory effects of GBE on cation channels. (C) 2004 Elsevier Inc. All rights reserved.

Land-cover changes in an urban lake watershed in a mega-city, Central China

Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity.

Integration of double-fluorescence expression vectors into zebrafish genome for the selection of site-directed knockout/knockin

Production of zebrafish by modifying endogenous growth hormone (GH) gene through homologous recombination is described here. We first constructed the targeting vectors pGHT1.7k and pGHT2.8k, which were used for the knockout/knockin of the endogenous GH gene of zebrafish, and injected these two vectors into the embryos of zebrafish. Overall, the rate of targeted integration with the characteristic of germ line transmission in zebrafish was 1.7x10(-6). In one experimental patch, the integrating efficiency of pGHT2.8k was higher than that of pGHT1.7k, but the lethal effect of pGHT2.8k was stronger than that of pGHT1.7k. The clones with the correct integration of target genes were identified by a simple screening procedure based on green fluorescent protein (GFP) and RFP dual selection, which corresponded to homologous recombination and random insertion, respectively. The potential homologous recombination zebrafish was further bred to produce a heterozygous F-1 generation, selected based on the presence of GFP. The potential targeted integration of exogenous GH genes into a zebrafish genome at the P-0 generation was further verified by polymerase chain reaction and Southern blot analysis. Approximately 2.5% of potential founder knockout and knockin zebrafish had the characteristic of germ line transmission. In this study, we developed an efficient method for producing the targeted gene modification in zebrafish for future studies on genetic modifications and gene functions using this model organism.

