FEULGEN MICROSPECTROPHOTOMETRIC INVESTIGATION OF THE LIFE HISTORY OF FRITSCHIELLA TUBEROSA(CHLOROPHYCEAE)1

A Feulgen microspectrophotometric analysis of successive generations of Fritschiella tuberosa Iyengar revealed an asexual repeating of one generation rather than an obligate alternation of isomorphic generations as previously described. F. tuberosa regularly reproduces asexually by the release of one quadriflagellate zoospore produced/cell in all parts of the upright and prostrate portions of the thallus. In the vegetative thalli, nuclei in the G₁ (pre-synthesis), synthesis, and G₂ (post-synthesis) phases of the mitotic cycle are all well-represented.     

STUDIES ON THE BIOGEOGRAPHY AND ECOLOGY OF THE FRESHWATER PHAEOPHYCEAN ALGA HERIBAUDIELLA FLUVIATILIS1

A biogeographical survey of the freshwater brown alga Heribaudiella fluviatilis (Areschoug) Svedelius was conducted in southern British Columbia (Canada) and northern Washington (U.S.A.). Surveys of 121 reaches on streams and rivers revealed 25 populations, including the first record for the U.S.A. A strongly noncoastal distribution provides no evidence of a marine-based source for its distribution in the region. Streams with Heribaudiella typically have a: current velocity greater than 1.0 m · s^?1; rocky substrata; range of width from 1.7–60 m; broad range of Ca concentration; and, ranged from heavily shaded to fully open location. Although once thought rare in North America, it was fairly widespread in the region and often abundant within a given sampling site. Biogeographic and ecological data suggest that Heribaudiella may be a common, but often overlooked, component of the flora of rivers.     

陆地生态系统碳密度格局研究概述

 准确了解陆地生态系统中碳密度的时空格局及其影响因子和作用机制,对于估算和预测不同类型生态系统中的植被和土壤的碳存储能力、判定碳汇、制定缓解全球变化的合理政策措施,具有重要意义。该文综述了现有研究中发现的世界陆地生态系统碳密度空间分布的地带性规律及中国陆地生态系统碳密度格局的独特特点。在全球尺度上,植被碳密度分布与植物生物量格局基本一致,除北方森林外其余大部分随纬度升高而减小;土壤碳密度则随纬度升高而增大。陆地生态系统中北方森林和热带森林的总体碳密度最高,不同的是,前者的碳主要集中在土壤中,而后者则集中在植被中。但在区域尺度上,由于气候、地形及人类活动影响,这种规律性可能会发生变化甚至不起作用。水热条件、土壤养分、生物多样性、气候和大气CO2浓度的变化以及土地利用与覆盖变化等是碳密度空间格局形成和发生变化的驱动因子。在某一特定区域,它们通过直接或间接提高植被净初级生产力,抑制呼吸和分解作用来增加陆地生态系统碳密度。综合分析特定时空条件下各因子对碳存储量的影响是解释碳密度分布现状,预测碳密度格局变化的关键,但目前的研究对各项驱动因子的作用机制、影响强度及多个因子间的相互作用仍不是很清楚,需要加强该方面的研究力度。碳密度研究中的数据获取、机理分析和过程模拟等方面仍存在很大的不确定性,因此有必要建立规范统一的碳密度测量估算系统和更为精准有效的估算模型,进行多尺度、多精度水平的综合研究。     

华南地区淡水水鳖科植物的生态特征和群落学观察

本文讨论了华南地区淡水水鳖科植物的生活条件、水生生态的适应特点,研究了该科植物水白菜、水菜花、水筛、黑藻、苦草、大苦草、软骨草等植物所组成群落的群落学特征。     

成都蚊虫种类及生态调查报告

关于成都的蚊虫种类,Legendre(1908)、Best(1932)、Crook(1939)、孟庆华(1943)及徐国清(1948)曾作过一些初步调查,共查出9种蚊虫。为配合流行性乙型脑炎的研究,作者等又进行了此项工作。