How much variation in tree mortality is predicted by soil and topography in Central Amazonia?

Tree mortality in Amazonia has been related to regional variation in soil, topography and climatic disturbances, but the magnitude of the effect of these factors on tree mortality at local and mesoscales remains poorly determined. We investigated tree mortality in 72 1-ha permanent plots spanning 64 km² of tropical moist forest in Reserva Ducke, Manaus, Brazil. Plots were censused three times (2000-2003, 2003-2005, and 2005-2008), resulting in two census intervals. The relationships of soil and topography to tree mortality were dependent on tree size. Small- and medium-sized trees (1 ? dbh < 30 cm) had similar relationships of mortality with soil and topography, while large trees (dbh ? 30 cm) showed different (or no) relationships. The effects of soil and topography on tree mortality also varied temporally. In the second census interval after storms, soil and topography explained about one-fourth of the spatial variation in mortality of small- and medium-sized trees (<30 cm dbh), whereas no effects were detected in the first census interval. In particular, soil fertility was the most important predictor of tree mortality in the study area. Topography alone (altitude and slope) was associated with only 12% of the spatial variation in tree mortality and the magnitude of the effect of soil and topography on tree mortality also increased after storms. In general, plots on more fertile soils, on steep slopes and sandy soils in valleys showed greater tree mortality than those on plateau with well-drained clayey soils. Therefore, disturbance history and tree size should be included when scaling up tree mortality from local to regional scales. As much variation remains unexplained, other landscape features, such as watershed morphology and wind exposure, may be necessary to make more precise predictions on patterns of tree mortality in Central Amazonia.     

中性造纸施胶剂的研究

以苯乙烯、二甲基氨乙基甲基丙烯酸酯和松香为原料,合成阳离子型中性施胶剂。在第一报研究的基础上,以硫酸盐未漂白浆纸袋纸为对象,将合成的施胶剂与松香胶在施胶效果、絮凝效果及增强效果方面进行了比较,并探讨了该中性施胶剂在技术上的可行性和经济上的合理性。实验表明,该合成施胶剂的施胶效果大体与松香胶相同,且有明显的絮凝效果和增强效果。在添加0.5％时,可降低纤维流失率约2％。除撕裂度略有下降外,可使纸张强度指标提高20—30％。得到与同样用量松香胶施胶纸相同的强度指标,可降低定量约10％,或可配合40％的阔叶浆或可填充15％的碳酸钙。当叩解度低时,施胶度高。因此,若降低打浆度采用本施胶剂,既可保证强度又可提高施胶度。     

“城市意象”的概念逻辑关系

本文深入解析了"城市意象"中四组概念的逻辑关系,管窥蠡测的探视了该书的基本概念的内涵与外延,探讨了城市元素或系统本身和相互之间的矛盾和消融的关系。     

丹顶鹤早期生长发育规律的初步研究

对 6只幼鹤 (初生及 1～ 1 3周 )的体重、体尺和 9只成鹤的体尺进行测定 ,将幼鹤体重、体尺测定结果拟合生长曲线方程 ,并与成鹤的体尺指标进行比较。结果表明 :幼鹤早期生长发育阶段可划分为 3个时期 :第 1时期 (0～ 2周龄 )是快速生长期 ,第 2时期 (3～ 7周龄 )是急速生长期 ,第 3时期 (8～ 1 3周龄 )是缓慢生长期。Logistic生长曲线方程能很好地拟合丹顶鹤早期的生长发育 ,拟合精度 (R2 )均大于 0 .9955。幼鹤 1 3周龄时各项体尺指标均达到成鹤的 86%以上 ,并呈现出体长较体宽发育快的特点     

一类中立型微分方程的指数稳定性

利用微分差分不等式研究了一类多个变时滞变系数的中立型微分大系统的零解在度量空同C1中的全局指数稳定性.     