沈阳城市森林生态系统健康与管理研究

本文系统研究了沈阳城市森林的布局与结构、城市森林功能、城市森林病虫害发生与树木健康状况和城市自然资源与社会经济状况等指标对沈阳城市森林生态系统健康与管理的影响。同时一，采用2种生态系统健康评价方法对沈阳城市森林生态系统健康状况进行了评价，并提出了沈阳城市森林生态系统健康管理的对策。研究结果如下：1、截至2004年末，沈阳城市森林植被覆盖率已经达到35％，城市森林林地分布基本合理，但需要进一步加强道路林地、居住区林地和城郊大面积生态林建设。2、沈阳城市森林以乔木为主，乔灌株数比为1.7：1，乔灌的覆盖度比约为7:1。3、沈阳城市森林不同类型林地中植物组成不同。公园林地中有74个属，137个种（变种）；庭院林地中有53个属，104个种（变种）；居住区林地中有45个属，81个种（变种）；道路林地中有43个属，94个种（变种）；运河风景林地中有75个属，142个种（变种）；棋盘山风景林地中有48个属，118个种（变种）。4、公园林地、庭院林地、居住区林地、道路林地和运河风景林地的Shannon一Wiener多样性指数分别为2.78、3.05、3.15、3.18和3.18，均匀度指数分别为0.56、0.66、0.72、0.70和0.64。除了棋盘山风景林地外，沈阳城市森林中栽植总量超过乔木总量5％的乔木树种有7个属，分别为李、柳树、杨树、桧柏、榆树、槐树和银杏，7种树木总量达到了全部乔木总量的82.09％；栽植总量超过灌木总量5％的灌木树种也有7个属，分别为水腊、丁香、李属，小聚、玫瑰、忍冬和连翘，7个属灌木总量达到了全部灌木总量的87.92％。5、公园林地、庭院林地、道路林地和防护林地中OBH＜20cm、20cm＜DBH＜60cm和DBH＞60cm树木的比例分别为：57.9％、40.0％、2.1％，49.2％、47.8％、3.0％，65.3％、33.1％、1.6％和64.6％、34.9％、0.5％，表明沈阳城市森林树木的规格总体上偏小。6、经样方调查和CITYgreen模型计算，沈阳城市森林的生态效益约2.0亿USD／yr.。公园林地、庭院林地和风景林地的景观指标相对较高；道路林地和居住区林地的景观效果一般；防护林地的景观效果较差。7、目前已经发现的沈阳城市森林病害约600余种，虫害约700余种，其中杨树主要病虫害39种，柳树的主要病虫害有33种，榆树和槐树的主要病虫害均为，1种。杨柳树腐烂病、光肩星天牛、天幕毛虫、桃红颈天牛和美国白蛾等是近10年来沈阳城市森林中普遍发生和造成严重危害的主要病虫害。沈阳城市森林主要树木的平均健康指数为2.68，处于一般健康状态。8、沈阳城市森林的土壤和水资源状况均不利于树木的健康生长，沈阳的社会经济发展也有待于进一步提高。9、经过生物指示物法（光肩星天牛为生物指示物）、专家权重法、公众问卷调查和对比研究，沈阳城市森林生态系统总体上处于亚健康状态。10、通过对沈阳城市森林资源、管理状况的调查研究和健康状况的评价，本文提出了沈阳城市森林生态系统健康管理的对策，包括合理规划沈阳城市森林林地布局，增加道路林地、居住区林地和城郊林地的面积和植被覆盖率；调整树木种类组成，避免单一或少数树种的大量栽植，提高生物多样性水平；保护大树和古树；增加城市森林管理资金的投入；应用先进技术，采取科学的病虫害防治和植物养护方法，促进树木的健康生长等。This project systematically studied the urban forest ecosystem health and management in Shenyang. The study explored factors, such as urban forest structure, distribution, pests, aesthetic value, ecological benefit, natural resources and socieo-economic status, that affecting the urban forest ecosystem health and management. Two methods were used to evaluate the ecosystem health. This project also proposed Shenyang's urban forest ecosystem health management strategies. The research results can be summarized as follows: 1. As of the end of 2004, urban forest coverage in Shenyang is about 35%, and is in relatively even patch distribution pattern. However, the street trees and roadside forest patches, residential block forest patches should be enhanced. 2. Trees are the major component of the Shenyang s urban forest, followed by shrubs. The quantity ratio of tree to shrub is about 1.7:1, and the coverage ratio of trees to shrub is about 7:1. 3. Species composition varies by location. There are 74 genera, 137 species (including varieties) in the public parks; 53 genera, 104 species (and var.) in the green spaces of the institution (including school), factory, and company; 45 genera, 81 species (var.) in residential blocks; 43 genera, 94 species (var.) in streets and roadside forest patches; 75 genera, 142 species (var.) in the Canal landscape forest patches; 48 genera, 118 species (var.) in the Qipan Mountain recreation forest. 4. The Shannon-Woener indices varies in parks, in institution, factory, and company yards, in streets and roadside forest patches, in residential blocks.there are 2.78, 3.05, 3.18, 3.15, 3.18, respectively; and the evenness indices are 0.56, 0.66, 0.70, 0.72, 0.64, respectively. Besides the Qipan Mountain forest patches, trees of 7 genera, Prunus spp., Salix spp., Populus spp., Sabina spp., Ulmus spp., Robinia spp. and Ginkgo biloba are of more than 5% the total urban trees, respectively. In fact, trees from these 7 genera are about 82% of all trees in Shenyang's urban forests. In terms of shrubs, species of 7 genera, Ligustrum spp., Syringa spp., Prunus spp., Berberis spp., Rosa spp., Lonicera spp., and Forsythia spp. are more than 5% the total urban shrubs, respectively. 88% of all the shrubs in Shenyang s urban forest are from these 7 genera. 5. The diameter class of DBH<20cm, 20cm60cm of trees in parks, in institution, factory, and company yards, in in streets and roadside forests, and in protective forests are 57.9%, 40.0%, 2.1%; 49.2%, 47.8%, 3.0%; 65.3%, 33.1%, 1.6%; and 64.6%, 34.9%, 0.5%, respectively. The result indicated that the DBH is relatively small in Shenyang s urban forests. 6. Using random plots sampling and CITYgreen model calculation, the ecological benefit of Shenyang's urban is about 0.2 billion US dollars per year. The aesthetic value of parks, institution and company yards, and scenary forest patches is relative high; however, the aesthetic value of protective forest patches is low. 7. There are more than 600 types of diseases and more than 700 kinds of insects in Shenyang's urban forest. Among them, Populus spp., Salix spp., Ulmus spp. and Robinia spp., are attached mainly by 39, 33, 11, and 11, difference types of pests respectively. The rot disease of the Populus spp. and Salix spp., and the insects such as, Anoplophora glabripennis, Malacosoma neustria, Aromia bungii, and Hyphantria cunea are major pests in Shenyang s urban forest for the past 10 years. The trees health condition is relatively poor by having the average health index of 2.68 for major species. 8. The urban soil and water resource are not favorable to tree's growth in Shenyang, and so is the socieo-economic status. 9. Through using bio-indicator, professional and public evaluation, and comparision with other urban forests, it can be concluded that the status of Shenyang s urban forest is not very healthy in general. 10. To improve the urban forest ecosystem health in Shenyang, a better urban forest design need to be implemented to enhance the area and vegetation coverage of the street and roadside forests, the residential block forests, and the surburb forest Species biodiversity need to be enhanced by adjust the species composition of urban forest trees to reduce the single or several tree species populations and to plant more varieties. A better fundings for urban forest health management need to be budgeted. Advanced technologies in tree care and scientific measures to control pests need to be adopted to prove better care for plants and to keep trees grow healthfully.

