不同生境条件下西藏原始冷杉林凋落物分解特征与土壤养分的关系

[目的]研究不同生境条件下(林内、林外、林缘)藏东南急尖长苞冷杉林(Abies georgei var.smithii)凋落物分解特征与土壤养分特征之间的关系,为深入了解高寒高山森林生态系统物质循环过程提供依据。[方法]采用野外分解袋法和室内分析相结合,在林内、林外、林缘3种不同生境条件下对藏东南急尖长苞冷杉林凋落物进行了原位分解试验。[结果]分解速率总体上呈现出:林内林缘林外的特点,逐月分解率的变异系数表现为:林内(34.83%)林缘(57.35%)林外(72.09%);Olson指数衰减模型的模拟结果显示不同生境条件下(林内、林缘、林外)凋落物分解50%需要的时间为2.11,2.52,2.34 a,分解95%需要的时间为8.96,10.01,10.84 a;3种不同生境土壤养分在空间上差异显著,林内生境中与凋落物分解速率呈现极显著相关的土壤养分因子有土壤总有机碳(TOC)含量、N含量、土壤微生物量碳(SMBC)含量、土壤微生物量氮(SMBN)含量以及W_C∶W_N值;林外、林缘生境中与凋落物分解速率相关性最大的为土壤TOC含量,其次为W_C∶W_N值。[结论]生境条件的差异对凋落物分解速率有显著影响,在不同的生境条件下对凋落物分解影响起主导作用的土壤养分因素不同,凋落物—土壤生物地化循环紧密联系,相互作用关系复杂,生境作用效应突出。     

珍稀濒危植物长苞铁杉群落物种多度分布模型研究

用Weibull分布模型拟合珍稀濒危植物长苞铁杉群落物种多度分布结果表明 ,长苞铁杉群落乔木层、灌木层物种多度分布均符合Weibull分布 ,Weibull分布模型应用于珍稀濒危植物长苞铁杉群落物种多度分布具可行性     

西藏高原砂生槐种群生活史特征

采用相邻格子法,以西藏山南地区雅鲁藏布江中游河谷砂生槐种群为研究对象,分别在半固定沙地和固定沙地设立20 m×30 m的样方,研究了不同生境条件下砂生槐种群径级结构、静态生命表、存活曲线等生活史特征的异同及其影响因素。结果表明,西藏高原砂生槐在半固定沙地和固定沙地2种生境中的种群径级结构均呈现基部宽,顶部窄,随径级增大个体植株数减少的趋势。半固定沙地砂生槐种群是增长型种群,固定沙地砂生槐种群结构偏向成熟型。砂生槐种群在幼苗阶段死亡率较高,进入中龄期后死亡率有所降低。半固定沙地和固定沙地的砂生槐种群均呈DeeveyΠ型（直线型）分布。     

玉米铁甲虫自然种群生命表的初步研究

玉米铁甲虫自然种群指数较高 ,I值为 30 .97。其全世代的平均种群累计死亡率为 64.0 7%。各虫态的自然死亡率差异极显著。越夏越冬成虫和 1～ 2龄幼虫的死亡率较高 ,分别为 38.1 %和 2 1 .7%。低龄幼虫的死亡原因主要为高温引起的自然死亡和天敌的捕食 ,而成虫则主要为白僵菌感染致死。玉米铁甲虫不同时期产下的卵 ,其幼虫自然存活率有较大差异 ,在产卵盛期和高峰期产下的卵 ,1～ 2龄幼虫存活率较高 ,而产卵盛末期产下的卵 ,则存活率较低     

西花蓟马孤雌产雄生殖繁育的后代种群生命表的建立

孤雌生殖是西花蓟马(Frankliniella occidentalis)繁殖的一种重要方式。前期研究发现,西花蓟马在高温下,雌性的存活率远大于雄性。为探究高温处理后仅有雌性西花蓟马孤雌产雄的情况下其后代建立种群的可能性,试验设定:高温(45℃,2 h)处理西花蓟马单个雌性个体,分别进行孤雌产雄生殖后,雄性子代(F1代)与其母系回交产生F2代;高温(45℃,2 h)处理西花蓟马多个雌性个体,进行孤雌产雄生殖后,雄性子代(F1代)与亲代多个雌性个体共存情况下进行交配产生F2代。两组处理模式下建立F2代实验种群生命表。结果表明,上述两种处理模式,母代雌性个体与子代雄性个体交配后均可产生后代,雄性F1代与其母系回交产生的F2代的雌雄性比为1.05∶1;与亲代多个雌性个体共存下交配产生的F2代性比为1.55∶1。雄性F1代与其母系回交产生的F2代的平均单雌产卵量(F)和内禀增长率(rm)显著小于与亲代多个雌性个体共存下交配产生的F2代(P0.05);各龄期的平均发育历期、平均产卵前期和平均总产卵前期2个繁殖力参数以及净生殖率(R0)、平均世代周期(T)2个种群参数,前者则比后者长(P0.05);另周限增长率(λ)两者之间无显著差异。研究表明西花蓟马在孤雌产雄状态下仍然可以在短期建立种群,具有较强的抗高温能力和繁殖能力,为其成功入侵奠定了生态学基础。     

