内蒙古多伦县蔡木山保护区的保护价值和有效管理途径

内蒙古多伦县蔡木山保护区地处森林向草原过渡的一个十分特殊的区域,所在地为滦河水系上游各支流的发源地。它位于浑善达克沙地的南缘,生态系统类型多种多样。它的管理好坏与京津地区的生态安全有密切的关系,所以,必需加强其生物多样性的保护和持续利用。本文在于简要介绍它的基本特点和有效管理途径,提出一些建议,供有关方面参考。     

长白落叶松人工林林隙间伐对林下更新及植物多样性的影响

2009年7月中旬,以佳木斯孟家岗林场间伐8年后的34年生长白落叶松人工纯林为对象,分析均匀间伐、大林隙和小林隙的林下更新和植物多样性。结果表明:与均匀间伐相比,林隙内出现了树高超过1.5m的胡桃楸、山杨和春榆等喜光阔叶树种,大林隙中出现树高超过2m的胡桃楸幼树;林隙内更新树种的个体密度、平均高和平均地径明显增加,大林隙尤为显著(P<0.05);林隙内木本植物的Simpson多样性指数和盖度均显著高于均匀间伐(P<0.05);与小林隙相比,大林隙内木本和草本植物盖度均显著增加(P<0.05);木本植物竞争种的重要值表现为大林隙>小林隙>均匀间伐,耐胁迫种的重要值相反(P<0.05);大林隙内1年生草本植物的重要值显著高于小林隙和均匀间伐(P<0.05),多年生草本植物则相反(P<0.05);大林隙Grime'功能群中杂草种的重要值高于小林隙和均匀间伐,耐胁迫种则相反(P<0.05);小林隙与均匀间伐的草本植物不同生活型及Grime'功能群的组成差异不明显(P>0.05);林隙间伐结合均匀间伐可以将长白落叶松人工纯林改造成长白落叶松针阔混交异龄林,较单独实施均匀间伐更有利于林下更新和植物多样性的提高,间伐林隙应...     

Refinement of rooting depths using satellite-based evapotranspiration seasonality for ecosystem modeling in California

Accurate determination of rooting depths in terrestrial biosphere models is important for simulating terrestrial water and carbon cycles. In this study, we developed a method for optimizing rooting depth using satellite-based evapotranspiration (ET) seasonality and an ecosystem model by minimizing the differences between satellite-based and simulated ET. We then analyzed the impacts of rooting depth optimization on the simulated ET and gross primary production (GPP) seasonality in California, USA. First, we conducted a point-based evaluation of the methods against flux observations in California and tested the sensitivities of the simulated ET seasonality to the rooting depth settings. We then extended it spatially by estimating spatial patterns of rooting depth and analyzing the sensitivities of the simulated ET and GPP seasonalities to the rooting depth settings. We found large differences in the optimized and soil survey (STATSGO)-based rooting depths over the northern forest regions. In these regions, the deep rooting depths (>3 m) estimated in the study successfully reproduced the satellite-based ET seasonality, which peaks in summer, whereas the STATSGO-based rooting depth (<1.5 m) failed to sustain a high ET in summer. The rooting depth refinement also has large effects on simulated GPP; the annual GPP in these regions is increased by 50–100% due to sufficient soil water during the summer. In the grassy and shrubby regions of central and southern California, the estimated rooting depths are similar to those of STATSGO, probably due to the shallow rooting depth in these ecosystems. Our analysis suggests that setting a rooting depth is important for terrestrial ecosystem modeling and that satellite-based data could help both to estimate the spatial variability of rooting depths and to improve water and carbon cycle modeling.     

A short discussion on the chemical composition of allophane based on the data of Yoshinaga in 1966

Many scientists have attempted to discern the chemical composition and the structure of allophane (2, 4–6). Yoshinaga (7) presented the chemical composition of eighteen samples of pure allophane in detail, and concluded as follows: All samples consisted principally of silica, alumina, and water. The silica-alumina molecular ratio ranged from about 1.3 to 2. Molecular ratios of ignition loss (+H₂0) and total water (±H₂O) to alumina were nearly constant, with the averages about 2.5 and 5.7, respectively. The chemical composition of soil allophane fell into a relatively narrow range, and the change in the percentage composition of the three major elements had a regularity.     

黄泛区潮土-冬小麦系统中尿素的转化和化肥氮去向

在田间条件下,用~(15)N标记的微区试验法研究了潮土-冬小麦系统中尿素的转化和化肥氮的去向。结果表明:土壤中尿素水解后,主要进行硝化和生物固定,而被粘土矿物固定的量很少;小麦返青后,随着气温上升,生物固定的标记氮不断分解,其量可达总生物固定量的60％。作为基肥条施的尿素,其损失略高于作返青肥或拔节肥表施后随即灌水的处理。氮素损失主要发生在春季气温回升后的生长期间,当季的淋洗损失极微。在较为适宜的用量和施用技术下,化肥氮的损失仍达33—45％,其中以碳酸氢铵为最高,次为硫酸铵和硝酸铵,而尿素和硝酸铵中的硝态氮损失最低。     

岷江上游退化森林生态系统的恢复与重建

岷江上游区内广漠的森林,本是岷江流域得天独厚的大自然保护屏障,然而这些林地多分布在高山峡谷坡面上,由于长期过伐,森林的蓄水保水性能降低,生物多样性遭到破坏,自然灾害频繁,泥石流、滑坡增加,荒漠化面积不断扩大。概述了岷江上游退化森林生态系统的主要特征和现状,提出了恢复与重建的建议。     

丝状真菌遗传转化系统研究进展

近年来,丝状真菌的分子生物学研究发展非常迅速,尤其是丝状真菌遗传转化研究取得了长足的进展。对丝状真菌遗传转化系统的最新研究进展进行综述,主要包括丝状真菌的转化方法、选择标记、转化系统的应用等。     

试论森林生态系统是一类复杂适应性系统

介绍了复杂适应性系统理论产生的背景、概念和核心思想, 进而指出其在解决当代资源与环境问题以及生物、生态、经济、社会等复杂系统及复杂性管理中的开拓性意义; 从森林生态系统的特点出发, 说明其是一类复杂适应性系统, 指出该理论对于研究森林生态系统的复杂性与林业生态建设的重大意义。     

Construction and Development of the Dagangshan Forest Ecosystem Research Station

Established by the former Ministry of Forestry in 1986, Dagangshan Forest Ecosystem Research Station is one of the 14 national key sites in the field of ecosystem research. In this paper, the basic situation of Dagangshan Forest Ecosystem Station is described, including geographic location, natural conditions, biological resources, research conditions, instruments, achievement, prospects etc.     

抗虫相关基因KTI 对青花菜的转化及其对小菜蛾抗性的分析

 以青花菜（Brassica oleracea L. ssp. italica）下胚轴为外植体,通过农杆菌介导的遗传转化方 法将来源于杨树的Kunitz 型丝氨酸胰蛋白酶抑制剂（KTI）基因导入青花菜品系‘09LR-11’中,获得13 株卡那霉素抗性植株。以KTI 特异引物对转基因植株进行PCR 检测,其中8 株为KTI 阳性植株。Southern blot 分析进一步表明,基因KTI 已成功整合到青花菜基因组中。RT-PCR 检测表明,KTI 在转基因青花菜 中已成功表达。通过室内叶片离体试验和田间观察,初步证明转KTI 青花菜对小菜蛾幼虫具有一定抗性