岷江源头区植被景观与流域土壤侵蚀的动态相关性

作为复杂的生态过程之一，土壤侵蚀常常被空间景观异质性影响。深入地研究土壤侵蚀与植被景观的相关性对以减少水土流失为目的的河流中上游生态恢复工作来说十分重要。本文利用遥感和GIS 技术，对岷江源头区的植被景观和土壤侵蚀动态（1974年～2002 年）进行分析，并从景观生态学的角度，系统地研究了整体植被景观和不同的植被景观类型的景观特征与土壤侵蚀量、侵蚀模数以及土壤侵蚀强度的相关性，得出的结论主要有以下几个方面：1. 从植被景观特征与土壤侵蚀量和土壤侵蚀模数的相关性的角度出发，森林能最大限度地控制土壤侵蚀，草地对土壤侵蚀的控制能力不及森林，而且能在一定程度上增加土壤侵蚀。灌丛与土壤侵蚀量和土壤侵蚀模数的关系则比较复杂，还需要进一步地研究。农用地与森林、灌丛、草地等植被类型不同，它的增加将会明显地增加产沙量。随着各景观类型（灌丛除外）分布的镶嵌性的增强，土壤侵蚀量和侵蚀模数会减少。2. 从植被景观特征与土壤侵蚀强度的相关性的角度出发，在景观水平上，植被景观的景观多样性指数、景观破碎度指数、景观形状指数和景观聚集度指数均与土壤侵蚀强度有明显的相关性。在较轻侵蚀强度的区域中的植被景观具有更丰富的多样性和更低的破碎程度，景观的组分和结构都更加复杂，景观斑块的形状也比较复杂。同时，植被景观的空间异质性也较强。3. 从不同景观类型对土壤侵蚀强度的控制能力大小看：针叶林> 落叶阔叶林>针阔混交林> 灌丛> 草地> 农用地。同时，对于除农用地以外的其他植被景观类型来说，增加其平均斑块面积和形状的复杂性会在一定程度上减少土壤侵蚀强度。而对于农用地来说，斑块形状的简单化以及分布形式的均匀镶嵌化则是减少土壤侵蚀强度的有效手段。 As a complex ecological process, soil erosion is affected by the spatial landscape heterogeneity.The relation between soil erosion and landscape characteristic weights a lot in ecosystemrestoration that aim to control the soil erosion in watershed. By means of RS and GIStechniques, this study analyzed dynamic variations in landscape characteristic and soil erosionin the Minjiang headwater region over a period of 28 years to elucidate the interrelationshipsbetween landscape characteristics and soil erosion. The results are as follows:1. In terms of relation between landscape characteristics and soil erosion module, forest canmitigate the soil erosion much better than grass. The relation between shrub and soil erosionmodule is rather complicated that requests further more study to confirm how those two factorscorrelated with each other. Cultivated land differs from other landscape classes in creatingconditions most favorable for soil erosion. Moreover, the dispersion of all landscape classes,except for shrub, correlates with soil module negatively.II2. In terms of relation between landscape characteristics and soil erosion strength, the diversityindex, fragment index, shape index and contagion index of the vegetation in Minjiangheadwater region at landscape-level correlated with soil erosion clearly. Vegetation landscapein No and Slight erosion region is more diverse, fragmental and constructed in more complexway. The shape of those vegetation patches is also more complicated. The spatial heterogeneityof the vegetation landscape is much more evident than that located in moderate and strong erosion region too.3. At class-level, different landscape classes affected soil erosion strength in different ways.Taking the mitigating effect on erosion strength into consideration, landscape classes can bearranged in this turn: coniferous forest > Deciduous forest > Mixed forest > Shrub > Grassland > Cultivated land. At the same time, for most landscape classes, except for cultivated land,increase the mean patch size and complicate the shape of patch will help to relieve the erosionstrength. However, for cultivated land, simplifying the shape of patch and scattering thepatches have the same effect.