西藏色季拉山急尖长苞冷杉林枯枝落叶及苔藓层的生物量与持水性能

急尖长苞冷杉原始林作为藏东南森林群落的主体之一,具有重要的水源涵养和水土保持的作用。对西藏色季拉山东坡不同坡向的急尖长苞冷杉原始林下苔藓与枯枝落叶层贮量和持水量进行了试验研究。结果表明：阴坡的苔藓厚度大于阳坡,阴坡的厚度12.1-15.3 cm,阳坡仅4.5-8.3 cm,阴坡苔藓的厚度是阳坡的1.5-3.4倍,阴坡苔藓的贮量7.127×10^4kg/hm^2远大于阳坡的2.285×10^4kg/hm^2,阴坡是阳坡的3.1倍。而最大持水量以阴坡的枯枝落叶层为最大,为1 556.7 kg/hm^2,阳坡为1 177.3 kg/hm^2。枯枝落叶层持水性能优于苔藓,说明枯枝落叶层在森林的水源涵养方面发挥了更为重要的作用。同时,人为活动少的原始天然林系统的功能是完整且巨大的,更进一步说明加强原始天然林的保护是保存原始生态系统的必需。     

濒危黑颈长尾雉圈养种群的RAPD遗传多样性分析

运用RAPD技术对黑颈长尾雉圈养种群的遗传多样性进行了分析。从50条随机引物中筛选出14条引物,对24个个体的基因组DNA进行了PCR扩增,从检测出的119个位点中有98个多态位点,占总位点的82．35％,标记的分子量大小范围是0．2～3kb。24个个体问的遗传距离幅度0．1597～0．4874,平均是0．2810;用软件NTsys2．10e构建了24个个体相互关系的分支图,24个个体可分为3个类群。实验表明：黑颈长尾雉圈养种群的遗传多样性水平较高,圈养种群内遗传差异性较大。     

尖孢镰刀菌碳化硅量子点标记及其长时程荧光成像

致病性尖孢镰刀菌（Fusarium oxysporum）的荧光标记与活体细胞的长时程荧光成像示踪是研究其侵染机制较为有效的方法之一。采用化学腐蚀法制备出SiC量子点标记材料,研究了化学腐蚀法制备工艺过程,对SiC量子点标记材料的微观结构及光学性能进行检测分析,而后对尖孢镰刀菌进行标记及长时程荧光成像,结果表明,SiC量子点具有良好的生物相容性及光学性能,发射光颜色与其尺寸有内在关联性,腐蚀过程中即可在表面形成多种亲有机物功能团。尖孢镰刀菌生长初期SiC量子点将标记在分生孢子细胞膜处,而后通过内吞作用,进入活体细胞内部并形成稳定标记。进一步研究发现,SiC量子点无细胞毒性,可以实现活体细胞的长时程荧光成像,同时对其标记特征及原理进行了初步分析讨论。这对于尖孢镰刀菌侵染致病过程组织学与细胞学特征研究,揭示其致病机理、发展新型植株枯萎防治方法提供直观依据和理论分析基础。     

