不同烟草品种对云南烟草野火病菌的抗性鉴定*

 采用采自云南省不同地点、不同生理小种的24株烟草野火病菌对24个不同烟草品种及两个野生种黄花烟和长花烟进行抗病性鉴定分析。结果表明,不同抗性品种对不同生理小种的抗性反应差异显著,根据接种后不同烟草品种的形成的病斑直径,将其划分为4个等级：高抗、中抗、中感、高感。辽烟15,G28对于烟草野火病菌0,1号生理小种均表现为高感,而云南省大面积栽培的K326、红花大金元、云烟87等对于两个生理小种均表现为中感,而两个野生种黄花烟和长花烟均表现为高抗,可以作为烟草野火病抗性育种优先利用的种质资源。     

防治烟草野火病拮抗细菌菌株的筛选

从多种植株根际土壤中和烟草叶面分离到188个细菌分离物,室内抑菌圈法测定抑菌效果,温室测定防效,结果筛选出有明显抑菌作用的菌株21个,温室采用高压喷雾接种烟草野火病菌株,普通喷雾接种生防菌菌株,建立了以病斑减轻率和病斑扩展抑制率2个指标的活体筛选方法,温室防效试验筛选出防效较好的菌株6个,其中2e,1010D防效较好,其次为C3和3g。病斑减轻率为58％～91％,病斑扩展抑制率为56．58％～78．08％。这为生产上防治烟草野火病提供了新思路。     

论野火的三属性

野火泛指发生于野外植被中的火、归纳发现有３个基本属性,自然性,灾害性和工具性,对这３个属性进行明确的定义和认识,有助于理解野火的意义,为研究和生产奠定科学系统的理论基础。自然属性一是指其自然存在、二是指其对自然界有影响,三是指其他受其他自然因子制约。灾是自然界不可控事件造成的超越一定程度界线的损失。灾害属性即经济属性。每一次火都造成巨大的经济损失,包括林资源和草资源预防和扑救开始。工具是指可以拿来     

关于使用 Pro/Engineer wildfire软件设计三维机械零件的几点技巧在教学中的探讨

本文对使用Pro/Engineer Wildfire 软件设计三维机械零件在教学中遇到的若干问题作了深入细致的分析,并提出了相应的解决技巧.     

Effects of ground fires on understorey bird assemblages in Amazonian forests

Avifaunal responses to understorey fire disturbance and subsequent changes in habitat structure were examined within 20 burnt and unburnt forest plots of 0.25 ha (10×250 m), 10-15 months after an unprecedented understorey fire swept through the Tapajós-Arapiuns Extractive Reserve of central Brazilian Amazonia following the severe 1997-1998 El-Niño dry season. Although these surface fires in the previously undisturbed primary forest were relatively mild, they resulted in dramatic changes in forest structure consistent with those found elsewhere in Amazonia. Bird species negatively affected by these changes tended to be the least common, the most disturbance-sensitive, and habitat specialists. Considering different guilds, ant followers, dead-leaf gleaners, terrestrial gleaners, and arboreal sallying insectivores were the most negatively affected, whereas nectivores and arboreal granivores became more abundant in the burnt forest. The results highlight the severe consequences of even relatively mild surface fires in neotropical forests, and the importance of controlling haphazard frontier expansion for the conservation of susceptible species that are endemic to fire-prone regions.     

烟草野火病菌初侵染源的研究

为探明烟草野火病菌的初侵染源，应用SPA－ELISA，间接－ELISA反应试剂盒对从田间及温室中采集的土壤、烟株根围、田间杂草、种子等进行了检测，明确云南烟草野火病的初侵染源主要为种子和根部残体。     

烟草野火病“天气促病指数”表解模型的建立

在对野火病各流行环节定量研究的基础上，提出了可以进行烟草野火病短期预测的“天气促病指数表解模型”。这种模型是建立在对植物病原细菌从植物体内经雨露浸出到植物体表，再进一步侵染新的寄主植物健康部位这一过程的逼真模拟基础上，所以它具有机理模型的特点和优点，这种模型虽不能进行数值预测，但可以进行较为的病情发展趋势，而且不需要计算机，只要查表就可以进行预测的有关运算，是一种较有应用潜力的模型。     

防治烟草野火病的药剂筛选及应用研究

为较好地防治烟草野火病，选用6种药剂对烟草野火病菌进行抑菌试验，筛选出2种效果较好的药剂，即新植霉素和农用链霉素，同时，通过对不同地区来源的烟草野火病菌的抑菌试验，发现云南部分地区的烟草野火病菌对农用链霉素具有抗药性。     

Landscape characteristics of disturbed shrubsteppe habitats in southwestern Idaho (U.S.A.)

We compared 5 zones in shrubsteppe habitats of southwestern Idaho to determine the effect of differing disturbance combinations on landscapes that once shared historically similar disturbance regimes. The primary consequence of agriculture, wildfires, and extensive fires ignited by the military during training activities was loss of native shrubs from the landscape. Agriculture created large square blocks on the landscape, and the landscape contained fewer small patches and more large shrub patches than non-agricultural areas. In contrast, fires left a more fragmented landscape. Repeated fires did not change the distribution of patch sizes, but decreased the total area of remaining shrublands and increased the distance between remaining shrub patches that provide seed sources. Military training with tracked vehicles was associated with a landscape characterized by small, closely spaced, shrub patches.Our results support the general model hypothesized for conversion of shrublands to annual grasslands by disturbance. Larger shrub patches in our region, historically resistant to fire spread and large-scale fires because of a perennial bunchgrass understory, were more fragmented than small patches. Presence of cheatgrass (Bromus tectorum), an exotic annual, was positively related to landscape patchiness and negatively related to number of shrub cells. Thus, cheatgrass dominance can contribute to further fragmentation and loss of the shrub patch by facilitating spread of subsequent fires, carried by continuous fuels, through the patch. The synergistic processes of fragmentation of shrub patches by disturbance, invasion and subsequent dominance by exotic annuals, and fire are converting shrubsteppe in southwestern Idaho to a new state dominated by exotic annual grasslands and high fire frequencies.     

Introduction: Working Forests in the Tropics: Policy and Market Impacts on Conservation and Management

Abstract

Tropical forests are very rich in biological diversity and form an important economic and ecological resource. This biodiversity is of great value for communities living in or near these forests as a ready source of subsistence and cash income, and for the world at large as a source of tropical timber and non-timber products and a repository of genetic and chemical information. However, this biological complexity is diminishing rapidly. We analyze the main human (anthropogenic) actions causing loss of tropical forest biodiversity along with the strategies of management for forest biodiversity. Not only is the biophysical component important in management for biodiversity, but the active participation and support of local people, national governments, and the international community as a whole are essential to effective and sustainable development of tropical forests. This development strategy ensures that socioeconomic and environmental benefits are provided for present and future generations.