克隆植物东方草莓对异质生境的适应对策

克隆植物被认为比非克隆植物更宜于利用异质性环境。在复杂的空间异质环境中，克隆植物可能形成了各种有效利用环境异质性的适应对策。对于克隆植物适应机制的研究，前人已做了大量的工作，特别是从形态和生物量分配等方面对简单异质生境下克隆植物的克隆整合和克隆分工进行了详细的研究。本研究以分布广泛的克隆植物东方草莓（Fragaria orientalis）作为研究对象，应用野外调查和实验生态学方法，采用多对比度单资源模型和不同向双资源模型，从形态和生理生态的角度，研究复杂异质生境下克隆植物的整合和分工及其耗益问题，分析不同类型的生境对克隆植物整合和分工的修饰作用，进而探讨克隆植物对异质生境的适应策略。克隆构型和分株种群特征是植物克隆生长及其生态适应对策研究的基本内容。本文通过野外调查，研究在不同光照条件下东方草莓克隆构型、分株种群特征以及点分布格局。结果表明：东方草莓的克隆构型随光照发生相应的变化，低光照下其匍匐茎节间长和分枝角度均增大而分枝强度减小；随光照减弱，东方草莓分株种群的生物量、根冠比和分株种群密度显著降低；不同光照下东方草莓分株均以随机分布为主但不同尺度下有所差异，其分布格局强度依次为旷地<林缘<林下。结合克隆植物对资源的利用对策，探讨了克隆构型和分株种群特征以及分布格局随环境条件变化的生态适应意义。不同生境斑块条件下克隆植物可能采取不同的适应对策。采用盆栽实验，研究不同水分对比度下克隆整合及其生理生态特征，并对单向和交互资源中东方草莓的克隆整合做了对比研究。结果显示：高的水分对比度能够促进东方草莓的克隆整合，并能刺激相连分株增加光合作用，东方草莓体内的氧化—抗氧化系统也II随对比度做出相应的反应。耗-益分析表明胁迫分株的受益是以供给分株的损耗为代价的，但从克隆片段总体来说是受益的。单向资源中东方草莓生长的绝对值高于交互资源，但耗-益分析表明生长于交互资源下东方草莓的克隆整合获益大于生长于单向资源下东方草莓的克隆整合获益。长期生长于特定生境的克隆植物，在进化过程中其克隆整合和克隆分工在对资源异质性的适应策略方面可能有所侧重。采用盆栽实验对来自不同海拔梯度的东方草莓的克隆整合和克隆分工对异质资源的适应对策进行了研究。实验结果表明，来自高海拔的东方草莓可塑性较差。来自两个海拔的东方草莓对切断匍匐茎的表现有所差异，总体上切断匍匐茎对来自高海拔的东方草莓影响更大些。另外，来自高海拔的东方草莓表现出更高的克隆分工。IIIClonal plants are known to be more suitable for the habitats of heterogeneousresources than nonclonal plants, perhaps due to their well developed adaptivestrategies to environmental heterogeneity. Many studies have been done on theadaptive mechanisms of clonal plants, especially on the clonal integration anddivision of labor with morphology and biomass allocation under simpleheterogeneous habitats. Based on field surveys, laboratory experiments, multi-contrastunidirectional resource model and reciprocal resource model, Fragaria orientalis, aRosaceae stoloniferous herb that widely distributes in China, was used to study thisplant’s morphological and physiological responses to complicated heterogeneoushabitats in terms of its clonal integration, division of labor and cost-benefit, as well astheir modifications by different habitats, so as to better understand the adaptivestrategies of clonal plants under heterogeneous environments.Clonal architecture and ramet population characteristics are of the major concernin the studies on growth and adaptive strategies of clonal plants. Clonal architecture,ramet population characteristics and spatial point pattern of F. orientalis underdifferent light intensity were studied with field observations. The results showed that,clonal architecture changed with light availability: Internode-lengths and branchangels of stolons were larger while branch intensities were smaller under lower lightintensity than those under higher light intensity; Biomass of ramet population,root-shoot ratio and density of ramet population decreased significantly with reduce oflight intensity; Under all light intensities, spatial pattern of ramets was mainlyrandomly distributed but it changed with different scales, with pattern intensity as:open space < forest edge < understory. Adaptation significance of the clonal architecture, the ramet population characteristics and the spatial pattern changing withdifferent environments was discussed according to these results.Clonal plants may take different adaptive strategies under different patches. Withpot culture, clonal integration and physiological parameters of F. orientalis underdifferent water contrasts were studied, and clonal integration under unilateralresources and reciprocal resources were also compared. The results suggested that,high water contrast improve the clonal integration of F. orientalis and increase thephotosynthesis of connected ramets. Oxidative and antioxidative system of F.orientalis also responded with changing water contrasts. According to cost-benefitanalysis, the drought-stressed ramets obtained benefits from the connectedwell-watered ramets, and as a whole, the clonal fragment could also get benefits.Growth of F. orientalis in homogeneous resources was better than that inheterogeneous resources, but the whole plant got more benefit through clonalintegration in heterogeneous resources than in homogeneous resources.Pot culture experiments were also used to study the adaptive strategies inutilizing heterogeneous resources by the plant populations from different altitudes.The results showed that, F. orientalis from alpine zones were shorter and lessexpanded with poorer clonal plasticity than those from middle mountains. F.orientalis from two different altitudes showed different responses to stolon severing,and as a whole, stolon severing had more influence on F. orientalis from alpine zones.In addition, F. orientalis from alpine zones exhibited higher division of labor, whichsuggested that clonal plants from different habitats develop their own adaptivemechanisms in their clonal integration and division of labor in response toenvironmental heterogeneity.