基于ICP—AES的濒危植物长序榆的元素分布及其与土壤因子的关系

采用ICP-AES法测定了九龙山自然保护区(JL1,JL2,JL3)3个代表性样地长序榆根、茎、皮、叶内的金属元素含量,并与土壤中对应的金属元素含量及肥力因素进行了相关性研究。结果表明:(1)大部分金属元素虽然在群落间存在一定的差异,但差异没有达到显著水平;Mn元素在群落之间却存在显著差异。(2)长序榆不同器官元素含量存在一定差异,各元素在不同器官中的变化趋势和变异程度呈现不一致现象。(3)长序榆植物体内11中元素中,两两之间存在极显著的正相关有Mg,Mn和Mo 3种元素;Fe和Cr之间、Sb和Mn,Cr之间、Ca和Th均存在极显著的正相关;其他元素之间存在一定的相关性。Ca和Th均有很大的富集系数,且两者之间存在极显著的正相关,说明长序榆对Ca和Th的吸收具有特殊性。(4)Mg和Mn这两种元素相对于植物体内的其他元素和土壤各元素间相关性显著;长序榆植物体元素含量与土壤中的肥力因素的相互关系并无明显一致的规律,说明不同群落内长序榆元素含量的差异并不是主要由土壤中肥力因素决定的,而是其它生境因子综合影响的结果。     

甘肃鼢鼠的生命表和种群动态分析

根据５１５只甘肃鼢鼠的年龄分布和性比,编制了甘肃鼢鼠种群的静态生命表,绘制了死亡曲线和存活曲线图,计算了甘肃鼢鼠种群的内禀增长能力,结果是;甘肃鼢鼠种群的净增殖率Ｒ０＝１．８０７５,内禀增长能力ｒｍ＝０．４０５６,种群数量的翻倍时间大约为２０个月,周限增长率λ＝１．００２３。以上数据表示,甘肃鼢鼠是一个增长速度缓慢,数量相对稳定的动物种群,这对防治比较有利。     

Population viability and species interactions: Life outside the single-species vacuum

Population viability analysis (PVA) has become a widely used set of tools for evaluating relative extinction risk and prioritizing management options among imperiled populations. While PVA is a widely sanctioned tool in conservation biology, the field of population viability is in its infancy with respect to species interactions. In this paper, I review available methods for evaluating extinction risk when species interactions contribute significantly to population viability. This review includes an evaluation of six broad categories of species interactions (predation, disease, competition, mutualism, parasitism and host-parasitoid interactions) in population viability analysis, with a particular focus on predation as a case study. I first evaluated how often species interactions are considered when PVA is applied to population data from imperiled species. I identified 378 articles in commonly cited conservation journals, of which 24 attempted a viability analysis for populations threatened by interactions with other species. Most of these PVA’s treat a putative species interaction as a constant source of mortality rather than a coupled, dynamic population process. Second, I reviewed the literature to identify the availability of time-series of abundance data for two interacting species in which at least one species was threatened or endangered. Adequate time-series data were available for both species comprising an interacting pair in only 9 out of 407 papers reviewed. Third, I used a stochastic, fully stage-structured predator prey model to create time-series data (vital rates and projection matrices) in order to quantify the efficacy of two matrix-based, single-species PVA approaches. Simple single-species PVAs confound stochastic variation with population cycles induced by species interactions (in this case predation). As a result these models provide conservatively biased forecasts of viability. Unfortunately, the data needed to construct more complex PVA’s with feedback and multi-species stochasticity are rarely collected. I close with a discussion of key advances needed to “escape the population vacuum” in a move toward more realistic estimates of extinction risk.     

Model Analysis of Corn Response to Applied Nitrogen and Plant Population Density

Abstract

The extended logistic model relates seasonal dry matter and plant nutrient uptake to applied nutrient level. It has been shown to apply to data for annuals such as corn (Zea mays L.) and perennials such as bermudagrass (Cynodon dactylon L.) and bahiagrass (Paspalum notatum Flügge). The linear parameters in the model have been shown to depend on water availability and harvest interval (for perennials). Further work is needed to relate model parameters to plant characteristics. In this article, data from a field experiment with corn at six nitrogen levels (0, 0.5, 1.0, 2.0, 3.0, and 5.0 g N plant^?1) and three plant population densities (3, 6, and 9 plants m^?2; 3, 6, and 9 10⁴ plants ha^?1) are used to provide insight into this question. It turns out that all five model parameters are dependent on plant density, approaching maximum values at 8.3 plants m^?2. Three of the parameters approach zero as density approaches zero, which seems intuitively correct. It is concluded that lower and upper limits of plant nitrogen concentration are independent of population density and are functions of the particular plant species. Detailed procedures are described for estimation of model parameters.     