贵州烤烟常规化学成分与中性香气物质的相关分析

为了摸清贵州烟叶原料质量,提高其可用性,以贵州4个烤烟产区的33个烟叶样品为材料,采用多变量统计分析方法对其常规化学成分与中性香气物质含量的相关性进行分析。结果表明:贵州烤烟常规化学成分在不同地区间存在广泛的差异,但还原糖含量在地区间稳定性较好;常规化学成分和众多香气成分都存在密切相关,其相关系数达到极显著或显著水平;常规化学成分与中性香气物质之间的第Ⅰ典型相关系数(0.911**)达极显著水平,共得到6个与典型变量相关显著的性状,分别为烟碱、钾、美拉德反应产物、芳香族氨酸降解产物含量、糖碱比和氮碱比。     

从杂合子适合度取值范围看自然选择单位的4种学说的内在统一

[目的]探讨关于自然选择单位的4种学说的内在联系。[方法]建立数学模型,探讨适合度的随机交配群体两种基因频率在后代的变化规律。[结果]根据研究中建立的数学模型,发现突变基因必须在纯和杂2方面都满足自然选择的要求,而且能在杂合状态下表现出高适合度,才更容易被保留下来,这就兼顾到个体的适应与集体的适应。[结论]该研究结果显示关于自然选择单位的4种学说是可共存的,彼此间分享了一个共同的前提。     

关于自然选择单位的四种学说的内在统一(英文)

[目的]探讨关于自然选择单位的4种学说的内在联系。[方法]通过建立数学模型,探讨遗传群体杂合子适合度取值范围,阐明自然选择单位的4种学说的内在联系。[结果]根据研究中建立的数学模型,发现突变基因必须在纯和杂2方面都满足自然选择的要求,而且能在杂合状态下表现出高适合度,才更容易被保留下来,这就兼顾到个体的适应与集体的适应。从而在理论上统一了个体选择,集体选择,基因选择及木村资生的中性学说。[结论]该研究结果显示关于自然选择单位的4种学说是可共存的,彼此间分享了一个共同的前提。     

马尾松高产脂种子园嫁接技术

以广西藤县马尾松高产脂种子园为研究对象,对嫁接成活率及生长量的影响因子进行研究。结果表明:①嫁接人员的技术熟练程度和采穗母树的年龄是决定嫁接成活率和生长量的关键。②嫁接宜采用穗条全包保湿的方法,坡向对嫁接成活率影响不大。③无性系嫁接成活率及生长量与采穗母树的年龄呈极显著负相关,而与产脂力呈正相关,但与无性系母树来源地、母树年龄和大小没有相关性。④无性系生长量和其内部变异系数皆较大,且与无性系相关。     

Pod Dehiscence in Relation to Chemical Components of Pod Shell in Soybean

Abstract

The relationship between chemical components of pod shell and pod dehiscence was investigated using 25 soybean cultivars; 16 with easily dehiscing pods (susceptible cultivars) and 9 with hardly dehiscing pods (resistant cultivars). After air-drying for about three weeks, the pod shells were ground and analyzed for the contents of neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), hemi-cellulose (HCe), cellulose (Ce), uronic acid and calcium. The correlation of the contents of chemical components with the percentage of pod dehiscence (%PD) was examined by principal component analysis. The first principal ingredient score was given by the formula; score = – 0.421[ADF] – 0.038[ADL] + 0.821[HCe] – 0.382[Ce] + 20.556, where, [ADF], [ADL], [HCe] and [Ce] are percentage of each component in dried pod shell. This score gave an eigenvalue of 30.2 and contribution rate of 97.1%, and the score was higher in the susceptible cultivars than in the resistant cultivars on the average. The multiple regression analysis of the relationship between %PD and the content of chemical components also showed that %PD was best predicted by the regression equation with two chemical components, [HCe] and [Ce]. Water retention capacity and cellulose crystallinity of the pod shell were less different between the susceptible and resistant cultivars. The results in this study suggested that the chemical analysis of dry pod shell may provide useful information on breeding and selection of the resistant cultivars.