Responses of a Widespread Weed and an Endangered Congeneric Plant to Potassium

Acid rain is leading to soil potassium (K) loss. A hydroponic experiment was conducted to determine the growth and physiological and stoichiometrical traits of Mosla hangchowensis (an endangered plant) and M. scabra (a weed) in response to three K concentrations. For M. hangchowensis, compared with standard Knop's solution (K₃), low K (K₀) induced reductions in net photosynthetic rate, soluble protein content, superoxide dismutase activity, total biomass, tissue K concentration, and leaf nitrogen (N) concentration and induced increases in malondialdehyde content and tissue sodium (Na) concentration (P < 0.05). In contrast, none of these factors were affected by K₀ for M. scabra. Critical values of N/K and K/P (phosphorus) ratios in shoots indicated that limitation in K uptake occurred for M. hangchowensis but not M. scabra under K₀. The continuing decline of K content due to acid rain may worsen the situation of M. hangchowensis, whereas M. scabra can maintain vigorous growth and develop well in the future.     

烟台市人口分析及预测

利用时间序列分析模型和GM(1,1)模型拟合了烟台市人口数量,并对未来4年烟台市人口进行了预测.结果显示,二次滑动平均模型的相对误差波动范围为-0.731%～0.70%,均接近于0,预测精度最高.利用二次滑动平均模型预测未来4年烟台市人口分别为646.395万人、646.445万人、646.495万人和646.545万人,人口有逐年缓慢上升的趋势.     

Analysis of Variance of Integro-Differential Equations with Application to Population Dynamics of Cotton Aphids

The population dynamics of cotton aphids is usually described by mechanistic models, in the form of integro-differential equations (IDEs), with the IDE parameters representing some key properties of the dynamics. Investigation of treatment effects on the population dynamics of cotton aphids is a central issue in developing successful chemical and biological controls for cotton aphids. Motivated by this important agricultural problem, we propose a framework of analysis of variance (ANOVA) of IDEs. The main challenge in estimating the IDE-based ANOVA model is that IDEs usually have no analytic solution, and repeatedly solving IDEs numerically leads to a high computational cost. We propose a penalized spline method in which spline functions are used to estimate the IDE solutions and the penalty function is defined by the IDEs. The estimated IDE solutions, as implicit functions of the parameters, are inputs in a nonlinear least squares criterion, which in turn is minimized by a Gauss–Newton algorithm. The proposed method is illustrated using simulation and an observed cotton aphid data set.     

Exposure to SO2 and water stress in Picea Abies (L.) Karsten

The purpose of this research was to analyze the responses of Norway spruce Picea abies (L.) Karsten to SO₂, at a subnecrotic concentration (230 μg SO₂ m^?3 ), and to water stress using seedlings and 5 yr-old plants. In a first period, the plants were exposed to SO₂ for 6 weeks; then they were simultaneously exposed to SO₂ and to water stress for 1 week for the case of seedlings and 2 weeks for the 5 yr-old plants. The plants were then rewatered, but maintained under exposure to SO₂. Their morphological and physiological characteristics were analyzed and compared to non-SO₂ exposed plants. It was shown that there were no differences between SO₂ exposed and non-exposed irrigated plants, specifically water content and water potential were not altered. After water stress the non-SO₂ exposed seedlings and plants showed good revival upon rewatering. In contrast, the two simultaneous stresses were very damaging to the plants. Despite a better initial recovery upon rewatering, 50% of the continuously SO₂ exposed plants died and, after 5 weeks of rewatering, the remainder showed altered water content and water potential. These results are discussed.     

基于RIL群体的玉米纹枯病抗性QTL分析

利用包含339个家系的重组自交系(RIL)群体为定位群体,构建包含133个SSR标记的遗传连锁图谱,覆盖玉米基因组1658cM,标记平均距离为12.56cM.分别于2008年四川雅安和2009年四川雅安、绵阳和重庆3地,采用麦粒嵌入法人工接茵,于接茵后15d调查以上4点各个家系的病斑高和稳位高,接茵后40天对重庆和绵阳再进行第2次调查,并计算相应各时间段和各地点的病情指数.研究结果共检测到基于病斑高的抗性相关QTL 7个,分别位于6、8、9和10染色体上,平均加性效应和贡献率分别为1.61％和4.52％;检测到基于病情指数的抗性相关QTL 11个,分别位于2、4、5、8和9染色体上,加性效应和可解释表型方差大小分别在0.0165～0.0545和2.81％～7.29％之间.其中,利用病情指数和病斑高在标记区间bnlg1583-dupssr06和bnlg 1714-umc2343共同检测到了抗性相关QTL.以上结果为今后开展玉米抗纹枯病的精细定位和分子标记辅助育种奠定了一定的理论和材料基础.